text: /*!
   * Vue.js v2.3.0
   * (c) 2014-2021 Evan You
   * Released under the MIT License.
   */
  (function (global, factory) {
  	typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
  	typeof define === 'function' && define.amd ? define(factory) :
  	(global.Vue = factory());
  }(this, (function () { 'use strict';
  
  /*  */
  
  // these helpers produces better vm code in JS engines due to their
  // explicitness and function inlining
  function isUndef (v) {
    return v === undefined || v === null
  }
  
  function isDef (v) {
    return v !== undefined && v !== null
  }
  
  function isTrue (v) {
    return v === true
  }
  
  /**
   * Check if value is primitive
   */
  function isPrimitive (value) {
    return typeof value === 'string' || typeof value === 'number'
  }
  
  /**
   * Quick object check - this is primarily used to tell
   * Objects from primitive values when we know the value
   * is a JSON-compliant type.
   */
  function isObject (obj) {
    return obj !== null && typeof obj === 'object'
  }
  
  var toString = Object.prototype.toString;
  
  /**
   * Strict object type check. Only returns true
   * for plain JavaScript objects.
   */
  function isPlainObject (obj) {
    return toString.call(obj) === '[object Object]'
  }
  
  function isRegExp (v) {
    return toString.call(v) === '[object RegExp]'
  }
  
  /**
   * Convert a value to a string that is actually rendered.
   */
  function _toString (val) {
    return val == null
      ? ''
      : typeof val === 'object'
        ? JSON.stringify(val, null, 2)
        : String(val)
  }
  
  /**
   * Convert a input value to a number for persistence.
   * If the conversion fails, return original string.
   */
  function toNumber (val) {
    var n = parseFloat(val);
    return isNaN(n) ? val : n
  }
  
  /**
   * Make a map and return a function for checking if a key
   * is in that map.
   */
  function makeMap (
    str,
    expectsLowerCase
  ) {
    var map = Object.create(null);
    var list = str.split(',');
    for (var i = 0; i < list.length; i++) {
      map[list[i]] = true;
    }
    return expectsLowerCase
      ? function (val) { return map[val.toLowerCase()]; }
      : function (val) { return map[val]; }
  }
  
  /**
   * Check if a tag is a built-in tag.
   */
  var isBuiltInTag = makeMap('slot,component', true);
  
  /**
   * Remove an item from an array
   */
  function remove (arr, item) {
    if (arr.length) {
      var index = arr.indexOf(item);
      if (index > -1) {
        return arr.splice(index, 1)
      }
    }
  }
  
  /**
   * Check whether the object has the property.
   */
  var hasOwnProperty = Object.prototype.hasOwnProperty;
  function hasOwn (obj, key) {
    return hasOwnProperty.call(obj, key)
  }
  
  /**
   * Create a cached version of a pure function.
   */
  function cached (fn) {
    var cache = Object.create(null);
    return (function cachedFn (str) {
      var hit = cache[str];
      return hit || (cache[str] = fn(str))
    })
  }
  
  /**
   * Camelize a hyphen-delimited string.
   */
  var camelizeRE = /-(\w)/g;
  var camelize = cached(function (str) {
    return str.replace(camelizeRE, function (_, c) { return c ? c.toUpperCase() : ''; })
  });
  
  /**
   * Capitalize a string.
   */
  var capitalize = cached(function (str) {
    return str.charAt(0).toUpperCase() + str.slice(1)
  });
  
  /**
   * Hyphenate a camelCase string.
   */
  var hyphenateRE = /([^-])([A-Z])/g;
  var hyphenate = cached(function (str) {
    return str
      .replace(hyphenateRE, '$1-$2')
      .replace(hyphenateRE, '$1-$2')
      .toLowerCase()
  });
  
  /**
   * Simple bind, faster than native
   */
  function bind (fn, ctx) {
    function boundFn (a) {
      var l = arguments.length;
      return l
        ? l > 1
          ? fn.apply(ctx, arguments)
          : fn.call(ctx, a)
        : fn.call(ctx)
    }
    // record original fn length
    boundFn._length = fn.length;
    return boundFn
  }
  
  /**
   * Convert an Array-like object to a real Array.
   */
  function toArray (list, start) {
    start = start || 0;
    var i = list.length - start;
    var ret = new Array(i);
    while (i--) {
      ret[i] = list[i + start];
    }
    return ret
  }
  
  /**
   * Mix properties into target object.
   */
  function extend (to, _from) {
    for (var key in _from) {
      to[key] = _from[key];
    }
    return to
  }
  
  /**
   * Merge an Array of Objects into a single Object.
   */
  function toObject (arr) {
    var res = {};
    for (var i = 0; i < arr.length; i++) {
      if (arr[i]) {
        extend(res, arr[i]);
      }
    }
    return res
  }
  
  /**
   * Perform no operation.
   */
  function noop () {}
  
  /**
   * Always return false.
   */
  var no = function () { return false; };
  
  /**
   * Return same value
   */
  var identity = function (_) { return _; };
  
  /**
   * Generate a static keys string from compiler modules.
   */
  function genStaticKeys (modules) {
    return modules.reduce(function (keys, m) {
      return keys.concat(m.staticKeys || [])
    }, []).join(',')
  }
  
  /**
   * Check if two values are loosely equal - that is,
   * if they are plain objects, do they have the same shape?
   */
  function looseEqual (a, b) {
    var isObjectA = isObject(a);
    var isObjectB = isObject(b);
    if (isObjectA && isObjectB) {
      try {
        return JSON.stringify(a) === JSON.stringify(b)
      } catch (e) {
        // possible circular reference
        return a === b
      }
    } else if (!isObjectA && !isObjectB) {
      return String(a) === String(b)
    } else {
      return false
    }
  }
  
  function looseIndexOf (arr, val) {
    for (var i = 0; i < arr.length; i++) {
      if (looseEqual(arr[i], val)) { return i }
    }
    return -1
  }
  
  /**
   * Ensure a function is called only once.
   */
  function once (fn) {
    var called = false;
    return function () {
      if (!called) {
        called = true;
        fn.apply(this, arguments);
      }
    }
  }
  
  var SSR_ATTR = 'data-server-rendered';
  
  var ASSET_TYPES = [
    'component',
    'directive',
    'filter'
  ];
  
  var LIFECYCLE_HOOKS = [
    'beforeCreate',
    'created',
    'beforeMount',
    'mounted',
    'beforeUpdate',
    'updated',
    'beforeDestroy',
    'destroyed',
    'activated',
    'deactivated'
  ];
  
  /*  */
  
  var config = ({
    /**
     * Option merge strategies (used in core/util/options)
     */
    optionMergeStrategies: Object.create(null),
  
    /**
     * Whether to suppress warnings.
     */
    silent: false,
  
    /**
     * Show production mode tip message on boot?
     */
    productionTip: "development" !== 'production',
  
    /**
     * Whether to enable devtools
     */
    devtools: "development" !== 'production',
  
    /**
     * Whether to record perf
     */
    performance: false,
  
    /**
     * Error handler for watcher errors
     */
    errorHandler: null,
  
    /**
     * Ignore certain custom elements
     */
    ignoredElements: [],
  
    /**
     * Custom user key aliases for v-on
     */
    keyCodes: Object.create(null),
  
    /**
     * Check if a tag is reserved so that it cannot be registered as a
     * component. This is platform-dependent and may be overwritten.
     */
    isReservedTag: no,
  
    /**
     * Check if an attribute is reserved so that it cannot be used as a component
     * prop. This is platform-dependent and may be overwritten.
     */
    isReservedAttr: no,
  
    /**
     * Check if a tag is an unknown element.
     * Platform-dependent.
     */
    isUnknownElement: no,
  
    /**
     * Get the namespace of an element
     */
    getTagNamespace: noop,
  
    /**
     * Parse the real tag name for the specific platform.
     */
    parsePlatformTagName: identity,
  
    /**
     * Check if an attribute must be bound using property, e.g. value
     * Platform-dependent.
     */
    mustUseProp: no,
  
    /**
     * Exposed for legacy reasons
     */
    _lifecycleHooks: LIFECYCLE_HOOKS
  });
  
  /*  */
  
  var emptyObject = Object.freeze({});
  
  /**
   * Check if a string starts with $ or _
   */
  function isReserved (str) {
    var c = (str + '').charCodeAt(0);
    return c === 0x24 || c === 0x5F
  }
  
  /**
   * Define a property.
   */
  function def (obj, key, val, enumerable) {
    Object.defineProperty(obj, key, {
      value: val,
      enumerable: !!enumerable,
      writable: true,
      configurable: true
    });
  }
  
  /**
   * Parse simple path.
   */
  var bailRE = /[^\w.$]/;
  function parsePath (path) {
    if (bailRE.test(path)) {
      return
    }
    var segments = path.split('.');
    return function (obj) {
      for (var i = 0; i < segments.length; i++) {
        if (!obj) { return }
        obj = obj[segments[i]];
      }
      return obj
    }
  }
  
  var warn = noop;
  var tip = noop;
  var formatComponentName;
  
  {
    var hasConsole = typeof console !== 'undefined';
    var classifyRE = /(?:^|[-_])(\w)/g;
    var classify = function (str) { return str
      .replace(classifyRE, function (c) { return c.toUpperCase(); })
      .replace(/[-_]/g, ''); };
  
    warn = function (msg, vm) {
      if (hasConsole && (!config.silent)) {
        console.error("[Vue warn]: " + msg + (
          vm ? generateComponentTrace(vm) : ''
        ));
      }
    };
  
    tip = function (msg, vm) {
      if (hasConsole && (!config.silent)) {
        console.warn("[Vue tip]: " + msg + (
          vm ? generateComponentTrace(vm) : ''
        ));
      }
    };
  
    formatComponentName = function (vm, includeFile) {
      if (vm.$root === vm) {
        return '<Root>'
      }
      var name = typeof vm === 'string'
        ? vm
        : typeof vm === 'function' && vm.options
          ? vm.options.name
          : vm._isVue
            ? vm.$options.name || vm.$options._componentTag
            : vm.name;
  
      var file = vm._isVue && vm.$options.__file;
      if (!name && file) {
        var match = file.match(/([^/\\]+)\.vue$/);
        name = match && match[1];
      }
  
      return (
        (name ? ("<" + (classify(name)) + ">") : "<Anonymous>") +
        (file && includeFile !== false ? (" at " + file) : '')
      )
    };
  
    var repeat = function (str, n) {
      var res = '';
      while (n) {
        if (n % 2 === 1) { res += str; }
        if (n > 1) { str += str; }
        n >>= 1;
      }
      return res
    };
  
    var generateComponentTrace = function (vm) {
      if (vm._isVue && vm.$parent) {
        var tree = [];
        var currentRecursiveSequence = 0;
        while (vm) {
          if (tree.length > 0) {
            var last = tree[tree.length - 1];
            if (last.constructor === vm.constructor) {
              currentRecursiveSequence++;
              vm = vm.$parent;
              continue
            } else if (currentRecursiveSequence > 0) {
              tree[tree.length - 1] = [last, currentRecursiveSequence];
              currentRecursiveSequence = 0;
            }
          }
          tree.push(vm);
          vm = vm.$parent;
        }
        return '\n\nfound in\n\n' + tree
          .map(function (vm, i) { return ("" + (i === 0 ? '---> ' : repeat(' ', 5 + i * 2)) + (Array.isArray(vm)
              ? ((formatComponentName(vm[0])) + "... (" + (vm[1]) + " recursive calls)")
              : formatComponentName(vm))); })
          .join('\n')
      } else {
        return ("\n\n(found in " + (formatComponentName(vm)) + ")")
      }
    };
  }
  
  function handleError (err, vm, info) {
    if (config.errorHandler) {
      config.errorHandler.call(null, err, vm, info);
    } else {
      {
        warn(("Error in " + info + ": \"" + (err.toString()) + "\""), vm);
      }
      /* istanbul ignore else */
      if (inBrowser && typeof console !== 'undefined') {
        console.error(err);
      } else {
        throw err
      }
    }
  }
  
  /*  */
  /* globals MutationObserver */
  
  var hasProto = '__proto__' in {};
  
  // Browser environment sniffing
  var inBrowser = typeof window !== 'undefined';
  var UA = inBrowser && window.navigator.userAgent.toLowerCase();
  var isIE = UA && /msie|trident/.test(UA);
  var isIE9 = UA && UA.indexOf('msie 9.0') > 0;
  var isEdge = UA && UA.indexOf('edge/') > 0;
  var isAndroid = UA && UA.indexOf('android') > 0;
  var isIOS = UA && /iphone|ipad|ipod|ios/.test(UA);
  var isChrome = UA && /chrome\/\d+/.test(UA) && !isEdge;
  
  var supportsPassive = false;
  if (inBrowser) {
    try {
      var opts = {};
      Object.defineProperty(opts, 'passive', ({
        get: function get () {
          /* istanbul ignore next */
          supportsPassive = true;
        }
      } )); // https://github.com/facebook/flow/issues/285
      window.addEventListener('test-passive', null, opts);
    } catch (e) {}
  }
  
  // this needs to be lazy-evaled because vue may be required before
  // vue-server-renderer can set VUE_ENV
  var _isServer;
  var isServerRendering = function () {
    if (_isServer === undefined) {
      /* istanbul ignore if */
      if (!inBrowser && typeof global !== 'undefined') {
        // detect presence of vue-server-renderer and avoid
        // Webpack shimming the process
        _isServer = global['process'].env.VUE_ENV === 'server';
      } else {
        _isServer = false;
      }
    }
    return _isServer
  };
  
  // detect devtools
  var devtools = inBrowser && window.__VUE_DEVTOOLS_GLOBAL_HOOK__;
  
  /* istanbul ignore next */
  function isNative (Ctor) {
    return typeof Ctor === 'function' && /native code/.test(Ctor.toString())
  }
  
  var hasSymbol =
    typeof Symbol !== 'undefined' && isNative(Symbol) &&
    typeof Reflect !== 'undefined' && isNative(Reflect.ownKeys);
  
  /**
   * Defer a task to execute it asynchronously.
   */
  var nextTick = (function () {
    var callbacks = [];
    var pending = false;
    var timerFunc;
  
    function nextTickHandler () {
      pending = false;
      var copies = callbacks.slice(0);
      callbacks.length = 0;
      for (var i = 0; i < copies.length; i++) {
        copies[i]();
      }
    }
  
    // the nextTick behavior leverages the microtask queue, which can be accessed
    // via either native Promise.then or MutationObserver.
    // MutationObserver has wider support, however it is seriously bugged in
    // UIWebView in iOS >= 9.3.3 when triggered in touch event handlers. It
    // completely stops working after triggering a few times... so, if native
    // Promise is available, we will use it:
    /* istanbul ignore if */
    if (typeof Promise !== 'undefined' && isNative(Promise)) {
      var p = Promise.resolve();
      var logError = function (err) { console.error(err); };
      timerFunc = function () {
        p.then(nextTickHandler).catch(logError);
        // in problematic UIWebViews, Promise.then doesn't completely break, but
        // it can get stuck in a weird state where callbacks are pushed into the
        // microtask queue but the queue isn't being flushed, until the browser
        // needs to do some other work, e.g. handle a timer. Therefore we can
        // "force" the microtask queue to be flushed by adding an empty timer.
        if (isIOS) { setTimeout(noop); }
      };
    } else if (typeof MutationObserver !== 'undefined' && (
      isNative(MutationObserver) ||
      // PhantomJS and iOS 7.x
      MutationObserver.toString() === '[object MutationObserverConstructor]'
    )) {
      // use MutationObserver where native Promise is not available,
      // e.g. PhantomJS IE11, iOS7, Android 4.4
      var counter = 1;
      var observer = new MutationObserver(nextTickHandler);
      var textNode = document.createTextNode(String(counter));
      observer.observe(textNode, {
        characterData: true
      });
      timerFunc = function () {
        counter = (counter + 1) % 2;
        textNode.data = String(counter);
      };
    } else {
      // fallback to setTimeout
      /* istanbul ignore next */
      timerFunc = function () {
        setTimeout(nextTickHandler, 0);
      };
    }
  
    return function queueNextTick (cb, ctx) {
      var _resolve;
      callbacks.push(function () {
        if (cb) {
          try {
            cb.call(ctx);
          } catch (e) {
            handleError(e, ctx, 'nextTick');
          }
        } else if (_resolve) {
          _resolve(ctx);
        }
      });
      if (!pending) {
        pending = true;
        timerFunc();
      }
      if (!cb && typeof Promise !== 'undefined') {
        return new Promise(function (resolve, reject) {
          _resolve = resolve;
        })
      }
    }
  })();
  
  var _Set;
  /* istanbul ignore if */
  if (typeof Set !== 'undefined' && isNative(Set)) {
    // use native Set when available.
    _Set = Set;
  } else {
    // a non-standard Set polyfill that only works with primitive keys.
    _Set = (function () {
      function Set () {
        this.set = Object.create(null);
      }
      Set.prototype.has = function has (key) {
        return this.set[key] === true
      };
      Set.prototype.add = function add (key) {
        this.set[key] = true;
      };
      Set.prototype.clear = function clear () {
        this.set = Object.create(null);
      };
  
      return Set;
    }());
  }
  
  /*  */
  
  
  var uid = 0;
  
  /**
   * A dep is an observable that can have multiple
   * directives subscribing to it.
   */
  var Dep = function Dep () {
    this.id = uid++; // Dep对象的唯一标识
    this.subs = []; // 保存watcher
  };
  
  Dep.prototype.addSub = function addSub (sub) {
    this.subs.push(sub);
  };
  
  Dep.prototype.removeSub = function removeSub (sub) {
    remove(this.subs, sub);
  };
  // 依赖收集，当存在Dep.target的时候添加观察者对象
  Dep.prototype.depend = function depend () {
    if (Dep.target) {
      Dep.target.addDep(this);
    }
  };
  // 通知所有订阅者
  Dep.prototype.notify = function notify () {
    // stabilize the subscriber list first
    var subs = this.subs.slice();
    for (var i = 0, l = subs.length; i < l; i++) {
      subs[i].update();
    }
  };
  
  // the current target watcher being evaluated.
  // this is globally unique because there could be only one
  // watcher being evaluated at any time.
  // 依赖收集完需要将Dep.target设为null，防止后面重复添加依赖
  Dep.target = null;
  var targetStack = [];
  
  function pushTarget (_target) {
    if (Dep.target) { targetStack.push(Dep.target); }
    Dep.target = _target;
  }
  
  function popTarget () {
    Dep.target = targetStack.pop();
  }
  
  /*
   * not type checking this file because flow doesn't play well with
   * dynamically accessing methods on Array prototype
   */
  
  var arrayProto = Array.prototype;
  // 创建一个新的数组对象，修改该对象上的数组的七个方法，防止污染原生数组方法
  var arrayMethods = Object.create(arrayProto);[
    'push',
    'pop',
    'shift',
    'unshift',
    'splice',
    'sort',
    'reverse'
  ]
  .forEach(function (method) {
    // cache original method
    // 缓存原生的方法
    var original = arrayProto[method];
    def(arrayMethods, method, function mutator () {
      var arguments$1 = arguments;
  
      // avoid leaking arguments:
      // http://jsperf.com/closure-with-arguments
      var i = arguments.length;
      var args = new Array(i);
      while (i--) {
        args[i] = arguments$1[i];
      }
      // 调用原生的数组方法
      var result = original.apply(this, args);
      var ob = this.__ob__;
      var inserted;
      // push、unshift、splice参数大于2时，要重新调用ob.observeArray，因为这三种情况都是像数组中添加新的元素，所以需要重新观察每个子元素。
      switch (method) {
        case 'push':
          inserted = args;
          break
        case 'unshift':
          inserted = args;
          break
        case 'splice':
          inserted = args.slice(2);
          break
      }
      if (inserted) { ob.observeArray(inserted); }
      // notify change
      // dep通知所有注册的观察者进行响应式处理
      ob.dep.notify();
      return result
    });
  });
  
  /*  */
  
  var arrayKeys = Object.getOwnPropertyNames(arrayMethods);
  
  /**
   * By default, when a reactive property is set, the new value is
   * also converted to become reactive. However when passing down props,
   * we don't want to force conversion because the value may be a nested value
   * under a frozen data structure. Converting it would defeat the optimization.
   */
  var observerState = {
    shouldConvert: true,
    isSettingProps: false
  };
  
  /**
   * Observer class that are attached to each observed
   * object. Once attached, the observer converts target
   * object's property keys into getter/setters that
   * collect dependencies and dispatches updates.
   */
  // 遍历对象的所有属性并将其进行双向绑定s
  var Observer = function Observer (value) {
    this.value = value;
    this.dep = new Dep(); // 每一个observer都有一个dep
    this.vmCount = 0;
    // 添加__ob__来标示value有对应的Observer，在下面121行observer方法中会进行判断
    def(value, '__ob__', this);
    // 如果是数组，将修改后可以截获响应的数组方法替换掉该数组的原型中的原生方法，达到监听数组数据变化响应的效果。
  
    // 这里如果当前浏览器支持__proto__属性，则直接覆盖当前数组对象原型上的原生数组方法，
    // 如果不支持该属性，则直接覆盖数组对象的原型
    if (Array.isArray(value)) {
      var augment = hasProto
        ? protoAugment // 直接覆盖原型的方法来修改目标对象
        : copyAugment; // 定义（覆盖）目标对象或数组的某一个方法
      augment(value, arrayMethods, arrayKeys);
      // 如果是数组则需要遍历数组的每一个成员进行observe
      this.observeArray(value);
    } else {
      // 处理对象
      this.walk(value);
    }
  };
  
  /**
   * Walk through each property and convert them into
   * getter/setters. This method should only be called when
   * value type is Object.
   */
  // 给对象中的每个属性添加getters/setters
  Observer.prototype.walk = function walk (obj) {
    var keys = Object.keys(obj);
    for (var i = 0; i < keys.length; i++) {
      defineReactive$$1(obj, keys[i], obj[keys[i]]);
    }
  };
  
  /**
   * Observe a list of Array items.
   */
  // 观察数组
  Observer.prototype.observeArray = function observeArray (items) {
    for (var i = 0, l = items.length; i < l; i++) {
      observe(items[i]);
    }
  };
  
  // helpers
  
  /**
   * Augment an target Object or Array by intercepting
   * the prototype chain using __proto__
   */
  function protoAugment (target, src) {
    /* eslint-disable no-proto */
    target.__proto__ = src;
    /* eslint-enable no-proto */
  }
  
  /**
   * Augment an target Object or Array by defining
   * hidden properties.
   */
  /* istanbul ignore next */
  function copyAugment (target, src, keys) {
    for (var i = 0, l = keys.length; i < l; i++) {
      var key = keys[i];
      def(target, key, src[key]);
    }
  }
  
  /**
   * Attempt to create an observer instance for a value,
   * returns the new observer if successfully observed,
   * or the existing observer if the value already has one.
   */
  // 为所有value为对象的值递归地观察
  // 单例模式
  function observe (value, asRootData) {
    if (!isObject(value)) {
      return
    }
    var ob;
    // 判断是否有observer实例
    // Vue的响应式数据都会有一个__ob__的属性作为标记，里面存放了该属性的观察器，也就是Observer的实例，防止重复绑定。
    if (hasOwn(value, '__ob__') && value.__ob__ instanceof Observer) {
      ob = value.__ob__;
    } else if (
      // 这里的判断是为了确保value是单纯的对象，而不是函数或者是Regexp等情况
      observerState.shouldConvert &&
      !isServerRendering() &&
      (Array.isArray(value) || isPlainObject(value)) &&
      Object.isExtensible(value) &&
      !value._isVue
    ) {
      ob = new Observer(value);
    }
    if (asRootData && ob) {
      // 如果是根数据则计数，后面Observer中的observer的asRootData非true
      ob.vmCount++;
    }
    return ob
  }
  
  /**
   * Define a reactive property on an Object.
   * 响应式参数
   */
  function defineReactive$$1 (
    obj,
    key,
    val,
    customSetter
  ) {
    var dep = new Dep();
  
    var property = Object.getOwnPropertyDescriptor(obj, key);
    if (property && property.configurable === false) {
      return
    }
  
    // cater for pre-defined getter/setters
    // 用户自定义的
    var getter = property && property.get;
    var setter = property && property.set;
  
    var childOb = observe(val);
    Object.defineProperty(obj, key, {
      enumerable: true,
      configurable: true,
      get: function reactiveGetter () {
        var value = getter ? getter.call(obj) : val;
        if (Dep.target) {
          dep.depend();
          if (childOb) {
            childOb.dep.depend();
          }
          if (Array.isArray(value)) {
            dependArray(value);
          }
        }
        return value
      },
      set: function reactiveSetter (newVal) {
        var value = getter ? getter.call(obj) : val;
        /* eslint-disable no-self-compare */
        if (newVal === value || (newVal !== newVal && value !== value)) {
          return
        }
        /* eslint-enable no-self-compare */
        // 开发模式输出错误
        if ("development" !== 'production' && customSetter) {
          customSetter();
        }
        if (setter) {
          setter.call(obj, newVal);
        } else {
          val = newVal;
        }
        childOb = observe(newVal);
        dep.notify();
      }
    });
  }
  
  /**
   * Set a property on an object. Adds the new property and
   * triggers change notification if the property doesn't
   * already exist.
   */
  function set (target, key, val) {
    if (Array.isArray(target) && typeof key === 'number') {
      target.length = Math.max(target.length, key);
      target.splice(key, 1, val);
      return val
    }
    if (hasOwn(target, key)) {
      target[key] = val;
      return val
    }
    var ob = (target ).__ob__;
    if (target._isVue || (ob && ob.vmCount)) {
      "development" !== 'production' && warn(
        'Avoid adding reactive properties to a Vue instance or its root $data ' +
        'at runtime - declare it upfront in the data option.'
      );
      return val
    }
    if (!ob) {
      target[key] = val;
      return val
    }
    defineReactive$$1(ob.value, key, val);
    ob.dep.notify();
    return val
  }
  
  /**
   * Delete a property and trigger change if necessary.
   */
  function del (target, key) {
    if (Array.isArray(target) && typeof key === 'number') {
      target.splice(key, 1);
      return
    }
    var ob = (target ).__ob__;
    if (target._isVue || (ob && ob.vmCount)) {
      "development" !== 'production' && warn(
        'Avoid deleting properties on a Vue instance or its root $data ' +
        '- just set it to null.'
      );
      return
    }
    if (!hasOwn(target, key)) {
      return
    }
    delete target[key];
    if (!ob) {
      return
    }
    ob.dep.notify();
  }
  
  /**
   * Collect dependencies on array elements when the array is touched, since
   * we cannot intercept array element access like property getters.
   */
  function dependArray (value) {
    for (var e = (void 0), i = 0, l = value.length; i < l; i++) {
      e = value[i];
      e && e.__ob__ && e.__ob__.dep.depend();
      if (Array.isArray(e)) {
        dependArray(e);
      }
    }
  }
  
  /*  */
  
  var strats = config.optionMergeStrategies;
  
  /**
   * Options with restrictions
   */
  {
    strats.el = strats.propsData = function (parent, child, vm, key) {
      if (!vm) {
        warn(
          "option \"" + key + "\" can only be used during instance " +
          'creation with the `new` keyword.'
        );
      }
      return defaultStrat(parent, child)
    };
  }
  
  /**
   * Helper that recursively merges two data objects together.
   */
  function mergeData (to, from) {
    if (!from) { return to }
    var key, toVal, fromVal;
    var keys = Object.keys(from);
    for (var i = 0; i < keys.length; i++) {
      key = keys[i];
      toVal = to[key];
      fromVal = from[key];
      if (!hasOwn(to, key)) {
        set(to, key, fromVal);
      } else if (isPlainObject(toVal) && isPlainObject(fromVal)) {
        mergeData(toVal, fromVal);
      }
    }
    return to
  }
  
  /**
   * Data
   */
  strats.data = function (
    parentVal,
    childVal,
    vm
  ) {
    if (!vm) {
      // in a Vue.extend merge, both should be functions
      if (!childVal) {
        return parentVal
      }
      if (typeof childVal !== 'function') {
        "development" !== 'production' && warn(
          'The "data" option should be a function ' +
          'that returns a per-instance value in component ' +
          'definitions.',
          vm
        );
        return parentVal
      }
      if (!parentVal) {
        return childVal
      }
      // when parentVal & childVal are both present,
      // we need to return a function that returns the
      // merged result of both functions... no need to
      // check if parentVal is a function here because
      // it has to be a function to pass previous merges.
      return function mergedDataFn () {
        return mergeData(
          childVal.call(this),
          parentVal.call(this)
        )
      }
    } else if (parentVal || childVal) {
      return function mergedInstanceDataFn () {
        // instance merge
        var instanceData = typeof childVal === 'function'
          ? childVal.call(vm)
          : childVal;
        var defaultData = typeof parentVal === 'function'
          ? parentVal.call(vm)
          : undefined;
        if (instanceData) {
          return mergeData(instanceData, defaultData)
        } else {
          return defaultData
        }
      }
    }
  };
  
  /**
   * Hooks and props are merged as arrays.
   */
  function mergeHook (
    parentVal,
    childVal
  ) {
    return childVal
      ? parentVal
        ? parentVal.concat(childVal)
        : Array.isArray(childVal)
          ? childVal
          : [childVal]
      : parentVal
  }
  
  LIFECYCLE_HOOKS.forEach(function (hook) {
    strats[hook] = mergeHook;
  });
  
  /**
   * Assets
   *
   * When a vm is present (instance creation), we need to do
   * a three-way merge between constructor options, instance
   * options and parent options.
   */
  function mergeAssets (parentVal, childVal) {
    var res = Object.create(parentVal || null);
    return childVal
      ? extend(res, childVal)
      : res
  }
  
  ASSET_TYPES.forEach(function (type) {
    strats[type + 's'] = mergeAssets;
  });
  
  /**
   * Watchers.
   *
   * Watchers hashes should not overwrite one
   * another, so we merge them as arrays.
   */
  strats.watch = function (parentVal, childVal) {
    /* istanbul ignore if */
    if (!childVal) { return Object.create(parentVal || null) }
    if (!parentVal) { return childVal }
    var ret = {};
    extend(ret, parentVal);
    for (var key in childVal) {
      var parent = ret[key];
      var child = childVal[key];
      if (parent && !Array.isArray(parent)) {
        parent = [parent];
      }
      ret[key] = parent
        ? parent.concat(child)
        : [child];
    }
    return ret
  };
  
  /**
   * Other object hashes.
   */
  strats.props =
  strats.methods =
  strats.computed = function (parentVal, childVal) {
    if (!childVal) { return Object.create(parentVal || null) }
    if (!parentVal) { return childVal }
    var ret = Object.create(null);
    extend(ret, parentVal);
    extend(ret, childVal);
    return ret
  };
  
  /**
   * Default strategy.
   */
  var defaultStrat = function (parentVal, childVal) {
    return childVal === undefined
      ? parentVal
      : childVal
  };
  
  /**
   * Validate component names
   */
  function checkComponents (options) {
    for (var key in options.components) {
      var lower = key.toLowerCase();
      if (isBuiltInTag(lower) || config.isReservedTag(lower)) {
        warn(
          'Do not use built-in or reserved HTML elements as component ' +
          'id: ' + key
        );
      }
    }
  }
  
  /**
   * Ensure all props option syntax are normalized into the
   * Object-based format.
   */
  function normalizeProps (options) {
    var props = options.props;
    if (!props) { return }
    var res = {};
    var i, val, name;
    if (Array.isArray(props)) {
      i = props.length;
      while (i--) {
        val = props[i];
        if (typeof val === 'string') {
          name = camelize(val);
          res[name] = { type: null };
        } else {
          warn('props must be strings when using array syntax.');
        }
      }
    } else if (isPlainObject(props)) {
      for (var key in props) {
        val = props[key];
        name = camelize(key);
        res[name] = isPlainObject(val)
          ? val
          : { type: val };
      }
    }
    options.props = res;
  }
  
  /**
   * Normalize raw function directives into object format.
   */
  function normalizeDirectives (options) {
    var dirs = options.directives;
    if (dirs) {
      for (var key in dirs) {
        var def = dirs[key];
        if (typeof def === 'function') {
          dirs[key] = { bind: def, update: def };
        }
      }
    }
  }
  
  /**
   * Merge two option objects into a new one.
   * Core utility used in both instantiation and inheritance.
   */
  function mergeOptions (
    parent,
    child,
    vm
  ) {
    {
      checkComponents(child);
    }
  
    if (typeof child === 'function') {
      child = child.options;
    }
    // 格式化child的Props
    normalizeProps(child);
    // 格式化child的Directive
    normalizeDirectives(child);
    var extendsFrom = child.extends;
    if (extendsFrom) {
      parent = mergeOptions(parent, extendsFrom, vm);
    }
    if (child.mixins) {
      for (var i = 0, l = child.mixins.length; i < l; i++) {
        parent = mergeOptions(parent, child.mixins[i], vm);
      }
    }
    var options = {};
    var key;
    for (key in parent) {
      mergeField(key);
    }
    for (key in child) {
      if (!hasOwn(parent, key)) {
        mergeField(key);
      }
    }
    function mergeField (key) {
      var strat = strats[key] || defaultStrat;
      options[key] = strat(parent[key], child[key], vm, key);
    }
    return options
  }
  
  /**
   * Resolve an asset.
   * This function is used because child instances need access
   * to assets defined in its ancestor chain.
   */
  function resolveAsset (
    options,
    type,
    id,
    warnMissing
  ) {
    /* istanbul ignore if */
    if (typeof id !== 'string') {
      return
    }
    var assets = options[type];
    // check local registration variations first
    if (hasOwn(assets, id)) { return assets[id] }
    var camelizedId = camelize(id);
    if (hasOwn(assets, camelizedId)) { return assets[camelizedId] }
    var PascalCaseId = capitalize(camelizedId);
    if (hasOwn(assets, PascalCaseId)) { return assets[PascalCaseId] }
    // fallback to prototype chain
    var res = assets[id] || assets[camelizedId] || assets[PascalCaseId];
    if ("development" !== 'production' && warnMissing && !res) {
      warn(
        'Failed to resolve ' + type.slice(0, -1) + ': ' + id,
        options
      );
    }
    return res
  }
  
  /*  */
  
  function validateProp (
    key,
    propOptions,
    propsData,
    vm
  ) {
    var prop = propOptions[key];
    var absent = !hasOwn(propsData, key);
    var value = propsData[key];
    // handle boolean props
    if (isType(Boolean, prop.type)) {
      if (absent && !hasOwn(prop, 'default')) {
        value = false;
      } else if (!isType(String, prop.type) && (value === '' || value === hyphenate(key))) {
        value = true;
      }
    }
    // check default value
    if (value === undefined) {
      value = getPropDefaultValue(vm, prop, key);
      // since the default value is a fresh copy,
      // make sure to observe it.
      var prevShouldConvert = observerState.shouldConvert;
      observerState.shouldConvert = true;
      observe(value);
      observerState.shouldConvert = prevShouldConvert;
    }
    {
      assertProp(prop, key, value, vm, absent);
    }
    return value
  }
  
  /**
   * Get the default value of a prop.
   */
  function getPropDefaultValue (vm, prop, key) {
    // no default, return undefined
    if (!hasOwn(prop, 'default')) {
      return undefined
    }
    var def = prop.default;
    // warn against non-factory defaults for Object & Array
    if ("development" !== 'production' && isObject(def)) {
      warn(
        'Invalid default value for prop "' + key + '": ' +
        'Props with type Object/Array must use a factory function ' +
        'to return the default value.',
        vm
      );
    }
    // the raw prop value was also undefined from previous render,
    // return previous default value to avoid unnecessary watcher trigger
    if (vm && vm.$options.propsData &&
      vm.$options.propsData[key] === undefined &&
      vm._props[key] !== undefined) {
      return vm._props[key]
    }
    // call factory function for non-Function types
    // a value is Function if its prototype is function even across different execution context
    return typeof def === 'function' && getType(prop.type) !== 'Function'
      ? def.call(vm)
      : def
  }
  
  /**
   * Assert whether a prop is valid.
   */
  function assertProp (
    prop,
    name,
    value,
    vm,
    absent
  ) {
    if (prop.required && absent) {
      warn(
        'Missing required prop: "' + name + '"',
        vm
      );
      return
    }
    if (value == null && !prop.required) {
      return
    }
    var type = prop.type;
    var valid = !type || type === true;
    var expectedTypes = [];
    if (type) {
      if (!Array.isArray(type)) {
        type = [type];
      }
      for (var i = 0; i < type.length && !valid; i++) {
        var assertedType = assertType(value, type[i]);
        expectedTypes.push(assertedType.expectedType || '');
        valid = assertedType.valid;
      }
    }
    if (!valid) {
      warn(
        'Invalid prop: type check failed for prop "' + name + '".' +
        ' Expected ' + expectedTypes.map(capitalize).join(', ') +
        ', got ' + Object.prototype.toString.call(value).slice(8, -1) + '.',
        vm
      );
      return
    }
    var validator = prop.validator;
    if (validator) {
      if (!validator(value)) {
        warn(
          'Invalid prop: custom validator check failed for prop "' + name + '".',
          vm
        );
      }
    }
  }
  
  var simpleCheckRE = /^(String|Number|Boolean|Function|Symbol)$/;
  
  function assertType (value, type) {
    var valid;
    var expectedType = getType(type);
    if (simpleCheckRE.test(expectedType)) {
      valid = typeof value === expectedType.toLowerCase();
    } else if (expectedType === 'Object') {
      valid = isPlainObject(value);
    } else if (expectedType === 'Array') {
      valid = Array.isArray(value);
    } else {
      valid = value instanceof type;
    }
    return {
      valid: valid,
      expectedType: expectedType
    }
  }
  
  /**
   * Use function string name to check built-in types,
   * because a simple equality check will fail when running
   * across different vms / iframes.
   */
  function getType (fn) {
    var match = fn && fn.toString().match(/^\s*function (\w+)/);
    return match ? match[1] : ''
  }
  
  function isType (type, fn) {
    if (!Array.isArray(fn)) {
      return getType(fn) === getType(type)
    }
    for (var i = 0, len = fn.length; i < len; i++) {
      if (getType(fn[i]) === getType(type)) {
        return true
      }
    }
    /* istanbul ignore next */
    return false
  }
  
  var mark;
  var measure;
  
  {
    var perf = inBrowser && window.performance;
    /* istanbul ignore if */
    if (
      perf &&
      perf.mark &&
      perf.measure &&
      perf.clearMarks &&
      perf.clearMeasures
    ) {
      mark = function (tag) { return perf.mark(tag); };
      measure = function (name, startTag, endTag) {
        perf.measure(name, startTag, endTag);
        perf.clearMarks(startTag);
        perf.clearMarks(endTag);
        perf.clearMeasures(name);
      };
    }
  }
  
  /* not type checking this file because flow doesn't play well with Proxy */
  
  var initProxy;
  
  {
    var allowedGlobals = makeMap(
      'Infinity,undefined,NaN,isFinite,isNaN,' +
      'parseFloat,parseInt,decodeURI,decodeURIComponent,encodeURI,encodeURIComponent,' +
      'Math,Number,Date,Array,Object,Boolean,String,RegExp,Map,Set,JSON,Intl,' +
      'require' // for Webpack/Browserify
    );
  
    var warnNonPresent = function (target, key) {
      warn(
        "Property or method \"" + key + "\" is not defined on the instance but " +
        "referenced during render. Make sure to declare reactive data " +
        "properties in the data option.",
        target
      );
    };
  
    var hasProxy =
      typeof Proxy !== 'undefined' &&
      Proxy.toString().match(/native code/);
  
    if (hasProxy) {
      var isBuiltInModifier = makeMap('stop,prevent,self,ctrl,shift,alt,meta');
      config.keyCodes = new Proxy(config.keyCodes, {
        set: function set (target, key, value) {
          if (isBuiltInModifier(key)) {
            warn(("Avoid overwriting built-in modifier in config.keyCodes: ." + key));
            return false
          } else {
            target[key] = value;
            return true
          }
        }
      });
    }
  
    var hasHandler = {
      has: function has (target, key) {
        var has = key in target;
        var isAllowed = allowedGlobals(key) || key.charAt(0) === '_';
        if (!has && !isAllowed) {
          warnNonPresent(target, key);
        }
        return has || !isAllowed
      }
    };
  
    var getHandler = {
      get: function get (target, key) {
        if (typeof key === 'string' && !(key in target)) {
          warnNonPresent(target, key);
        }
        return target[key]
      }
    };
  
    initProxy = function initProxy (vm) {
      if (hasProxy) {
        // determine which proxy handler to use
        var options = vm.$options;
        var handlers = options.render && options.render._withStripped
          ? getHandler
          : hasHandler;
        vm._renderProxy = new Proxy(vm, handlers);
      } else {
        vm._renderProxy = vm;
      }
    };
  }
  
  /*  */
  
  var VNode = function VNode (
    tag,
    data,
    children,
    text,
    elm,
    context,
    componentOptions
  ) {
    this.tag = tag;
    this.data = data;
    this.children = children;
    this.text = text;
    this.elm = elm;
    this.ns = undefined;
    this.context = context;
    this.functionalContext = undefined;
    this.key = data && data.key;
    this.componentOptions = componentOptions;
    this.componentInstance = undefined;
    this.parent = undefined;
    this.raw = false;
    this.isStatic = false;
    this.isRootInsert = true;
    this.isComment = false;
    this.isCloned = false;
    this.isOnce = false;
  };
  
  var prototypeAccessors = { child: {} };
  
  // DEPRECATED: alias for componentInstance for backwards compat.
  /* istanbul ignore next */
  prototypeAccessors.child.get = function () {
    return this.componentInstance
  };
  
  Object.defineProperties( VNode.prototype, prototypeAccessors );
  
  var createEmptyVNode = function () {
    var node = new VNode();
    node.text = '';
    node.isComment = true;
    return node
  };
  
  function createTextVNode (val) {
    return new VNode(undefined, undefined, undefined, String(val))
  }
  
  // optimized shallow clone
  // used for static nodes and slot nodes because they may be reused across
  // multiple renders, cloning them avoids errors when DOM manipulations rely
  // on their elm reference.
  function cloneVNode (vnode) {
    var cloned = new VNode(
      vnode.tag,
      vnode.data,
      vnode.children,
      vnode.text,
      vnode.elm,
      vnode.context,
      vnode.componentOptions
    );
    cloned.ns = vnode.ns;
    cloned.isStatic = vnode.isStatic;
    cloned.key = vnode.key;
    cloned.isCloned = true;
    return cloned
  }
  
  function cloneVNodes (vnodes) {
    var len = vnodes.length;
    var res = new Array(len);
    for (var i = 0; i < len; i++) {
      res[i] = cloneVNode(vnodes[i]);
    }
    return res
  }
  
  /*  */
  
  var normalizeEvent = cached(function (name) {
    var passive = name.charAt(0) === '&';
    name = passive ? name.slice(1) : name;
    var once$$1 = name.charAt(0) === '~'; // Prefixed last, checked first
    name = once$$1 ? name.slice(1) : name;
    var capture = name.charAt(0) === '!';
    name = capture ? name.slice(1) : name;
    return {
      name: name,
      once: once$$1,
      capture: capture,
      passive: passive
    }
  });
  
  function createFnInvoker (fns) {
    function invoker () {
      var arguments$1 = arguments;
  
      var fns = invoker.fns;
      if (Array.isArray(fns)) {
        for (var i = 0; i < fns.length; i++) {
          fns[i].apply(null, arguments$1);
        }
      } else {
        // return handler return value for single handlers
        return fns.apply(null, arguments)
      }
    }
    invoker.fns = fns;
    return invoker
  }
  
  function updateListeners (
    on,
    oldOn,
    add,
    remove$$1,
    vm
  ) {
    var name, cur, old, event;
    for (name in on) {
      cur = on[name];
      old = oldOn[name];
      event = normalizeEvent(name);
      if (isUndef(cur)) {
        "development" !== 'production' && warn(
          "Invalid handler for event \"" + (event.name) + "\": got " + String(cur),
          vm
        );
      } else if (isUndef(old)) {
        if (isUndef(cur.fns)) {
          cur = on[name] = createFnInvoker(cur);
        }
        add(event.name, cur, event.once, event.capture, event.passive);
      } else if (cur !== old) {
        old.fns = cur;
        on[name] = old;
      }
    }
    for (name in oldOn) {
      if (isUndef(on[name])) {
        event = normalizeEvent(name);
        remove$$1(event.name, oldOn[name], event.capture);
      }
    }
  }
  
  /*  */
  
  function mergeVNodeHook (def, hookKey, hook) {
    var invoker;
    var oldHook = def[hookKey];
  
    function wrappedHook () {
      hook.apply(this, arguments);
      // important: remove merged hook to ensure it's called only once
      // and prevent memory leak
      remove(invoker.fns, wrappedHook);
    }
  
    if (isUndef(oldHook)) {
      // no existing hook
      invoker = createFnInvoker([wrappedHook]);
    } else {
      /* istanbul ignore if */
      if (isDef(oldHook.fns) && isTrue(oldHook.merged)) {
        // already a merged invoker
        invoker = oldHook;
        invoker.fns.push(wrappedHook);
      } else {
        // existing plain hook
        invoker = createFnInvoker([oldHook, wrappedHook]);
      }
    }
  
    invoker.merged = true;
    def[hookKey] = invoker;
  }
  
  /*  */
  
  function extractPropsFromVNodeData (
    data,
    Ctor,
    tag
  ) {
    // we are only extracting raw values here.
    // validation and default values are handled in the child
    // component itself.
    var propOptions = Ctor.options.props;
    if (isUndef(propOptions)) {
      return
    }
    var res = {};
    var attrs = data.attrs;
    var props = data.props;
    if (isDef(attrs) || isDef(props)) {
      for (var key in propOptions) {
        var altKey = hyphenate(key);
        {
          var keyInLowerCase = key.toLowerCase();
          if (
            key !== keyInLowerCase &&
            attrs && hasOwn(attrs, keyInLowerCase)
          ) {
            tip(
              "Prop \"" + keyInLowerCase + "\" is passed to component " +
              (formatComponentName(tag || Ctor)) + ", but the declared prop name is" +
              " \"" + key + "\". " +
              "Note that HTML attributes are case-insensitive and camelCased " +
              "props need to use their kebab-case equivalents when using in-DOM " +
              "templates. You should probably use \"" + altKey + "\" instead of \"" + key + "\"."
            );
          }
        }
        checkProp(res, props, key, altKey, true) ||
        checkProp(res, attrs, key, altKey, false);
      }
    }
    return res
  }
  
  function checkProp (
    res,
    hash,
    key,
    altKey,
    preserve
  ) {
    if (isDef(hash)) {
      if (hasOwn(hash, key)) {
        res[key] = hash[key];
        if (!preserve) {
          delete hash[key];
        }
        return true
      } else if (hasOwn(hash, altKey)) {
        res[key] = hash[altKey];
        if (!preserve) {
          delete hash[altKey];
        }
        return true
      }
    }
    return false
  }
  
  /*  */
  
  function simpleNormalizeChildren (children) {
    for (var i = 0; i < children.length; i++) {
      if (Array.isArray(children[i])) {
        return Array.prototype.concat.apply([], children)
      }
    }
    return children
  }
  
  // 2. When the children contains constructs that always generated nested Arrays,
  // e.g. <template>, <slot>, v-for, or when the children is provided by user
  // with hand-written render functions / JSX. In such cases a full normalization
  // is needed to cater to all possible types of children values.
  function normalizeChildren (children) {
    return isPrimitive(children)
      ? [createTextVNode(children)]
      : Array.isArray(children)
        ? normalizeArrayChildren(children)
        : undefined
  }
  
  function normalizeArrayChildren (children, nestedIndex) {
    var res = [];
    var i, c, last;
    for (i = 0; i < children.length; i++) {
      c = children[i];
      if (isUndef(c) || typeof c === 'boolean') { continue }
      last = res[res.length - 1];
      //  nested
      if (Array.isArray(c)) {
        res.push.apply(res, normalizeArrayChildren(c, ((nestedIndex || '') + "_" + i)));
      } else if (isPrimitive(c)) {
        if (isDef(last) && isDef(last.text)) {
          (last).text += String(c);
        } else if (c !== '') {
          // convert primitive to vnode
          res.push(createTextVNode(c));
        }
      } else {
        if (isDef(c.text) && isDef(last) && isDef(last.text)) {
          res[res.length - 1] = createTextVNode(last.text + c.text);
        } else {
          // default key for nested array children (likely generated by v-for)
          if (isDef(c.tag) && isUndef(c.key) && isDef(nestedIndex)) {
            c.key = "__vlist" + ((nestedIndex)) + "_" + i + "__";
          }
          res.push(c);
        }
      }
    }
    return res
  }
  
  /*  */
  
  function ensureCtor (comp, base) {
    return isObject(comp)
      ? base.extend(comp)
      : comp
  }
  
  function resolveAsyncComponent (
    factory,
    baseCtor,
    context
  ) {
    if (isTrue(factory.error) && isDef(factory.errorComp)) {
      return factory.errorComp
    }
  
    if (isDef(factory.resolved)) {
      return factory.resolved
    }
  
    if (isTrue(factory.loading) && isDef(factory.loadingComp)) {
      return factory.loadingComp
    }
  
    if (isDef(factory.contexts)) {
      // already pending
      factory.contexts.push(context);
    } else {
      var contexts = factory.contexts = [context];
      var sync = true;
  
      var forceRender = function () {
        for (var i = 0, l = contexts.length; i < l; i++) {
          contexts[i].$forceUpdate();
        }
      };
  
      var resolve = once(function (res) {
        // cache resolved
        factory.resolved = ensureCtor(res, baseCtor);
        // invoke callbacks only if this is not a synchronous resolve
        // (async resolves are shimmed as synchronous during SSR)
        if (!sync) {
          forceRender();
        }
      });
  
      var reject = once(function (reason) {
        "development" !== 'production' && warn(
          "Failed to resolve async component: " + (String(factory)) +
          (reason ? ("\nReason: " + reason) : '')
        );
        if (isDef(factory.errorComp)) {
          factory.error = true;
          forceRender();
        }
      });
  
      var res = factory(resolve, reject);
  
      if (isObject(res)) {
        if (typeof res.then === 'function') {
          // () => Promise
          if (isUndef(factory.resolved)) {
            res.then(resolve, reject);
          }
        } else if (isDef(res.component) && typeof res.component.then === 'function') {
          res.component.then(resolve, reject);
  
          if (isDef(res.error)) {
            factory.errorComp = ensureCtor(res.error, baseCtor);
          }
  
          if (isDef(res.loading)) {
            factory.loadingComp = ensureCtor(res.loading, baseCtor);
            if (res.delay === 0) {
              factory.loading = true;
            } else {
              setTimeout(function () {
                if (isUndef(factory.resolved) && isUndef(factory.error)) {
                  factory.loading = true;
                  forceRender();
                }
              }, res.delay || 200);
            }
          }
  
          if (isDef(res.timeout)) {
            setTimeout(function () {
              reject(
                "timeout (" + (res.timeout) + "ms)"
              );
            }, res.timeout);
          }
        }
      }
  
      sync = false;
      // return in case resolved synchronously
      return factory.loading
        ? factory.loadingComp
        : factory.resolved
    }
  }
  
  /*  */
  
  function getFirstComponentChild (children) {
    if (Array.isArray(children)) {
      for (var i = 0; i < children.length; i++) {
        var c = children[i];
        if (isDef(c) && isDef(c.componentOptions)) {
          return c
        }
      }
    }
  }
  
  /*  */
  
  /*  */
  
  function initEvents (vm) {
    vm._events = Object.create(null);
    vm._hasHookEvent = false;
    // init parent attached events
    var listeners = vm.$options._parentListeners;
    if (listeners) {
      // _parentListeners是父组件中绑定在自定义标签上的事件，供子组件处理。
      updateComponentListeners(vm, listeners);
    }
  }
  
  var target;
  
  function add (event, fn, once$$1) {
    if (once$$1) {
      target.$once(event, fn);
    } else {
      target.$on(event, fn);
    }
  }
  
  function remove$1 (event, fn) {
    target.$off(event, fn);
  }
  
  function updateComponentListeners (
    vm,
    listeners,
    oldListeners
  ) {
    target = vm;
    updateListeners(listeners, oldListeners || {}, add, remove$1, vm);
  }
  
  function eventsMixin (Vue) {
    var hookRE = /^hook:/;
    Vue.prototype.$on = function (event, fn) {
      var this$1 = this;
  
      var vm = this;
      if (Array.isArray(event)) {
        for (var i = 0, l = event.length; i < l; i++) {
          this$1.$on(event[i], fn);
        }
      } else {
        (vm._events[event] || (vm._events[event] = [])).push(fn);
        // optimize hook:event cost by using a boolean flag marked at registration
        // instead of a hash lookup
        if (hookRE.test(event)) {
          vm._hasHookEvent = true;
        }
      }
      return vm
    };
  
    Vue.prototype.$once = function (event, fn) {
      var vm = this;
      function on () {
        vm.$off(event, on);
        fn.apply(vm, arguments);
      }
      on.fn = fn;
      vm.$on(event, on);
      return vm
    };
  
    Vue.prototype.$off = function (event, fn) {
      var this$1 = this;
  
      var vm = this;
      // all
      if (!arguments.length) {
        vm._events = Object.create(null);
        return vm
      }
      // array of events
      if (Array.isArray(event)) {
        for (var i$1 = 0, l = event.length; i$1 < l; i$1++) {
          this$1.$off(event[i$1], fn);
        }
        return vm
      }
      // specific event
      var cbs = vm._events[event];
      if (!cbs) {
        return vm
      }
      if (arguments.length === 1) {
        vm._events[event] = null;
        return vm
      }
      // specific handler
      var cb;
      var i = cbs.length;
      while (i--) {
        cb = cbs[i];
        if (cb === fn || cb.fn === fn) {
          cbs.splice(i, 1);
          break
        }
      }
      return vm
    };
  
    Vue.prototype.$emit = function (event) {
      var vm = this;
      {
        var lowerCaseEvent = event.toLowerCase();
        if (lowerCaseEvent !== event && vm._events[lowerCaseEvent]) {
          tip(
            "Event \"" + lowerCaseEvent + "\" is emitted in component " +
            (formatComponentName(vm)) + " but the handler is registered for \"" + event + "\". " +
            "Note that HTML attributes are case-insensitive and you cannot use " +
            "v-on to listen to camelCase events when using in-DOM templates. " +
            "You should probably use \"" + (hyphenate(event)) + "\" instead of \"" + event + "\"."
          );
        }
      }
      var cbs = vm._events[event];
      if (cbs) {
        cbs = cbs.length > 1 ? toArray(cbs) : cbs;
        var args = toArray(arguments, 1);
        for (var i = 0, l = cbs.length; i < l; i++) {
          cbs[i].apply(vm, args);
        }
      }
      return vm
    };
  }
  
  /*  */
  
  /**
   * Runtime helper for resolving raw children VNodes into a slot object.
   */
  function resolveSlots (
    children,
    context
  ) {
    var slots = {};
    if (!children) {
      return slots
    }
    var defaultSlot = [];
    for (var i = 0, l = children.length; i < l; i++) {
      var child = children[i];
      // named slots should only be respected if the vnode was rendered in the
      // same context.
      if ((child.context === context || child.functionalContext === context) &&
          child.data && child.data.slot != null) {
        var name = child.data.slot;
        var slot = (slots[name] || (slots[name] = []));
        if (child.tag === 'template') {
          slot.push.apply(slot, child.children);
        } else {
          slot.push(child);
        }
      } else {
        defaultSlot.push(child);
      }
    }
    // ignore whitespace
    if (!defaultSlot.every(isWhitespace)) {
      slots.default = defaultSlot;
    }
    return slots
  }
  
  function isWhitespace (node) {
    return node.isComment || node.text === ' '
  }
  
  function resolveScopedSlots (
    fns
  ) {
    var res = {};
    for (var i = 0; i < fns.length; i++) {
      res[fns[i][0]] = fns[i][1];
    }
    return res
  }
  
  /*  */
  
  var activeInstance = null;
  
  function initLifecycle (vm) {
    var options = vm.$options;
  
    // locate first non-abstract parent
    var parent = options.parent;
    // 判断是否是抽象组件，组件的父子关系建立会跳过抽象组件，抽象组件比如keep-alive、transition等。
    if (parent && !options.abstract) {
      while (parent.$options.abstract && parent.$parent) {
        parent = parent.$parent;
      }
      parent.$children.push(vm);
    }
  
    vm.$parent = parent;
    vm.$root = parent ? parent.$root : vm; // 所有的子组件$root都指向顶级组件
  
    vm.$children = [];
    vm.$refs = {};
  
    vm._watcher = null;
    vm._inactive = null;
    vm._directInactive = false;
    vm._isMounted = false;
    vm._isDestroyed = false;
    vm._isBeingDestroyed = false;
  }
  
  function lifecycleMixin (Vue) {
    Vue.prototype._update = function (vnode, hydrating) {
      var vm = this;
      if (vm._isMounted) {
        callHook(vm, 'beforeUpdate');
      }
      var prevEl = vm.$el;
      var prevVnode = vm._vnode;
      var prevActiveInstance = activeInstance;
      activeInstance = vm;
      vm._vnode = vnode;
      // Vue.prototype.__patch__ is injected in entry points
      // based on the rendering backend used.
      if (!prevVnode) {
        // initial render
        vm.$el = vm.__patch__(
          vm.$el, vnode, hydrating, false /* removeOnly */,
          vm.$options._parentElm,
          vm.$options._refElm
        );
      } else {
        // updates
        vm.$el = vm.__patch__(prevVnode, vnode);
      }
      activeInstance = prevActiveInstance;
      // update __vue__ reference
      if (prevEl) {
        prevEl.__vue__ = null;
      }
      if (vm.$el) {
        vm.$el.__vue__ = vm;
      }
      // if parent is an HOC, update its $el as well
      if (vm.$vnode && vm.$parent && vm.$vnode === vm.$parent._vnode) {
        vm.$parent.$el = vm.$el;
      }
      // updated hook is called by the scheduler to ensure that children are
      // updated in a parent's updated hook.
    };
  
    Vue.prototype.$forceUpdate = function () {
      var vm = this;
      if (vm._watcher) {
        vm._watcher.update();
      }
    };
  
    Vue.prototype.$destroy = function () {
      var vm = this;
      if (vm._isBeingDestroyed) {
        return
      }
      callHook(vm, 'beforeDestroy');
      vm._isBeingDestroyed = true;
      // remove self from parent
      var parent = vm.$parent;
      if (parent && !parent._isBeingDestroyed && !vm.$options.abstract) {
        remove(parent.$children, vm);
      }
      // teardown watchers
      if (vm._watcher) {
        vm._watcher.teardown();
      }
      var i = vm._watchers.length;
      while (i--) {
        vm._watchers[i].teardown();
      }
      // remove reference from data ob
      // frozen object may not have observer.
      if (vm._data.__ob__) {
        vm._data.__ob__.vmCount--;
      }
      // call the last hook...
      vm._isDestroyed = true;
      // invoke destroy hooks on current rendered tree
      vm.__patch__(vm._vnode, null);
      // fire destroyed hook
      callHook(vm, 'destroyed');
      // turn off all instance listeners.
      vm.$off();
      // remove __vue__ reference
      if (vm.$el) {
        vm.$el.__vue__ = null;
      }
      // remove reference to DOM nodes (prevents leak)
      vm.$options._parentElm = vm.$options._refElm = null;
    };
  }
  
  function mountComponent (
    vm,
    el,
    hydrating
  ) {
    vm.$el = el;
    if (!vm.$options.render) {
      vm.$options.render = createEmptyVNode;
      {
        /* istanbul ignore if */
        if ((vm.$options.template && vm.$options.template.charAt(0) !== '#') ||
          vm.$options.el || el) {
          warn(
            'You are using the runtime-only build of Vue where the template ' +
            'compiler is not available. Either pre-compile the templates into ' +
            'render functions, or use the compiler-included build.',
            vm
          );
        } else {
          warn(
            'Failed to mount component: template or render function not defined.',
            vm
          );
        }
      }
    }
    callHook(vm, 'beforeMount');
  
    var updateComponent;
    /* istanbul ignore if */
    if ("development" !== 'production' && config.performance && mark) {
      updateComponent = function () {
        var name = vm._name;
        var id = vm._uid;
        var startTag = "vue-perf-start:" + id;
        var endTag = "vue-perf-end:" + id;
  
        mark(startTag);
        var vnode = vm._render();
        mark(endTag);
        measure((name + " render"), startTag, endTag);
  
        mark(startTag);
        vm._update(vnode, hydrating);
        mark(endTag);
        measure((name + " patch"), startTag, endTag);
      };
    } else {
      updateComponent = function () {
        vm._update(vm._render(), hydrating);
      };
    }
  
    vm._watcher = new Watcher(vm, updateComponent, noop);
    hydrating = false;
  
    // manually mounted instance, call mounted on self
    // mounted is called for render-created child components in its inserted hook
    if (vm.$vnode == null) {
      vm._isMounted = true;
      callHook(vm, 'mounted');
    }
    return vm
  }
  
  function updateChildComponent (
    vm,
    propsData,
    listeners,
    parentVnode,
    renderChildren
  ) {
    // determine whether component has slot children
    // we need to do this before overwriting $options._renderChildren
    var hasChildren = !!(
      renderChildren ||               // has new static slots
      vm.$options._renderChildren ||  // has old static slots
      parentVnode.data.scopedSlots || // has new scoped slots
      vm.$scopedSlots !== emptyObject // has old scoped slots
    );
  
    vm.$options._parentVnode = parentVnode;
    vm.$vnode = parentVnode; // update vm's placeholder node without re-render
    if (vm._vnode) { // update child tree's parent
      vm._vnode.parent = parentVnode;
    }
    vm.$options._renderChildren = renderChildren;
  
    // update props
    if (propsData && vm.$options.props) {
      observerState.shouldConvert = false;
      {
        observerState.isSettingProps = true;
      }
      var props = vm._props;
      var propKeys = vm.$options._propKeys || [];
      for (var i = 0; i < propKeys.length; i++) {
        var key = propKeys[i];
        props[key] = validateProp(key, vm.$options.props, propsData, vm);
      }
      observerState.shouldConvert = true;
      {
        observerState.isSettingProps = false;
      }
      // keep a copy of raw propsData
      vm.$options.propsData = propsData;
    }
    // update listeners
    if (listeners) {
      var oldListeners = vm.$options._parentListeners;
      vm.$options._parentListeners = listeners;
      updateComponentListeners(vm, listeners, oldListeners);
    }
    // resolve slots + force update if has children
    if (hasChildren) {
      vm.$slots = resolveSlots(renderChildren, parentVnode.context);
      vm.$forceUpdate();
    }
  }
  
  function isInInactiveTree (vm) {
    while (vm && (vm = vm.$parent)) {
      if (vm._inactive) { return true }
    }
    return false
  }
  
  function activateChildComponent (vm, direct) {
    if (direct) {
      vm._directInactive = false;
      if (isInInactiveTree(vm)) {
        return
      }
    } else if (vm._directInactive) {
      return
    }
    if (vm._inactive || vm._inactive === null) {
      vm._inactive = false;
      for (var i = 0; i < vm.$children.length; i++) {
        activateChildComponent(vm.$children[i]);
      }
      callHook(vm, 'activated');
    }
  }
  
  function deactivateChildComponent (vm, direct) {
    if (direct) {
      vm._directInactive = true;
      if (isInInactiveTree(vm)) {
        return
      }
    }
    if (!vm._inactive) {
      vm._inactive = true;
      for (var i = 0; i < vm.$children.length; i++) {
        deactivateChildComponent(vm.$children[i]);
      }
      callHook(vm, 'deactivated');
    }
  }
  
  function callHook (vm, hook) {
    var handlers = vm.$options[hook];
    if (handlers) {
      for (var i = 0, j = handlers.length; i < j; i++) {
        try {
          handlers[i].call(vm);
        } catch (e) {
          handleError(e, vm, (hook + " hook"));
        }
      }
    }
    if (vm._hasHookEvent) {
      vm.$emit('hook:' + hook);
    }
  }
  
  /*  */
  
  
  var MAX_UPDATE_COUNT = 100;
  
  var queue = [];
  var activatedChildren = [];
  var has = {};
  var circular = {};
  var waiting = false;
  var flushing = false;
  var index = 0;
  
  /**
   * Reset the scheduler's state.
   */
  function resetSchedulerState () {
    queue.length = activatedChildren.length = 0;
    has = {};
    {
      circular = {};
    }
    waiting = flushing = false;
  }
  
  /**
   * Flush both queues and run the watchers.
   */
  function flushSchedulerQueue () {
    flushing = true;
    var watcher, id;
  
    // Sort queue before flush.
    // This ensures that:
    // 1. Components are updated from parent to child. (because parent is always
    //    created before the child)
    // 2. A component's user watchers are run before its render watcher (because
    //    user watchers are created before the render watcher)
    // 3. If a component is destroyed during a parent component's watcher run,
    //    its watchers can be skipped.
    queue.sort(function (a, b) { return a.id - b.id; });
  
    // do not cache length because more watchers might be pushed
    // as we run existing watchers
    for (index = 0; index < queue.length; index++) {
      watcher = queue[index];
      id = watcher.id;
      has[id] = null;
      watcher.run();
      // in dev build, check and stop circular updates.
      if ("development" !== 'production' && has[id] != null) {
        circular[id] = (circular[id] || 0) + 1;
        if (circular[id] > MAX_UPDATE_COUNT) {
          warn(
            'You may have an infinite update loop ' + (
              watcher.user
                ? ("in watcher with expression \"" + (watcher.expression) + "\"")
                : "in a component render function."
            ),
            watcher.vm
          );
          break
        }
      }
    }
  
    // keep copies of post queues before resetting state
    var activatedQueue = activatedChildren.slice();
    var updatedQueue = queue.slice();
  
    resetSchedulerState();
  
    // call component updated and activated hooks
    callActivatedHooks(activatedQueue);
    callUpdateHooks(updatedQueue);
  
    // devtool hook
    /* istanbul ignore if */
    if (devtools && config.devtools) {
      devtools.emit('flush');
    }
  }
  
  function callUpdateHooks (queue) {
    var i = queue.length;
    while (i--) {
      var watcher = queue[i];
      var vm = watcher.vm;
      if (vm._watcher === watcher && vm._isMounted) {
        callHook(vm, 'updated');
      }
    }
  }
  
  /**
   * Queue a kept-alive component that was activated during patch.
   * The queue will be processed after the entire tree has been patched.
   */
  function queueActivatedComponent (vm) {
    // setting _inactive to false here so that a render function can
    // rely on checking whether it's in an inactive tree (e.g. router-view)
    vm._inactive = false;
    activatedChildren.push(vm);
  }
  
  function callActivatedHooks (queue) {
    for (var i = 0; i < queue.length; i++) {
      queue[i]._inactive = true;
      activateChildComponent(queue[i], true /* true */);
    }
  }
  
  /**
   * Push a watcher into the watcher queue.
   * Jobs with duplicate IDs will be skipped unless it's
   * pushed when the queue is being flushed.
   */
  // watcher队列
  // 我们的watcher有从小到大的唯一id，在页面更新时，会按照一定的顺序依次更新，这里做了一个判断，如果watcher列表正在更新，则把新的watcher添加到对应的位置，并更新。否则，在下一个nextTick中执行flushSchedulerQueue。
  function queueWatcher (watcher) {
    var id = watcher.id;
    if (has[id] == null) {
      has[id] = true;
      if (!flushing) {
        queue.push(watcher);
      } else {
        // if already flushing, splice the watcher based on its id
        // if already past its id, it will be run next immediately.
        var i = queue.length - 1;
        while (i >= 0 && queue[i].id > watcher.id) {
          i--;
        }
        queue.splice(Math.max(i, index) + 1, 0, watcher);
      }
      // queue the flush
      if (!waiting) {
        waiting = true;
        nextTick(flushSchedulerQueue);
      }
    }
  }
  
  /*  */
  
  var uid$2 = 0;
  
  /**
   * A watcher parses an expression, collects dependencies,
   * and fires callback when the expression value changes.
   * This is used for both the $watch() api and directives.
   */
  var Watcher = function Watcher (
    vm,
    expOrFn,
    cb, // 回调
    options
  ) {
    this.vm = vm;
    // 存放订阅者实例
    vm._watchers.push(this);
    // options
    if (options) {
      this.deep = !!options.deep;
      this.user = !!options.user;
      this.lazy = !!options.lazy;
      this.sync = !!options.sync;
    } else {
      this.deep = this.user = this.lazy = this.sync = false;
    }
    this.cb = cb;
    this.id = ++uid$2; // uid for batching
    this.active = true;
    this.dirty = this.lazy; // for lazy watchers
    this.deps = [];
    this.newDeps = [];
    this.depIds = new _Set();
    this.newDepIds = new _Set();
    this.expression = expOrFn.toString();
    // parse expression for getter
    // 把表达式expOrFn解析成getter
    if (typeof expOrFn === 'function') {
      this.getter = expOrFn;
    } else {
      this.getter = parsePath(expOrFn);
      if (!this.getter) {
        this.getter = function () {};
        "development" !== 'production' && warn(
          "Failed watching path: \"" + expOrFn + "\" " +
          'Watcher only accepts simple dot-delimited paths. ' +
          'For full control, use a function instead.',
          vm
          );
        }
      }
    // 执行this.get
    this.value = this.lazy
      ? undefined
      : this.get();
  };
  
  /**
   * Evaluate the getter, and re-collect dependencies.
   */
  // 获得getter，并重新收集依赖项。  
  Watcher.prototype.get = function get () {
    // 将自身watcher观察者实例设置给Dep.target，用以依赖收集
    pushTarget(this);
    var value;
    var vm = this.vm;
     /*
      执行了getter操作，看似执行了渲染操作，其实是执行了依赖收集。
      在将Dep.target设置为自身观察者实例以后，执行getter操作。
      譬如说现在的的data中可能有a、b、c三个数据，getter渲染需要依赖a跟c，
      那么在执行getter的时候就会触发a跟c两个数据的getter函数，
      在getter函数中即可判断Dep.target是否存在然后完成依赖收集，
      将该观察者对象放入闭包中的Dep的subs中去。
    */
    if (this.user) {
      try {
        value = this.getter.call(vm, vm);
      } catch (e) {
        handleError(e, vm, ("getter for watcher \"" + (this.expression) + "\""));
      }
    } else {
      value = this.getter.call(vm, vm);
    }
    // "touch" every property so they are all tracked as
    // dependencies for deep watching
    // 深度递归监听
    if (this.deep) {
      traverse(value);
    }
    popTarget();
    this.cleanupDeps();
    return value
  };
  
  /**
   * Add a dependency to this directive.
   */
  Watcher.prototype.addDep = function addDep (dep) {
    var id = dep.id;
    if (!this.newDepIds.has(id)) {
      this.newDepIds.add(id);
      this.newDeps.push(dep);
      if (!this.depIds.has(id)) {
        dep.addSub(this);
      }
    }
  };
  
  /**
   * Clean up for dependency collection.
   */
  Watcher.prototype.cleanupDeps = function cleanupDeps () {
      var this$1 = this;
  
    var i = this.deps.length;
    while (i--) {
      var dep = this$1.deps[i];
      if (!this$1.newDepIds.has(dep.id)) {
        dep.removeSub(this$1);
      }
    }
    var tmp = this.depIds;
    this.depIds = this.newDepIds;
    this.newDepIds = tmp;
    this.newDepIds.clear();
    tmp = this.deps;
    this.deps = this.newDeps;
    this.newDeps = tmp;
    this.newDeps.length = 0;
  };
  
  /**
   * Subscriber interface.
   * Will be called when a dependency changes.
   */
  // 依赖项变化时触发
  Watcher.prototype.update = function update () {
    /* istanbul ignore else */
    if (this.lazy) {
      this.dirty = true;
    } else if (this.sync) {
      // 同步则直接渲染
      this.run();
    } else {
      // 异步推送到观察者队列中，由调度者调用
      queueWatcher(this);
    }
  };
  
  /**
   * Scheduler job interface.
   * Will be called by the scheduler.
   */
  // 更新模板
  Watcher.prototype.run = function run () {
    if (this.active) {
      // 调用this.get来获取修改之后的value值
      var value = this.get();
      if (
        value !== this.value ||
        // Deep watchers and watchers on Object/Arrays should fire even
        // when the value is the same, because the value may
        // have mutated.
        isObject(value) ||
        this.deep
      ) {
        // set new value
        // 设置新的值
        var oldValue = this.value;
        this.value = value;
        // 触发回调渲染视图
        if (this.user) {
          try {
            this.cb.call(this.vm, value, oldValue);
          } catch (e) {
            handleError(e, this.vm, ("callback for watcher \"" + (this.expression) + "\""));
          }
        } else {
          this.cb.call(this.vm, value, oldValue);
        }
      }
    }
  };
  
  /**
   * Evaluate the value of the watcher.
   * This only gets called for lazy watchers.
   */
  Watcher.prototype.evaluate = function evaluate () {
    this.value = this.get();
    this.dirty = false;
  };
  
  /**
   * Depend on all deps collected by this watcher.
   */
  Watcher.prototype.depend = function depend () {
      var this$1 = this;
  
    var i = this.deps.length;
    while (i--) {
      this$1.deps[i].depend();
    }
  };
  
  /**
   * Remove self from all dependencies' subscriber list.
   */
  Watcher.prototype.teardown = function teardown () {
      var this$1 = this;
  
    if (this.active) {
      // remove self from vm's watcher list
      // this is a somewhat expensive operation so we skip it
      // if the vm is being destroyed.
      if (!this.vm._isBeingDestroyed) {
        remove(this.vm._watchers, this);
      }
      var i = this.deps.length;
      while (i--) {
        this$1.deps[i].removeSub(this$1);
      }
      this.active = false;
    }
  };
  
  var seenObjects = new _Set();
  function traverse (val) {
    seenObjects.clear();
    _traverse(val, seenObjects);
  }
  
  function _traverse (val, seen) {
    var i, keys;
    var isA = Array.isArray(val);
    if ((!isA && !isObject(val)) || !Object.isExtensible(val)) {
      return
    }
    if (val.__ob__) {
      var depId = val.__ob__.dep.id;
      if (seen.has(depId)) {
        return
      }
      seen.add(depId);
    }
    if (isA) {
      i = val.length;
      while (i--) { _traverse(val[i], seen); }
    } else {
      keys = Object.keys(val);
      i = keys.length;
      while (i--) { _traverse(val[keys[i]], seen); }
    }
  }
  
  /*  */
  
  var sharedPropertyDefinition = {
    enumerable: true,
    configurable: true,
    get: noop,
    set: noop
  };
  // 添加代理
  // 将props上的数据代理到vm上
  // 我们就可以使用this.text代替this.props.text了
  function proxy (target, sourceKey, key) {
    sharedPropertyDefinition.get = function proxyGetter () {
      return this[sourceKey][key]
    };
    sharedPropertyDefinition.set = function proxySetter (val) {
      this[sourceKey][key] = val;
    };
    Object.defineProperty(target, key, sharedPropertyDefinition);
  }
  
  function initState (vm) {
    // 当前实例创建观察者
    vm._watchers = [];
    var opts = vm.$options;
    // 初始化Props
    if (opts.props) { initProps(vm, opts.props); }
    // 初始化Methods
    if (opts.methods) { initMethods(vm, opts.methods); }
    // 初始化data
    if (opts.data) {
      initData(vm);
    } else {
      observe(vm._data = {}, true /* asRootData */);
    }
    if (opts.computed) { initComputed(vm, opts.computed); }
    if (opts.watch) { initWatch(vm, opts.watch); }
  }
  
  var isReservedProp = {
    key: 1,
    ref: 1,
    slot: 1
  };
  
  function initProps (vm, propsOptions) {
    var propsData = vm.$options.propsData || {};
    var props = vm._props = {};
    // cache prop keys so that future props updates can iterate using Array
    // instead of dynamic object key enumeration.
    var keys = vm.$options._propKeys = [];
    var isRoot = !vm.$parent;
    // root instance props should be converted
    observerState.shouldConvert = isRoot;
    var loop = function ( key ) {
      keys.push(key);
      var value = validateProp(key, propsOptions, propsData, vm);
      /* istanbul ignore else */
      {
        if (isReservedProp[key] || config.isReservedAttr(key)) {
          warn(
            ("\"" + key + "\" is a reserved attribute and cannot be used as component prop."),
            vm
          );
        }
        defineReactive$$1(props, key, value, function () {
          if (vm.$parent && !observerState.isSettingProps) {
            warn(
              "Avoid mutating a prop directly since the value will be " +
              "overwritten whenever the parent component re-renders. " +
              "Instead, use a data or computed property based on the prop's " +
              "value. Prop being mutated: \"" + key + "\"",
              vm
            );
          }
        });
      }
      // static props are already proxied on the component's prototype
      // during Vue.extend(). We only need to proxy props defined at
      // instantiation here.
      if (!(key in vm)) {
        proxy(vm, "_props", key);
      }
    };
  
    for (var key in propsOptions) loop( key );
    observerState.shouldConvert = true;
  }
  
  function initData (vm) {
    // 拿到data
    var data = vm.$options.data;
    data = vm._data = typeof data === 'function'
      ? getData(data, vm)
      : data || {};
      // 判断对象
    if (!isPlainObject(data)) {
      data = {};
      "development" !== 'production' && warn(
        'data functions should return an object:\n' +
        'https://vuejs.org/v2/guide/components.html#data-Must-Be-a-Function',
        vm
      );
    }
    // proxy data on instance
    /// 遍历data对象
    var keys = Object.keys(data);
    var props = vm.$options.props;
    var i = keys.length;
    // 遍历data中的数据
    while (i--) {
      // 保证data中的key与props中的key不重复，props优先
      if (props && hasOwn(props, keys[i])) {
        "development" !== 'production' && warn(
          "The data property \"" + (keys[i]) + "\" is already declared as a prop. " +
          "Use prop default value instead.",
          vm
        );
        // 是否是保留字段
      } else if (!isReserved(keys[i])) {
        // 将data上面的属性代理到了vm实例上
        proxy(vm, "_data", keys[i]);
      }
    }
    // observe data
    // 开始对数据进行绑定，这里有尤大大的注释asRootData，
    // 这步作为根数据，下面会进行递归observe进行对深层对象的绑定
    observe(data, true /* asRootData */);
  }
  
  function getData (data, vm) {
    try {
      return data.call(vm)
    } catch (e) {
      handleError(e, vm, "data()");
      return {}
    }
  }
  
  var computedWatcherOptions = { lazy: true };
  
  function initComputed (vm, computed) {
    var watchers = vm._computedWatchers = Object.create(null);
  
    for (var key in computed) {
      var userDef = computed[key];
      var getter = typeof userDef === 'function' ? userDef : userDef.get;
      {
        if (getter === undefined) {
          warn(
            ("No getter function has been defined for computed property \"" + key + "\"."),
            vm
          );
          getter = noop;
        }
      }
      // create internal watcher for the computed property.
      watchers[key] = new Watcher(vm, getter, noop, computedWatcherOptions);
  
      // component-defined computed properties are already defined on the
      // component prototype. We only need to define computed properties defined
      // at instantiation here.
      if (!(key in vm)) {
        defineComputed(vm, key, userDef);
      } else {
        if (key in vm.$data) {
          warn(("The computed property \"" + key + "\" is already defined in data."), vm);
        } else if (vm.$options.props && key in vm.$options.props) {
          warn(("The computed property \"" + key + "\" is already defined as a prop."), vm);
        }
      }
    }
  }
  
  function defineComputed (target, key, userDef) {
    if (typeof userDef === 'function') {
      sharedPropertyDefinition.get = createComputedGetter(key);
      sharedPropertyDefinition.set = noop;
    } else {
      sharedPropertyDefinition.get = userDef.get
        ? userDef.cache !== false
          ? createComputedGetter(key)
          : userDef.get
        : noop;
      sharedPropertyDefinition.set = userDef.set
        ? userDef.set
        : noop;
    }
    Object.defineProperty(target, key, sharedPropertyDefinition);
  }
  
  function createComputedGetter (key) {
    return function computedGetter () {
      var watcher = this._computedWatchers && this._computedWatchers[key];
      if (watcher) {
        if (watcher.dirty) {
          watcher.evaluate();
        }
        if (Dep.target) {
          watcher.depend();
        }
        return watcher.value
      }
    }
  }
  
  function initMethods (vm, methods) {
    var props = vm.$options.props;
    for (var key in methods) {
      vm[key] = methods[key] == null ? noop : bind(methods[key], vm);
      {
        if (methods[key] == null) {
          warn(
            "method \"" + key + "\" has an undefined value in the component definition. " +
            "Did you reference the function correctly?",
            vm
          );
        }
        if (props && hasOwn(props, key)) {
          warn(
            ("method \"" + key + "\" has already been defined as a prop."),
            vm
          );
        }
      }
    }
  }
  
  function initWatch (vm, watch) {
    for (var key in watch) {
      var handler = watch[key];
      if (Array.isArray(handler)) {
        for (var i = 0; i < handler.length; i++) {
          createWatcher(vm, key, handler[i]);
        }
      } else {
        createWatcher(vm, key, handler);
      }
    }
  }
  
  function createWatcher (vm, key, handler) {
    var options;
    if (isPlainObject(handler)) {
      options = handler;
      handler = handler.handler;
    }
    if (typeof handler === 'string') {
      handler = vm[handler];
    }
    vm.$watch(key, handler, options);
  }
  
  function stateMixin (Vue) {
    // flow somehow has problems with directly declared definition object
    // when using Object.defineProperty, so we have to procedurally build up
    // the object here.
    var dataDef = {};
    dataDef.get = function () { return this._data };
    var propsDef = {};
    propsDef.get = function () { return this._props };
    {
      dataDef.set = function (newData) {
        warn(
          'Avoid replacing instance root $data. ' +
          'Use nested data properties instead.',
          this
        );
      };
      propsDef.set = function () {
        warn("$props is readonly.", this);
      };
    }
    Object.defineProperty(Vue.prototype, '$data', dataDef);
    Object.defineProperty(Vue.prototype, '$props', propsDef);
  
    Vue.prototype.$set = set;
    Vue.prototype.$delete = del;
  
    Vue.prototype.$watch = function (
      expOrFn,
      cb,
      options
    ) {
      var vm = this;
      options = options || {};
      options.user = true;
      var watcher = new Watcher(vm, expOrFn, cb, options);
      if (options.immediate) {
        cb.call(vm, watcher.value);
      }
      return function unwatchFn () {
        watcher.teardown();
      }
    };
  }
  
  /*  */
  
  function initProvide (vm) {
    var provide = vm.$options.provide;
    if (provide) {
      vm._provided = typeof provide === 'function'
        ? provide.call(vm)
        : provide;
    }
  }
  
  function initInjections (vm) {
    var result = resolveInject(vm.$options.inject, vm);
    if (result) {
      Object.keys(result).forEach(function (key) {
        /* istanbul ignore else */
        {
          defineReactive$$1(vm, key, result[key], function () {
            warn(
              "Avoid mutating an injected value directly since the changes will be " +
              "overwritten whenever the provided component re-renders. " +
              "injection being mutated: \"" + key + "\"",
              vm
            );
          });
        }
      });
    }
  }
  
  // 上面和这个方法共同将父组件_provided中定义的值通过inject注入到子组件，且这些属性不会被观察
  function resolveInject (inject, vm) {
    if (inject) {
      // inject is :any because flow is not smart enough to figure out cached
      // isArray here
      var isArray = Array.isArray(inject);
      var result = Object.create(null);
      var keys = isArray
        ? inject
        : hasSymbol
          ? Reflect.ownKeys(inject)
          : Object.keys(inject);
  
      for (var i = 0; i < keys.length; i++) {
        var key = keys[i];
        var provideKey = isArray ? key : inject[key];
        var source = vm;
        while (source) {
          if (source._provided && provideKey in source._provided) {
            result[key] = source._provided[provideKey];
            break
          }
          source = source.$parent;
        }
      }
      return result
    }
  }
  
  /*  */
  
  function createFunctionalComponent (
    Ctor,
    propsData,
    data,
    context,
    children
  ) {
    var props = {};
    var propOptions = Ctor.options.props;
    if (isDef(propOptions)) {
      for (var key in propOptions) {
        props[key] = validateProp(key, propOptions, propsData);
      }
    } else {
      if (isDef(data.attrs)) { mergeProps(props, data.attrs); }
      if (isDef(data.props)) { mergeProps(props, data.props); }
    }
    // ensure the createElement function in functional components
    // gets a unique context - this is necessary for correct named slot check
    var _context = Object.create(context);
    var h = function (a, b, c, d) { return createElement(_context, a, b, c, d, true); };
    var vnode = Ctor.options.render.call(null, h, {
      data: data,
      props: props,
      children: children,
      parent: context,
      listeners: data.on || {},
      injections: resolveInject(Ctor.options.inject, context),
      slots: function () { return resolveSlots(children, context); }
    });
    if (vnode instanceof VNode) {
      vnode.functionalContext = context;
      if (data.slot) {
        (vnode.data || (vnode.data = {})).slot = data.slot;
      }
    }
    return vnode
  }
  
  function mergeProps (to, from) {
    for (var key in from) {
      to[camelize(key)] = from[key];
    }
  }
  
  /*  */
  
  var componentVNodeHooks = {
    init: function init (
      vnode,
      hydrating,
      parentElm,
      refElm
    ) {
      if (!vnode.componentInstance || vnode.componentInstance._isDestroyed) {
        var child = vnode.componentInstance = createComponentInstanceForVnode(
          vnode,
          activeInstance,
          parentElm,
          refElm
        );
        child.$mount(hydrating ? vnode.elm : undefined, hydrating);
      } else if (vnode.data.keepAlive) {
        // kept-alive components, treat as a patch
        var mountedNode = vnode; // work around flow
        componentVNodeHooks.prepatch(mountedNode, mountedNode);
      }
    },
  
    prepatch: function prepatch (oldVnode, vnode) {
      var options = vnode.componentOptions;
      var child = vnode.componentInstance = oldVnode.componentInstance;
      updateChildComponent(
        child,
        options.propsData, // updated props
        options.listeners, // updated listeners
        vnode, // new parent vnode
        options.children // new children
      );
    },
  
    insert: function insert (vnode) {
      var context = vnode.context;
      var componentInstance = vnode.componentInstance;
      if (!componentInstance._isMounted) {
        componentInstance._isMounted = true;
        callHook(componentInstance, 'mounted');
      }
      if (vnode.data.keepAlive) {
        if (context._isMounted) {
          // vue-router#1212
          // During updates, a kept-alive component's child components may
          // change, so directly walking the tree here may call activated hooks
          // on incorrect children. Instead we push them into a queue which will
          // be processed after the whole patch process ended.
          queueActivatedComponent(componentInstance);
        } else {
          activateChildComponent(componentInstance, true /* direct */);
        }
      }
    },
  
    destroy: function destroy (vnode) {
      var componentInstance = vnode.componentInstance;
      if (!componentInstance._isDestroyed) {
        if (!vnode.data.keepAlive) {
          componentInstance.$destroy();
        } else {
          deactivateChildComponent(componentInstance, true /* direct */);
        }
      }
    }
  };
  
  var hooksToMerge = Object.keys(componentVNodeHooks);
  
  function createComponent (
    Ctor,
    data,
    context,
    children,
    tag
  ) {
    if (isUndef(Ctor)) {
      return
    }
  
    var baseCtor = context.$options._base;
  
    // plain options object: turn it into a constructor
    if (isObject(Ctor)) {
      Ctor = baseCtor.extend(Ctor);
    }
  
    // if at this stage it's not a constructor or an async component factory,
    // reject.
    if (typeof Ctor !== 'function') {
      {
        warn(("Invalid Component definition: " + (String(Ctor))), context);
      }
      return
    }
  
    // async component
    if (isUndef(Ctor.cid)) {
      Ctor = resolveAsyncComponent(Ctor, baseCtor, context);
      if (Ctor === undefined) {
        // return nothing if this is indeed an async component
        // wait for the callback to trigger parent update.
        return
      }
    }
  
    // resolve constructor options in case global mixins are applied after
    // component constructor creation
    resolveConstructorOptions(Ctor);
  
    data = data || {};
  
    // transform component v-model data into props & events
    if (isDef(data.model)) {
      transformModel(Ctor.options, data);
    }
  
    // extract props
    var propsData = extractPropsFromVNodeData(data, Ctor, tag);
  
    // functional component
    if (isTrue(Ctor.options.functional)) {
      return createFunctionalComponent(Ctor, propsData, data, context, children)
    }
  
    // extract listeners, since these needs to be treated as
    // child component listeners instead of DOM listeners
    var listeners = data.on;
    // replace with listeners with .native modifier
    data.on = data.nativeOn;
  
    if (isTrue(Ctor.options.abstract)) {
      // abstract components do not keep anything
      // other than props & listeners
      data = {};
    }
  
    // merge component management hooks onto the placeholder node
    mergeHooks(data);
  
    // return a placeholder vnode
    var name = Ctor.options.name || tag;
    var vnode = new VNode(
      ("vue-component-" + (Ctor.cid) + (name ? ("-" + name) : '')),
      data, undefined, undefined, undefined, context,
      { Ctor: Ctor, propsData: propsData, listeners: listeners, tag: tag, children: children }
    );
    return vnode
  }
  
  function createComponentInstanceForVnode (
    vnode, // we know it's MountedComponentVNode but flow doesn't
    parent, // activeInstance in lifecycle state
    parentElm,
    refElm
  ) {
    var vnodeComponentOptions = vnode.componentOptions;
    var options = {
      _isComponent: true,
      parent: parent,
      propsData: vnodeComponentOptions.propsData,
      _componentTag: vnodeComponentOptions.tag,
      _parentVnode: vnode,
      _parentListeners: vnodeComponentOptions.listeners,
      _renderChildren: vnodeComponentOptions.children,
      _parentElm: parentElm || null,
      _refElm: refElm || null
    };
    // check inline-template render functions
    var inlineTemplate = vnode.data.inlineTemplate;
    if (isDef(inlineTemplate)) {
      options.render = inlineTemplate.render;
      options.staticRenderFns = inlineTemplate.staticRenderFns;
    }
    return new vnodeComponentOptions.Ctor(options)
  }
  
  function mergeHooks (data) {
    if (!data.hook) {
      data.hook = {};
    }
    for (var i = 0; i < hooksToMerge.length; i++) {
      var key = hooksToMerge[i];
      var fromParent = data.hook[key];
      var ours = componentVNodeHooks[key];
      data.hook[key] = fromParent ? mergeHook$1(ours, fromParent) : ours;
    }
  }
  
  function mergeHook$1 (one, two) {
    return function (a, b, c, d) {
      one(a, b, c, d);
      two(a, b, c, d);
    }
  }
  
  // transform component v-model info (value and callback) into
  // prop and event handler respectively.
  function transformModel (options, data) {
    var prop = (options.model && options.model.prop) || 'value';
    var event = (options.model && options.model.event) || 'input';(data.props || (data.props = {}))[prop] = data.model.value;
    var on = data.on || (data.on = {});
    if (isDef(on[event])) {
      on[event] = [data.model.callback].concat(on[event]);
    } else {
      on[event] = data.model.callback;
    }
  }
  
  /*  */
  
  var SIMPLE_NORMALIZE = 1;
  var ALWAYS_NORMALIZE = 2;
  
  // wrapper function for providing a more flexible interface
  // without getting yelled at by flow
  function createElement (
    context,
    tag,
    data,
    children,
    normalizationType,
    alwaysNormalize
  ) {
    if (Array.isArray(data) || isPrimitive(data)) {
      normalizationType = children;
      children = data;
      data = undefined;
    }
    if (isTrue(alwaysNormalize)) {
      normalizationType = ALWAYS_NORMALIZE;
    }
    return _createElement(context, tag, data, children, normalizationType)
  }
  
  function _createElement (
    context,
    tag,
    data,
    children,
    normalizationType
  ) {
    if (isDef(data) && isDef((data).__ob__)) {
      "development" !== 'production' && warn(
        "Avoid using observed data object as vnode data: " + (JSON.stringify(data)) + "\n" +
        'Always create fresh vnode data objects in each render!',
        context
      );
      return createEmptyVNode()
    }
    if (!tag) {
      // in case of component :is set to falsy value
      return createEmptyVNode()
    }
    // support single function children as default scoped slot
    if (Array.isArray(children) &&
        typeof children[0] === 'function') {
      data = data || {};
      data.scopedSlots = { default: children[0] };
      children.length = 0;
    }
    if (normalizationType === ALWAYS_NORMALIZE) {
      children = normalizeChildren(children);
    } else if (normalizationType === SIMPLE_NORMALIZE) {
      children = simpleNormalizeChildren(children);
    }
    var vnode, ns;
    if (typeof tag === 'string') {
      var Ctor;
      ns = config.getTagNamespace(tag);
      if (config.isReservedTag(tag)) {
        // platform built-in elements
        vnode = new VNode(
          config.parsePlatformTagName(tag), data, children,
          undefined, undefined, context
        );
      } else if (isDef(Ctor = resolveAsset(context.$options, 'components', tag))) {
        // component
        vnode = createComponent(Ctor, data, context, children, tag);
      } else {
        // unknown or unlisted namespaced elements
        // check at runtime because it may get assigned a namespace when its
        // parent normalizes children
        vnode = new VNode(
          tag, data, children,
          undefined, undefined, context
        );
      }
    } else {
      // direct component options / constructor
      vnode = createComponent(tag, data, context, children);
    }
    if (vnode !== undefined) {
      if (ns) { applyNS(vnode, ns); }
      return vnode
    } else {
      return createEmptyVNode()
    }
  }
  
  function applyNS (vnode, ns) {
    vnode.ns = ns;
    if (vnode.tag === 'foreignObject') {
      // use default namespace inside foreignObject
      return
    }
    if (Array.isArray(vnode.children)) {
      for (var i = 0, l = vnode.children.length; i < l; i++) {
        var child = vnode.children[i];
        if (isDef(child.tag) && isUndef(child.ns)) {
          applyNS(child, ns);
        }
      }
    }
  }
  
  /*  */
  
  function renderList (
    val,
    render
  ) {
    var ret, i, l, keys, key;
    if (Array.isArray(val) || typeof val === 'string') {
      ret = new Array(val.length);
      for (i = 0, l = val.length; i < l; i++) {
        ret[i] = render(val[i], i);
      }
    } else if (typeof val === 'number') {
      ret = new Array(val);
      for (i = 0; i < val; i++) {
        ret[i] = render(i + 1, i);
      }
    } else if (isObject(val)) {
      keys = Object.keys(val);
      ret = new Array(keys.length);
      for (i = 0, l = keys.length; i < l; i++) {
        key = keys[i];
        ret[i] = render(val[key], key, i);
      }
    }
    return ret
  }
  
  /*  */
  
  function renderSlot (
    name,
    fallback,
    props,
    bindObject
  ) {
    var scopedSlotFn = this.$scopedSlots[name];
    if (scopedSlotFn) { // scoped slot
      props = props || {};
      if (bindObject) {
        extend(props, bindObject);
      }
      return scopedSlotFn(props) || fallback
    } else {
      var slotNodes = this.$slots[name];
      // warn duplicate slot usage
      if (slotNodes && "development" !== 'production') {
        slotNodes._rendered && warn(
          "Duplicate presence of slot \"" + name + "\" found in the same render tree " +
          "- this will likely cause render errors.",
          this
        );
        slotNodes._rendered = true;
      }
      return slotNodes || fallback
    }
  }
  
  /*  */
  
  function resolveFilter (id) {
    return resolveAsset(this.$options, 'filters', id, true) || identity
  }
  
  /*  */
  
  function checkKeyCodes (
    eventKeyCode,
    key,
    builtInAlias
  ) {
    var keyCodes = config.keyCodes[key] || builtInAlias;
    if (Array.isArray(keyCodes)) {
      return keyCodes.indexOf(eventKeyCode) === -1
    } else {
      return keyCodes !== eventKeyCode
    }
  }
  
  /*  */
  
  function bindObjectProps (
    data,
    tag,
    value,
    asProp
  ) {
    if (value) {
      if (!isObject(value)) {
        "development" !== 'production' && warn(
          'v-bind without argument expects an Object or Array value',
          this
        );
      } else {
        if (Array.isArray(value)) {
          value = toObject(value);
        }
        var hash;
        for (var key in value) {
          if (key === 'class' || key === 'style') {
            hash = data;
          } else {
            var type = data.attrs && data.attrs.type;
            hash = asProp || config.mustUseProp(tag, type, key)
              ? data.domProps || (data.domProps = {})
              : data.attrs || (data.attrs = {});
          }
          if (!(key in hash)) {
            hash[key] = value[key];
          }
        }
      }
    }
    return data
  }
  
  /*  */
  
  function renderStatic (
    index,
    isInFor
  ) {
    var tree = this._staticTrees[index];
    // if has already-rendered static tree and not inside v-for,
    // we can reuse the same tree by doing a shallow clone.
    if (tree && !isInFor) {
      return Array.isArray(tree)
        ? cloneVNodes(tree)
        : cloneVNode(tree)
    }
    // otherwise, render a fresh tree.
    tree = this._staticTrees[index] =
      this.$options.staticRenderFns[index].call(this._renderProxy);
    markStatic(tree, ("__static__" + index), false);
    return tree
  }
  
  /**
   * Runtime helper for v-once.
   * Effectively it means marking the node as static with a unique key.
   */
  function markOnce (
    tree,
    index,
    key
  ) {
    markStatic(tree, ("__once__" + index + (key ? ("_" + key) : "")), true);
    return tree
  }
  
  function markStatic (
    tree,
    key,
    isOnce
  ) {
    if (Array.isArray(tree)) {
      for (var i = 0; i < tree.length; i++) {
        if (tree[i] && typeof tree[i] !== 'string') {
          markStaticNode(tree[i], (key + "_" + i), isOnce);
        }
      }
    } else {
      markStaticNode(tree, key, isOnce);
    }
  }
  
  function markStaticNode (node, key, isOnce) {
    node.isStatic = true;
    node.key = key;
    node.isOnce = isOnce;
  }
  
  /*  */
  
  function initRender (vm) {
    vm._vnode = null; // the root of the child tree
    vm._staticTrees = null;
    var parentVnode = vm.$vnode = vm.$options._parentVnode; // the placeholder node in parent tree
    var renderContext = parentVnode && parentVnode.context;
    vm.$slots = resolveSlots(vm.$options._renderChildren, renderContext);
    vm.$scopedSlots = emptyObject;
    // bind the createElement fn to this instance
    // so that we get proper render context inside it.
    // args order: tag, data, children, normalizationType, alwaysNormalize
    // internal version is used by render functions compiled from templates
    //将createElement fn绑定到这个实例  
    //使我们在它里面得到适当的渲染上下文。  
    //参数顺序:tag, data, children, normalizationType, alwaynormalize  
    //内部版本由模板编译的呈现函数使用  
    vm._c = function (a, b, c, d) { return createElement(vm, a, b, c, d, false); };
    // normalization is always applied for the public version, used in
    // user-written render functions.
    //在公共版本中使用  
    //用户编写的呈现函数。 
    vm.$createElement = function (a, b, c, d) { return createElement(vm, a, b, c, d, true); };
  }
  
  function renderMixin (Vue) {
    Vue.prototype.$nextTick = function (fn) {
      return nextTick(fn, this)
    };
  
    Vue.prototype._render = function () {
      var vm = this;
      var ref = vm.$options;
      var render = ref.render;
      var staticRenderFns = ref.staticRenderFns;
      var _parentVnode = ref._parentVnode;
  
      if (vm._isMounted) {
        // clone slot nodes on re-renders
        for (var key in vm.$slots) {
          vm.$slots[key] = cloneVNodes(vm.$slots[key]);
        }
      }
  
      vm.$scopedSlots = (_parentVnode && _parentVnode.data.scopedSlots) || emptyObject;
  
      if (staticRenderFns && !vm._staticTrees) {
        vm._staticTrees = [];
      }
      // set parent vnode. this allows render functions to have access
      // to the data on the placeholder node.
      vm.$vnode = _parentVnode;
      // render self
      var vnode;
      try {
        vnode = render.call(vm._renderProxy, vm.$createElement);
      } catch (e) {
        handleError(e, vm, "render function");
        // return error render result,
        // or previous vnode to prevent render error causing blank component
        /* istanbul ignore else */
        {
          vnode = vm.$options.renderError
            ? vm.$options.renderError.call(vm._renderProxy, vm.$createElement, e)
            : vm._vnode;
        }
      }
      // return empty vnode in case the render function errored out
      if (!(vnode instanceof VNode)) {
        if ("development" !== 'production' && Array.isArray(vnode)) {
          warn(
            'Multiple root nodes returned from render function. Render function ' +
            'should return a single root node.',
            vm
          );
        }
        vnode = createEmptyVNode();
      }
      // set parent
      vnode.parent = _parentVnode;
      return vnode
    };
  
    // internal render helpers.
    // these are exposed on the instance prototype to reduce generated render
    // code size.
    Vue.prototype._o = markOnce;
    Vue.prototype._n = toNumber;
    Vue.prototype._s = _toString;
    Vue.prototype._l = renderList;
    Vue.prototype._t = renderSlot;
    Vue.prototype._q = looseEqual;
    Vue.prototype._i = looseIndexOf;
    Vue.prototype._m = renderStatic;
    Vue.prototype._f = resolveFilter;
    Vue.prototype._k = checkKeyCodes;
    Vue.prototype._b = bindObjectProps;
    Vue.prototype._v = createTextVNode;
    Vue.prototype._e = createEmptyVNode;
    Vue.prototype._u = resolveScopedSlots;
  }
  
  /*  */
  
  var uid$1 = 0;
  
  function initMixin (Vue) {
    Vue.prototype._init = function (options) {
      var vm = this;
      // a uid
      vm._uid = uid$1++;
  
      var startTag, endTag;
      /* istanbul ignore if */
      // 性能统计相关
      if ("development" !== 'production' && config.performance && mark) {
        startTag = "vue-perf-init:" + (vm._uid);
        endTag = "vue-perf-end:" + (vm._uid);
        mark(startTag);
      }
  
      // a flag to avoid this being observed
      // 监听对象变化时用于过滤vue实例
      // 可在log(vue实例)的$root下面找到
      vm._isVue = true;
      // merge options
      // 合并options
      // _isComponent是只有在内部创建组件时才会加上true
      if (options && options._isComponent) {
        // optimize internal component instantiation
        // since dynamic options merging is pretty slow, and none of the
        // internal component options needs special treatment.
        initInternalComponent(vm, options);
      } else {
        vm.$options = mergeOptions(
          resolveConstructorOptions(vm.constructor),
          options || {},
          vm
        );
      }
      /* istanbul ignore else */
      {
        initProxy(vm);
      }
      // expose real self
      vm._self = vm;
      // 初始化生命周期
      initLifecycle(vm);
      // 初始化事件相关的属性
      initEvents(vm);
      // 这里给vm添加了一些虚拟dom、slot等相关的属性和方法。
      initRender(vm);
      // 调用beforeCreate钩子
      callHook(vm, 'beforeCreate');
      // 处理注入
      initInjections(vm); // resolve injections before data/props
      initState(vm);
      initProvide(vm); // resolve provide after data/props
      // 调用created钩子
      // create阶段，基本就是对传入数据的格式化、数据的双向绑定、以及一些属性的初始化
      callHook(vm, 'created');
  
      /* istanbul ignore if */
      // 性能相关
      if ("development" !== 'production' && config.performance && mark) {
        vm._name = formatComponentName(vm, false);
        mark(endTag);
        measure(((vm._name) + " init"), startTag, endTag);
      }
  
      if (vm.$options.el) {
        vm.$mount(vm.$options.el);
      }
    };
  }
  
  function initInternalComponent (vm, options) {
    var opts = vm.$options = Object.create(vm.constructor.options);
    // doing this because it's faster than dynamic enumeration.
    opts.parent = options.parent;
    opts.propsData = options.propsData;
    opts._parentVnode = options._parentVnode;
    opts._parentListeners = options._parentListeners;
    opts._renderChildren = options._renderChildren;
    opts._componentTag = options._componentTag;
    opts._parentElm = options._parentElm;
    opts._refElm = options._refElm;
    if (options.render) {
      opts.render = options.render;
      opts.staticRenderFns = options.staticRenderFns;
    }
  }
  
  function resolveConstructorOptions (Ctor) {
    var options = Ctor.options;
    // 有super属性，说明Ctor是通过Vue.extend()方法创建的子类
    if (Ctor.super) {
      // Ctor就是vm.constructor也就是Vue对象，在/src/core/global-api/index文件中，我们给Vue添加了一些全局的属性或方法。
      var superOptions = resolveConstructorOptions(Ctor.super);
      var cachedSuperOptions = Ctor.superOptions;
      if (superOptions !== cachedSuperOptions) {
        // super option changed,
        // need to resolve new options.
        Ctor.superOptions = superOptions;
        // check if there are any late-modified/attached options (#4976)
        var modifiedOptions = resolveModifiedOptions(Ctor);
        // update base extend options
        if (modifiedOptions) {
          extend(Ctor.extendOptions, modifiedOptions);
        }
        options = Ctor.options = mergeOptions(superOptions, Ctor.extendOptions);
        if (options.name) {
          options.components[options.name] = Ctor;
        }
      }
    }
    return options
  }
  
  function resolveModifiedOptions (Ctor) {
    var modified;
    var latest = Ctor.options;
    var extended = Ctor.extendOptions;
    var sealed = Ctor.sealedOptions;
    for (var key in latest) {
      if (latest[key] !== sealed[key]) {
        if (!modified) { modified = {}; }
        modified[key] = dedupe(latest[key], extended[key], sealed[key]);
      }
    }
    return modified
  }
  
  function dedupe (latest, extended, sealed) {
    // compare latest and sealed to ensure lifecycle hooks won't be duplicated
    // between merges
    if (Array.isArray(latest)) {
      var res = [];
      sealed = Array.isArray(sealed) ? sealed : [sealed];
      extended = Array.isArray(extended) ? extended : [extended];
      for (var i = 0; i < latest.length; i++) {
        // push original options and not sealed options to exclude duplicated options
        if (extended.indexOf(latest[i]) >= 0 || sealed.indexOf(latest[i]) < 0) {
          res.push(latest[i]);
        }
      }
      return res
    } else {
      return latest
    }
  }
  
  function Vue$3 (options) {
    if ("development" !== 'production' &&
      !(this instanceof Vue$3)) {
      warn('Vue is a constructor and should be called with the `new` keyword');
    }
    // 此方法是在`initMixin`中添加的
    this._init(options);
  }
  
  initMixin(Vue$3);
  stateMixin(Vue$3);
  eventsMixin(Vue$3);
  lifecycleMixin(Vue$3);
  renderMixin(Vue$3);
  
  /*  */
  
  function initUse (Vue) {
    Vue.use = function (plugin) {
      /* istanbul ignore if */
      if (plugin.installed) {
        return
      }
      // additional parameters
      var args = toArray(arguments, 1);
      args.unshift(this);
      if (typeof plugin.install === 'function') {
        plugin.install.apply(plugin, args);
      } else if (typeof plugin === 'function') {
        plugin.apply(null, args);
      }
      plugin.installed = true;
      return this
    };
  }
  
  /*  */
  
  function initMixin$1 (Vue) {
    Vue.mixin = function (mixin) {
      this.options = mergeOptions(this.options, mixin);
    };
  }
  
  /*  */
  
  function initExtend (Vue) {
    /**
     * Each instance constructor, including Vue, has a unique
     * cid. This enables us to create wrapped "child
     * constructors" for prototypal inheritance and cache them.
     */
    Vue.cid = 0;
    var cid = 1;
  
    /**
     * Class inheritance
     */
    Vue.extend = function (extendOptions) {
      extendOptions = extendOptions || {};
      var Super = this;
      var SuperId = Super.cid;
      var cachedCtors = extendOptions._Ctor || (extendOptions._Ctor = {});
      if (cachedCtors[SuperId]) {
        return cachedCtors[SuperId]
      }
  
      var name = extendOptions.name || Super.options.name;
      {
        if (!/^[a-zA-Z][\w-]*$/.test(name)) {
          warn(
            'Invalid component name: "' + name + '". Component names ' +
            'can only contain alphanumeric characters and the hyphen, ' +
            'and must start with a letter.'
          );
        }
      }
  
      var Sub = function VueComponent (options) {
        this._init(options);
      };
      Sub.prototype = Object.create(Super.prototype);
      Sub.prototype.constructor = Sub;
      Sub.cid = cid++;
      Sub.options = mergeOptions(
        Super.options,
        extendOptions
      );
      Sub['super'] = Super;
  
      // For props and computed properties, we define the proxy getters on
      // the Vue instances at extension time, on the extended prototype. This
      // avoids Object.defineProperty calls for each instance created.
      if (Sub.options.props) {
        initProps$1(Sub);
      }
      if (Sub.options.computed) {
        initComputed$1(Sub);
      }
  
      // allow further extension/mixin/plugin usage
      Sub.extend = Super.extend;
      Sub.mixin = Super.mixin;
      Sub.use = Super.use;
  
      // create asset registers, so extended classes
      // can have their private assets too.
      ASSET_TYPES.forEach(function (type) {
        Sub[type] = Super[type];
      });
      // enable recursive self-lookup
      if (name) {
        Sub.options.components[name] = Sub;
      }
  
      // keep a reference to the super options at extension time.
      // later at instantiation we can check if Super's options have
      // been updated.
      Sub.superOptions = Super.options;
      Sub.extendOptions = extendOptions;
      Sub.sealedOptions = extend({}, Sub.options);
  
      // cache constructor
      cachedCtors[SuperId] = Sub;
      return Sub
    };
  }
  
  function initProps$1 (Comp) {
    var props = Comp.options.props;
    for (var key in props) {
      proxy(Comp.prototype, "_props", key);
    }
  }
  
  function initComputed$1 (Comp) {
    var computed = Comp.options.computed;
    for (var key in computed) {
      defineComputed(Comp.prototype, key, computed[key]);
    }
  }
  
  /*  */
  
  function initAssetRegisters (Vue) {
    /**
     * Create asset registration methods.
     */
    ASSET_TYPES.forEach(function (type) {
      Vue[type] = function (
        id,
        definition
      ) {
        if (!definition) {
          return this.options[type + 's'][id]
        } else {
          /* istanbul ignore if */
          {
            if (type === 'component' && config.isReservedTag(id)) {
              warn(
                'Do not use built-in or reserved HTML elements as component ' +
                'id: ' + id
              );
            }
          }
          if (type === 'component' && isPlainObject(definition)) {
            definition.name = definition.name || id;
            definition = this.options._base.extend(definition);
          }
          if (type === 'directive' && typeof definition === 'function') {
            definition = { bind: definition, update: definition };
          }
          this.options[type + 's'][id] = definition;
          return definition
        }
      };
    });
  }
  
  /*  */
  
  var patternTypes = [String, RegExp];
  
  function getComponentName (opts) {
    return opts && (opts.Ctor.options.name || opts.tag)
  }
  
  function matches (pattern, name) {
    if (typeof pattern === 'string') {
      return pattern.split(',').indexOf(name) > -1
    } else if (isRegExp(pattern)) {
      return pattern.test(name)
    }
    /* istanbul ignore next */
    return false
  }
  
  function pruneCache (cache, current, filter) {
    for (var key in cache) {
      var cachedNode = cache[key];
      if (cachedNode) {
        var name = getComponentName(cachedNode.componentOptions);
        if (name && !filter(name)) {
          if (cachedNode !== current) {
            pruneCacheEntry(cachedNode);
          }
          cache[key] = null;
        }
      }
    }
  }
  
  function pruneCacheEntry (vnode) {
    if (vnode) {
      vnode.componentInstance.$destroy();
    }
  }
  
  var KeepAlive = {
    name: 'keep-alive',
    abstract: true,
  
    props: {
      include: patternTypes,
      exclude: patternTypes
    },
  
    created: function created () {
      this.cache = Object.create(null);
    },
  
    destroyed: function destroyed () {
      var this$1 = this;
  
      for (var key in this$1.cache) {
        pruneCacheEntry(this$1.cache[key]);
      }
    },
  
    watch: {
      include: function include (val) {
        pruneCache(this.cache, this._vnode, function (name) { return matches(val, name); });
      },
      exclude: function exclude (val) {
        pruneCache(this.cache, this._vnode, function (name) { return !matches(val, name); });
      }
    },
  
    render: function render () {
      var vnode = getFirstComponentChild(this.$slots.default);
      var componentOptions = vnode && vnode.componentOptions;
      if (componentOptions) {
        // check pattern
        var name = getComponentName(componentOptions);
        if (name && (
          (this.include && !matches(this.include, name)) ||
          (this.exclude && matches(this.exclude, name))
        )) {
          return vnode
        }
        var key = vnode.key == null
          // same constructor may get registered as different local components
          // so cid alone is not enough (#3269)
          ? componentOptions.Ctor.cid + (componentOptions.tag ? ("::" + (componentOptions.tag)) : '')
          : vnode.key;
        if (this.cache[key]) {
          vnode.componentInstance = this.cache[key].componentInstance;
        } else {
          this.cache[key] = vnode;
        }
        vnode.data.keepAlive = true;
      }
      return vnode
    }
  };
  
  var builtInComponents = {
    KeepAlive: KeepAlive
  };
  
  /*  */
  
  function initGlobalAPI (Vue) {
    // config
    var configDef = {};
    configDef.get = function () { return config; };
    {
      configDef.set = function () {
        warn(
          'Do not replace the Vue.config object, set individual fields instead.'
        );
      };
    }
    Object.defineProperty(Vue, 'config', configDef);
  
    // exposed util methods.
    // NOTE: these are not considered part of the public API - avoid relying on
    // them unless you are aware of the risk.
    Vue.util = {
      warn: warn,
      extend: extend,
      mergeOptions: mergeOptions,
      defineReactive: defineReactive$$1
    };
  
    Vue.set = set;
    Vue.delete = del;
    Vue.nextTick = nextTick;
  
    Vue.options = Object.create(null);
    ASSET_TYPES.forEach(function (type) {
      Vue.options[type + 's'] = Object.create(null);
    });
  
    // this is used to identify the "base" constructor to extend all plain-object
    // components with in Weex's multi-instance scenarios.
    Vue.options._base = Vue;
  
    extend(Vue.options.components, builtInComponents);
  
    initUse(Vue);
    initMixin$1(Vue);
    initExtend(Vue);
    initAssetRegisters(Vue);
  }
  
  initGlobalAPI(Vue$3);
  
  Object.defineProperty(Vue$3.prototype, '$isServer', {
    get: isServerRendering
  });
  
  Vue$3.version = '2.3.0';
  
  /*  */
  
  var isReservedAttr = makeMap('style,class');
  
  // attributes that should be using props for binding
  var acceptValue = makeMap('input,textarea,option,select');
  var mustUseProp = function (tag, type, attr) {
    return (
      (attr === 'value' && acceptValue(tag)) && type !== 'button' ||
      (attr === 'selected' && tag === 'option') ||
      (attr === 'checked' && tag === 'input') ||
      (attr === 'muted' && tag === 'video')
    )
  };
  
  var isEnumeratedAttr = makeMap('contenteditable,draggable,spellcheck');
  
  var isBooleanAttr = makeMap(
    'allowfullscreen,async,autofocus,autoplay,checked,compact,controls,declare,' +
    'default,defaultchecked,defaultmuted,defaultselected,defer,disabled,' +
    'enabled,formnovalidate,hidden,indeterminate,inert,ismap,itemscope,loop,multiple,' +
    'muted,nohref,noresize,noshade,novalidate,nowrap,open,pauseonexit,readonly,' +
    'required,reversed,scoped,seamless,selected,sortable,translate,' +
    'truespeed,typemustmatch,visible'
  );
  
  var xlinkNS = 'http://www.w3.org/1999/xlink';
  
  var isXlink = function (name) {
    return name.charAt(5) === ':' && name.slice(0, 5) === 'xlink'
  };
  
  var getXlinkProp = function (name) {
    return isXlink(name) ? name.slice(6, name.length) : ''
  };
  
  var isFalsyAttrValue = function (val) {
    return val == null || val === false
  };
  
  /*  */
  
  function genClassForVnode (vnode) {
    var data = vnode.data;
    var parentNode = vnode;
    var childNode = vnode;
    while (isDef(childNode.componentInstance)) {
      childNode = childNode.componentInstance._vnode;
      if (childNode.data) {
        data = mergeClassData(childNode.data, data);
      }
    }
    while (isDef(parentNode = parentNode.parent)) {
      if (parentNode.data) {
        data = mergeClassData(data, parentNode.data);
      }
    }
    return genClassFromData(data)
  }
  
  function mergeClassData (child, parent) {
    return {
      staticClass: concat(child.staticClass, parent.staticClass),
      class: isDef(child.class)
        ? [child.class, parent.class]
        : parent.class
    }
  }
  
  function genClassFromData (data) {
    var dynamicClass = data.class;
    var staticClass = data.staticClass;
    if (isDef(staticClass) || isDef(dynamicClass)) {
      return concat(staticClass, stringifyClass(dynamicClass))
    }
    /* istanbul ignore next */
    return ''
  }
  
  function concat (a, b) {
    return a ? b ? (a + ' ' + b) : a : (b || '')
  }
  
  function stringifyClass (value) {
    if (isUndef(value)) {
      return ''
    }
    if (typeof value === 'string') {
      return value
    }
    var res = '';
    if (Array.isArray(value)) {
      var stringified;
      for (var i = 0, l = value.length; i < l; i++) {
        if (isDef(value[i])) {
          if (isDef(stringified = stringifyClass(value[i])) && stringified !== '') {
            res += stringified + ' ';
          }
        }
      }
      return res.slice(0, -1)
    }
    if (isObject(value)) {
      for (var key in value) {
        if (value[key]) { res += key + ' '; }
      }
      return res.slice(0, -1)
    }
    /* istanbul ignore next */
    return res
  }
  
  /*  */
  
  var namespaceMap = {
    svg: 'http://www.w3.org/2000/svg',
    math: 'http://www.w3.org/1998/Math/MathML'
  };
  
  var isHTMLTag = makeMap(
    'html,body,base,head,link,meta,style,title,' +
    'address,article,aside,footer,header,h1,h2,h3,h4,h5,h6,hgroup,nav,section,' +
    'div,dd,dl,dt,figcaption,figure,hr,img,li,main,ol,p,pre,ul,' +
    'a,b,abbr,bdi,bdo,br,cite,code,data,dfn,em,i,kbd,mark,q,rp,rt,rtc,ruby,' +
    's,samp,small,span,strong,sub,sup,time,u,var,wbr,area,audio,map,track,video,' +
    'embed,object,param,source,canvas,script,noscript,del,ins,' +
    'caption,col,colgroup,table,thead,tbody,td,th,tr,' +
    'button,datalist,fieldset,form,input,label,legend,meter,optgroup,option,' +
    'output,progress,select,textarea,' +
    'details,dialog,menu,menuitem,summary,' +
    'content,element,shadow,template'
  );
  
  // this map is intentionally selective, only covering SVG elements that may
  // contain child elements.
  var isSVG = makeMap(
    'svg,animate,circle,clippath,cursor,defs,desc,ellipse,filter,font-face,' +
    'foreignObject,g,glyph,image,line,marker,mask,missing-glyph,path,pattern,' +
    'polygon,polyline,rect,switch,symbol,text,textpath,tspan,use,view',
    true
  );
  
  var isPreTag = function (tag) { return tag === 'pre'; };
  
  var isReservedTag = function (tag) {
    return isHTMLTag(tag) || isSVG(tag)
  };
  
  function getTagNamespace (tag) {
    if (isSVG(tag)) {
      return 'svg'
    }
    // basic support for MathML
    // note it doesn't support other MathML elements being component roots
    if (tag === 'math') {
      return 'math'
    }
  }
  
  var unknownElementCache = Object.create(null);
  function isUnknownElement (tag) {
    /* istanbul ignore if */
    if (!inBrowser) {
      return true
    }
    if (isReservedTag(tag)) {
      return false
    }
    tag = tag.toLowerCase();
    /* istanbul ignore if */
    if (unknownElementCache[tag] != null) {
      return unknownElementCache[tag]
    }
    var el = document.createElement(tag);
    if (tag.indexOf('-') > -1) {
      // http://stackoverflow.com/a/28210364/1070244
      return (unknownElementCache[tag] = (
        el.constructor === window.HTMLUnknownElement ||
        el.constructor === window.HTMLElement
      ))
    } else {
      return (unknownElementCache[tag] = /HTMLUnknownElement/.test(el.toString()))
    }
  }
  
  /*  */
  
  function query (el) {
    if (typeof el === 'string') {
      var selected = document.querySelector(el);
      if (!selected) {
        "development" !== 'production' && warn(
          'Cannot find element: ' + el
        );
        return document.createElement('div')
      }
      return selected
    } else {
      return el
    }
  }
  
  /*  */
  
  function createElement$1 (tagName, vnode) {
    var elm = document.createElement(tagName);
    if (tagName !== 'select') {
      return elm
    }
    // false or null will remove the attribute but undefined will not
    if (vnode.data && vnode.data.attrs && vnode.data.attrs.multiple !== undefined) {
      elm.setAttribute('multiple', 'multiple');
    }
    return elm
  }
  
  function createElementNS (namespace, tagName) {
    return document.createElementNS(namespaceMap[namespace], tagName)
  }
  
  function createTextNode (text) {
    return document.createTextNode(text)
  }
  
  function createComment (text) {
    return document.createComment(text)
  }
  
  function insertBefore (parentNode, newNode, referenceNode) {
    parentNode.insertBefore(newNode, referenceNode);
  }
  
  function removeChild (node, child) {
    node.removeChild(child);
  }
  
  function appendChild (node, child) {
    node.appendChild(child);
  }
  
  function parentNode (node) {
    return node.parentNode
  }
  
  function nextSibling (node) {
    return node.nextSibling
  }
  
  function tagName (node) {
    return node.tagName
  }
  
  function setTextContent (node, text) {
    node.textContent = text;
  }
  
  function setAttribute (node, key, val) {
    node.setAttribute(key, val);
  }
  
  
  var nodeOps = Object.freeze({
  	createElement: createElement$1,
  	createElementNS: createElementNS,
  	createTextNode: createTextNode,
  	createComment: createComment,
  	insertBefore: insertBefore,
  	removeChild: removeChild,
  	appendChild: appendChild,
  	parentNode: parentNode,
  	nextSibling: nextSibling,
  	tagName: tagName,
  	setTextContent: setTextContent,
  	setAttribute: setAttribute
  });
  
  /*  */
  
  var ref = {
    create: function create (_, vnode) {
      registerRef(vnode);
    },
    update: function update (oldVnode, vnode) {
      if (oldVnode.data.ref !== vnode.data.ref) {
        registerRef(oldVnode, true);
        registerRef(vnode);
      }
    },
    destroy: function destroy (vnode) {
      registerRef(vnode, true);
    }
  };
  
  function registerRef (vnode, isRemoval) {
    var key = vnode.data.ref;
    if (!key) { return }
  
    var vm = vnode.context;
    var ref = vnode.componentInstance || vnode.elm;
    var refs = vm.$refs;
    if (isRemoval) {
      if (Array.isArray(refs[key])) {
        remove(refs[key], ref);
      } else if (refs[key] === ref) {
        refs[key] = undefined;
      }
    } else {
      if (vnode.data.refInFor) {
        if (Array.isArray(refs[key]) && refs[key].indexOf(ref) < 0) {
          refs[key].push(ref);
        } else {
          refs[key] = [ref];
        }
      } else {
        refs[key] = ref;
      }
    }
  }
  
  /**
   * Virtual DOM patching algorithm based on Snabbdom by
   * Simon Friis Vindum (@paldepind)
   * Licensed under the MIT License
   * https://github.com/paldepind/snabbdom/blob/master/LICENSE
   *
   * modified by Evan You (@yyx990803)
   *
  
  /*
   * Not type-checking this because this file is perf-critical and the cost
   * of making flow understand it is not worth it.
   */
  
  var emptyNode = new VNode('', {}, []);
  
  var hooks = ['create', 'activate', 'update', 'remove', 'destroy'];
  
  function sameVnode (a, b) {
    return (
      a.key === b.key &&
      a.tag === b.tag &&
      a.isComment === b.isComment &&
      isDef(a.data) === isDef(b.data) &&
      sameInputType(a, b)
    )
  }
  
  // Some browsers do not support dynamically changing type for <input>
  // so they need to be treated as different nodes
  function sameInputType (a, b) {
    if (a.tag !== 'input') { return true }
    var i;
    var typeA = isDef(i = a.data) && isDef(i = i.attrs) && i.type;
    var typeB = isDef(i = b.data) && isDef(i = i.attrs) && i.type;
    return typeA === typeB
  }
  
  function createKeyToOldIdx (children, beginIdx, endIdx) {
    var i, key;
    var map = {};
    for (i = beginIdx; i <= endIdx; ++i) {
      key = children[i].key;
      if (isDef(key)) { map[key] = i; }
    }
    return map
  }
  
  function createPatchFunction (backend) {
    var i, j;
    var cbs = {};
  
    var modules = backend.modules;
    var nodeOps = backend.nodeOps;
  
    for (i = 0; i < hooks.length; ++i) {
      cbs[hooks[i]] = [];
      for (j = 0; j < modules.length; ++j) {
        if (isDef(modules[j][hooks[i]])) {
          cbs[hooks[i]].push(modules[j][hooks[i]]);
        }
      }
    }
  
    function emptyNodeAt (elm) {
      return new VNode(nodeOps.tagName(elm).toLowerCase(), {}, [], undefined, elm)
    }
  
    function createRmCb (childElm, listeners) {
      function remove$$1 () {
        if (--remove$$1.listeners === 0) {
          removeNode(childElm);
        }
      }
      remove$$1.listeners = listeners;
      return remove$$1
    }
  
    function removeNode (el) {
      var parent = nodeOps.parentNode(el);
      // element may have already been removed due to v-html / v-text
      if (isDef(parent)) {
        nodeOps.removeChild(parent, el);
      }
    }
  
    var inPre = 0;
    function createElm (vnode, insertedVnodeQueue, parentElm, refElm, nested) {
      vnode.isRootInsert = !nested; // for transition enter check
      if (createComponent(vnode, insertedVnodeQueue, parentElm, refElm)) {
        return
      }
  
      var data = vnode.data;
      var children = vnode.children;
      var tag = vnode.tag;
      if (isDef(tag)) {
        {
          if (data && data.pre) {
            inPre++;
          }
          if (
            !inPre &&
            !vnode.ns &&
            !(config.ignoredElements.length && config.ignoredElements.indexOf(tag) > -1) &&
            config.isUnknownElement(tag)
          ) {
            warn(
              'Unknown custom element: <' + tag + '> - did you ' +
              'register the component correctly? For recursive components, ' +
              'make sure to provide the "name" option.',
              vnode.context
            );
          }
        }
        vnode.elm = vnode.ns
          ? nodeOps.createElementNS(vnode.ns, tag)
          : nodeOps.createElement(tag, vnode);
        setScope(vnode);
  
        /* istanbul ignore if */
        {
          createChildren(vnode, children, insertedVnodeQueue);
          if (isDef(data)) {
            invokeCreateHooks(vnode, insertedVnodeQueue);
          }
          insert(parentElm, vnode.elm, refElm);
        }
  
        if ("development" !== 'production' && data && data.pre) {
          inPre--;
        }
      } else if (isTrue(vnode.isComment)) {
        vnode.elm = nodeOps.createComment(vnode.text);
        insert(parentElm, vnode.elm, refElm);
      } else {
        vnode.elm = nodeOps.createTextNode(vnode.text);
        insert(parentElm, vnode.elm, refElm);
      }
    }
  
    function createComponent (vnode, insertedVnodeQueue, parentElm, refElm) {
      var i = vnode.data;
      if (isDef(i)) {
        var isReactivated = isDef(vnode.componentInstance) && i.keepAlive;
        if (isDef(i = i.hook) && isDef(i = i.init)) {
          i(vnode, false /* hydrating */, parentElm, refElm);
        }
        // after calling the init hook, if the vnode is a child component
        // it should've created a child instance and mounted it. the child
        // component also has set the placeholder vnode's elm.
        // in that case we can just return the element and be done.
        if (isDef(vnode.componentInstance)) {
          initComponent(vnode, insertedVnodeQueue);
          if (isTrue(isReactivated)) {
            reactivateComponent(vnode, insertedVnodeQueue, parentElm, refElm);
          }
          return true
        }
      }
    }
  
    function initComponent (vnode, insertedVnodeQueue) {
      if (isDef(vnode.data.pendingInsert)) {
        insertedVnodeQueue.push.apply(insertedVnodeQueue, vnode.data.pendingInsert);
      }
      vnode.elm = vnode.componentInstance.$el;
      if (isPatchable(vnode)) {
        invokeCreateHooks(vnode, insertedVnodeQueue);
        setScope(vnode);
      } else {
        // empty component root.
        // skip all element-related modules except for ref (#3455)
        registerRef(vnode);
        // make sure to invoke the insert hook
        insertedVnodeQueue.push(vnode);
      }
    }
  
    function reactivateComponent (vnode, insertedVnodeQueue, parentElm, refElm) {
      var i;
      // hack for #4339: a reactivated component with inner transition
      // does not trigger because the inner node's created hooks are not called
      // again. It's not ideal to involve module-specific logic in here but
      // there doesn't seem to be a better way to do it.
      var innerNode = vnode;
      while (innerNode.componentInstance) {
        innerNode = innerNode.componentInstance._vnode;
        if (isDef(i = innerNode.data) && isDef(i = i.transition)) {
          for (i = 0; i < cbs.activate.length; ++i) {
            cbs.activate[i](emptyNode, innerNode);
          }
          insertedVnodeQueue.push(innerNode);
          break
        }
      }
      // unlike a newly created component,
      // a reactivated keep-alive component doesn't insert itself
      insert(parentElm, vnode.elm, refElm);
    }
  
    function insert (parent, elm, ref) {
      if (isDef(parent)) {
        if (isDef(ref)) {
          if (ref.parentNode === parent) {
            nodeOps.insertBefore(parent, elm, ref);
          }
        } else {
          nodeOps.appendChild(parent, elm);
        }
      }
    }
  
    function createChildren (vnode, children, insertedVnodeQueue) {
      if (Array.isArray(children)) {
        for (var i = 0; i < children.length; ++i) {
          createElm(children[i], insertedVnodeQueue, vnode.elm, null, true);
        }
      } else if (isPrimitive(vnode.text)) {
        nodeOps.appendChild(vnode.elm, nodeOps.createTextNode(vnode.text));
      }
    }
  
    function isPatchable (vnode) {
      while (vnode.componentInstance) {
        vnode = vnode.componentInstance._vnode;
      }
      return isDef(vnode.tag)
    }
  
    function invokeCreateHooks (vnode, insertedVnodeQueue) {
      for (var i$1 = 0; i$1 < cbs.create.length; ++i$1) {
        cbs.create[i$1](emptyNode, vnode);
      }
      i = vnode.data.hook; // Reuse variable
      if (isDef(i)) {
        if (isDef(i.create)) { i.create(emptyNode, vnode); }
        if (isDef(i.insert)) { insertedVnodeQueue.push(vnode); }
      }
    }
  
    // set scope id attribute for scoped CSS.
    // this is implemented as a special case to avoid the overhead
    // of going through the normal attribute patching process.
    function setScope (vnode) {
      var i;
      var ancestor = vnode;
      while (ancestor) {
        if (isDef(i = ancestor.context) && isDef(i = i.$options._scopeId)) {
          nodeOps.setAttribute(vnode.elm, i, '');
        }
        ancestor = ancestor.parent;
      }
      // for slot content they should also get the scopeId from the host instance.
      if (isDef(i = activeInstance) &&
          i !== vnode.context &&
          isDef(i = i.$options._scopeId)) {
        nodeOps.setAttribute(vnode.elm, i, '');
      }
    }
  
    function addVnodes (parentElm, refElm, vnodes, startIdx, endIdx, insertedVnodeQueue) {
      for (; startIdx <= endIdx; ++startIdx) {
        createElm(vnodes[startIdx], insertedVnodeQueue, parentElm, refElm);
      }
    }
  
    function invokeDestroyHook (vnode) {
      var i, j;
      var data = vnode.data;
      if (isDef(data)) {
        if (isDef(i = data.hook) && isDef(i = i.destroy)) { i(vnode); }
        for (i = 0; i < cbs.destroy.length; ++i) { cbs.destroy[i](vnode); }
      }
      if (isDef(i = vnode.children)) {
        for (j = 0; j < vnode.children.length; ++j) {
          invokeDestroyHook(vnode.children[j]);
        }
      }
    }
  
    function removeVnodes (parentElm, vnodes, startIdx, endIdx) {
      for (; startIdx <= endIdx; ++startIdx) {
        var ch = vnodes[startIdx];
        if (isDef(ch)) {
          if (isDef(ch.tag)) {
            removeAndInvokeRemoveHook(ch);
            invokeDestroyHook(ch);
          } else { // Text node
            removeNode(ch.elm);
          }
        }
      }
    }
  
    function removeAndInvokeRemoveHook (vnode, rm) {
      if (isDef(rm) || isDef(vnode.data)) {
        var i;
        var listeners = cbs.remove.length + 1;
        if (isDef(rm)) {
          // we have a recursively passed down rm callback
          // increase the listeners count
          rm.listeners += listeners;
        } else {
          // directly removing
          rm = createRmCb(vnode.elm, listeners);
        }
        // recursively invoke hooks on child component root node
        if (isDef(i = vnode.componentInstance) && isDef(i = i._vnode) && isDef(i.data)) {
          removeAndInvokeRemoveHook(i, rm);
        }
        for (i = 0; i < cbs.remove.length; ++i) {
          cbs.remove[i](vnode, rm);
        }
        if (isDef(i = vnode.data.hook) && isDef(i = i.remove)) {
          i(vnode, rm);
        } else {
          rm();
        }
      } else {
        removeNode(vnode.elm);
      }
    }
  
    function updateChildren (parentElm, oldCh, newCh, insertedVnodeQueue, removeOnly) {
      var oldStartIdx = 0;
      var newStartIdx = 0;
      var oldEndIdx = oldCh.length - 1;
      var oldStartVnode = oldCh[0];
      var oldEndVnode = oldCh[oldEndIdx];
      var newEndIdx = newCh.length - 1;
      var newStartVnode = newCh[0];
      var newEndVnode = newCh[newEndIdx];
      var oldKeyToIdx, idxInOld, elmToMove, refElm;
  
      // removeOnly is a special flag used only by <transition-group>
      // to ensure removed elements stay in correct relative positions
      // during leaving transitions
      var canMove = !removeOnly;
  
      while (oldStartIdx <= oldEndIdx && newStartIdx <= newEndIdx) {
        if (isUndef(oldStartVnode)) {
          oldStartVnode = oldCh[++oldStartIdx]; // Vnode has been moved left
        } else if (isUndef(oldEndVnode)) {
          oldEndVnode = oldCh[--oldEndIdx];
        } else if (sameVnode(oldStartVnode, newStartVnode)) {
          patchVnode(oldStartVnode, newStartVnode, insertedVnodeQueue);
          oldStartVnode = oldCh[++oldStartIdx];
          newStartVnode = newCh[++newStartIdx];
        } else if (sameVnode(oldEndVnode, newEndVnode)) {
          patchVnode(oldEndVnode, newEndVnode, insertedVnodeQueue);
          oldEndVnode = oldCh[--oldEndIdx];
          newEndVnode = newCh[--newEndIdx];
        } else if (sameVnode(oldStartVnode, newEndVnode)) { // Vnode moved right
          patchVnode(oldStartVnode, newEndVnode, insertedVnodeQueue);
          canMove && nodeOps.insertBefore(parentElm, oldStartVnode.elm, nodeOps.nextSibling(oldEndVnode.elm));
          oldStartVnode = oldCh[++oldStartIdx];
          newEndVnode = newCh[--newEndIdx];
        } else if (sameVnode(oldEndVnode, newStartVnode)) { // Vnode moved left
          patchVnode(oldEndVnode, newStartVnode, insertedVnodeQueue);
          canMove && nodeOps.insertBefore(parentElm, oldEndVnode.elm, oldStartVnode.elm);
          oldEndVnode = oldCh[--oldEndIdx];
          newStartVnode = newCh[++newStartIdx];
        } else {
          if (isUndef(oldKeyToIdx)) { oldKeyToIdx = createKeyToOldIdx(oldCh, oldStartIdx, oldEndIdx); }
          idxInOld = isDef(newStartVnode.key) ? oldKeyToIdx[newStartVnode.key] : null;
          if (isUndef(idxInOld)) { // New element
            createElm(newStartVnode, insertedVnodeQueue, parentElm, oldStartVnode.elm);
            newStartVnode = newCh[++newStartIdx];
          } else {
            elmToMove = oldCh[idxInOld];
            /* istanbul ignore if */
            if ("development" !== 'production' && !elmToMove) {
              warn(
                'It seems there are duplicate keys that is causing an update error. ' +
                'Make sure each v-for item has a unique key.'
              );
            }
            if (sameVnode(elmToMove, newStartVnode)) {
              patchVnode(elmToMove, newStartVnode, insertedVnodeQueue);
              oldCh[idxInOld] = undefined;
              canMove && nodeOps.insertBefore(parentElm, newStartVnode.elm, oldStartVnode.elm);
              newStartVnode = newCh[++newStartIdx];
            } else {
              // same key but different element. treat as new element
              createElm(newStartVnode, insertedVnodeQueue, parentElm, oldStartVnode.elm);
              newStartVnode = newCh[++newStartIdx];
            }
          }
        }
      }
      if (oldStartIdx > oldEndIdx) {
        refElm = isUndef(newCh[newEndIdx + 1]) ? null : newCh[newEndIdx + 1].elm;
        addVnodes(parentElm, refElm, newCh, newStartIdx, newEndIdx, insertedVnodeQueue);
      } else if (newStartIdx > newEndIdx) {
        removeVnodes(parentElm, oldCh, oldStartIdx, oldEndIdx);
      }
    }
  
    function patchVnode (oldVnode, vnode, insertedVnodeQueue, removeOnly) {
      if (oldVnode === vnode) {
        return
      }
      // reuse element for static trees.
      // note we only do this if the vnode is cloned -
      // if the new node is not cloned it means the render functions have been
      // reset by the hot-reload-api and we need to do a proper re-render.
      if (isTrue(vnode.isStatic) &&
          isTrue(oldVnode.isStatic) &&
          vnode.key === oldVnode.key &&
          (isTrue(vnode.isCloned) || isTrue(vnode.isOnce))) {
        vnode.elm = oldVnode.elm;
        vnode.componentInstance = oldVnode.componentInstance;
        return
      }
      var i;
      var data = vnode.data;
      if (isDef(data) && isDef(i = data.hook) && isDef(i = i.prepatch)) {
        i(oldVnode, vnode);
      }
      var elm = vnode.elm = oldVnode.elm;
      var oldCh = oldVnode.children;
      var ch = vnode.children;
      if (isDef(data) && isPatchable(vnode)) {
        for (i = 0; i < cbs.update.length; ++i) { cbs.update[i](oldVnode, vnode); }
        if (isDef(i = data.hook) && isDef(i = i.update)) { i(oldVnode, vnode); }
      }
      if (isUndef(vnode.text)) {
        if (isDef(oldCh) && isDef(ch)) {
          if (oldCh !== ch) { updateChildren(elm, oldCh, ch, insertedVnodeQueue, removeOnly); }
        } else if (isDef(ch)) {
          if (isDef(oldVnode.text)) { nodeOps.setTextContent(elm, ''); }
          addVnodes(elm, null, ch, 0, ch.length - 1, insertedVnodeQueue);
        } else if (isDef(oldCh)) {
          removeVnodes(elm, oldCh, 0, oldCh.length - 1);
        } else if (isDef(oldVnode.text)) {
          nodeOps.setTextContent(elm, '');
        }
      } else if (oldVnode.text !== vnode.text) {
        nodeOps.setTextContent(elm, vnode.text);
      }
      if (isDef(data)) {
        if (isDef(i = data.hook) && isDef(i = i.postpatch)) { i(oldVnode, vnode); }
      }
    }
  
    function invokeInsertHook (vnode, queue, initial) {
      // delay insert hooks for component root nodes, invoke them after the
      // element is really inserted
      if (isTrue(initial) && isDef(vnode.parent)) {
        vnode.parent.data.pendingInsert = queue;
      } else {
        for (var i = 0; i < queue.length; ++i) {
          queue[i].data.hook.insert(queue[i]);
        }
      }
    }
  
    var bailed = false;
    // list of modules that can skip create hook during hydration because they
    // are already rendered on the client or has no need for initialization
    var isRenderedModule = makeMap('attrs,style,class,staticClass,staticStyle,key');
  
    // Note: this is a browser-only function so we can assume elms are DOM nodes.
    function hydrate (elm, vnode, insertedVnodeQueue) {
      {
        if (!assertNodeMatch(elm, vnode)) {
          return false
        }
      }
      vnode.elm = elm;
      var tag = vnode.tag;
      var data = vnode.data;
      var children = vnode.children;
      if (isDef(data)) {
        if (isDef(i = data.hook) && isDef(i = i.init)) { i(vnode, true /* hydrating */); }
        if (isDef(i = vnode.componentInstance)) {
          // child component. it should have hydrated its own tree.
          initComponent(vnode, insertedVnodeQueue);
          return true
        }
      }
      if (isDef(tag)) {
        if (isDef(children)) {
          // empty element, allow client to pick up and populate children
          if (!elm.hasChildNodes()) {
            createChildren(vnode, children, insertedVnodeQueue);
          } else {
            var childrenMatch = true;
            var childNode = elm.firstChild;
            for (var i$1 = 0; i$1 < children.length; i$1++) {
              if (!childNode || !hydrate(childNode, children[i$1], insertedVnodeQueue)) {
                childrenMatch = false;
                break
              }
              childNode = childNode.nextSibling;
            }
            // if childNode is not null, it means the actual childNodes list is
            // longer than the virtual children list.
            if (!childrenMatch || childNode) {
              if ("development" !== 'production' &&
                  typeof console !== 'undefined' &&
                  !bailed) {
                bailed = true;
                console.warn('Parent: ', elm);
                console.warn('Mismatching childNodes vs. VNodes: ', elm.childNodes, children);
              }
              return false
            }
          }
        }
        if (isDef(data)) {
          for (var key in data) {
            if (!isRenderedModule(key)) {
              invokeCreateHooks(vnode, insertedVnodeQueue);
              break
            }
          }
        }
      } else if (elm.data !== vnode.text) {
        elm.data = vnode.text;
      }
      return true
    }
  
    function assertNodeMatch (node, vnode) {
      if (isDef(vnode.tag)) {
        return (
          vnode.tag.indexOf('vue-component') === 0 ||
          vnode.tag.toLowerCase() === (node.tagName && node.tagName.toLowerCase())
        )
      } else {
        return node.nodeType === (vnode.isComment ? 8 : 3)
      }
    }
  
    return function patch (oldVnode, vnode, hydrating, removeOnly, parentElm, refElm) {
      if (isUndef(vnode)) {
        if (isDef(oldVnode)) { invokeDestroyHook(oldVnode); }
        return
      }
  
      var isInitialPatch = false;
      var insertedVnodeQueue = [];
  
      if (isUndef(oldVnode)) {
        // empty mount (likely as component), create new root element
        isInitialPatch = true;
        createElm(vnode, insertedVnodeQueue, parentElm, refElm);
      } else {
        var isRealElement = isDef(oldVnode.nodeType);
        if (!isRealElement && sameVnode(oldVnode, vnode)) {
          // patch existing root node
          patchVnode(oldVnode, vnode, insertedVnodeQueue, removeOnly);
        } else {
          if (isRealElement) {
            // mounting to a real element
            // check if this is server-rendered content and if we can perform
            // a successful hydration.
            if (oldVnode.nodeType === 1 && oldVnode.hasAttribute(SSR_ATTR)) {
              oldVnode.removeAttribute(SSR_ATTR);
              hydrating = true;
            }
            if (isTrue(hydrating)) {
              if (hydrate(oldVnode, vnode, insertedVnodeQueue)) {
                invokeInsertHook(vnode, insertedVnodeQueue, true);
                return oldVnode
              } else {
                warn(
                  'The client-side rendered virtual DOM tree is not matching ' +
                  'server-rendered content. This is likely caused by incorrect ' +
                  'HTML markup, for example nesting block-level elements inside ' +
                  '<p>, or missing <tbody>. Bailing hydration and performing ' +
                  'full client-side render.'
                );
              }
            }
            // either not server-rendered, or hydration failed.
            // create an empty node and replace it
            oldVnode = emptyNodeAt(oldVnode);
          }
          // replacing existing element
          var oldElm = oldVnode.elm;
          var parentElm$1 = nodeOps.parentNode(oldElm);
          createElm(
            vnode,
            insertedVnodeQueue,
            // extremely rare edge case: do not insert if old element is in a
            // leaving transition. Only happens when combining transition +
            // keep-alive + HOCs. (#4590)
            oldElm._leaveCb ? null : parentElm$1,
            nodeOps.nextSibling(oldElm)
          );
  
          if (isDef(vnode.parent)) {
            // component root element replaced.
            // update parent placeholder node element, recursively
            var ancestor = vnode.parent;
            while (ancestor) {
              ancestor.elm = vnode.elm;
              ancestor = ancestor.parent;
            }
            if (isPatchable(vnode)) {
              for (var i = 0; i < cbs.create.length; ++i) {
                cbs.create[i](emptyNode, vnode.parent);
              }
            }
          }
  
          if (isDef(parentElm$1)) {
            removeVnodes(parentElm$1, [oldVnode], 0, 0);
          } else if (isDef(oldVnode.tag)) {
            invokeDestroyHook(oldVnode);
          }
        }
      }
  
      invokeInsertHook(vnode, insertedVnodeQueue, isInitialPatch);
      return vnode.elm
    }
  }
  
  /*  */
  
  var directives = {
    create: updateDirectives,
    update: updateDirectives,
    destroy: function unbindDirectives (vnode) {
      updateDirectives(vnode, emptyNode);
    }
  };
  
  function updateDirectives (oldVnode, vnode) {
    if (oldVnode.data.directives || vnode.data.directives) {
      _update(oldVnode, vnode);
    }
  }
  
  function _update (oldVnode, vnode) {
    var isCreate = oldVnode === emptyNode;
    var isDestroy = vnode === emptyNode;
    var oldDirs = normalizeDirectives$1(oldVnode.data.directives, oldVnode.context);
    var newDirs = normalizeDirectives$1(vnode.data.directives, vnode.context);
  
    var dirsWithInsert = [];
    var dirsWithPostpatch = [];
  
    var key, oldDir, dir;
    for (key in newDirs) {
      oldDir = oldDirs[key];
      dir = newDirs[key];
      if (!oldDir) {
        // new directive, bind
        callHook$1(dir, 'bind', vnode, oldVnode);
        if (dir.def && dir.def.inserted) {
          dirsWithInsert.push(dir);
        }
      } else {
        // existing directive, update
        dir.oldValue = oldDir.value;
        callHook$1(dir, 'update', vnode, oldVnode);
        if (dir.def && dir.def.componentUpdated) {
          dirsWithPostpatch.push(dir);
        }
      }
    }
  
    if (dirsWithInsert.length) {
      var callInsert = function () {
        for (var i = 0; i < dirsWithInsert.length; i++) {
          callHook$1(dirsWithInsert[i], 'inserted', vnode, oldVnode);
        }
      };
      if (isCreate) {
        mergeVNodeHook(vnode.data.hook || (vnode.data.hook = {}), 'insert', callInsert);
      } else {
        callInsert();
      }
    }
  
    if (dirsWithPostpatch.length) {
      mergeVNodeHook(vnode.data.hook || (vnode.data.hook = {}), 'postpatch', function () {
        for (var i = 0; i < dirsWithPostpatch.length; i++) {
          callHook$1(dirsWithPostpatch[i], 'componentUpdated', vnode, oldVnode);
        }
      });
    }
  
    if (!isCreate) {
      for (key in oldDirs) {
        if (!newDirs[key]) {
          // no longer present, unbind
          callHook$1(oldDirs[key], 'unbind', oldVnode, oldVnode, isDestroy);
        }
      }
    }
  }
  
  var emptyModifiers = Object.create(null);
  
  function normalizeDirectives$1 (
    dirs,
    vm
  ) {
    var res = Object.create(null);
    if (!dirs) {
      return res
    }
    var i, dir;
    for (i = 0; i < dirs.length; i++) {
      dir = dirs[i];
      if (!dir.modifiers) {
        dir.modifiers = emptyModifiers;
      }
      res[getRawDirName(dir)] = dir;
      dir.def = resolveAsset(vm.$options, 'directives', dir.name, true);
    }
    return res
  }
  
  function getRawDirName (dir) {
    return dir.rawName || ((dir.name) + "." + (Object.keys(dir.modifiers || {}).join('.')))
  }
  
  function callHook$1 (dir, hook, vnode, oldVnode, isDestroy) {
    var fn = dir.def && dir.def[hook];
    if (fn) {
      try {
        fn(vnode.elm, dir, vnode, oldVnode, isDestroy);
      } catch (e) {
        handleError(e, vnode.context, ("directive " + (dir.name) + " " + hook + " hook"));
      }
    }
  }
  
  var baseModules = [
    ref,
    directives
  ];
  
  /*  */
  
  function updateAttrs (oldVnode, vnode) {
    if (isUndef(oldVnode.data.attrs) && isUndef(vnode.data.attrs)) {
      return
    }
    var key, cur, old;
    var elm = vnode.elm;
    var oldAttrs = oldVnode.data.attrs || {};
    var attrs = vnode.data.attrs || {};
    // clone observed objects, as the user probably wants to mutate it
    if (isDef(attrs.__ob__)) {
      attrs = vnode.data.attrs = extend({}, attrs);
    }
  
    for (key in attrs) {
      cur = attrs[key];
      old = oldAttrs[key];
      if (old !== cur) {
        setAttr(elm, key, cur);
      }
    }
    // #4391: in IE9, setting type can reset value for input[type=radio]
    /* istanbul ignore if */
    if (isIE9 && attrs.value !== oldAttrs.value) {
      setAttr(elm, 'value', attrs.value);
    }
    for (key in oldAttrs) {
      if (isUndef(attrs[key])) {
        if (isXlink(key)) {
          elm.removeAttributeNS(xlinkNS, getXlinkProp(key));
        } else if (!isEnumeratedAttr(key)) {
          elm.removeAttribute(key);
        }
      }
    }
  }
  
  function setAttr (el, key, value) {
    if (isBooleanAttr(key)) {
      // set attribute for blank value
      // e.g. <option disabled>Select one</option>
      if (isFalsyAttrValue(value)) {
        el.removeAttribute(key);
      } else {
        el.setAttribute(key, key);
      }
    } else if (isEnumeratedAttr(key)) {
      el.setAttribute(key, isFalsyAttrValue(value) || value === 'false' ? 'false' : 'true');
    } else if (isXlink(key)) {
      if (isFalsyAttrValue(value)) {
        el.removeAttributeNS(xlinkNS, getXlinkProp(key));
      } else {
        el.setAttributeNS(xlinkNS, key, value);
      }
    } else {
      if (isFalsyAttrValue(value)) {
        el.removeAttribute(key);
      } else {
        el.setAttribute(key, value);
      }
    }
  }
  
  var attrs = {
    create: updateAttrs,
    update: updateAttrs
  };
  
  /*  */
  
  function updateClass (oldVnode, vnode) {
    var el = vnode.elm;
    var data = vnode.data;
    var oldData = oldVnode.data;
    if (
      isUndef(data.staticClass) &&
      isUndef(data.class) && (
        isUndef(oldData) || (
          isUndef(oldData.staticClass) &&
          isUndef(oldData.class)
        )
      )
    ) {
      return
    }
  
    var cls = genClassForVnode(vnode);
  
    // handle transition classes
    var transitionClass = el._transitionClasses;
    if (isDef(transitionClass)) {
      cls = concat(cls, stringifyClass(transitionClass));
    }
  
    // set the class
    if (cls !== el._prevClass) {
      el.setAttribute('class', cls);
      el._prevClass = cls;
    }
  }
  
  var klass = {
    create: updateClass,
    update: updateClass
  };
  
  /*  */
  
  var validDivisionCharRE = /[\w).+\-_$\]]/;
  
  function parseFilters (exp) {
    var inSingle = false;
    var inDouble = false;
    var inTemplateString = false;
    var inRegex = false;
    var curly = 0;
    var square = 0;
    var paren = 0;
    var lastFilterIndex = 0;
    var c, prev, i, expression, filters;
  
    for (i = 0; i < exp.length; i++) {
      prev = c;
      c = exp.charCodeAt(i);
      if (inSingle) {
        if (c === 0x27 && prev !== 0x5C) { inSingle = false; }
      } else if (inDouble) {
        if (c === 0x22 && prev !== 0x5C) { inDouble = false; }
      } else if (inTemplateString) {
        if (c === 0x60 && prev !== 0x5C) { inTemplateString = false; }
      } else if (inRegex) {
        if (c === 0x2f && prev !== 0x5C) { inRegex = false; }
      } else if (
        c === 0x7C && // pipe
        exp.charCodeAt(i + 1) !== 0x7C &&
        exp.charCodeAt(i - 1) !== 0x7C &&
        !curly && !square && !paren
      ) {
        if (expression === undefined) {
          // first filter, end of expression
          lastFilterIndex = i + 1;
          expression = exp.slice(0, i).trim();
        } else {
          pushFilter();
        }
      } else {
        switch (c) {
          case 0x22: inDouble = true; break         // "
          case 0x27: inSingle = true; break         // '
          case 0x60: inTemplateString = true; break // `
          case 0x28: paren++; break                 // (
          case 0x29: paren--; break                 // )
          case 0x5B: square++; break                // [
          case 0x5D: square--; break                // ]
          case 0x7B: curly++; break                 // {
          case 0x7D: curly--; break                 // }
        }
        if (c === 0x2f) { // /
          var j = i - 1;
          var p = (void 0);
          // find first non-whitespace prev char
          for (; j >= 0; j--) {
            p = exp.charAt(j);
            if (p !== ' ') { break }
          }
          if (!p || !validDivisionCharRE.test(p)) {
            inRegex = true;
          }
        }
      }
    }
  
    if (expression === undefined) {
      expression = exp.slice(0, i).trim();
    } else if (lastFilterIndex !== 0) {
      pushFilter();
    }
  
    function pushFilter () {
      (filters || (filters = [])).push(exp.slice(lastFilterIndex, i).trim());
      lastFilterIndex = i + 1;
    }
  
    if (filters) {
      for (i = 0; i < filters.length; i++) {
        expression = wrapFilter(expression, filters[i]);
      }
    }
  
    return expression
  }
  
  function wrapFilter (exp, filter) {
    var i = filter.indexOf('(');
    if (i < 0) {
      // _f: resolveFilter
      return ("_f(\"" + filter + "\")(" + exp + ")")
    } else {
      var name = filter.slice(0, i);
      var args = filter.slice(i + 1);
      return ("_f(\"" + name + "\")(" + exp + "," + args)
    }
  }
  
  /*  */
  
  function baseWarn (msg) {
    console.error(("[Vue compiler]: " + msg));
  }
  
  function pluckModuleFunction (
    modules,
    key
  ) {
    return modules
      ? modules.map(function (m) { return m[key]; }).filter(function (_) { return _; })
      : []
  }
  
  function addProp (el, name, value) {
    (el.props || (el.props = [])).push({ name: name, value: value });
  }
  
  function addAttr (el, name, value) {
    (el.attrs || (el.attrs = [])).push({ name: name, value: value });
  }
  
  function addDirective (
    el,
    name,
    rawName,
    value,
    arg,
    modifiers
  ) {
    (el.directives || (el.directives = [])).push({ name: name, rawName: rawName, value: value, arg: arg, modifiers: modifiers });
  }
  
  function addHandler (
    el,
    name,
    value,
    modifiers,
    important,
    warn
  ) {
    // warn prevent and passive modifier
    /* istanbul ignore if */
    if (
      "development" !== 'production' && warn &&
      modifiers && modifiers.prevent && modifiers.passive
    ) {
      warn(
        'passive and prevent can\'t be used together. ' +
        'Passive handler can\'t prevent default event.'
      );
    }
    // check capture modifier
    if (modifiers && modifiers.capture) {
      delete modifiers.capture;
      name = '!' + name; // mark the event as captured
    }
    if (modifiers && modifiers.once) {
      delete modifiers.once;
      name = '~' + name; // mark the event as once
    }
    /* istanbul ignore if */
    if (modifiers && modifiers.passive) {
      delete modifiers.passive;
      name = '&' + name; // mark the event as passive
    }
    var events;
    if (modifiers && modifiers.native) {
      delete modifiers.native;
      events = el.nativeEvents || (el.nativeEvents = {});
    } else {
      events = el.events || (el.events = {});
    }
    var newHandler = { value: value, modifiers: modifiers };
    var handlers = events[name];
    /* istanbul ignore if */
    if (Array.isArray(handlers)) {
      important ? handlers.unshift(newHandler) : handlers.push(newHandler);
    } else if (handlers) {
      events[name] = important ? [newHandler, handlers] : [handlers, newHandler];
    } else {
      events[name] = newHandler;
    }
  }
  
  function getBindingAttr (
    el,
    name,
    getStatic
  ) {
    var dynamicValue =
      getAndRemoveAttr(el, ':' + name) ||
      getAndRemoveAttr(el, 'v-bind:' + name);
    if (dynamicValue != null) {
      return parseFilters(dynamicValue)
    } else if (getStatic !== false) {
      var staticValue = getAndRemoveAttr(el, name);
      if (staticValue != null) {
        return JSON.stringify(staticValue)
      }
    }
  }
  
  function getAndRemoveAttr (el, name) {
    var val;
    if ((val = el.attrsMap[name]) != null) {
      var list = el.attrsList;
      for (var i = 0, l = list.length; i < l; i++) {
        if (list[i].name === name) {
          list.splice(i, 1);
          break
        }
      }
    }
    return val
  }
  
  /*  */
  
  /**
   * Cross-platform code generation for component v-model
   */
  function genComponentModel (
    el,
    value,
    modifiers
  ) {
    var ref = modifiers || {};
    var number = ref.number;
    var trim = ref.trim;
  
    var baseValueExpression = '$$v';
    var valueExpression = baseValueExpression;
    if (trim) {
      valueExpression =
        "(typeof " + baseValueExpression + " === 'string'" +
          "? " + baseValueExpression + ".trim()" +
          ": " + baseValueExpression + ")";
    }
    if (number) {
      valueExpression = "_n(" + valueExpression + ")";
    }
    var assignment = genAssignmentCode(value, valueExpression);
  
    el.model = {
      value: ("(" + value + ")"),
      expression: ("\"" + value + "\""),
      callback: ("function (" + baseValueExpression + ") {" + assignment + "}")
    };
  }
  
  /**
   * Cross-platform codegen helper for generating v-model value assignment code.
   */
  function genAssignmentCode (
    value,
    assignment
  ) {
    var modelRs = parseModel(value);
    if (modelRs.idx === null) {
      return (value + "=" + assignment)
    } else {
      return "var $$exp = " + (modelRs.exp) + ", $$idx = " + (modelRs.idx) + ";" +
        "if (!Array.isArray($$exp)){" +
          value + "=" + assignment + "}" +
        "else{$$exp.splice($$idx, 1, " + assignment + ")}"
    }
  }
  
  /**
   * parse directive model to do the array update transform. a[idx] = val => $$a.splice($$idx, 1, val)
   *
   * for loop possible cases:
   *
   * - test
   * - test[idx]
   * - test[test1[idx]]
   * - test["a"][idx]
   * - xxx.test[a[a].test1[idx]]
   * - test.xxx.a["asa"][test1[idx]]
   *
   */
  
  var len;
  var str;
  var chr;
  var index$1;
  var expressionPos;
  var expressionEndPos;
  
  function parseModel (val) {
    str = val;
    len = str.length;
    index$1 = expressionPos = expressionEndPos = 0;
  
    if (val.indexOf('[') < 0 || val.lastIndexOf(']') < len - 1) {
      return {
        exp: val,
        idx: null
      }
    }
  
    while (!eof()) {
      chr = next();
      /* istanbul ignore if */
      if (isStringStart(chr)) {
        parseString(chr);
      } else if (chr === 0x5B) {
        parseBracket(chr);
      }
    }
  
    return {
      exp: val.substring(0, expressionPos),
      idx: val.substring(expressionPos + 1, expressionEndPos)
    }
  }
  
  function next () {
    return str.charCodeAt(++index$1)
  }
  
  function eof () {
    return index$1 >= len
  }
  
  function isStringStart (chr) {
    return chr === 0x22 || chr === 0x27
  }
  
  function parseBracket (chr) {
    var inBracket = 1;
    expressionPos = index$1;
    while (!eof()) {
      chr = next();
      if (isStringStart(chr)) {
        parseString(chr);
        continue
      }
      if (chr === 0x5B) { inBracket++; }
      if (chr === 0x5D) { inBracket--; }
      if (inBracket === 0) {
        expressionEndPos = index$1;
        break
      }
    }
  }
  
  function parseString (chr) {
    var stringQuote = chr;
    while (!eof()) {
      chr = next();
      if (chr === stringQuote) {
        break
      }
    }
  }
  
  /*  */
  
  var warn$1;
  
  // in some cases, the event used has to be determined at runtime
  // so we used some reserved tokens during compile.
  var RANGE_TOKEN = '__r';
  var CHECKBOX_RADIO_TOKEN = '__c';
  
  function model (
    el,
    dir,
    _warn
  ) {
    warn$1 = _warn;
    var value = dir.value;
    var modifiers = dir.modifiers;
    var tag = el.tag;
    var type = el.attrsMap.type;
  
    {
      var dynamicType = el.attrsMap['v-bind:type'] || el.attrsMap[':type'];
      if (tag === 'input' && dynamicType) {
        warn$1(
          "<input :type=\"" + dynamicType + "\" v-model=\"" + value + "\">:\n" +
          "v-model does not support dynamic input types. Use v-if branches instead."
        );
      }
      // inputs with type="file" are read only and setting the input's
      // value will throw an error.
      if (tag === 'input' && type === 'file') {
        warn$1(
          "<" + (el.tag) + " v-model=\"" + value + "\" type=\"file\">:\n" +
          "File inputs are read only. Use a v-on:change listener instead."
        );
      }
    }
  
    if (tag === 'select') {
      genSelect(el, value, modifiers);
    } else if (tag === 'input' && type === 'checkbox') {
      genCheckboxModel(el, value, modifiers);
    } else if (tag === 'input' && type === 'radio') {
      genRadioModel(el, value, modifiers);
    } else if (tag === 'input' || tag === 'textarea') {
      genDefaultModel(el, value, modifiers);
    } else if (!config.isReservedTag(tag)) {
      genComponentModel(el, value, modifiers);
      // component v-model doesn't need extra runtime
      return false
    } else {
      warn$1(
        "<" + (el.tag) + " v-model=\"" + value + "\">: " +
        "v-model is not supported on this element type. " +
        'If you are working with contenteditable, it\'s recommended to ' +
        'wrap a library dedicated for that purpose inside a custom component.'
      );
    }
  
    // ensure runtime directive metadata
    return true
  }
  
  function genCheckboxModel (
    el,
    value,
    modifiers
  ) {
    var number = modifiers && modifiers.number;
    var valueBinding = getBindingAttr(el, 'value') || 'null';
    var trueValueBinding = getBindingAttr(el, 'true-value') || 'true';
    var falseValueBinding = getBindingAttr(el, 'false-value') || 'false';
    addProp(el, 'checked',
      "Array.isArray(" + value + ")" +
        "?_i(" + value + "," + valueBinding + ")>-1" + (
          trueValueBinding === 'true'
            ? (":(" + value + ")")
            : (":_q(" + value + "," + trueValueBinding + ")")
        )
    );
    addHandler(el, CHECKBOX_RADIO_TOKEN,
      "var $$a=" + value + "," +
          '$$el=$event.target,' +
          "$$c=$$el.checked?(" + trueValueBinding + "):(" + falseValueBinding + ");" +
      'if(Array.isArray($$a)){' +
        "var $$v=" + (number ? '_n(' + valueBinding + ')' : valueBinding) + "," +
            '$$i=_i($$a,$$v);' +
        "if($$c){$$i<0&&(" + value + "=$$a.concat($$v))}" +
        "else{$$i>-1&&(" + value + "=$$a.slice(0,$$i).concat($$a.slice($$i+1)))}" +
      "}else{" + (genAssignmentCode(value, '$$c')) + "}",
      null, true
    );
  }
  
  function genRadioModel (
      el,
      value,
      modifiers
  ) {
    var number = modifiers && modifiers.number;
    var valueBinding = getBindingAttr(el, 'value') || 'null';
    valueBinding = number ? ("_n(" + valueBinding + ")") : valueBinding;
    addProp(el, 'checked', ("_q(" + value + "," + valueBinding + ")"));
    addHandler(el, CHECKBOX_RADIO_TOKEN, genAssignmentCode(value, valueBinding), null, true);
  }
  
  function genSelect (
      el,
      value,
      modifiers
  ) {
    var number = modifiers && modifiers.number;
    var selectedVal = "Array.prototype.filter" +
      ".call($event.target.options,function(o){return o.selected})" +
      ".map(function(o){var val = \"_value\" in o ? o._value : o.value;" +
      "return " + (number ? '_n(val)' : 'val') + "})";
  
    var assignment = '$event.target.multiple ? $$selectedVal : $$selectedVal[0]';
    var code = "var $$selectedVal = " + selectedVal + ";";
    code = code + " " + (genAssignmentCode(value, assignment));
    addHandler(el, 'change', code, null, true);
  }
  
  function genDefaultModel (
    el,
    value,
    modifiers
  ) {
    var type = el.attrsMap.type;
    var ref = modifiers || {};
    var lazy = ref.lazy;
    var number = ref.number;
    var trim = ref.trim;
    var needCompositionGuard = !lazy && type !== 'range';
    var event = lazy
      ? 'change'
      : type === 'range'
        ? RANGE_TOKEN
        : 'input';
  
    var valueExpression = '$event.target.value';
    if (trim) {
      valueExpression = "$event.target.value.trim()";
    }
    if (number) {
      valueExpression = "_n(" + valueExpression + ")";
    }
  
    var code = genAssignmentCode(value, valueExpression);
    if (needCompositionGuard) {
      code = "if($event.target.composing)return;" + code;
    }
  
    addProp(el, 'value', ("(" + value + ")"));
    addHandler(el, event, code, null, true);
    if (trim || number || type === 'number') {
      addHandler(el, 'blur', '$forceUpdate()');
    }
  }
  
  /*  */
  
  function normalizeEvents (on) {
    var event;
    /* istanbul ignore if */
    if (isDef(on[RANGE_TOKEN])) {
      // IE input[type=range] only supports `change` event
      event = isIE ? 'change' : 'input';
      on[event] = [].concat(on[RANGE_TOKEN], on[event] || []);
      delete on[RANGE_TOKEN];
    }
    if (isDef(on[CHECKBOX_RADIO_TOKEN])) {
      // Chrome fires microtasks in between click/change, leads to #4521
      event = isChrome ? 'click' : 'change';
      on[event] = [].concat(on[CHECKBOX_RADIO_TOKEN], on[event] || []);
      delete on[CHECKBOX_RADIO_TOKEN];
    }
  }
  
  var target$1;
  
  function add$1 (
    event,
    handler,
    once$$1,
    capture,
    passive
  ) {
    if (once$$1) {
      var oldHandler = handler;
      var _target = target$1; // save current target element in closure
      handler = function (ev) {
        var res = arguments.length === 1
          ? oldHandler(ev)
          : oldHandler.apply(null, arguments);
        if (res !== null) {
          remove$2(event, handler, capture, _target);
        }
      };
    }
    target$1.addEventListener(
      event,
      handler,
      supportsPassive
        ? { capture: capture, passive: passive }
        : capture
    );
  }
  
  function remove$2 (
    event,
    handler,
    capture,
    _target
  ) {
    (_target || target$1).removeEventListener(event, handler, capture);
  }
  
  function updateDOMListeners (oldVnode, vnode) {
    if (isUndef(oldVnode.data.on) && isUndef(vnode.data.on)) {
      return
    }
    var on = vnode.data.on || {};
    var oldOn = oldVnode.data.on || {};
    target$1 = vnode.elm;
    normalizeEvents(on);
    updateListeners(on, oldOn, add$1, remove$2, vnode.context);
  }
  
  var events = {
    create: updateDOMListeners,
    update: updateDOMListeners
  };
  
  /*  */
  
  function updateDOMProps (oldVnode, vnode) {
    if (isUndef(oldVnode.data.domProps) && isUndef(vnode.data.domProps)) {
      return
    }
    var key, cur;
    var elm = vnode.elm;
    var oldProps = oldVnode.data.domProps || {};
    var props = vnode.data.domProps || {};
    // clone observed objects, as the user probably wants to mutate it
    if (isDef(props.__ob__)) {
      props = vnode.data.domProps = extend({}, props);
    }
  
    for (key in oldProps) {
      if (isUndef(props[key])) {
        elm[key] = '';
      }
    }
    for (key in props) {
      cur = props[key];
      // ignore children if the node has textContent or innerHTML,
      // as these will throw away existing DOM nodes and cause removal errors
      // on subsequent patches (#3360)
      if (key === 'textContent' || key === 'innerHTML') {
        if (vnode.children) { vnode.children.length = 0; }
        if (cur === oldProps[key]) { continue }
      }
  
      if (key === 'value') {
        // store value as _value as well since
        // non-string values will be stringified
        elm._value = cur;
        // avoid resetting cursor position when value is the same
        var strCur = cur == null ? '' : String(cur);
        if (shouldUpdateValue(elm, vnode, strCur)) {
          elm.value = strCur;
        }
      } else {
        elm[key] = cur;
      }
    }
  }
  
  // check platforms/web/util/attrs.js acceptValue
  
  
  function shouldUpdateValue (
    elm,
    vnode,
    checkVal
  ) {
    return (!elm.composing && (
      vnode.tag === 'option' ||
      isDirty(elm, checkVal) ||
      isInputChanged(elm, checkVal)
    ))
  }
  
  function isDirty (elm, checkVal) {
    // return true when textbox (.number and .trim) loses focus and its value is not equal to the updated value
    return document.activeElement !== elm && elm.value !== checkVal
  }
  
  function isInputChanged (elm, newVal) {
    var value = elm.value;
    var modifiers = elm._vModifiers; // injected by v-model runtime
    if ((isDef(modifiers) && modifiers.number) || elm.type === 'number') {
      return toNumber(value) !== toNumber(newVal)
    }
    if (isDef(modifiers) && modifiers.trim) {
      return value.trim() !== newVal.trim()
    }
    return value !== newVal
  }
  
  var domProps = {
    create: updateDOMProps,
    update: updateDOMProps
  };
  
  /*  */
  
  var parseStyleText = cached(function (cssText) {
    var res = {};
    var listDelimiter = /;(?![^(]*\))/g;
    var propertyDelimiter = /:(.+)/;
    cssText.split(listDelimiter).forEach(function (item) {
      if (item) {
        var tmp = item.split(propertyDelimiter);
        tmp.length > 1 && (res[tmp[0].trim()] = tmp[1].trim());
      }
    });
    return res
  });
  
  // merge static and dynamic style data on the same vnode
  function normalizeStyleData (data) {
    var style = normalizeStyleBinding(data.style);
    // static style is pre-processed into an object during compilation
    // and is always a fresh object, so it's safe to merge into it
    return data.staticStyle
      ? extend(data.staticStyle, style)
      : style
  }
  
  // normalize possible array / string values into Object
  function normalizeStyleBinding (bindingStyle) {
    if (Array.isArray(bindingStyle)) {
      return toObject(bindingStyle)
    }
    if (typeof bindingStyle === 'string') {
      return parseStyleText(bindingStyle)
    }
    return bindingStyle
  }
  
  /**
   * parent component style should be after child's
   * so that parent component's style could override it
   */
  function getStyle (vnode, checkChild) {
    var res = {};
    var styleData;
  
    if (checkChild) {
      var childNode = vnode;
      while (childNode.componentInstance) {
        childNode = childNode.componentInstance._vnode;
        if (childNode.data && (styleData = normalizeStyleData(childNode.data))) {
          extend(res, styleData);
        }
      }
    }
  
    if ((styleData = normalizeStyleData(vnode.data))) {
      extend(res, styleData);
    }
  
    var parentNode = vnode;
    while ((parentNode = parentNode.parent)) {
      if (parentNode.data && (styleData = normalizeStyleData(parentNode.data))) {
        extend(res, styleData);
      }
    }
    return res
  }
  
  /*  */
  
  var cssVarRE = /^--/;
  var importantRE = /\s*!important$/;
  var setProp = function (el, name, val) {
    /* istanbul ignore if */
    if (cssVarRE.test(name)) {
      el.style.setProperty(name, val);
    } else if (importantRE.test(val)) {
      el.style.setProperty(name, val.replace(importantRE, ''), 'important');
    } else {
      var normalizedName = normalize(name);
      if (Array.isArray(val)) {
        // Support values array created by autoprefixer, e.g.
        // {display: ["-webkit-box", "-ms-flexbox", "flex"]}
        // Set them one by one, and the browser will only set those it can recognize
        for (var i = 0, len = val.length; i < len; i++) {
          el.style[normalizedName] = val[i];
        }
      } else {
        el.style[normalizedName] = val;
      }
    }
  };
  
  var prefixes = ['Webkit', 'Moz', 'ms'];
  
  var testEl;
  var normalize = cached(function (prop) {
    testEl = testEl || document.createElement('div');
    prop = camelize(prop);
    if (prop !== 'filter' && (prop in testEl.style)) {
      return prop
    }
    var upper = prop.charAt(0).toUpperCase() + prop.slice(1);
    for (var i = 0; i < prefixes.length; i++) {
      var prefixed = prefixes[i] + upper;
      if (prefixed in testEl.style) {
        return prefixed
      }
    }
  });
  
  function updateStyle (oldVnode, vnode) {
    var data = vnode.data;
    var oldData = oldVnode.data;
  
    if (isUndef(data.staticStyle) && isUndef(data.style) &&
        isUndef(oldData.staticStyle) && isUndef(oldData.style)) {
      return
    }
  
    var cur, name;
    var el = vnode.elm;
    var oldStaticStyle = oldData.staticStyle;
    var oldStyleBinding = oldData.normalizedStyle || oldData.style || {};
  
    // if static style exists, stylebinding already merged into it when doing normalizeStyleData
    var oldStyle = oldStaticStyle || oldStyleBinding;
  
    var style = normalizeStyleBinding(vnode.data.style) || {};
  
    // store normalized style under a different key for next diff
    // make sure to clone it if it's reactive, since the user likley wants
    // to mutate it.
    vnode.data.normalizedStyle = isDef(style.__ob__)
      ? extend({}, style)
      : style;
  
    var newStyle = getStyle(vnode, true);
  
    for (name in oldStyle) {
      if (isUndef(newStyle[name])) {
        setProp(el, name, '');
      }
    }
    for (name in newStyle) {
      cur = newStyle[name];
      if (cur !== oldStyle[name]) {
        // ie9 setting to null has no effect, must use empty string
        setProp(el, name, cur == null ? '' : cur);
      }
    }
  }
  
  var style = {
    create: updateStyle,
    update: updateStyle
  };
  
  /*  */
  
  /**
   * Add class with compatibility for SVG since classList is not supported on
   * SVG elements in IE
   */
  function addClass (el, cls) {
    /* istanbul ignore if */
    if (!cls || !(cls = cls.trim())) {
      return
    }
  
    /* istanbul ignore else */
    if (el.classList) {
      if (cls.indexOf(' ') > -1) {
        cls.split(/\s+/).forEach(function (c) { return el.classList.add(c); });
      } else {
        el.classList.add(cls);
      }
    } else {
      var cur = " " + (el.getAttribute('class') || '') + " ";
      if (cur.indexOf(' ' + cls + ' ') < 0) {
        el.setAttribute('class', (cur + cls).trim());
      }
    }
  }
  
  /**
   * Remove class with compatibility for SVG since classList is not supported on
   * SVG elements in IE
   */
  function removeClass (el, cls) {
    /* istanbul ignore if */
    if (!cls || !(cls = cls.trim())) {
      return
    }
  
    /* istanbul ignore else */
    if (el.classList) {
      if (cls.indexOf(' ') > -1) {
        cls.split(/\s+/).forEach(function (c) { return el.classList.remove(c); });
      } else {
        el.classList.remove(cls);
      }
    } else {
      var cur = " " + (el.getAttribute('class') || '') + " ";
      var tar = ' ' + cls + ' ';
      while (cur.indexOf(tar) >= 0) {
        cur = cur.replace(tar, ' ');
      }
      el.setAttribute('class', cur.trim());
    }
  }
  
  /*  */
  
  function resolveTransition (def$$1) {
    if (!def$$1) {
      return
    }
    /* istanbul ignore else */
    if (typeof def$$1 === 'object') {
      var res = {};
      if (def$$1.css !== false) {
        extend(res, autoCssTransition(def$$1.name || 'v'));
      }
      extend(res, def$$1);
      return res
    } else if (typeof def$$1 === 'string') {
      return autoCssTransition(def$$1)
    }
  }
  
  var autoCssTransition = cached(function (name) {
    return {
      enterClass: (name + "-enter"),
      enterToClass: (name + "-enter-to"),
      enterActiveClass: (name + "-enter-active"),
      leaveClass: (name + "-leave"),
      leaveToClass: (name + "-leave-to"),
      leaveActiveClass: (name + "-leave-active")
    }
  });
  
  var hasTransition = inBrowser && !isIE9;
  var TRANSITION = 'transition';
  var ANIMATION = 'animation';
  
  // Transition property/event sniffing
  var transitionProp = 'transition';
  var transitionEndEvent = 'transitionend';
  var animationProp = 'animation';
  var animationEndEvent = 'animationend';
  if (hasTransition) {
    /* istanbul ignore if */
    if (window.ontransitionend === undefined &&
      window.onwebkittransitionend !== undefined) {
      transitionProp = 'WebkitTransition';
      transitionEndEvent = 'webkitTransitionEnd';
    }
    if (window.onanimationend === undefined &&
      window.onwebkitanimationend !== undefined) {
      animationProp = 'WebkitAnimation';
      animationEndEvent = 'webkitAnimationEnd';
    }
  }
  
  // binding to window is necessary to make hot reload work in IE in strict mode
  var raf = inBrowser && window.requestAnimationFrame
    ? window.requestAnimationFrame.bind(window)
    : setTimeout;
  
  function nextFrame (fn) {
    raf(function () {
      raf(fn);
    });
  }
  
  function addTransitionClass (el, cls) {
    (el._transitionClasses || (el._transitionClasses = [])).push(cls);
    addClass(el, cls);
  }
  
  function removeTransitionClass (el, cls) {
    if (el._transitionClasses) {
      remove(el._transitionClasses, cls);
    }
    removeClass(el, cls);
  }
  
  function whenTransitionEnds (
    el,
    expectedType,
    cb
  ) {
    var ref = getTransitionInfo(el, expectedType);
    var type = ref.type;
    var timeout = ref.timeout;
    var propCount = ref.propCount;
    if (!type) { return cb() }
    var event = type === TRANSITION ? transitionEndEvent : animationEndEvent;
    var ended = 0;
    var end = function () {
      el.removeEventListener(event, onEnd);
      cb();
    };
    var onEnd = function (e) {
      if (e.target === el) {
        if (++ended >= propCount) {
          end();
        }
      }
    };
    setTimeout(function () {
      if (ended < propCount) {
        end();
      }
    }, timeout + 1);
    el.addEventListener(event, onEnd);
  }
  
  var transformRE = /\b(transform|all)(,|$)/;
  
  function getTransitionInfo (el, expectedType) {
    var styles = window.getComputedStyle(el);
    var transitionDelays = styles[transitionProp + 'Delay'].split(', ');
    var transitionDurations = styles[transitionProp + 'Duration'].split(', ');
    var transitionTimeout = getTimeout(transitionDelays, transitionDurations);
    var animationDelays = styles[animationProp + 'Delay'].split(', ');
    var animationDurations = styles[animationProp + 'Duration'].split(', ');
    var animationTimeout = getTimeout(animationDelays, animationDurations);
  
    var type;
    var timeout = 0;
    var propCount = 0;
    /* istanbul ignore if */
    if (expectedType === TRANSITION) {
      if (transitionTimeout > 0) {
        type = TRANSITION;
        timeout = transitionTimeout;
        propCount = transitionDurations.length;
      }
    } else if (expectedType === ANIMATION) {
      if (animationTimeout > 0) {
        type = ANIMATION;
        timeout = animationTimeout;
        propCount = animationDurations.length;
      }
    } else {
      timeout = Math.max(transitionTimeout, animationTimeout);
      type = timeout > 0
        ? transitionTimeout > animationTimeout
          ? TRANSITION
          : ANIMATION
        : null;
      propCount = type
        ? type === TRANSITION
          ? transitionDurations.length
          : animationDurations.length
        : 0;
    }
    var hasTransform =
      type === TRANSITION &&
      transformRE.test(styles[transitionProp + 'Property']);
    return {
      type: type,
      timeout: timeout,
      propCount: propCount,
      hasTransform: hasTransform
    }
  }
  
  function getTimeout (delays, durations) {
    /* istanbul ignore next */
    while (delays.length < durations.length) {
      delays = delays.concat(delays);
    }
  
    return Math.max.apply(null, durations.map(function (d, i) {
      return toMs(d) + toMs(delays[i])
    }))
  }
  
  function toMs (s) {
    return Number(s.slice(0, -1)) * 1000
  }
  
  /*  */
  
  function enter (vnode, toggleDisplay) {
    var el = vnode.elm;
  
    // call leave callback now
    if (isDef(el._leaveCb)) {
      el._leaveCb.cancelled = true;
      el._leaveCb();
    }
  
    var data = resolveTransition(vnode.data.transition);
    if (isUndef(data)) {
      return
    }
  
    /* istanbul ignore if */
    if (isDef(el._enterCb) || el.nodeType !== 1) {
      return
    }
  
    var ref = (data);
    var css = ref.css;
    var type = ref.type;
    var enterClass = ref.enterClass;
    var enterToClass = ref.enterToClass;
    var enterActiveClass = ref.enterActiveClass;
    var appearClass = ref.appearClass;
    var appearToClass = ref.appearToClass;
    var appearActiveClass = ref.appearActiveClass;
    var beforeEnter = ref.beforeEnter;
    var enter = ref.enter;
    var afterEnter = ref.afterEnter;
    var enterCancelled = ref.enterCancelled;
    var beforeAppear = ref.beforeAppear;
    var appear = ref.appear;
    var afterAppear = ref.afterAppear;
    var appearCancelled = ref.appearCancelled;
    var duration = ref.duration;
  
    // activeInstance will always be the <transition> component managing this
    // transition. One edge case to check is when the <transition> is placed
    // as the root node of a child component. In that case we need to check
    // <transition>'s parent for appear check.
    var context = activeInstance;
    var transitionNode = activeInstance.$vnode;
    while (transitionNode && transitionNode.parent) {
      transitionNode = transitionNode.parent;
      context = transitionNode.context;
    }
  
    var isAppear = !context._isMounted || !vnode.isRootInsert;
  
    if (isAppear && !appear && appear !== '') {
      return
    }
  
    var startClass = isAppear && appearClass
      ? appearClass
      : enterClass;
    var activeClass = isAppear && appearActiveClass
      ? appearActiveClass
      : enterActiveClass;
    var toClass = isAppear && appearToClass
      ? appearToClass
      : enterToClass;
  
    var beforeEnterHook = isAppear
      ? (beforeAppear || beforeEnter)
      : beforeEnter;
    var enterHook = isAppear
      ? (typeof appear === 'function' ? appear : enter)
      : enter;
    var afterEnterHook = isAppear
      ? (afterAppear || afterEnter)
      : afterEnter;
    var enterCancelledHook = isAppear
      ? (appearCancelled || enterCancelled)
      : enterCancelled;
  
    var explicitEnterDuration = toNumber(
      isObject(duration)
        ? duration.enter
        : duration
    );
  
    if ("development" !== 'production' && explicitEnterDuration != null) {
      checkDuration(explicitEnterDuration, 'enter', vnode);
    }
  
    var expectsCSS = css !== false && !isIE9;
    var userWantsControl = getHookArgumentsLength(enterHook);
  
    var cb = el._enterCb = once(function () {
      if (expectsCSS) {
        removeTransitionClass(el, toClass);
        removeTransitionClass(el, activeClass);
      }
      if (cb.cancelled) {
        if (expectsCSS) {
          removeTransitionClass(el, startClass);
        }
        enterCancelledHook && enterCancelledHook(el);
      } else {
        afterEnterHook && afterEnterHook(el);
      }
      el._enterCb = null;
    });
  
    if (!vnode.data.show) {
      // remove pending leave element on enter by injecting an insert hook
      mergeVNodeHook(vnode.data.hook || (vnode.data.hook = {}), 'insert', function () {
        var parent = el.parentNode;
        var pendingNode = parent && parent._pending && parent._pending[vnode.key];
        if (pendingNode &&
            pendingNode.tag === vnode.tag &&
            pendingNode.elm._leaveCb) {
          pendingNode.elm._leaveCb();
        }
        enterHook && enterHook(el, cb);
      });
    }
  
    // start enter transition
    beforeEnterHook && beforeEnterHook(el);
    if (expectsCSS) {
      addTransitionClass(el, startClass);
      addTransitionClass(el, activeClass);
      nextFrame(function () {
        addTransitionClass(el, toClass);
        removeTransitionClass(el, startClass);
        if (!cb.cancelled && !userWantsControl) {
          if (isValidDuration(explicitEnterDuration)) {
            setTimeout(cb, explicitEnterDuration);
          } else {
            whenTransitionEnds(el, type, cb);
          }
        }
      });
    }
  
    if (vnode.data.show) {
      toggleDisplay && toggleDisplay();
      enterHook && enterHook(el, cb);
    }
  
    if (!expectsCSS && !userWantsControl) {
      cb();
    }
  }
  
  function leave (vnode, rm) {
    var el = vnode.elm;
  
    // call enter callback now
    if (isDef(el._enterCb)) {
      el._enterCb.cancelled = true;
      el._enterCb();
    }
  
    var data = resolveTransition(vnode.data.transition);
    if (isUndef(data)) {
      return rm()
    }
  
    /* istanbul ignore if */
    if (isDef(el._leaveCb) || el.nodeType !== 1) {
      return
    }
  
    var ref = (data);
    var css = ref.css;
    var type = ref.type;
    var leaveClass = ref.leaveClass;
    var leaveToClass = ref.leaveToClass;
    var leaveActiveClass = ref.leaveActiveClass;
    var beforeLeave = ref.beforeLeave;
    var leave = ref.leave;
    var afterLeave = ref.afterLeave;
    var leaveCancelled = ref.leaveCancelled;
    var delayLeave = ref.delayLeave;
    var duration = ref.duration;
  
    var expectsCSS = css !== false && !isIE9;
    var userWantsControl = getHookArgumentsLength(leave);
  
    var explicitLeaveDuration = toNumber(
      isObject(duration)
        ? duration.leave
        : duration
    );
  
    if ("development" !== 'production' && explicitLeaveDuration != null) {
      checkDuration(explicitLeaveDuration, 'leave', vnode);
    }
  
    var cb = el._leaveCb = once(function () {
      if (el.parentNode && el.parentNode._pending) {
        el.parentNode._pending[vnode.key] = null;
      }
      if (expectsCSS) {
        removeTransitionClass(el, leaveToClass);
        removeTransitionClass(el, leaveActiveClass);
      }
      if (cb.cancelled) {
        if (expectsCSS) {
          removeTransitionClass(el, leaveClass);
        }
        leaveCancelled && leaveCancelled(el);
      } else {
        rm();
        afterLeave && afterLeave(el);
      }
      el._leaveCb = null;
    });
  
    if (delayLeave) {
      delayLeave(performLeave);
    } else {
      performLeave();
    }
  
    function performLeave () {
      // the delayed leave may have already been cancelled
      if (cb.cancelled) {
        return
      }
      // record leaving element
      if (!vnode.data.show) {
        (el.parentNode._pending || (el.parentNode._pending = {}))[vnode.key] = vnode;
      }
      beforeLeave && beforeLeave(el);
      if (expectsCSS) {
        addTransitionClass(el, leaveClass);
        addTransitionClass(el, leaveActiveClass);
        nextFrame(function () {
          addTransitionClass(el, leaveToClass);
          removeTransitionClass(el, leaveClass);
          if (!cb.cancelled && !userWantsControl) {
            if (isValidDuration(explicitLeaveDuration)) {
              setTimeout(cb, explicitLeaveDuration);
            } else {
              whenTransitionEnds(el, type, cb);
            }
          }
        });
      }
      leave && leave(el, cb);
      if (!expectsCSS && !userWantsControl) {
        cb();
      }
    }
  }
  
  // only used in dev mode
  function checkDuration (val, name, vnode) {
    if (typeof val !== 'number') {
      warn(
        "<transition> explicit " + name + " duration is not a valid number - " +
        "got " + (JSON.stringify(val)) + ".",
        vnode.context
      );
    } else if (isNaN(val)) {
      warn(
        "<transition> explicit " + name + " duration is NaN - " +
        'the duration expression might be incorrect.',
        vnode.context
      );
    }
  }
  
  function isValidDuration (val) {
    return typeof val === 'number' && !isNaN(val)
  }
  
  /**
   * Normalize a transition hook's argument length. The hook may be:
   * - a merged hook (invoker) with the original in .fns
   * - a wrapped component method (check ._length)
   * - a plain function (.length)
   */
  function getHookArgumentsLength (fn) {
    if (isUndef(fn)) {
      return false
    }
    var invokerFns = fn.fns;
    if (isDef(invokerFns)) {
      // invoker
      return getHookArgumentsLength(
        Array.isArray(invokerFns)
          ? invokerFns[0]
          : invokerFns
      )
    } else {
      return (fn._length || fn.length) > 1
    }
  }
  
  function _enter (_, vnode) {
    if (vnode.data.show !== true) {
      enter(vnode);
    }
  }
  
  var transition = inBrowser ? {
    create: _enter,
    activate: _enter,
    remove: function remove$$1 (vnode, rm) {
      /* istanbul ignore else */
      if (vnode.data.show !== true) {
        leave(vnode, rm);
      } else {
        rm();
      }
    }
  } : {};
  
  var platformModules = [
    attrs,
    klass,
    events,
    domProps,
    style,
    transition
  ];
  
  /*  */
  
  var modules = platformModules.concat(baseModules);
  
  var patch = createPatchFunction({ nodeOps: nodeOps, modules: modules });
  
  /**
   * Not type checking this file because flow doesn't like attaching
   * properties to Elements.
   */
  
  if (isIE9) {
    // http://www.matts411.com/post/internet-explorer-9-oninput/
    document.addEventListener('selectionchange', function () {
      var el = document.activeElement;
      if (el && el.vmodel) {
        trigger(el, 'input');
      }
    });
  }
  
  var model$1 = {
    inserted: function inserted (el, binding, vnode) {
      if (vnode.tag === 'select') {
        var cb = function () {
          setSelected(el, binding, vnode.context);
        };
        cb();
        /* istanbul ignore if */
        if (isIE || isEdge) {
          setTimeout(cb, 0);
        }
      } else if (vnode.tag === 'textarea' || el.type === 'text' || el.type === 'password') {
        el._vModifiers = binding.modifiers;
        if (!binding.modifiers.lazy) {
          // Safari < 10.2 & UIWebView doesn't fire compositionend when
          // switching focus before confirming composition choice
          // this also fixes the issue where some browsers e.g. iOS Chrome
          // fires "change" instead of "input" on autocomplete.
          el.addEventListener('change', onCompositionEnd);
          if (!isAndroid) {
            el.addEventListener('compositionstart', onCompositionStart);
            el.addEventListener('compositionend', onCompositionEnd);
          }
          /* istanbul ignore if */
          if (isIE9) {
            el.vmodel = true;
          }
        }
      }
    },
    componentUpdated: function componentUpdated (el, binding, vnode) {
      if (vnode.tag === 'select') {
        setSelected(el, binding, vnode.context);
        // in case the options rendered by v-for have changed,
        // it's possible that the value is out-of-sync with the rendered options.
        // detect such cases and filter out values that no longer has a matching
        // option in the DOM.
        var needReset = el.multiple
          ? binding.value.some(function (v) { return hasNoMatchingOption(v, el.options); })
          : binding.value !== binding.oldValue && hasNoMatchingOption(binding.value, el.options);
        if (needReset) {
          trigger(el, 'change');
        }
      }
    }
  };
  
  function setSelected (el, binding, vm) {
    var value = binding.value;
    var isMultiple = el.multiple;
    if (isMultiple && !Array.isArray(value)) {
      "development" !== 'production' && warn(
        "<select multiple v-model=\"" + (binding.expression) + "\"> " +
        "expects an Array value for its binding, but got " + (Object.prototype.toString.call(value).slice(8, -1)),
        vm
      );
      return
    }
    var selected, option;
    for (var i = 0, l = el.options.length; i < l; i++) {
      option = el.options[i];
      if (isMultiple) {
        selected = looseIndexOf(value, getValue(option)) > -1;
        if (option.selected !== selected) {
          option.selected = selected;
        }
      } else {
        if (looseEqual(getValue(option), value)) {
          if (el.selectedIndex !== i) {
            el.selectedIndex = i;
          }
          return
        }
      }
    }
    if (!isMultiple) {
      el.selectedIndex = -1;
    }
  }
  
  function hasNoMatchingOption (value, options) {
    for (var i = 0, l = options.length; i < l; i++) {
      if (looseEqual(getValue(options[i]), value)) {
        return false
      }
    }
    return true
  }
  
  function getValue (option) {
    return '_value' in option
      ? option._value
      : option.value
  }
  
  function onCompositionStart (e) {
    e.target.composing = true;
  }
  
  function onCompositionEnd (e) {
    e.target.composing = false;
    trigger(e.target, 'input');
  }
  
  function trigger (el, type) {
    var e = document.createEvent('HTMLEvents');
    e.initEvent(type, true, true);
    el.dispatchEvent(e);
  }
  
  /*  */
  
  function locateNode (vnode) {
    return vnode.componentInstance && (!vnode.data || !vnode.data.transition)
      ? locateNode(vnode.componentInstance._vnode)
      : vnode
  }
  
  var show = {
    bind: function bind (el, ref, vnode) {
      var value = ref.value;
  
      vnode = locateNode(vnode);
      var transition = vnode.data && vnode.data.transition;
      var originalDisplay = el.__vOriginalDisplay =
        el.style.display === 'none' ? '' : el.style.display;
      if (value && transition && !isIE9) {
        vnode.data.show = true;
        enter(vnode, function () {
          el.style.display = originalDisplay;
        });
      } else {
        el.style.display = value ? originalDisplay : 'none';
      }
    },
  
    update: function update (el, ref, vnode) {
      var value = ref.value;
      var oldValue = ref.oldValue;
  
      /* istanbul ignore if */
      if (value === oldValue) { return }
      vnode = locateNode(vnode);
      var transition = vnode.data && vnode.data.transition;
      if (transition && !isIE9) {
        vnode.data.show = true;
        if (value) {
          enter(vnode, function () {
            el.style.display = el.__vOriginalDisplay;
          });
        } else {
          leave(vnode, function () {
            el.style.display = 'none';
          });
        }
      } else {
        el.style.display = value ? el.__vOriginalDisplay : 'none';
      }
    },
  
    unbind: function unbind (
      el,
      binding,
      vnode,
      oldVnode,
      isDestroy
    ) {
      if (!isDestroy) {
        el.style.display = el.__vOriginalDisplay;
      }
    }
  };
  
  var platformDirectives = {
    model: model$1,
    show: show
  };
  
  /*  */
  
  // Provides transition support for a single element/component.
  // supports transition mode (out-in / in-out)
  
  var transitionProps = {
    name: String,
    appear: Boolean,
    css: Boolean,
    mode: String,
    type: String,
    enterClass: String,
    leaveClass: String,
    enterToClass: String,
    leaveToClass: String,
    enterActiveClass: String,
    leaveActiveClass: String,
    appearClass: String,
    appearActiveClass: String,
    appearToClass: String,
    duration: [Number, String, Object]
  };
  
  // in case the child is also an abstract component, e.g. <keep-alive>
  // we want to recursively retrieve the real component to be rendered
  function getRealChild (vnode) {
    var compOptions = vnode && vnode.componentOptions;
    if (compOptions && compOptions.Ctor.options.abstract) {
      return getRealChild(getFirstComponentChild(compOptions.children))
    } else {
      return vnode
    }
  }
  
  function extractTransitionData (comp) {
    var data = {};
    var options = comp.$options;
    // props
    for (var key in options.propsData) {
      data[key] = comp[key];
    }
    // events.
    // extract listeners and pass them directly to the transition methods
    var listeners = options._parentListeners;
    for (var key$1 in listeners) {
      data[camelize(key$1)] = listeners[key$1];
    }
    return data
  }
  
  function placeholder (h, rawChild) {
    if (/\d-keep-alive$/.test(rawChild.tag)) {
      return h('keep-alive', {
        props: rawChild.componentOptions.propsData
      })
    }
  }
  
  function hasParentTransition (vnode) {
    while ((vnode = vnode.parent)) {
      if (vnode.data.transition) {
        return true
      }
    }
  }
  
  function isSameChild (child, oldChild) {
    return oldChild.key === child.key && oldChild.tag === child.tag
  }
  
  var Transition = {
    name: 'transition',
    props: transitionProps,
    abstract: true,
  
    render: function render (h) {
      var this$1 = this;
  
      var children = this.$slots.default;
      if (!children) {
        return
      }
  
      // filter out text nodes (possible whitespaces)
      children = children.filter(function (c) { return c.tag; });
      /* istanbul ignore if */
      if (!children.length) {
        return
      }
  
      // warn multiple elements
      if ("development" !== 'production' && children.length > 1) {
        warn(
          '<transition> can only be used on a single element. Use ' +
          '<transition-group> for lists.',
          this.$parent
        );
      }
  
      var mode = this.mode;
  
      // warn invalid mode
      if ("development" !== 'production' &&
          mode && mode !== 'in-out' && mode !== 'out-in') {
        warn(
          'invalid <transition> mode: ' + mode,
          this.$parent
        );
      }
  
      var rawChild = children[0];
  
      // if this is a component root node and the component's
      // parent container node also has transition, skip.
      if (hasParentTransition(this.$vnode)) {
        return rawChild
      }
  
      // apply transition data to child
      // use getRealChild() to ignore abstract components e.g. keep-alive
      var child = getRealChild(rawChild);
      /* istanbul ignore if */
      if (!child) {
        return rawChild
      }
  
      if (this._leaving) {
        return placeholder(h, rawChild)
      }
  
      // ensure a key that is unique to the vnode type and to this transition
      // component instance. This key will be used to remove pending leaving nodes
      // during entering.
      var id = "__transition-" + (this._uid) + "-";
      child.key = child.key == null
        ? id + child.tag
        : isPrimitive(child.key)
          ? (String(child.key).indexOf(id) === 0 ? child.key : id + child.key)
          : child.key;
  
      var data = (child.data || (child.data = {})).transition = extractTransitionData(this);
      var oldRawChild = this._vnode;
      var oldChild = getRealChild(oldRawChild);
  
      // mark v-show
      // so that the transition module can hand over the control to the directive
      if (child.data.directives && child.data.directives.some(function (d) { return d.name === 'show'; })) {
        child.data.show = true;
      }
  
      if (oldChild && oldChild.data && !isSameChild(child, oldChild)) {
        // replace old child transition data with fresh one
        // important for dynamic transitions!
        var oldData = oldChild && (oldChild.data.transition = extend({}, data));
        // handle transition mode
        if (mode === 'out-in') {
          // return placeholder node and queue update when leave finishes
          this._leaving = true;
          mergeVNodeHook(oldData, 'afterLeave', function () {
            this$1._leaving = false;
            this$1.$forceUpdate();
          });
          return placeholder(h, rawChild)
        } else if (mode === 'in-out') {
          var delayedLeave;
          var performLeave = function () { delayedLeave(); };
          mergeVNodeHook(data, 'afterEnter', performLeave);
          mergeVNodeHook(data, 'enterCancelled', performLeave);
          mergeVNodeHook(oldData, 'delayLeave', function (leave) { delayedLeave = leave; });
        }
      }
  
      return rawChild
    }
  };
  
  /*  */
  
  // Provides transition support for list items.
  // supports move transitions using the FLIP technique.
  
  // Because the vdom's children update algorithm is "unstable" - i.e.
  // it doesn't guarantee the relative positioning of removed elements,
  // we force transition-group to update its children into two passes:
  // in the first pass, we remove all nodes that need to be removed,
  // triggering their leaving transition; in the second pass, we insert/move
  // into the final desired state. This way in the second pass removed
  // nodes will remain where they should be.
  
  var props = extend({
    tag: String,
    moveClass: String
  }, transitionProps);
  
  delete props.mode;
  
  var TransitionGroup = {
    props: props,
  
    render: function render (h) {
      var tag = this.tag || this.$vnode.data.tag || 'span';
      var map = Object.create(null);
      var prevChildren = this.prevChildren = this.children;
      var rawChildren = this.$slots.default || [];
      var children = this.children = [];
      var transitionData = extractTransitionData(this);
  
      for (var i = 0; i < rawChildren.length; i++) {
        var c = rawChildren[i];
        if (c.tag) {
          if (c.key != null && String(c.key).indexOf('__vlist') !== 0) {
            children.push(c);
            map[c.key] = c
            ;(c.data || (c.data = {})).transition = transitionData;
          } else {
            var opts = c.componentOptions;
            var name = opts ? (opts.Ctor.options.name || opts.tag || '') : c.tag;
            warn(("<transition-group> children must be keyed: <" + name + ">"));
          }
        }
      }
  
      if (prevChildren) {
        var kept = [];
        var removed = [];
        for (var i$1 = 0; i$1 < prevChildren.length; i$1++) {
          var c$1 = prevChildren[i$1];
          c$1.data.transition = transitionData;
          c$1.data.pos = c$1.elm.getBoundingClientRect();
          if (map[c$1.key]) {
            kept.push(c$1);
          } else {
            removed.push(c$1);
          }
        }
        this.kept = h(tag, null, kept);
        this.removed = removed;
      }
  
      return h(tag, null, children)
    },
  
    beforeUpdate: function beforeUpdate () {
      // force removing pass
      this.__patch__(
        this._vnode,
        this.kept,
        false, // hydrating
        true // removeOnly (!important, avoids unnecessary moves)
      );
      this._vnode = this.kept;
    },
  
    updated: function updated () {
      var children = this.prevChildren;
      var moveClass = this.moveClass || ((this.name || 'v') + '-move');
      if (!children.length || !this.hasMove(children[0].elm, moveClass)) {
        return
      }
  
      // we divide the work into three loops to avoid mixing DOM reads and writes
      // in each iteration - which helps prevent layout thrashing.
      children.forEach(callPendingCbs);
      children.forEach(recordPosition);
      children.forEach(applyTranslation);
  
      // force reflow to put everything in position
      var body = document.body;
      var f = body.offsetHeight; // eslint-disable-line
  
      children.forEach(function (c) {
        if (c.data.moved) {
          var el = c.elm;
          var s = el.style;
          addTransitionClass(el, moveClass);
          s.transform = s.WebkitTransform = s.transitionDuration = '';
          el.addEventListener(transitionEndEvent, el._moveCb = function cb (e) {
            if (!e || /transform$/.test(e.propertyName)) {
              el.removeEventListener(transitionEndEvent, cb);
              el._moveCb = null;
              removeTransitionClass(el, moveClass);
            }
          });
        }
      });
    },
  
    methods: {
      hasMove: function hasMove (el, moveClass) {
        /* istanbul ignore if */
        if (!hasTransition) {
          return false
        }
        if (this._hasMove != null) {
          return this._hasMove
        }
        // Detect whether an element with the move class applied has
        // CSS transitions. Since the element may be inside an entering
        // transition at this very moment, we make a clone of it and remove
        // all other transition classes applied to ensure only the move class
        // is applied.
        var clone = el.cloneNode();
        if (el._transitionClasses) {
          el._transitionClasses.forEach(function (cls) { removeClass(clone, cls); });
        }
        addClass(clone, moveClass);
        clone.style.display = 'none';
        this.$el.appendChild(clone);
        var info = getTransitionInfo(clone);
        this.$el.removeChild(clone);
        return (this._hasMove = info.hasTransform)
      }
    }
  };
  
  function callPendingCbs (c) {
    /* istanbul ignore if */
    if (c.elm._moveCb) {
      c.elm._moveCb();
    }
    /* istanbul ignore if */
    if (c.elm._enterCb) {
      c.elm._enterCb();
    }
  }
  
  function recordPosition (c) {
    c.data.newPos = c.elm.getBoundingClientRect();
  }
  
  function applyTranslation (c) {
    var oldPos = c.data.pos;
    var newPos = c.data.newPos;
    var dx = oldPos.left - newPos.left;
    var dy = oldPos.top - newPos.top;
    if (dx || dy) {
      c.data.moved = true;
      var s = c.elm.style;
      s.transform = s.WebkitTransform = "translate(" + dx + "px," + dy + "px)";
      s.transitionDuration = '0s';
    }
  }
  
  var platformComponents = {
    Transition: Transition,
    TransitionGroup: TransitionGroup
  };
  
  /*  */
  
  Vue$3.config.mustUseProp = mustUseProp;
  Vue$3.config.isReservedTag = isReservedTag;
  Vue$3.config.isReservedAttr = isReservedAttr;
  Vue$3.config.getTagNamespace = getTagNamespace;
  Vue$3.config.isUnknownElement = isUnknownElement;
  
  // install platform runtime directives & components
  extend(Vue$3.options.directives, platformDirectives);
  extend(Vue$3.options.components, platformComponents);
  
  // install platform patch function
  Vue$3.prototype.__patch__ = inBrowser ? patch : noop;
  
  // public mount method
  Vue$3.prototype.$mount = function (
    el,
    hydrating
  ) {
    el = el && inBrowser ? query(el) : undefined;
    return mountComponent(this, el, hydrating)
  };
  
  // devtools global hook
  /* istanbul ignore next */
  setTimeout(function () {
    if (config.devtools) {
      if (devtools) {
        devtools.emit('init', Vue$3);
      } else if ("development" !== 'production' && isChrome) {
        console[console.info ? 'info' : 'log'](
          'Download the Vue Devtools extension for a better development experience:\n' +
          'https://github.com/vuejs/vue-devtools'
        );
      }
    }
    if ("development" !== 'production' &&
        config.productionTip !== false &&
        inBrowser && typeof console !== 'undefined') {
      console[console.info ? 'info' : 'log'](
        "You are running Vue in development mode.\n" +
        "Make sure to turn on production mode when deploying for production.\n" +
        "See more tips at https://vuejs.org/guide/deployment.html"
      );
    }
  }, 0);
  
  /*  */
  
  function shouldDecode (content, encoded) {
    var div = document.createElement('div');
    div.innerHTML = "<div a=\"" + content + "\">";
    return div.innerHTML.indexOf(encoded) > 0
  }
  
  // #3663
  // IE encodes newlines inside attribute values while other browsers don't
  var shouldDecodeNewlines = inBrowser ? shouldDecode('\n', '&#10;') : false;
  
  /*  */
  
  var isUnaryTag = makeMap(
    'area,base,br,col,embed,frame,hr,img,input,isindex,keygen,' +
    'link,meta,param,source,track,wbr'
  );
  
  // Elements that you can, intentionally, leave open
  // (and which close themselves)
  var canBeLeftOpenTag = makeMap(
    'colgroup,dd,dt,li,options,p,td,tfoot,th,thead,tr,source'
  );
  
  // HTML5 tags https://html.spec.whatwg.org/multipage/indices.html#elements-3
  // Phrasing Content https://html.spec.whatwg.org/multipage/dom.html#phrasing-content
  var isNonPhrasingTag = makeMap(
    'address,article,aside,base,blockquote,body,caption,col,colgroup,dd,' +
    'details,dialog,div,dl,dt,fieldset,figcaption,figure,footer,form,' +
    'h1,h2,h3,h4,h5,h6,head,header,hgroup,hr,html,legend,li,menuitem,meta,' +
    'optgroup,option,param,rp,rt,source,style,summary,tbody,td,tfoot,th,thead,' +
    'title,tr,track'
  );
  
  /*  */
  
  var decoder;
  
  function decode (html) {
    decoder = decoder || document.createElement('div');
    decoder.innerHTML = html;
    return decoder.textContent
  }
  
  /**
   * Not type-checking this file because it's mostly vendor code.
   */
  
  /*!
   * HTML Parser By John Resig (ejohn.org)
   * Modified by Juriy "kangax" Zaytsev
   * Original code by Erik Arvidsson, Mozilla Public License
   * http://erik.eae.net/simplehtmlparser/simplehtmlparser.js
   */
  
  var singleAttrIdentifier = /([^\s"'<>/=]+)/;
  var singleAttrAssign = /(?:=)/;
  var singleAttrValues = [
    // attr value double quotes
    /"([^"]*)"+/.source,
    // attr value, single quotes
    /'([^']*)'+/.source,
    // attr value, no quotes
    /([^\s"'=<>`]+)/.source
  ];
  var attribute = new RegExp(
    '^\\s*' + singleAttrIdentifier.source +
    '(?:\\s*(' + singleAttrAssign.source + ')' +
    '\\s*(?:' + singleAttrValues.join('|') + '))?'
  );
  
  // could use https://www.w3.org/TR/1999/REC-xml-names-19990114/#NT-QName
  // but for Vue templates we can enforce a simple charset
  var ncname = '[a-zA-Z_][\\w\\-\\.]*';
  var qnameCapture = '((?:' + ncname + '\\:)?' + ncname + ')';
  var startTagOpen = new RegExp('^<' + qnameCapture);
  var startTagClose = /^\s*(\/?)>/;
  var endTag = new RegExp('^<\\/' + qnameCapture + '[^>]*>');
  var doctype = /^<!DOCTYPE [^>]+>/i;
  var comment = /^<!--/;
  var conditionalComment = /^<!\[/;
  
  var IS_REGEX_CAPTURING_BROKEN = false;
  'x'.replace(/x(.)?/g, function (m, g) {
    IS_REGEX_CAPTURING_BROKEN = g === '';
  });
  
  // Special Elements (can contain anything)
  var isPlainTextElement = makeMap('script,style,textarea', true);
  var reCache = {};
  
  var decodingMap = {
    '&lt;': '<',
    '&gt;': '>',
    '&quot;': '"',
    '&amp;': '&',
    '&#10;': '\n'
  };
  var encodedAttr = /&(?:lt|gt|quot|amp);/g;
  var encodedAttrWithNewLines = /&(?:lt|gt|quot|amp|#10);/g;
  
  function decodeAttr (value, shouldDecodeNewlines) {
    var re = shouldDecodeNewlines ? encodedAttrWithNewLines : encodedAttr;
    return value.replace(re, function (match) { return decodingMap[match]; })
  }
  
  function parseHTML (html, options) {
    var stack = [];
    var expectHTML = options.expectHTML;
    var isUnaryTag$$1 = options.isUnaryTag || no;
    var canBeLeftOpenTag$$1 = options.canBeLeftOpenTag || no;
    var index = 0;
    var last, lastTag;
    while (html) {
      last = html;
      // Make sure we're not in a plaintext content element like script/style
      if (!lastTag || !isPlainTextElement(lastTag)) {
        var textEnd = html.indexOf('<');
        if (textEnd === 0) {
          // Comment:
          if (comment.test(html)) {
            var commentEnd = html.indexOf('-->');
  
            if (commentEnd >= 0) {
              advance(commentEnd + 3);
              continue
            }
          }
  
          // http://en.wikipedia.org/wiki/Conditional_comment#Downlevel-revealed_conditional_comment
          if (conditionalComment.test(html)) {
            var conditionalEnd = html.indexOf(']>');
  
            if (conditionalEnd >= 0) {
              advance(conditionalEnd + 2);
              continue
            }
          }
  
          // Doctype:
          var doctypeMatch = html.match(doctype);
          if (doctypeMatch) {
            advance(doctypeMatch[0].length);
            continue
          }
  
          // End tag:
          var endTagMatch = html.match(endTag);
          if (endTagMatch) {
            var curIndex = index;
            advance(endTagMatch[0].length);
            parseEndTag(endTagMatch[1], curIndex, index);
            continue
          }
  
          // Start tag:
          var startTagMatch = parseStartTag();
          if (startTagMatch) {
            handleStartTag(startTagMatch);
            continue
          }
        }
  
        var text = (void 0), rest$1 = (void 0), next = (void 0);
        if (textEnd >= 0) {
          rest$1 = html.slice(textEnd);
          while (
            !endTag.test(rest$1) &&
            !startTagOpen.test(rest$1) &&
            !comment.test(rest$1) &&
            !conditionalComment.test(rest$1)
          ) {
            // < in plain text, be forgiving and treat it as text
            next = rest$1.indexOf('<', 1);
            if (next < 0) { break }
            textEnd += next;
            rest$1 = html.slice(textEnd);
          }
          text = html.substring(0, textEnd);
          advance(textEnd);
        }
  
        if (textEnd < 0) {
          text = html;
          html = '';
        }
  
        if (options.chars && text) {
          options.chars(text);
        }
      } else {
        var stackedTag = lastTag.toLowerCase();
        var reStackedTag = reCache[stackedTag] || (reCache[stackedTag] = new RegExp('([\\s\\S]*?)(</' + stackedTag + '[^>]*>)', 'i'));
        var endTagLength = 0;
        var rest = html.replace(reStackedTag, function (all, text, endTag) {
          endTagLength = endTag.length;
          if (!isPlainTextElement(stackedTag) && stackedTag !== 'noscript') {
            text = text
              .replace(/<!--([\s\S]*?)-->/g, '$1')
              .replace(/<!\[CDATA\[([\s\S]*?)]]>/g, '$1');
          }
          if (options.chars) {
            options.chars(text);
          }
          return ''
        });
        index += html.length - rest.length;
        html = rest;
        parseEndTag(stackedTag, index - endTagLength, index);
      }
  
      if (html === last) {
        options.chars && options.chars(html);
        if ("development" !== 'production' && !stack.length && options.warn) {
          options.warn(("Mal-formatted tag at end of template: \"" + html + "\""));
        }
        break
      }
    }
  
    // Clean up any remaining tags
    parseEndTag();
  
    function advance (n) {
      index += n;
      html = html.substring(n);
    }
  
    function parseStartTag () {
      var start = html.match(startTagOpen);
      if (start) {
        var match = {
          tagName: start[1],
          attrs: [],
          start: index
        };
        advance(start[0].length);
        var end, attr;
        while (!(end = html.match(startTagClose)) && (attr = html.match(attribute))) {
          advance(attr[0].length);
          match.attrs.push(attr);
        }
        if (end) {
          match.unarySlash = end[1];
          advance(end[0].length);
          match.end = index;
          return match
        }
      }
    }
  
    function handleStartTag (match) {
      var tagName = match.tagName;
      var unarySlash = match.unarySlash;
  
      if (expectHTML) {
        if (lastTag === 'p' && isNonPhrasingTag(tagName)) {
          parseEndTag(lastTag);
        }
        if (canBeLeftOpenTag$$1(tagName) && lastTag === tagName) {
          parseEndTag(tagName);
        }
      }
  
      var unary = isUnaryTag$$1(tagName) || tagName === 'html' && lastTag === 'head' || !!unarySlash;
  
      var l = match.attrs.length;
      var attrs = new Array(l);
      for (var i = 0; i < l; i++) {
        var args = match.attrs[i];
        // hackish work around FF bug https://bugzilla.mozilla.org/show_bug.cgi?id=369778
        if (IS_REGEX_CAPTURING_BROKEN && args[0].indexOf('""') === -1) {
          if (args[3] === '') { delete args[3]; }
          if (args[4] === '') { delete args[4]; }
          if (args[5] === '') { delete args[5]; }
        }
        var value = args[3] || args[4] || args[5] || '';
        attrs[i] = {
          name: args[1],
          value: decodeAttr(
            value,
            options.shouldDecodeNewlines
          )
        };
      }
  
      if (!unary) {
        stack.push({ tag: tagName, lowerCasedTag: tagName.toLowerCase(), attrs: attrs });
        lastTag = tagName;
      }
  
      if (options.start) {
        options.start(tagName, attrs, unary, match.start, match.end);
      }
    }
  
    function parseEndTag (tagName, start, end) {
      var pos, lowerCasedTagName;
      if (start == null) { start = index; }
      if (end == null) { end = index; }
  
      if (tagName) {
        lowerCasedTagName = tagName.toLowerCase();
      }
  
      // Find the closest opened tag of the same type
      if (tagName) {
        for (pos = stack.length - 1; pos >= 0; pos--) {
          if (stack[pos].lowerCasedTag === lowerCasedTagName) {
            break
          }
        }
      } else {
        // If no tag name is provided, clean shop
        pos = 0;
      }
  
      if (pos >= 0) {
        // Close all the open elements, up the stack
        for (var i = stack.length - 1; i >= pos; i--) {
          if ("development" !== 'production' &&
              (i > pos || !tagName) &&
              options.warn) {
            options.warn(
              ("tag <" + (stack[i].tag) + "> has no matching end tag.")
            );
          }
          if (options.end) {
            options.end(stack[i].tag, start, end);
          }
        }
  
        // Remove the open elements from the stack
        stack.length = pos;
        lastTag = pos && stack[pos - 1].tag;
      } else if (lowerCasedTagName === 'br') {
        if (options.start) {
          options.start(tagName, [], true, start, end);
        }
      } else if (lowerCasedTagName === 'p') {
        if (options.start) {
          options.start(tagName, [], false, start, end);
        }
        if (options.end) {
          options.end(tagName, start, end);
        }
      }
    }
  }
  
  /*  */
  
  var defaultTagRE = /\{\{((?:.|\n)+?)\}\}/g;
  var regexEscapeRE = /[-.*+?^${}()|[\]\/\\]/g;
  
  var buildRegex = cached(function (delimiters) {
    var open = delimiters[0].replace(regexEscapeRE, '\\$&');
    var close = delimiters[1].replace(regexEscapeRE, '\\$&');
    return new RegExp(open + '((?:.|\\n)+?)' + close, 'g')
  });
  
  function parseText (
    text,
    delimiters
  ) {
    var tagRE = delimiters ? buildRegex(delimiters) : defaultTagRE;
    if (!tagRE.test(text)) {
      return
    }
    var tokens = [];
    var lastIndex = tagRE.lastIndex = 0;
    var match, index;
    while ((match = tagRE.exec(text))) {
      index = match.index;
      // push text token
      if (index > lastIndex) {
        tokens.push(JSON.stringify(text.slice(lastIndex, index)));
      }
      // tag token
      var exp = parseFilters(match[1].trim());
      tokens.push(("_s(" + exp + ")"));
      lastIndex = index + match[0].length;
    }
    if (lastIndex < text.length) {
      tokens.push(JSON.stringify(text.slice(lastIndex)));
    }
    return tokens.join('+')
  }
  
  /*  */
  
  var onRE = /^@|^v-on:/;
  var dirRE = /^v-|^@|^:/;
  var forAliasRE = /(.*?)\s+(?:in|of)\s+(.*)/;
  var forIteratorRE = /\((\{[^}]*\}|[^,]*),([^,]*)(?:,([^,]*))?\)/;
  
  var argRE = /:(.*)$/;
  var bindRE = /^:|^v-bind:/;
  var modifierRE = /\.[^.]+/g;
  
  var decodeHTMLCached = cached(decode);
  
  // configurable state
  var warn$2;
  var delimiters;
  var transforms;
  var preTransforms;
  var postTransforms;
  var platformIsPreTag;
  var platformMustUseProp;
  var platformGetTagNamespace;
  
  /**
   * Convert HTML string to AST.
   */
  function parse (
    template,
    options
  ) {
    warn$2 = options.warn || baseWarn;
    platformGetTagNamespace = options.getTagNamespace || no;
    platformMustUseProp = options.mustUseProp || no;
    platformIsPreTag = options.isPreTag || no;
    preTransforms = pluckModuleFunction(options.modules, 'preTransformNode');
    transforms = pluckModuleFunction(options.modules, 'transformNode');
    postTransforms = pluckModuleFunction(options.modules, 'postTransformNode');
    delimiters = options.delimiters;
  
    var stack = [];
    var preserveWhitespace = options.preserveWhitespace !== false;
    var root;
    var currentParent;
    var inVPre = false;
    var inPre = false;
    var warned = false;
  
    function warnOnce (msg) {
      if (!warned) {
        warned = true;
        warn$2(msg);
      }
    }
  
    function endPre (element) {
      // check pre state
      if (element.pre) {
        inVPre = false;
      }
      if (platformIsPreTag(element.tag)) {
        inPre = false;
      }
    }
  
    parseHTML(template, {
      warn: warn$2,
      expectHTML: options.expectHTML,
      isUnaryTag: options.isUnaryTag,
      canBeLeftOpenTag: options.canBeLeftOpenTag,
      shouldDecodeNewlines: options.shouldDecodeNewlines,
      start: function start (tag, attrs, unary) {
        // check namespace.
        // inherit parent ns if there is one
        var ns = (currentParent && currentParent.ns) || platformGetTagNamespace(tag);
  
        // handle IE svg bug
        /* istanbul ignore if */
        if (isIE && ns === 'svg') {
          attrs = guardIESVGBug(attrs);
        }
  
        var element = {
          type: 1,
          tag: tag,
          attrsList: attrs,
          attrsMap: makeAttrsMap(attrs),
          parent: currentParent,
          children: []
        };
        if (ns) {
          element.ns = ns;
        }
  
        if (isForbiddenTag(element) && !isServerRendering()) {
          element.forbidden = true;
          "development" !== 'production' && warn$2(
            'Templates should only be responsible for mapping the state to the ' +
            'UI. Avoid placing tags with side-effects in your templates, such as ' +
            "<" + tag + ">" + ', as they will not be parsed.'
          );
        }
  
        // apply pre-transforms
        for (var i = 0; i < preTransforms.length; i++) {
          preTransforms[i](element, options);
        }
  
        if (!inVPre) {
          processPre(element);
          if (element.pre) {
            inVPre = true;
          }
        }
        if (platformIsPreTag(element.tag)) {
          inPre = true;
        }
        if (inVPre) {
          processRawAttrs(element);
        } else {
          processFor(element);
          processIf(element);
          processOnce(element);
          processKey(element);
  
          // determine whether this is a plain element after
          // removing structural attributes
          element.plain = !element.key && !attrs.length;
  
          processRef(element);
          processSlot(element);
          processComponent(element);
          for (var i$1 = 0; i$1 < transforms.length; i$1++) {
            transforms[i$1](element, options);
          }
          processAttrs(element);
        }
  
        function checkRootConstraints (el) {
          {
            if (el.tag === 'slot' || el.tag === 'template') {
              warnOnce(
                "Cannot use <" + (el.tag) + "> as component root element because it may " +
                'contain multiple nodes.'
              );
            }
            if (el.attrsMap.hasOwnProperty('v-for')) {
              warnOnce(
                'Cannot use v-for on stateful component root element because ' +
                'it renders multiple elements.'
              );
            }
          }
        }
  
        // tree management
        if (!root) {
          root = element;
          checkRootConstraints(root);
        } else if (!stack.length) {
          // allow root elements with v-if, v-else-if and v-else
          if (root.if && (element.elseif || element.else)) {
            checkRootConstraints(element);
            addIfCondition(root, {
              exp: element.elseif,
              block: element
            });
          } else {
            warnOnce(
              "Component template should contain exactly one root element. " +
              "If you are using v-if on multiple elements, " +
              "use v-else-if to chain them instead."
            );
          }
        }
        if (currentParent && !element.forbidden) {
          if (element.elseif || element.else) {
            processIfConditions(element, currentParent);
          } else if (element.slotScope) { // scoped slot
            currentParent.plain = false;
            var name = element.slotTarget || '"default"';(currentParent.scopedSlots || (currentParent.scopedSlots = {}))[name] = element;
          } else {
            currentParent.children.push(element);
            element.parent = currentParent;
          }
        }
        if (!unary) {
          currentParent = element;
          stack.push(element);
        } else {
          endPre(element);
        }
        // apply post-transforms
        for (var i$2 = 0; i$2 < postTransforms.length; i$2++) {
          postTransforms[i$2](element, options);
        }
      },
  
      end: function end () {
        // remove trailing whitespace
        var element = stack[stack.length - 1];
        var lastNode = element.children[element.children.length - 1];
        if (lastNode && lastNode.type === 3 && lastNode.text === ' ' && !inPre) {
          element.children.pop();
        }
        // pop stack
        stack.length -= 1;
        currentParent = stack[stack.length - 1];
        endPre(element);
      },
  
      chars: function chars (text) {
        if (!currentParent) {
          {
            if (text === template) {
              warnOnce(
                'Component template requires a root element, rather than just text.'
              );
            } else if ((text = text.trim())) {
              warnOnce(
                ("text \"" + text + "\" outside root element will be ignored.")
              );
            }
          }
          return
        }
        // IE textarea placeholder bug
        /* istanbul ignore if */
        if (isIE &&
            currentParent.tag === 'textarea' &&
            currentParent.attrsMap.placeholder === text) {
          return
        }
        var children = currentParent.children;
        text = inPre || text.trim()
          ? isTextTag(currentParent) ? text : decodeHTMLCached(text)
          // only preserve whitespace if its not right after a starting tag
          : preserveWhitespace && children.length ? ' ' : '';
        if (text) {
          var expression;
          if (!inVPre && text !== ' ' && (expression = parseText(text, delimiters))) {
            children.push({
              type: 2,
              expression: expression,
              text: text
            });
          } else if (text !== ' ' || !children.length || children[children.length - 1].text !== ' ') {
            children.push({
              type: 3,
              text: text
            });
          }
        }
      }
    });
    return root
  }
  
  function processPre (el) {
    if (getAndRemoveAttr(el, 'v-pre') != null) {
      el.pre = true;
    }
  }
  
  function processRawAttrs (el) {
    var l = el.attrsList.length;
    if (l) {
      var attrs = el.attrs = new Array(l);
      for (var i = 0; i < l; i++) {
        attrs[i] = {
          name: el.attrsList[i].name,
          value: JSON.stringify(el.attrsList[i].value)
        };
      }
    } else if (!el.pre) {
      // non root node in pre blocks with no attributes
      el.plain = true;
    }
  }
  
  function processKey (el) {
    var exp = getBindingAttr(el, 'key');
    if (exp) {
      if ("development" !== 'production' && el.tag === 'template') {
        warn$2("<template> cannot be keyed. Place the key on real elements instead.");
      }
      el.key = exp;
    }
  }
  
  function processRef (el) {
    var ref = getBindingAttr(el, 'ref');
    if (ref) {
      el.ref = ref;
      el.refInFor = checkInFor(el);
    }
  }
  
  function processFor (el) {
    var exp;
    if ((exp = getAndRemoveAttr(el, 'v-for'))) {
      var inMatch = exp.match(forAliasRE);
      if (!inMatch) {
        "development" !== 'production' && warn$2(
          ("Invalid v-for expression: " + exp)
        );
        return
      }
      el.for = inMatch[2].trim();
      var alias = inMatch[1].trim();
      var iteratorMatch = alias.match(forIteratorRE);
      if (iteratorMatch) {
        el.alias = iteratorMatch[1].trim();
        el.iterator1 = iteratorMatch[2].trim();
        if (iteratorMatch[3]) {
          el.iterator2 = iteratorMatch[3].trim();
        }
      } else {
        el.alias = alias;
      }
    }
  }
  
  function processIf (el) {
    var exp = getAndRemoveAttr(el, 'v-if');
    if (exp) {
      el.if = exp;
      addIfCondition(el, {
        exp: exp,
        block: el
      });
    } else {
      if (getAndRemoveAttr(el, 'v-else') != null) {
        el.else = true;
      }
      var elseif = getAndRemoveAttr(el, 'v-else-if');
      if (elseif) {
        el.elseif = elseif;
      }
    }
  }
  
  function processIfConditions (el, parent) {
    var prev = findPrevElement(parent.children);
    if (prev && prev.if) {
      addIfCondition(prev, {
        exp: el.elseif,
        block: el
      });
    } else {
      warn$2(
        "v-" + (el.elseif ? ('else-if="' + el.elseif + '"') : 'else') + " " +
        "used on element <" + (el.tag) + "> without corresponding v-if."
      );
    }
  }
  
  function findPrevElement (children) {
    var i = children.length;
    while (i--) {
      if (children[i].type === 1) {
        return children[i]
      } else {
        if ("development" !== 'production' && children[i].text !== ' ') {
          warn$2(
            "text \"" + (children[i].text.trim()) + "\" between v-if and v-else(-if) " +
            "will be ignored."
          );
        }
        children.pop();
      }
    }
  }
  
  function addIfCondition (el, condition) {
    if (!el.ifConditions) {
      el.ifConditions = [];
    }
    el.ifConditions.push(condition);
  }
  
  function processOnce (el) {
    var once$$1 = getAndRemoveAttr(el, 'v-once');
    if (once$$1 != null) {
      el.once = true;
    }
  }
  
  function processSlot (el) {
    if (el.tag === 'slot') {
      el.slotName = getBindingAttr(el, 'name');
      if ("development" !== 'production' && el.key) {
        warn$2(
          "`key` does not work on <slot> because slots are abstract outlets " +
          "and can possibly expand into multiple elements. " +
          "Use the key on a wrapping element instead."
        );
      }
    } else {
      var slotTarget = getBindingAttr(el, 'slot');
      if (slotTarget) {
        el.slotTarget = slotTarget === '""' ? '"default"' : slotTarget;
      }
      if (el.tag === 'template') {
        el.slotScope = getAndRemoveAttr(el, 'scope');
      }
    }
  }
  
  function processComponent (el) {
    var binding;
    if ((binding = getBindingAttr(el, 'is'))) {
      el.component = binding;
    }
    if (getAndRemoveAttr(el, 'inline-template') != null) {
      el.inlineTemplate = true;
    }
  }
  
  function processAttrs (el) {
    var list = el.attrsList;
    var i, l, name, rawName, value, modifiers, isProp;
    for (i = 0, l = list.length; i < l; i++) {
      name = rawName = list[i].name;
      value = list[i].value;
      if (dirRE.test(name)) {
        // mark element as dynamic
        el.hasBindings = true;
        // modifiers
        modifiers = parseModifiers(name);
        if (modifiers) {
          name = name.replace(modifierRE, '');
        }
        if (bindRE.test(name)) { // v-bind
          name = name.replace(bindRE, '');
          value = parseFilters(value);
          isProp = false;
          if (modifiers) {
            if (modifiers.prop) {
              isProp = true;
              name = camelize(name);
              if (name === 'innerHtml') { name = 'innerHTML'; }
            }
            if (modifiers.camel) {
              name = camelize(name);
            }
            if (modifiers.sync) {
              addHandler(
                el,
                ("update:" + (camelize(name))),
                genAssignmentCode(value, "$event")
              );
            }
          }
          if (isProp || platformMustUseProp(el.tag, el.attrsMap.type, name)) {
            addProp(el, name, value);
          } else {
            addAttr(el, name, value);
          }
        } else if (onRE.test(name)) { // v-on
          name = name.replace(onRE, '');
          addHandler(el, name, value, modifiers, false, warn$2);
        } else { // normal directives
          name = name.replace(dirRE, '');
          // parse arg
          var argMatch = name.match(argRE);
          var arg = argMatch && argMatch[1];
          if (arg) {
            name = name.slice(0, -(arg.length + 1));
          }
          addDirective(el, name, rawName, value, arg, modifiers);
          if ("development" !== 'production' && name === 'model') {
            checkForAliasModel(el, value);
          }
        }
      } else {
        // literal attribute
        {
          var expression = parseText(value, delimiters);
          if (expression) {
            warn$2(
              name + "=\"" + value + "\": " +
              'Interpolation inside attributes has been removed. ' +
              'Use v-bind or the colon shorthand instead. For example, ' +
              'instead of <div id="{{ val }}">, use <div :id="val">.'
            );
          }
        }
        addAttr(el, name, JSON.stringify(value));
      }
    }
  }
  
  function checkInFor (el) {
    var parent = el;
    while (parent) {
      if (parent.for !== undefined) {
        return true
      }
      parent = parent.parent;
    }
    return false
  }
  
  function parseModifiers (name) {
    var match = name.match(modifierRE);
    if (match) {
      var ret = {};
      match.forEach(function (m) { ret[m.slice(1)] = true; });
      return ret
    }
  }
  
  function makeAttrsMap (attrs) {
    var map = {};
    for (var i = 0, l = attrs.length; i < l; i++) {
      if (
        "development" !== 'production' &&
        map[attrs[i].name] && !isIE && !isEdge
      ) {
        warn$2('duplicate attribute: ' + attrs[i].name);
      }
      map[attrs[i].name] = attrs[i].value;
    }
    return map
  }
  
  // for script (e.g. type="x/template") or style, do not decode content
  function isTextTag (el) {
    return el.tag === 'script' || el.tag === 'style'
  }
  
  function isForbiddenTag (el) {
    return (
      el.tag === 'style' ||
      (el.tag === 'script' && (
        !el.attrsMap.type ||
        el.attrsMap.type === 'text/javascript'
      ))
    )
  }
  
  var ieNSBug = /^xmlns:NS\d+/;
  var ieNSPrefix = /^NS\d+:/;
  
  /* istanbul ignore next */
  function guardIESVGBug (attrs) {
    var res = [];
    for (var i = 0; i < attrs.length; i++) {
      var attr = attrs[i];
      if (!ieNSBug.test(attr.name)) {
        attr.name = attr.name.replace(ieNSPrefix, '');
        res.push(attr);
      }
    }
    return res
  }
  
  function checkForAliasModel (el, value) {
    var _el = el;
    while (_el) {
      if (_el.for && _el.alias === value) {
        warn$2(
          "<" + (el.tag) + " v-model=\"" + value + "\">: " +
          "You are binding v-model directly to a v-for iteration alias. " +
          "This will not be able to modify the v-for source array because " +
          "writing to the alias is like modifying a function local variable. " +
          "Consider using an array of objects and use v-model on an object property instead."
        );
      }
      _el = _el.parent;
    }
  }
  
  /*  */
  
  var isStaticKey;
  var isPlatformReservedTag;
  
  var genStaticKeysCached = cached(genStaticKeys$1);
  
  /**
   * Goal of the optimizer: walk the generated template AST tree
   * and detect sub-trees that are purely static, i.e. parts of
   * the DOM that never needs to change.
   *
   * Once we detect these sub-trees, we can:
   *
   * 1. Hoist them into constants, so that we no longer need to
   *    create fresh nodes for them on each re-render;
   * 2. Completely skip them in the patching process.
   */
  function optimize (root, options) {
    if (!root) { return }
    isStaticKey = genStaticKeysCached(options.staticKeys || '');
    isPlatformReservedTag = options.isReservedTag || no;
    // first pass: mark all non-static nodes.
    markStatic$1(root);
    // second pass: mark static roots.
    markStaticRoots(root, false);
  }
  
  function genStaticKeys$1 (keys) {
    return makeMap(
      'type,tag,attrsList,attrsMap,plain,parent,children,attrs' +
      (keys ? ',' + keys : '')
    )
  }
  
  function markStatic$1 (node) {
    node.static = isStatic(node);
    if (node.type === 1) {
      // do not make component slot content static. this avoids
      // 1. components not able to mutate slot nodes
      // 2. static slot content fails for hot-reloading
      if (
        !isPlatformReservedTag(node.tag) &&
        node.tag !== 'slot' &&
        node.attrsMap['inline-template'] == null
      ) {
        return
      }
      for (var i = 0, l = node.children.length; i < l; i++) {
        var child = node.children[i];
        markStatic$1(child);
        if (!child.static) {
          node.static = false;
        }
      }
    }
  }
  
  function markStaticRoots (node, isInFor) {
    if (node.type === 1) {
      if (node.static || node.once) {
        node.staticInFor = isInFor;
      }
      // For a node to qualify as a static root, it should have children that
      // are not just static text. Otherwise the cost of hoisting out will
      // outweigh the benefits and it's better off to just always render it fresh.
      if (node.static && node.children.length && !(
        node.children.length === 1 &&
        node.children[0].type === 3
      )) {
        node.staticRoot = true;
        return
      } else {
        node.staticRoot = false;
      }
      if (node.children) {
        for (var i = 0, l = node.children.length; i < l; i++) {
          markStaticRoots(node.children[i], isInFor || !!node.for);
        }
      }
      if (node.ifConditions) {
        walkThroughConditionsBlocks(node.ifConditions, isInFor);
      }
    }
  }
  
  function walkThroughConditionsBlocks (conditionBlocks, isInFor) {
    for (var i = 1, len = conditionBlocks.length; i < len; i++) {
      markStaticRoots(conditionBlocks[i].block, isInFor);
    }
  }
  
  function isStatic (node) {
    if (node.type === 2) { // expression
      return false
    }
    if (node.type === 3) { // text
      return true
    }
    return !!(node.pre || (
      !node.hasBindings && // no dynamic bindings
      !node.if && !node.for && // not v-if or v-for or v-else
      !isBuiltInTag(node.tag) && // not a built-in
      isPlatformReservedTag(node.tag) && // not a component
      !isDirectChildOfTemplateFor(node) &&
      Object.keys(node).every(isStaticKey)
    ))
  }
  
  function isDirectChildOfTemplateFor (node) {
    while (node.parent) {
      node = node.parent;
      if (node.tag !== 'template') {
        return false
      }
      if (node.for) {
        return true
      }
    }
    return false
  }
  
  /*  */
  
  var fnExpRE = /^\s*([\w$_]+|\([^)]*?\))\s*=>|^function\s*\(/;
  var simplePathRE = /^\s*[A-Za-z_$][\w$]*(?:\.[A-Za-z_$][\w$]*|\['.*?']|\[".*?"]|\[\d+]|\[[A-Za-z_$][\w$]*])*\s*$/;
  
  // keyCode aliases
  var keyCodes = {
    esc: 27,
    tab: 9,
    enter: 13,
    space: 32,
    up: 38,
    left: 37,
    right: 39,
    down: 40,
    'delete': [8, 46]
  };
  
  // #4868: modifiers that prevent the execution of the listener
  // need to explicitly return null so that we can determine whether to remove
  // the listener for .once
  var genGuard = function (condition) { return ("if(" + condition + ")return null;"); };
  
  var modifierCode = {
    stop: '$event.stopPropagation();',
    prevent: '$event.preventDefault();',
    self: genGuard("$event.target !== $event.currentTarget"),
    ctrl: genGuard("!$event.ctrlKey"),
    shift: genGuard("!$event.shiftKey"),
    alt: genGuard("!$event.altKey"),
    meta: genGuard("!$event.metaKey"),
    left: genGuard("'button' in $event && $event.button !== 0"),
    middle: genGuard("'button' in $event && $event.button !== 1"),
    right: genGuard("'button' in $event && $event.button !== 2")
  };
  
  function genHandlers (
    events,
    native,
    warn
  ) {
    var res = native ? 'nativeOn:{' : 'on:{';
    for (var name in events) {
      var handler = events[name];
      // #5330: warn click.right, since right clicks do not actually fire click events.
      if ("development" !== 'production' &&
          name === 'click' &&
          handler && handler.modifiers && handler.modifiers.right
        ) {
        warn(
          "Use \"contextmenu\" instead of \"click.right\" since right clicks " +
          "do not actually fire \"click\" events."
        );
      }
      res += "\"" + name + "\":" + (genHandler(name, handler)) + ",";
    }
    return res.slice(0, -1) + '}'
  }
  
  function genHandler (
    name,
    handler
  ) {
    if (!handler) {
      return 'function(){}'
    }
  
    if (Array.isArray(handler)) {
      return ("[" + (handler.map(function (handler) { return genHandler(name, handler); }).join(',')) + "]")
    }
  
    var isMethodPath = simplePathRE.test(handler.value);
    var isFunctionExpression = fnExpRE.test(handler.value);
  
    if (!handler.modifiers) {
      return isMethodPath || isFunctionExpression
        ? handler.value
        : ("function($event){" + (handler.value) + "}") // inline statement
    } else {
      var code = '';
      var genModifierCode = '';
      var keys = [];
      for (var key in handler.modifiers) {
        if (modifierCode[key]) {
          genModifierCode += modifierCode[key];
          // left/right
          if (keyCodes[key]) {
            keys.push(key);
          }
        } else {
          keys.push(key);
        }
      }
      if (keys.length) {
        code += genKeyFilter(keys);
      }
      // Make sure modifiers like prevent and stop get executed after key filtering
      if (genModifierCode) {
        code += genModifierCode;
      }
      var handlerCode = isMethodPath
        ? handler.value + '($event)'
        : isFunctionExpression
          ? ("(" + (handler.value) + ")($event)")
          : handler.value;
      return ("function($event){" + code + handlerCode + "}")
    }
  }
  
  function genKeyFilter (keys) {
    return ("if(!('button' in $event)&&" + (keys.map(genFilterCode).join('&&')) + ")return null;")
  }
  
  function genFilterCode (key) {
    var keyVal = parseInt(key, 10);
    if (keyVal) {
      return ("$event.keyCode!==" + keyVal)
    }
    var alias = keyCodes[key];
    return ("_k($event.keyCode," + (JSON.stringify(key)) + (alias ? ',' + JSON.stringify(alias) : '') + ")")
  }
  
  /*  */
  
  function bind$1 (el, dir) {
    el.wrapData = function (code) {
      return ("_b(" + code + ",'" + (el.tag) + "'," + (dir.value) + (dir.modifiers && dir.modifiers.prop ? ',true' : '') + ")")
    };
  }
  
  /*  */
  
  var baseDirectives = {
    bind: bind$1,
    cloak: noop
  };
  
  /*  */
  
  var warn$3;
  var transforms$1;
  var dataGenFns;
  var platformDirectives$1;
  var isPlatformReservedTag$1;
  var staticRenderFns;
  var onceCount;
  var currentOptions;
  
  function generate (
    ast,
    options
  ) {
    // save previous staticRenderFns so generate calls can be nested
    var prevStaticRenderFns = staticRenderFns;
    var currentStaticRenderFns = staticRenderFns = [];
    var prevOnceCount = onceCount;
    onceCount = 0;
    currentOptions = options;
    warn$3 = options.warn || baseWarn;
    transforms$1 = pluckModuleFunction(options.modules, 'transformCode');
    dataGenFns = pluckModuleFunction(options.modules, 'genData');
    platformDirectives$1 = options.directives || {};
    isPlatformReservedTag$1 = options.isReservedTag || no;
    var code = ast ? genElement(ast) : '_c("div")';
    staticRenderFns = prevStaticRenderFns;
    onceCount = prevOnceCount;
    return {
      render: ("with(this){return " + code + "}"),
      staticRenderFns: currentStaticRenderFns
    }
  }
  
  function genElement (el) {
    if (el.staticRoot && !el.staticProcessed) {
      return genStatic(el)
    } else if (el.once && !el.onceProcessed) {
      return genOnce(el)
    } else if (el.for && !el.forProcessed) {
      return genFor(el)
    } else if (el.if && !el.ifProcessed) {
      return genIf(el)
    } else if (el.tag === 'template' && !el.slotTarget) {
      return genChildren(el) || 'void 0'
    } else if (el.tag === 'slot') {
      return genSlot(el)
    } else {
      // component or element
      var code;
      if (el.component) {
        code = genComponent(el.component, el);
      } else {
        var data = el.plain ? undefined : genData(el);
  
        var children = el.inlineTemplate ? null : genChildren(el, true);
        code = "_c('" + (el.tag) + "'" + (data ? ("," + data) : '') + (children ? ("," + children) : '') + ")";
      }
      // module transforms
      for (var i = 0; i < transforms$1.length; i++) {
        code = transforms$1[i](el, code);
      }
      return code
    }
  }
  
  // hoist static sub-trees out
  function genStatic (el) {
    el.staticProcessed = true;
    staticRenderFns.push(("with(this){return " + (genElement(el)) + "}"));
    return ("_m(" + (staticRenderFns.length - 1) + (el.staticInFor ? ',true' : '') + ")")
  }
  
  // v-once
  function genOnce (el) {
    el.onceProcessed = true;
    if (el.if && !el.ifProcessed) {
      return genIf(el)
    } else if (el.staticInFor) {
      var key = '';
      var parent = el.parent;
      while (parent) {
        if (parent.for) {
          key = parent.key;
          break
        }
        parent = parent.parent;
      }
      if (!key) {
        "development" !== 'production' && warn$3(
          "v-once can only be used inside v-for that is keyed. "
        );
        return genElement(el)
      }
      return ("_o(" + (genElement(el)) + "," + (onceCount++) + (key ? ("," + key) : "") + ")")
    } else {
      return genStatic(el)
    }
  }
  
  function genIf (el) {
    el.ifProcessed = true; // avoid recursion
    return genIfConditions(el.ifConditions.slice())
  }
  
  function genIfConditions (conditions) {
    if (!conditions.length) {
      return '_e()'
    }
  
    var condition = conditions.shift();
    if (condition.exp) {
      return ("(" + (condition.exp) + ")?" + (genTernaryExp(condition.block)) + ":" + (genIfConditions(conditions)))
    } else {
      return ("" + (genTernaryExp(condition.block)))
    }
  
    // v-if with v-once should generate code like (a)?_m(0):_m(1)
    function genTernaryExp (el) {
      return el.once ? genOnce(el) : genElement(el)
    }
  }
  
  function genFor (el) {
    var exp = el.for;
    var alias = el.alias;
    var iterator1 = el.iterator1 ? ("," + (el.iterator1)) : '';
    var iterator2 = el.iterator2 ? ("," + (el.iterator2)) : '';
  
    if (
      "development" !== 'production' &&
      maybeComponent(el) && el.tag !== 'slot' && el.tag !== 'template' && !el.key
    ) {
      warn$3(
        "<" + (el.tag) + " v-for=\"" + alias + " in " + exp + "\">: component lists rendered with " +
        "v-for should have explicit keys. " +
        "See https://vuejs.org/guide/list.html#key for more info.",
        true /* tip */
      );
    }
  
    el.forProcessed = true; // avoid recursion
    return "_l((" + exp + ")," +
      "function(" + alias + iterator1 + iterator2 + "){" +
        "return " + (genElement(el)) +
      '})'
  }
  
  function genData (el) {
    var data = '{';
  
    // directives first.
    // directives may mutate the el's other properties before they are generated.
    var dirs = genDirectives(el);
    if (dirs) { data += dirs + ','; }
  
    // key
    if (el.key) {
      data += "key:" + (el.key) + ",";
    }
    // ref
    if (el.ref) {
      data += "ref:" + (el.ref) + ",";
    }
    if (el.refInFor) {
      data += "refInFor:true,";
    }
    // pre
    if (el.pre) {
      data += "pre:true,";
    }
    // record original tag name for components using "is" attribute
    if (el.component) {
      data += "tag:\"" + (el.tag) + "\",";
    }
    // module data generation functions
    for (var i = 0; i < dataGenFns.length; i++) {
      data += dataGenFns[i](el);
    }
    // attributes
    if (el.attrs) {
      data += "attrs:{" + (genProps(el.attrs)) + "},";
    }
    // DOM props
    if (el.props) {
      data += "domProps:{" + (genProps(el.props)) + "},";
    }
    // event handlers
    if (el.events) {
      data += (genHandlers(el.events, false, warn$3)) + ",";
    }
    if (el.nativeEvents) {
      data += (genHandlers(el.nativeEvents, true, warn$3)) + ",";
    }
    // slot target
    if (el.slotTarget) {
      data += "slot:" + (el.slotTarget) + ",";
    }
    // scoped slots
    if (el.scopedSlots) {
      data += (genScopedSlots(el.scopedSlots)) + ",";
    }
    // component v-model
    if (el.model) {
      data += "model:{value:" + (el.model.value) + ",callback:" + (el.model.callback) + ",expression:" + (el.model.expression) + "},";
    }
    // inline-template
    if (el.inlineTemplate) {
      var inlineTemplate = genInlineTemplate(el);
      if (inlineTemplate) {
        data += inlineTemplate + ",";
      }
    }
    data = data.replace(/,$/, '') + '}';
    // v-bind data wrap
    if (el.wrapData) {
      data = el.wrapData(data);
    }
    return data
  }
  
  function genDirectives (el) {
    var dirs = el.directives;
    if (!dirs) { return }
    var res = 'directives:[';
    var hasRuntime = false;
    var i, l, dir, needRuntime;
    for (i = 0, l = dirs.length; i < l; i++) {
      dir = dirs[i];
      needRuntime = true;
      var gen = platformDirectives$1[dir.name] || baseDirectives[dir.name];
      if (gen) {
        // compile-time directive that manipulates AST.
        // returns true if it also needs a runtime counterpart.
        needRuntime = !!gen(el, dir, warn$3);
      }
      if (needRuntime) {
        hasRuntime = true;
        res += "{name:\"" + (dir.name) + "\",rawName:\"" + (dir.rawName) + "\"" + (dir.value ? (",value:(" + (dir.value) + "),expression:" + (JSON.stringify(dir.value))) : '') + (dir.arg ? (",arg:\"" + (dir.arg) + "\"") : '') + (dir.modifiers ? (",modifiers:" + (JSON.stringify(dir.modifiers))) : '') + "},";
      }
    }
    if (hasRuntime) {
      return res.slice(0, -1) + ']'
    }
  }
  
  function genInlineTemplate (el) {
    var ast = el.children[0];
    if ("development" !== 'production' && (
      el.children.length > 1 || ast.type !== 1
    )) {
      warn$3('Inline-template components must have exactly one child element.');
    }
    if (ast.type === 1) {
      var inlineRenderFns = generate(ast, currentOptions);
      return ("inlineTemplate:{render:function(){" + (inlineRenderFns.render) + "},staticRenderFns:[" + (inlineRenderFns.staticRenderFns.map(function (code) { return ("function(){" + code + "}"); }).join(',')) + "]}")
    }
  }
  
  function genScopedSlots (slots) {
    return ("scopedSlots:_u([" + (Object.keys(slots).map(function (key) { return genScopedSlot(key, slots[key]); }).join(',')) + "])")
  }
  
  function genScopedSlot (key, el) {
    return "[" + key + ",function(" + (String(el.attrsMap.scope)) + "){" +
      "return " + (el.tag === 'template'
        ? genChildren(el) || 'void 0'
        : genElement(el)) + "}]"
  }
  
  function genChildren (el, checkSkip) {
    var children = el.children;
    if (children.length) {
      var el$1 = children[0];
      // optimize single v-for
      if (children.length === 1 &&
          el$1.for &&
          el$1.tag !== 'template' &&
          el$1.tag !== 'slot') {
        return genElement(el$1)
      }
      var normalizationType = checkSkip ? getNormalizationType(children) : 0;
      return ("[" + (children.map(genNode).join(',')) + "]" + (normalizationType ? ("," + normalizationType) : ''))
    }
  }
  
  // determine the normalization needed for the children array.
  // 0: no normalization needed
  // 1: simple normalization needed (possible 1-level deep nested array)
  // 2: full normalization needed
  function getNormalizationType (children) {
    var res = 0;
    for (var i = 0; i < children.length; i++) {
      var el = children[i];
      if (el.type !== 1) {
        continue
      }
      if (needsNormalization(el) ||
          (el.ifConditions && el.ifConditions.some(function (c) { return needsNormalization(c.block); }))) {
        res = 2;
        break
      }
      if (maybeComponent(el) ||
          (el.ifConditions && el.ifConditions.some(function (c) { return maybeComponent(c.block); }))) {
        res = 1;
      }
    }
    return res
  }
  
  function needsNormalization (el) {
    return el.for !== undefined || el.tag === 'template' || el.tag === 'slot'
  }
  
  function maybeComponent (el) {
    return !isPlatformReservedTag$1(el.tag)
  }
  
  function genNode (node) {
    if (node.type === 1) {
      return genElement(node)
    } else {
      return genText(node)
    }
  }
  
  function genText (text) {
    return ("_v(" + (text.type === 2
      ? text.expression // no need for () because already wrapped in _s()
      : transformSpecialNewlines(JSON.stringify(text.text))) + ")")
  }
  
  function genSlot (el) {
    var slotName = el.slotName || '"default"';
    var children = genChildren(el);
    var res = "_t(" + slotName + (children ? ("," + children) : '');
    var attrs = el.attrs && ("{" + (el.attrs.map(function (a) { return ((camelize(a.name)) + ":" + (a.value)); }).join(',')) + "}");
    var bind$$1 = el.attrsMap['v-bind'];
    if ((attrs || bind$$1) && !children) {
      res += ",null";
    }
    if (attrs) {
      res += "," + attrs;
    }
    if (bind$$1) {
      res += (attrs ? '' : ',null') + "," + bind$$1;
    }
    return res + ')'
  }
  
  // componentName is el.component, take it as argument to shun flow's pessimistic refinement
  function genComponent (componentName, el) {
    var children = el.inlineTemplate ? null : genChildren(el, true);
    return ("_c(" + componentName + "," + (genData(el)) + (children ? ("," + children) : '') + ")")
  }
  
  function genProps (props) {
    var res = '';
    for (var i = 0; i < props.length; i++) {
      var prop = props[i];
      res += "\"" + (prop.name) + "\":" + (transformSpecialNewlines(prop.value)) + ",";
    }
    return res.slice(0, -1)
  }
  
  // #3895, #4268
  function transformSpecialNewlines (text) {
    return text
      .replace(/\u2028/g, '\\u2028')
      .replace(/\u2029/g, '\\u2029')
  }
  
  /*  */
  
  var prohibitedKeywordRE = new RegExp('\\b' + (
    'do,if,for,let,new,try,var,case,else,with,await,break,catch,class,const,' +
    'super,throw,while,yield,delete,export,import,return,switch,default,' +
    'extends,finally,continue,debugger,function,arguments'
  ).split(',').join('\\b|\\b') + '\\b');
  
  // these unary operators should not be used as property/method names
  var unaryOperatorsRE = new RegExp('\\b' + (
    'delete,typeof,void'
  ).split(',').join('\\s*\\([^\\)]*\\)|\\b') + '\\s*\\([^\\)]*\\)');
  
  // check valid identifier for v-for
  var identRE = /[A-Za-z_$][\w$]*/;
  
  // strip strings in expressions
  var stripStringRE = /'(?:[^'\\]|\\.)*'|"(?:[^"\\]|\\.)*"|`(?:[^`\\]|\\.)*\$\{|\}(?:[^`\\]|\\.)*`|`(?:[^`\\]|\\.)*`/g;
  
  // detect problematic expressions in a template
  function detectErrors (ast) {
    var errors = [];
    if (ast) {
      checkNode(ast, errors);
    }
    return errors
  }
  
  function checkNode (node, errors) {
    if (node.type === 1) {
      for (var name in node.attrsMap) {
        if (dirRE.test(name)) {
          var value = node.attrsMap[name];
          if (value) {
            if (name === 'v-for') {
              checkFor(node, ("v-for=\"" + value + "\""), errors);
            } else if (onRE.test(name)) {
              checkEvent(value, (name + "=\"" + value + "\""), errors);
            } else {
              checkExpression(value, (name + "=\"" + value + "\""), errors);
            }
          }
        }
      }
      if (node.children) {
        for (var i = 0; i < node.children.length; i++) {
          checkNode(node.children[i], errors);
        }
      }
    } else if (node.type === 2) {
      checkExpression(node.expression, node.text, errors);
    }
  }
  
  function checkEvent (exp, text, errors) {
    var stipped = exp.replace(stripStringRE, '');
    var keywordMatch = stipped.match(unaryOperatorsRE);
    if (keywordMatch && stipped.charAt(keywordMatch.index - 1) !== '$') {
      errors.push(
        "avoid using JavaScript unary operator as property name: " +
        "\"" + (keywordMatch[0]) + "\" in expression " + (text.trim())
      );
    }
    checkExpression(exp, text, errors);
  }
  
  function checkFor (node, text, errors) {
    checkExpression(node.for || '', text, errors);
    checkIdentifier(node.alias, 'v-for alias', text, errors);
    checkIdentifier(node.iterator1, 'v-for iterator', text, errors);
    checkIdentifier(node.iterator2, 'v-for iterator', text, errors);
  }
  
  function checkIdentifier (ident, type, text, errors) {
    if (typeof ident === 'string' && !identRE.test(ident)) {
      errors.push(("invalid " + type + " \"" + ident + "\" in expression: " + (text.trim())));
    }
  }
  
  function checkExpression (exp, text, errors) {
    try {
      new Function(("return " + exp));
    } catch (e) {
      var keywordMatch = exp.replace(stripStringRE, '').match(prohibitedKeywordRE);
      if (keywordMatch) {
        errors.push(
          "avoid using JavaScript keyword as property name: " +
          "\"" + (keywordMatch[0]) + "\" in expression " + (text.trim())
        );
      } else {
        errors.push(("invalid expression: " + (text.trim())));
      }
    }
  }
  
  /*  */
  
  function baseCompile (
    template,
    options
  ) {
    // 1 解析template 生成ast
    var ast = parse(template.trim(), options);
    // 2 对ast进行优化 分析出静态不变的内容
    optimize(ast, options);
    // 3 根据ast生成render函数和staticRenderFns数组
    var code = generate(ast, options);
    return {
      ast: ast,
      render: code.render,
      staticRenderFns: code.staticRenderFns
    }
  }
  
  function makeFunction (code, errors) {
    try {
      return new Function(code)
    } catch (err) {
      errors.push({ err: err, code: code });
      return noop
    }
  }
  
  function createCompiler (baseOptions) {
    var functionCompileCache = Object.create(null);
  
    function compile (
      template,
      options
    ) {
      var finalOptions = Object.create(baseOptions);
      var errors = [];
      var tips = [];
      finalOptions.warn = function (msg, tip$$1) {
        (tip$$1 ? tips : errors).push(msg);
      };
  
      if (options) {
        // merge custom modules
        if (options.modules) {
          finalOptions.modules = (baseOptions.modules || []).concat(options.modules);
        }
        // merge custom directives
        if (options.directives) {
          finalOptions.directives = extend(
            Object.create(baseOptions.directives),
            options.directives
          );
        }
        // copy other options
        for (var key in options) {
          if (key !== 'modules' && key !== 'directives') {
            finalOptions[key] = options[key];
          }
        }
      }
  
      var compiled = baseCompile(template, finalOptions);
      {
        errors.push.apply(errors, detectErrors(compiled.ast));
      }
      compiled.errors = errors;
      compiled.tips = tips;
      return compiled
    }
  
    function compileToFunctions (
      template,
      options,
      vm
    ) {
      options = options || {};
  
      /* istanbul ignore if */
      {
        // detect possible CSP restriction
        try {
          new Function('return 1');
        } catch (e) {
          if (e.toString().match(/unsafe-eval|CSP/)) {
            warn(
              'It seems you are using the standalone build of Vue.js in an ' +
              'environment with Content Security Policy that prohibits unsafe-eval. ' +
              'The template compiler cannot work in this environment. Consider ' +
              'relaxing the policy to allow unsafe-eval or pre-compiling your ' +
              'templates into render functions.'
            );
          }
        }
      }
  
      // check cache
      var key = options.delimiters
        ? String(options.delimiters) + template
        : template;
      if (functionCompileCache[key]) {
        return functionCompileCache[key]
      }
  
      // compile
      var compiled = compile(template, options);
  
      // check compilation errors/tips
      {
        if (compiled.errors && compiled.errors.length) {
          warn(
            "Error compiling template:\n\n" + template + "\n\n" +
            compiled.errors.map(function (e) { return ("- " + e); }).join('\n') + '\n',
            vm
          );
        }
        if (compiled.tips && compiled.tips.length) {
          compiled.tips.forEach(function (msg) { return tip(msg, vm); });
        }
      }
  
      // turn code into functions
      var res = {};
      var fnGenErrors = [];
      res.render = makeFunction(compiled.render, fnGenErrors);
      var l = compiled.staticRenderFns.length;
      res.staticRenderFns = new Array(l);
      for (var i = 0; i < l; i++) {
        res.staticRenderFns[i] = makeFunction(compiled.staticRenderFns[i], fnGenErrors);
      }
  
      // check function generation errors.
      // this should only happen if there is a bug in the compiler itself.
      // mostly for codegen development use
      /* istanbul ignore if */
      {
        if ((!compiled.errors || !compiled.errors.length) && fnGenErrors.length) {
          warn(
            "Failed to generate render function:\n\n" +
            fnGenErrors.map(function (ref) {
              var err = ref.err;
              var code = ref.code;
  
              return ((err.toString()) + " in\n\n" + code + "\n");
          }).join('\n'),
            vm
          );
        }
      }
  
      return (functionCompileCache[key] = res)
    }
  
    return {
      compile: compile,
      compileToFunctions: compileToFunctions
    }
  }
  
  /*  */
  
  function transformNode (el, options) {
    var warn = options.warn || baseWarn;
    var staticClass = getAndRemoveAttr(el, 'class');
    if ("development" !== 'production' && staticClass) {
      var expression = parseText(staticClass, options.delimiters);
      if (expression) {
        warn(
          "class=\"" + staticClass + "\": " +
          'Interpolation inside attributes has been removed. ' +
          'Use v-bind or the colon shorthand instead. For example, ' +
          'instead of <div class="{{ val }}">, use <div :class="val">.'
        );
      }
    }
    if (staticClass) {
      el.staticClass = JSON.stringify(staticClass);
    }
    var classBinding = getBindingAttr(el, 'class', false /* getStatic */);
    if (classBinding) {
      el.classBinding = classBinding;
    }
  }
  
  function genData$1 (el) {
    var data = '';
    if (el.staticClass) {
      data += "staticClass:" + (el.staticClass) + ",";
    }
    if (el.classBinding) {
      data += "class:" + (el.classBinding) + ",";
    }
    return data
  }
  
  var klass$1 = {
    staticKeys: ['staticClass'],
    transformNode: transformNode,
    genData: genData$1
  };
  
  /*  */
  
  function transformNode$1 (el, options) {
    var warn = options.warn || baseWarn;
    var staticStyle = getAndRemoveAttr(el, 'style');
    if (staticStyle) {
      /* istanbul ignore if */
      {
        var expression = parseText(staticStyle, options.delimiters);
        if (expression) {
          warn(
            "style=\"" + staticStyle + "\": " +
            'Interpolation inside attributes has been removed. ' +
            'Use v-bind or the colon shorthand instead. For example, ' +
            'instead of <div style="{{ val }}">, use <div :style="val">.'
          );
        }
      }
      el.staticStyle = JSON.stringify(parseStyleText(staticStyle));
    }
  
    var styleBinding = getBindingAttr(el, 'style', false /* getStatic */);
    if (styleBinding) {
      el.styleBinding = styleBinding;
    }
  }
  
  function genData$2 (el) {
    var data = '';
    if (el.staticStyle) {
      data += "staticStyle:" + (el.staticStyle) + ",";
    }
    if (el.styleBinding) {
      data += "style:(" + (el.styleBinding) + "),";
    }
    return data
  }
  
  var style$1 = {
    staticKeys: ['staticStyle'],
    transformNode: transformNode$1,
    genData: genData$2
  };
  
  var modules$1 = [
    klass$1,
    style$1
  ];
  
  /*  */
  
  function text (el, dir) {
    if (dir.value) {
      addProp(el, 'textContent', ("_s(" + (dir.value) + ")"));
    }
  }
  
  /*  */
  
  function html (el, dir) {
    if (dir.value) {
      addProp(el, 'innerHTML', ("_s(" + (dir.value) + ")"));
    }
  }
  
  var directives$1 = {
    model: model,
    text: text,
    html: html
  };
  
  /*  */
  
  var baseOptions = {
    expectHTML: true,
    modules: modules$1,
    directives: directives$1,
    isPreTag: isPreTag,
    isUnaryTag: isUnaryTag,
    mustUseProp: mustUseProp,
    canBeLeftOpenTag: canBeLeftOpenTag,
    isReservedTag: isReservedTag,
    getTagNamespace: getTagNamespace,
    staticKeys: genStaticKeys(modules$1)
  };
  
  var ref$1 = createCompiler(baseOptions);
  var compileToFunctions = ref$1.compileToFunctions;
  
  /*  */
  
  var idToTemplate = cached(function (id) {
    // 类似document.querySelector
    var el = query(id);
    return el && el.innerHTML
  });
  
  var mount = Vue$3.prototype.$mount;
  Vue$3.prototype.$mount = function (
    el,
    hydrating
  ) {
    el = el && query(el);
  
    /* istanbul ignore if */
    if (el === document.body || el === document.documentElement) {
      "development" !== 'production' && warn(
        "Do not mount Vue to <html> or <body> - mount to normal elements instead."
      );
      return this
    }
  
    var options = this.$options;
    // 判断是否有render函数
    // resolve template/el and convert to render function
    if (!options.render) {
      var template = options.template;
      if (template) {
        if (typeof template === 'string') {
          if (template.charAt(0) === '#') {
            template = idToTemplate(template);
            /* istanbul ignore if */
            if ("development" !== 'production' && !template) {
              warn(
                ("Template element not found or is empty: " + (options.template)),
                this
              );
            }
          }
        } else if (template.nodeType) {
          template = template.innerHTML;
        } else {
          {
            warn('invalid template option:' + template, this);
          }
          return this
        }
      } else if (el) {
        template = getOuterHTML(el);
      }
      if (template) {
        /* istanbul ignore if */
        if ("development" !== 'production' && config.performance && mark) {
          mark('compile');
        }
  
        var ref = compileToFunctions(template, {
          shouldDecodeNewlines: shouldDecodeNewlines,
          delimiters: options.delimiters
        }, this);
        var render = ref.render;
        var staticRenderFns = ref.staticRenderFns;
        options.render = render;
        options.staticRenderFns = staticRenderFns;
  
        /* istanbul ignore if */
        if ("development" !== 'production' && config.performance && mark) {
          mark('compile end');
          measure(((this._name) + " compile"), 'compile', 'compile end');
        }
      }
    }
    return mount.call(this, el, hydrating)
  };
  
  /**
   * Get outerHTML of elements, taking care
   * of SVG elements in IE as well.
   */
  function getOuterHTML (el) {
    if (el.outerHTML) {
      return el.outerHTML
    } else {
      var container = document.createElement('div');
      container.appendChild(el.cloneNode(true));
      return container.innerHTML
    }
  }
  
  Vue$3.compile = compileToFunctions;
  
  return Vue$3;
  
  })));
  //# sourceMappingURL=vue.js.map
  