text: "use strict";
  
  function _typeof(obj) { if (typeof Symbol === "function" && typeof Symbol.iterator === "symbol") { _typeof = function _typeof(obj) { return typeof obj; }; } else { _typeof = function _typeof(obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; }; } return _typeof(obj); }
  
  function ownKeys(object, enumerableOnly) { var keys = Object.keys(object); if (Object.getOwnPropertySymbols) { var symbols = Object.getOwnPropertySymbols(object); if (enumerableOnly) symbols = symbols.filter(function (sym) { return Object.getOwnPropertyDescriptor(object, sym).enumerable; }); keys.push.apply(keys, symbols); } return keys; }
  
  function _objectSpread(target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i] != null ? arguments[i] : {}; if (i % 2) { ownKeys(source, true).forEach(function (key) { _defineProperty(target, key, source[key]); }); } else if (Object.getOwnPropertyDescriptors) { Object.defineProperties(target, Object.getOwnPropertyDescriptors(source)); } else { ownKeys(source).forEach(function (key) { Object.defineProperty(target, key, Object.getOwnPropertyDescriptor(source, key)); }); } } return target; }
  
  function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
  
  function asyncGeneratorStep(gen, resolve, reject, _next, _throw, key, arg) { try { var info = gen[key](arg); var value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { Promise.resolve(value).then(_next, _throw); } }
  
  function _asyncToGenerator(fn) { return function () { var self = this, args = arguments; return new Promise(function (resolve, reject) { var gen = fn.apply(self, args); function _next(value) { asyncGeneratorStep(gen, resolve, reject, _next, _throw, "next", value); } function _throw(err) { asyncGeneratorStep(gen, resolve, reject, _next, _throw, "throw", err); } _next(undefined); }); }; }
  
  function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
  
  function _defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } }
  
  function _createClass(Constructor, protoProps, staticProps) { if (protoProps) _defineProperties(Constructor.prototype, protoProps); if (staticProps) _defineProperties(Constructor, staticProps); return Constructor; }
  
  function _possibleConstructorReturn(self, call) { if (call && (_typeof(call) === "object" || typeof call === "function")) { return call; } return _assertThisInitialized(self); }
  
  function _assertThisInitialized(self) { if (self === void 0) { throw new ReferenceError("this hasn't been initialised - super() hasn't been called"); } return self; }
  
  function _getPrototypeOf(o) { _getPrototypeOf = Object.setPrototypeOf ? Object.getPrototypeOf : function _getPrototypeOf(o) { return o.__proto__ || Object.getPrototypeOf(o); }; return _getPrototypeOf(o); }
  
  function _inherits(subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function"); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, writable: true, configurable: true } }); if (superClass) _setPrototypeOf(subClass, superClass); }
  
  function _setPrototypeOf(o, p) { _setPrototypeOf = Object.setPrototypeOf || function _setPrototypeOf(o, p) { o.__proto__ = p; return o; }; return _setPrototypeOf(o, p); }
  
  var _require = require('events'),
      EventEmitter = _require.EventEmitter;
  
  var utils = require('./utils'); // =============================================================================
  // FlowControl - Used to slow down streaming to manageable speed
  // Implements a subset of Stream.Duplex: pipe() and write()
  
  
  var FlowControl =
  /*#__PURE__*/
  function (_EventEmitter) {
    _inherits(FlowControl, _EventEmitter);
  
    function FlowControl(options) {
      var _this;
  
      _classCallCheck(this, FlowControl);
  
      _this = _possibleConstructorReturn(this, _getPrototypeOf(FlowControl).call(this));
      _this.options = options = options || {}; // Buffer queue
  
      _this.queue = []; // Consumer streams
  
      _this.pipes = []; // Down-stream flow-control instances
  
      _this.children = []; // Up-stream flow-control instances
  
      _this.parent = options.parent; // Ensure we don't flush more than once at a time
  
      _this.flushing = false; // determine timeout for flow control delays
  
      if (options.gc) {
        var _options = options,
            gc = _options.gc;
  
        if (gc.getTimeout) {
          _this.getTimeout = gc.getTimeout;
        } else {
          // heap size below which we don't bother delaying
          var threshold = gc.threshold !== undefined ? gc.threshold : 150000000; // convert from heapsize to ms timeout
  
          var divisor = gc.divisor !== undefined ? gc.divisor : 500000;
  
          _this.getTimeout = function () {
            var memory = process.memoryUsage();
            var heapSize = memory.heapTotal;
            return heapSize < threshold ? 0 : Math.floor(heapSize / divisor);
          };
        }
      } else {
        _this.getTimeout = null;
      }
  
      return _this;
    }
  
    _createClass(FlowControl, [{
      key: "_write",
      value: function _write(dst, data, encoding) {
        // Write to a single destination and return a promise
        return new Promise(function (resolve, reject) {
          dst.write(data, encoding, function (error) {
            if (error) {
              reject(error);
            } else {
              resolve();
            }
          });
        });
      }
    }, {
      key: "_pipe",
      value: function () {
        var _pipe2 = _asyncToGenerator(
        /*#__PURE__*/
        regeneratorRuntime.mark(function _callee(chunk) {
          var _this2 = this;
  
          var promises;
          return regeneratorRuntime.wrap(function _callee$(_context) {
            while (1) {
              switch (_context.prev = _context.next) {
                case 0:
                  // Write chunk to all pipes. A chunk with no data is the end
                  promises = [];
                  this.pipes.forEach(function (pipe) {
                    if (chunk.data) {
                      if (pipe.sync) {
                        pipe.stream.write(chunk.data, chunk.encoding);
                      } else {
                        promises.push(_this2._write(pipe.stream, chunk.data, chunk.encoding));
                      }
                    } else {
                      pipe.stream.end();
                    }
                  });
  
                  if (!promises.length) {
                    promises.push(Promise.resolve());
                  }
  
                  _context.next = 5;
                  return Promise.all(promises);
  
                case 5:
                  try {
                    chunk.callback();
                  } catch (e) {// quietly ignore
                  }
  
                case 6:
                case "end":
                  return _context.stop();
              }
            }
          }, _callee, this);
        }));
  
        function _pipe(_x) {
          return _pipe2.apply(this, arguments);
        }
  
        return _pipe;
      }()
    }, {
      key: "_animate",
      value: function _animate() {
        var count = 0;
        var seq = ['|', '/', '-', '\\'];
        var cr = "\x1B[0G"; // was '\033[0G'
  
        return setInterval(function () {
          process.stdout.write(seq[count++ % 4] + cr);
        }, 100);
      }
    }, {
      key: "_delay",
      value: function _delay() {
        var _this3 = this;
  
        // in certain situations it may be useful to delay processing (e.g. for GC)
        var timeout = this.getTimeout && this.getTimeout();
  
        if (timeout) {
          return new Promise(function (resolve) {
            var anime = _this3._animate();
  
            setTimeout(function () {
              clearInterval(anime);
              resolve();
            }, timeout);
          });
        }
  
        return Promise.resolve();
      }
    }, {
      key: "_flush",
      value: function () {
        var _flush2 = _asyncToGenerator(
        /*#__PURE__*/
        regeneratorRuntime.mark(function _callee2() {
          var _this4 = this;
  
          return regeneratorRuntime.wrap(function _callee2$(_context2) {
            while (1) {
              switch (_context2.prev = _context2.next) {
                case 0:
                  if (!(this.queue && !this.flushing && !this.corked)) {
                    _context2.next = 9;
                    break;
                  }
  
                  if (!this.queue.length) {
                    _context2.next = 8;
                    break;
                  }
  
                  this.flushing = true;
                  _context2.next = 5;
                  return this._delay();
  
                case 5:
                  _context2.next = 7;
                  return this._pipe(this.queue.shift());
  
                case 7:
                  setImmediate(function () {
                    _this4.flushing = false;
  
                    _this4._flush();
                  });
  
                case 8:
                  if (!this.stem) {
                    // Signal up-stream that we're ready for more data
                    this.emit('drain');
                  }
  
                case 9:
                case "end":
                  return _context2.stop();
              }
            }
          }, _callee2, this);
        }));
  
        function _flush() {
          return _flush2.apply(this, arguments);
        }
  
        return _flush;
      }()
    }, {
      key: "write",
      value: function write(data, encoding, callback) {
        // Called by up-stream pipe
        if (encoding instanceof Function) {
          callback = encoding;
          encoding = 'utf8';
        }
  
        callback = callback || utils.nop;
  
        if (!this.queue) {
          throw new Error('Cannot write to stream after end');
        } // Always queue chunks and then flush
  
  
        this.queue.push({
          data: data,
          encoding: encoding,
          callback: callback
        });
  
        this._flush(); // restrict further incoming data if we have backed up buffers or
        // the children are still busy
  
  
        var stemFlow = this.corked || this.queue.length > 3;
        return !stemFlow;
      }
    }, {
      key: "end",
      value: function end() {
        var _this5 = this;
  
        // Signal from up-stream
        this.queue.push({
          callback: function callback() {
            _this5.queue = null;
  
            _this5.emit('finish');
          }
        });
  
        this._flush();
      }
    }, {
      key: "pipe",
      value: function pipe(stream, options) {
        options = options || {}; // some streams don't call callbacks
  
        var sync = options.sync || false;
        this.pipes.push({
          stream: stream,
          sync: sync
        });
      }
    }, {
      key: "unpipe",
      value: function unpipe(stream) {
        this.pipes = this.pipes.filter(function (pipe) {
          return pipe.stream !== stream;
        });
      }
    }, {
      key: "createChild",
      value: function createChild() {
        var _this6 = this;
  
        // Create a down-stream flow-control
        var options = _objectSpread({
          parent: this
        }, this.options);
  
        var child = new FlowControl(options);
        this.children.push(child);
        child.on('drain', function () {
          // a child is ready for more
          _this6._flush();
        });
        child.on('finish', function () {
          // One child has finished its stream. Remove it and continue
          _this6.children = _this6.children.filter(function (item) {
            return item !== child;
          });
  
          _this6._flush();
        });
        return child;
      }
    }, {
      key: "name",
      get: function get() {
        return ['FlowControl', this.parent ? 'Child' : 'Root', this.corked ? 'corked' : 'open'].join(' ');
      }
    }, {
      key: "corked",
      get: function get() {
        // We remain corked while we have children and at least one has data to consume
        return this.children.length > 0 && this.children.some(function (child) {
          return child.queue && child.queue.length;
        });
      }
    }, {
      key: "stem",
      get: function get() {
        // the decision to stem the incoming data depends on whether the children are corked
        // and how many buffers we have backed up
        return this.corked || !this.queue || this.queue.length > 2;
      }
    }]);
  
    return FlowControl;
  }(EventEmitter);
  
  module.exports = FlowControl;
  //# sourceMappingURL=flow-control.js.map
  