text: // Acorn is a tiny, fast JavaScript parser written in JavaScript.
  //
  // Acorn was written by Marijn Haverbeke and released under an MIT
  // license. The Unicode regexps (for identifiers and whitespace) were
  // taken from [Esprima](http://esprima.org) by Ariya Hidayat.
  //
  // Git repositories for Acorn are available at
  //
  //     http://marijnhaverbeke.nl/git/acorn
  //     https://github.com/marijnh/acorn.git
  //
  // Please use the [github bug tracker][ghbt] to report issues.
  //
  // [ghbt]: https://github.com/marijnh/acorn/issues
  //
  // This file defines the main parser interface. The library also comes
  // with a [error-tolerant parser][dammit] and an
  // [abstract syntax tree walker][walk], defined in other files.
  //
  // [dammit]: acorn_loose.js
  // [walk]: util/walk.js
  
  (function(root, mod) {
    if (typeof exports == "object" && typeof module == "object") return mod(exports); // CommonJS
    if (typeof define == "function" && define.amd) return define(["exports"], mod); // AMD
    mod(root.acorn || (root.acorn = {})); // Plain browser env
  })(this, function(exports) {
    "use strict";
  
    exports.version = "0.4.1";
  
    // The main exported interface (under `self.acorn` when in the
    // browser) is a `parse` function that takes a code string and
    // returns an abstract syntax tree as specified by [Mozilla parser
    // API][api], with the caveat that the SpiderMonkey-specific syntax
    // (`let`, `yield`, inline XML, etc) is not recognized.
    //
    // [api]: https://developer.mozilla.org/en-US/docs/SpiderMonkey/Parser_API
  
    var options, input, inputLen, sourceFile;
  
    exports.parse = function(inpt, opts) {
      input = String(inpt); inputLen = input.length;
      setOptions(opts);
      initTokenState();
      return parseTopLevel(options.program);
    };
  
    // A second optional argument can be given to further configure
    // the parser process. These options are recognized:
  
    var defaultOptions = exports.defaultOptions = {
      // `ecmaVersion` indicates the ECMAScript version to parse. Must
      // be either 3 or 5. This
      // influences support for strict mode, the set of reserved words, and
      // support for getters and setter.
      ecmaVersion: 5,
      // Turn on `strictSemicolons` to prevent the parser from doing
      // automatic semicolon insertion.
      strictSemicolons: false,
      // When `allowTrailingCommas` is false, the parser will not allow
      // trailing commas in array and object literals.
      allowTrailingCommas: true,
      // By default, reserved words are not enforced. Enable
      // `forbidReserved` to enforce them. When this option has the
      // value "everywhere", reserved words and keywords can also not be
      // used as property names.
      forbidReserved: false,
      // When enabled, a return at the top level is not considered an
      // error.
      allowReturnOutsideFunction: false,
      // When `locations` is on, `loc` properties holding objects with
      // `start` and `end` properties in `{line, column}` form (with
      // line being 1-based and column 0-based) will be attached to the
      // nodes.
      locations: false,
      // A function can be passed as `onComment` option, which will
      // cause Acorn to call that function with `(block, text, start,
      // end)` parameters whenever a comment is skipped. `block` is a
      // boolean indicating whether this is a block (`/* */`) comment,
      // `text` is the content of the comment, and `start` and `end` are
      // character offsets that denote the start and end of the comment.
      // When the `locations` option is on, two more parameters are
      // passed, the full `{line, column}` locations of the start and
      // end of the comments. Note that you are not allowed to call the
      // parser from the callback—that will corrupt its internal state.
      onComment: null,
      // Nodes have their start and end characters offsets recorded in
      // `start` and `end` properties (directly on the node, rather than
      // the `loc` object, which holds line/column data. To also add a
      // [semi-standardized][range] `range` property holding a `[start,
      // end]` array with the same numbers, set the `ranges` option to
      // `true`.
      //
      // [range]: https://bugzilla.mozilla.org/show_bug.cgi?id=745678
      ranges: false,
      // It is possible to parse multiple files into a single AST by
      // passing the tree produced by parsing the first file as
      // `program` option in subsequent parses. This will add the
      // toplevel forms of the parsed file to the `Program` (top) node
      // of an existing parse tree.
      program: null,
      // When `locations` is on, you can pass this to record the source
      // file in every node's `loc` object.
      sourceFile: null,
      // This value, if given, is stored in every node, whether
      // `locations` is on or off.
      directSourceFile: null
    };
  
    function setOptions(opts) {
      options = opts || {};
      for (var opt in defaultOptions) if (!Object.prototype.hasOwnProperty.call(options, opt))
        options[opt] = defaultOptions[opt];
      sourceFile = options.sourceFile || null;
    }
  
    // The `getLineInfo` function is mostly useful when the
    // `locations` option is off (for performance reasons) and you
    // want to find the line/column position for a given character
    // offset. `input` should be the code string that the offset refers
    // into.
  
    var getLineInfo = exports.getLineInfo = function(input, offset) {
      for (var line = 1, cur = 0;;) {
        lineBreak.lastIndex = cur;
        var match = lineBreak.exec(input);
        if (match && match.index < offset) {
          ++line;
          cur = match.index + match[0].length;
        } else break;
      }
      return {line: line, column: offset - cur};
    };
  
    // Acorn is organized as a tokenizer and a recursive-descent parser.
    // The `tokenize` export provides an interface to the tokenizer.
    // Because the tokenizer is optimized for being efficiently used by
    // the Acorn parser itself, this interface is somewhat crude and not
    // very modular. Performing another parse or call to `tokenize` will
    // reset the internal state, and invalidate existing tokenizers.
  
    exports.tokenize = function(inpt, opts) {
      input = String(inpt); inputLen = input.length;
      setOptions(opts);
      initTokenState();
  
      var t = {};
      function getToken(forceRegexp) {
        lastEnd = tokEnd;
        readToken(forceRegexp);
        t.start = tokStart; t.end = tokEnd;
        t.startLoc = tokStartLoc; t.endLoc = tokEndLoc;
        t.type = tokType; t.value = tokVal;
        return t;
      }
      getToken.jumpTo = function(pos, reAllowed) {
        tokPos = pos;
        if (options.locations) {
          tokCurLine = 1;
          tokLineStart = lineBreak.lastIndex = 0;
          var match;
          while ((match = lineBreak.exec(input)) && match.index < pos) {
            ++tokCurLine;
            tokLineStart = match.index + match[0].length;
          }
        }
        tokRegexpAllowed = reAllowed;
        skipSpace();
      };
      return getToken;
    };
  
    // State is kept in (closure-)global variables. We already saw the
    // `options`, `input`, and `inputLen` variables above.
  
    // The current position of the tokenizer in the input.
  
    var tokPos;
  
    // The start and end offsets of the current token.
  
    var tokStart, tokEnd;
  
    // When `options.locations` is true, these hold objects
    // containing the tokens start and end line/column pairs.
  
    var tokStartLoc, tokEndLoc;
  
    // The type and value of the current token. Token types are objects,
    // named by variables against which they can be compared, and
    // holding properties that describe them (indicating, for example,
    // the precedence of an infix operator, and the original name of a
    // keyword token). The kind of value that's held in `tokVal` depends
    // on the type of the token. For literals, it is the literal value,
    // for operators, the operator name, and so on.
  
    var tokType, tokVal;
  
    // Interal state for the tokenizer. To distinguish between division
    // operators and regular expressions, it remembers whether the last
    // token was one that is allowed to be followed by an expression.
    // (If it is, a slash is probably a regexp, if it isn't it's a
    // division operator. See the `parseStatement` function for a
    // caveat.)
  
    var tokRegexpAllowed;
  
    // When `options.locations` is true, these are used to keep
    // track of the current line, and know when a new line has been
    // entered.
  
    var tokCurLine, tokLineStart;
  
    // These store the position of the previous token, which is useful
    // when finishing a node and assigning its `end` position.
  
    var lastStart, lastEnd, lastEndLoc;
  
    // This is the parser's state. `inFunction` is used to reject
    // `return` statements outside of functions, `labels` to verify that
    // `break` and `continue` have somewhere to jump to, and `strict`
    // indicates whether strict mode is on.
  
    var inFunction, labels, strict;
  
    // This function is used to raise exceptions on parse errors. It
    // takes an offset integer (into the current `input`) to indicate
    // the location of the error, attaches the position to the end
    // of the error message, and then raises a `SyntaxError` with that
    // message.
  
    function raise(pos, message) {
      var loc = getLineInfo(input, pos);
      message += " (" + loc.line + ":" + loc.column + ")";
      var err = new SyntaxError(message);
      err.pos = pos; err.loc = loc; err.raisedAt = tokPos;
      throw err;
    }
  
    // Reused empty array added for node fields that are always empty.
  
    var empty = [];
  
    // ## Token types
  
    // The assignment of fine-grained, information-carrying type objects
    // allows the tokenizer to store the information it has about a
    // token in a way that is very cheap for the parser to look up.
  
    // All token type variables start with an underscore, to make them
    // easy to recognize.
  
    // These are the general types. The `type` property is only used to
    // make them recognizeable when debugging.
  
    var _num = {type: "num"}, _regexp = {type: "regexp"}, _string = {type: "string"};
    var _name = {type: "name"}, _eof = {type: "eof"};
  
    // Keyword tokens. The `keyword` property (also used in keyword-like
    // operators) indicates that the token originated from an
    // identifier-like word, which is used when parsing property names.
    //
    // The `beforeExpr` property is used to disambiguate between regular
    // expressions and divisions. It is set on all token types that can
    // be followed by an expression (thus, a slash after them would be a
    // regular expression).
    //
    // `isLoop` marks a keyword as starting a loop, which is important
    // to know when parsing a label, in order to allow or disallow
    // continue jumps to that label.
  
    var _break = {keyword: "break"}, _case = {keyword: "case", beforeExpr: true}, _catch = {keyword: "catch"};
    var _continue = {keyword: "continue"}, _debugger = {keyword: "debugger"}, _default = {keyword: "default"};
    var _do = {keyword: "do", isLoop: true}, _else = {keyword: "else", beforeExpr: true};
    var _finally = {keyword: "finally"}, _for = {keyword: "for", isLoop: true}, _function = {keyword: "function"};
    var _if = {keyword: "if"}, _return = {keyword: "return", beforeExpr: true}, _switch = {keyword: "switch"};
    var _throw = {keyword: "throw", beforeExpr: true}, _try = {keyword: "try"}, _var = {keyword: "var"};
    var _while = {keyword: "while", isLoop: true}, _with = {keyword: "with"}, _new = {keyword: "new", beforeExpr: true};
    var _this = {keyword: "this"};
  
    // The keywords that denote values.
  
    var _null = {keyword: "null", atomValue: null}, _true = {keyword: "true", atomValue: true};
    var _false = {keyword: "false", atomValue: false};
  
    // Some keywords are treated as regular operators. `in` sometimes
    // (when parsing `for`) needs to be tested against specifically, so
    // we assign a variable name to it for quick comparing.
  
    var _in = {keyword: "in", binop: 7, beforeExpr: true};
  
    // Map keyword names to token types.
  
    var keywordTypes = {"break": _break, "case": _case, "catch": _catch,
                        "continue": _continue, "debugger": _debugger, "default": _default,
                        "do": _do, "else": _else, "finally": _finally, "for": _for,
                        "function": _function, "if": _if, "return": _return, "switch": _switch,
                        "throw": _throw, "try": _try, "var": _var, "while": _while, "with": _with,
                        "null": _null, "true": _true, "false": _false, "new": _new, "in": _in,
                        "instanceof": {keyword: "instanceof", binop: 7, beforeExpr: true}, "this": _this,
                        "typeof": {keyword: "typeof", prefix: true, beforeExpr: true},
                        "void": {keyword: "void", prefix: true, beforeExpr: true},
                        "delete": {keyword: "delete", prefix: true, beforeExpr: true}};
  
    // Punctuation token types. Again, the `type` property is purely for debugging.
  
    var _bracketL = {type: "[", beforeExpr: true}, _bracketR = {type: "]"}, _braceL = {type: "{", beforeExpr: true};
    var _braceR = {type: "}"}, _parenL = {type: "(", beforeExpr: true}, _parenR = {type: ")"};
    var _comma = {type: ",", beforeExpr: true}, _semi = {type: ";", beforeExpr: true};
    var _colon = {type: ":", beforeExpr: true}, _dot = {type: "."}, _question = {type: "?", beforeExpr: true};
  
    // Operators. These carry several kinds of properties to help the
    // parser use them properly (the presence of these properties is
    // what categorizes them as operators).
    //
    // `binop`, when present, specifies that this operator is a binary
    // operator, and will refer to its precedence.
    //
    // `prefix` and `postfix` mark the operator as a prefix or postfix
    // unary operator. `isUpdate` specifies that the node produced by
    // the operator should be of type UpdateExpression rather than
    // simply UnaryExpression (`++` and `--`).
    //
    // `isAssign` marks all of `=`, `+=`, `-=` etcetera, which act as
    // binary operators with a very low precedence, that should result
    // in AssignmentExpression nodes.
  
    var _slash = {binop: 10, beforeExpr: true}, _eq = {isAssign: true, beforeExpr: true};
    var _assign = {isAssign: true, beforeExpr: true};
    var _incDec = {postfix: true, prefix: true, isUpdate: true}, _prefix = {prefix: true, beforeExpr: true};
    var _logicalOR = {binop: 1, beforeExpr: true};
    var _logicalAND = {binop: 2, beforeExpr: true};
    var _bitwiseOR = {binop: 3, beforeExpr: true};
    var _bitwiseXOR = {binop: 4, beforeExpr: true};
    var _bitwiseAND = {binop: 5, beforeExpr: true};
    var _equality = {binop: 6, beforeExpr: true};
    var _relational = {binop: 7, beforeExpr: true};
    var _bitShift = {binop: 8, beforeExpr: true};
    var _plusMin = {binop: 9, prefix: true, beforeExpr: true};
    var _multiplyModulo = {binop: 10, beforeExpr: true};
  
    // Provide access to the token types for external users of the
    // tokenizer.
  
    exports.tokTypes = {bracketL: _bracketL, bracketR: _bracketR, braceL: _braceL, braceR: _braceR,
                        parenL: _parenL, parenR: _parenR, comma: _comma, semi: _semi, colon: _colon,
                        dot: _dot, question: _question, slash: _slash, eq: _eq, name: _name, eof: _eof,
                        num: _num, regexp: _regexp, string: _string};
    for (var kw in keywordTypes) exports.tokTypes["_" + kw] = keywordTypes[kw];
  
    // This is a trick taken from Esprima. It turns out that, on
    // non-Chrome browsers, to check whether a string is in a set, a
    // predicate containing a big ugly `switch` statement is faster than
    // a regular expression, and on Chrome the two are about on par.
    // This function uses `eval` (non-lexical) to produce such a
    // predicate from a space-separated string of words.
    //
    // It starts by sorting the words by length.
  
    function makePredicate(words) {
      words = words.split(" ");
      var f = "", cats = [];
      out: for (var i = 0; i < words.length; ++i) {
        for (var j = 0; j < cats.length; ++j)
          if (cats[j][0].length == words[i].length) {
            cats[j].push(words[i]);
            continue out;
          }
        cats.push([words[i]]);
      }
      function compareTo(arr) {
        if (arr.length == 1) return f += "return str === " + JSON.stringify(arr[0]) + ";";
        f += "switch(str){";
        for (var i = 0; i < arr.length; ++i) f += "case " + JSON.stringify(arr[i]) + ":";
        f += "return true}return false;";
      }
  
      // When there are more than three length categories, an outer
      // switch first dispatches on the lengths, to save on comparisons.
  
      if (cats.length > 3) {
        cats.sort(function(a, b) {return b.length - a.length;});
        f += "switch(str.length){";
        for (var i = 0; i < cats.length; ++i) {
          var cat = cats[i];
          f += "case " + cat[0].length + ":";
          compareTo(cat);
        }
        f += "}";
  
      // Otherwise, simply generate a flat `switch` statement.
  
      } else {
        compareTo(words);
      }
      return new Function("str", f);
    }
  
    // The ECMAScript 3 reserved word list.
  
    var isReservedWord3 = makePredicate("abstract boolean byte char class double enum export extends final float goto implements import int interface long native package private protected public short static super synchronized throws transient volatile");
  
    // ECMAScript 5 reserved words.
  
    var isReservedWord5 = makePredicate("class enum extends super const export import");
  
    // The additional reserved words in strict mode.
  
    var isStrictReservedWord = makePredicate("implements interface let package private protected public static yield");
  
    // The forbidden variable names in strict mode.
  
    var isStrictBadIdWord = makePredicate("eval arguments");
  
    // And the keywords.
  
    var isKeyword = makePredicate("break case catch continue debugger default do else finally for function if return switch throw try var while with null true false instanceof typeof void delete new in this");
  
    // ## Character categories
  
    // Big ugly regular expressions that match characters in the
    // whitespace, identifier, and identifier-start categories. These
    // are only applied when a character is found to actually have a
    // code point above 128.
  
    var nonASCIIwhitespace = /[\u1680\u180e\u2000-\u200a\u202f\u205f\u3000\ufeff]/;
    var nonASCIIidentifierStartChars = "\xaa\xb5\xba\xc0-\xd6\xd8-\xf6\xf8-\u02c1\u02c6-\u02d1\u02e0-\u02e4\u02ec\u02ee\u0370-\u0374\u0376\u0377\u037a-\u037d\u0386\u0388-\u038a\u038c\u038e-\u03a1\u03a3-\u03f5\u03f7-\u0481\u048a-\u0527\u0531-\u0556\u0559\u0561-\u0587\u05d0-\u05ea\u05f0-\u05f2\u0620-\u064a\u066e\u066f\u0671-\u06d3\u06d5\u06e5\u06e6\u06ee\u06ef\u06fa-\u06fc\u06ff\u0710\u0712-\u072f\u074d-\u07a5\u07b1\u07ca-\u07ea\u07f4\u07f5\u07fa\u0800-\u0815\u081a\u0824\u0828\u0840-\u0858\u08a0\u08a2-\u08ac\u0904-\u0939\u093d\u0950\u0958-\u0961\u0971-\u0977\u0979-\u097f\u0985-\u098c\u098f\u0990\u0993-\u09a8\u09aa-\u09b0\u09b2\u09b6-\u09b9\u09bd\u09ce\u09dc\u09dd\u09df-\u09e1\u09f0\u09f1\u0a05-\u0a0a\u0a0f\u0a10\u0a13-\u0a28\u0a2a-\u0a30\u0a32\u0a33\u0a35\u0a36\u0a38\u0a39\u0a59-\u0a5c\u0a5e\u0a72-\u0a74\u0a85-\u0a8d\u0a8f-\u0a91\u0a93-\u0aa8\u0aaa-\u0ab0\u0ab2\u0ab3\u0ab5-\u0ab9\u0abd\u0ad0\u0ae0\u0ae1\u0b05-\u0b0c\u0b0f\u0b10\u0b13-\u0b28\u0b2a-\u0b30\u0b32\u0b33\u0b35-\u0b39\u0b3d\u0b5c\u0b5d\u0b5f-\u0b61\u0b71\u0b83\u0b85-\u0b8a\u0b8e-\u0b90\u0b92-\u0b95\u0b99\u0b9a\u0b9c\u0b9e\u0b9f\u0ba3\u0ba4\u0ba8-\u0baa\u0bae-\u0bb9\u0bd0\u0c05-\u0c0c\u0c0e-\u0c10\u0c12-\u0c28\u0c2a-\u0c33\u0c35-\u0c39\u0c3d\u0c58\u0c59\u0c60\u0c61\u0c85-\u0c8c\u0c8e-\u0c90\u0c92-\u0ca8\u0caa-\u0cb3\u0cb5-\u0cb9\u0cbd\u0cde\u0ce0\u0ce1\u0cf1\u0cf2\u0d05-\u0d0c\u0d0e-\u0d10\u0d12-\u0d3a\u0d3d\u0d4e\u0d60\u0d61\u0d7a-\u0d7f\u0d85-\u0d96\u0d9a-\u0db1\u0db3-\u0dbb\u0dbd\u0dc0-\u0dc6\u0e01-\u0e30\u0e32\u0e33\u0e40-\u0e46\u0e81\u0e82\u0e84\u0e87\u0e88\u0e8a\u0e8d\u0e94-\u0e97\u0e99-\u0e9f\u0ea1-\u0ea3\u0ea5\u0ea7\u0eaa\u0eab\u0ead-\u0eb0\u0eb2\u0eb3\u0ebd\u0ec0-\u0ec4\u0ec6\u0edc-\u0edf\u0f00\u0f40-\u0f47\u0f49-\u0f6c\u0f88-\u0f8c\u1000-\u102a\u103f\u1050-\u1055\u105a-\u105d\u1061\u1065\u1066\u106e-\u1070\u1075-\u1081\u108e\u10a0-\u10c5\u10c7\u10cd\u10d0-\u10fa\u10fc-\u1248\u124a-\u124d\u1250-\u1256\u1258\u125a-\u125d\u1260-\u1288\u128a-\u128d\u1290-\u12b0\u12b2-\u12b5\u12b8-\u12be\u12c0\u12c2-\u12c5\u12c8-\u12d6\u12d8-\u1310\u1312-\u1315\u1318-\u135a\u1380-\u138f\u13a0-\u13f4\u1401-\u166c\u166f-\u167f\u1681-\u169a\u16a0-\u16ea\u16ee-\u16f0\u1700-\u170c\u170e-\u1711\u1720-\u1731\u1740-\u1751\u1760-\u176c\u176e-\u1770\u1780-\u17b3\u17d7\u17dc\u1820-\u1877\u1880-\u18a8\u18aa\u18b0-\u18f5\u1900-\u191c\u1950-\u196d\u1970-\u1974\u1980-\u19ab\u19c1-\u19c7\u1a00-\u1a16\u1a20-\u1a54\u1aa7\u1b05-\u1b33\u1b45-\u1b4b\u1b83-\u1ba0\u1bae\u1baf\u1bba-\u1be5\u1c00-\u1c23\u1c4d-\u1c4f\u1c5a-\u1c7d\u1ce9-\u1cec\u1cee-\u1cf1\u1cf5\u1cf6\u1d00-\u1dbf\u1e00-\u1f15\u1f18-\u1f1d\u1f20-\u1f45\u1f48-\u1f4d\u1f50-\u1f57\u1f59\u1f5b\u1f5d\u1f5f-\u1f7d\u1f80-\u1fb4\u1fb6-\u1fbc\u1fbe\u1fc2-\u1fc4\u1fc6-\u1fcc\u1fd0-\u1fd3\u1fd6-\u1fdb\u1fe0-\u1fec\u1ff2-\u1ff4\u1ff6-\u1ffc\u2071\u207f\u2090-\u209c\u2102\u2107\u210a-\u2113\u2115\u2119-\u211d\u2124\u2126\u2128\u212a-\u212d\u212f-\u2139\u213c-\u213f\u2145-\u2149\u214e\u2160-\u2188\u2c00-\u2c2e\u2c30-\u2c5e\u2c60-\u2ce4\u2ceb-\u2cee\u2cf2\u2cf3\u2d00-\u2d25\u2d27\u2d2d\u2d30-\u2d67\u2d6f\u2d80-\u2d96\u2da0-\u2da6\u2da8-\u2dae\u2db0-\u2db6\u2db8-\u2dbe\u2dc0-\u2dc6\u2dc8-\u2dce\u2dd0-\u2dd6\u2dd8-\u2dde\u2e2f\u3005-\u3007\u3021-\u3029\u3031-\u3035\u3038-\u303c\u3041-\u3096\u309d-\u309f\u30a1-\u30fa\u30fc-\u30ff\u3105-\u312d\u3131-\u318e\u31a0-\u31ba\u31f0-\u31ff\u3400-\u4db5\u4e00-\u9fcc\ua000-\ua48c\ua4d0-\ua4fd\ua500-\ua60c\ua610-\ua61f\ua62a\ua62b\ua640-\ua66e\ua67f-\ua697\ua6a0-\ua6ef\ua717-\ua71f\ua722-\ua788\ua78b-\ua78e\ua790-\ua793\ua7a0-\ua7aa\ua7f8-\ua801\ua803-\ua805\ua807-\ua80a\ua80c-\ua822\ua840-\ua873\ua882-\ua8b3\ua8f2-\ua8f7\ua8fb\ua90a-\ua925\ua930-\ua946\ua960-\ua97c\ua984-\ua9b2\ua9cf\uaa00-\uaa28\uaa40-\uaa42\uaa44-\uaa4b\uaa60-\uaa76\uaa7a\uaa80-\uaaaf\uaab1\uaab5\uaab6\uaab9-\uaabd\uaac0\uaac2\uaadb-\uaadd\uaae0-\uaaea\uaaf2-\uaaf4\uab01-\uab06\uab09-\uab0e\uab11-\uab16\uab20-\uab26\uab28-\uab2e\uabc0-\uabe2\uac00-\ud7a3\ud7b0-\ud7c6\ud7cb-\ud7fb\uf900-\ufa6d\ufa70-\ufad9\ufb00-\ufb06\ufb13-\ufb17\ufb1d\ufb1f-\ufb28\ufb2a-\ufb36\ufb38-\ufb3c\ufb3e\ufb40\ufb41\ufb43\ufb44\ufb46-\ufbb1\ufbd3-\ufd3d\ufd50-\ufd8f\ufd92-\ufdc7\ufdf0-\ufdfb\ufe70-\ufe74\ufe76-\ufefc\uff21-\uff3a\uff41-\uff5a\uff66-\uffbe\uffc2-\uffc7\uffca-\uffcf\uffd2-\uffd7\uffda-\uffdc";
    var nonASCIIidentifierChars = "\u0300-\u036f\u0483-\u0487\u0591-\u05bd\u05bf\u05c1\u05c2\u05c4\u05c5\u05c7\u0610-\u061a\u0620-\u0649\u0672-\u06d3\u06e7-\u06e8\u06fb-\u06fc\u0730-\u074a\u0800-\u0814\u081b-\u0823\u0825-\u0827\u0829-\u082d\u0840-\u0857\u08e4-\u08fe\u0900-\u0903\u093a-\u093c\u093e-\u094f\u0951-\u0957\u0962-\u0963\u0966-\u096f\u0981-\u0983\u09bc\u09be-\u09c4\u09c7\u09c8\u09d7\u09df-\u09e0\u0a01-\u0a03\u0a3c\u0a3e-\u0a42\u0a47\u0a48\u0a4b-\u0a4d\u0a51\u0a66-\u0a71\u0a75\u0a81-\u0a83\u0abc\u0abe-\u0ac5\u0ac7-\u0ac9\u0acb-\u0acd\u0ae2-\u0ae3\u0ae6-\u0aef\u0b01-\u0b03\u0b3c\u0b3e-\u0b44\u0b47\u0b48\u0b4b-\u0b4d\u0b56\u0b57\u0b5f-\u0b60\u0b66-\u0b6f\u0b82\u0bbe-\u0bc2\u0bc6-\u0bc8\u0bca-\u0bcd\u0bd7\u0be6-\u0bef\u0c01-\u0c03\u0c46-\u0c48\u0c4a-\u0c4d\u0c55\u0c56\u0c62-\u0c63\u0c66-\u0c6f\u0c82\u0c83\u0cbc\u0cbe-\u0cc4\u0cc6-\u0cc8\u0cca-\u0ccd\u0cd5\u0cd6\u0ce2-\u0ce3\u0ce6-\u0cef\u0d02\u0d03\u0d46-\u0d48\u0d57\u0d62-\u0d63\u0d66-\u0d6f\u0d82\u0d83\u0dca\u0dcf-\u0dd4\u0dd6\u0dd8-\u0ddf\u0df2\u0df3\u0e34-\u0e3a\u0e40-\u0e45\u0e50-\u0e59\u0eb4-\u0eb9\u0ec8-\u0ecd\u0ed0-\u0ed9\u0f18\u0f19\u0f20-\u0f29\u0f35\u0f37\u0f39\u0f41-\u0f47\u0f71-\u0f84\u0f86-\u0f87\u0f8d-\u0f97\u0f99-\u0fbc\u0fc6\u1000-\u1029\u1040-\u1049\u1067-\u106d\u1071-\u1074\u1082-\u108d\u108f-\u109d\u135d-\u135f\u170e-\u1710\u1720-\u1730\u1740-\u1750\u1772\u1773\u1780-\u17b2\u17dd\u17e0-\u17e9\u180b-\u180d\u1810-\u1819\u1920-\u192b\u1930-\u193b\u1951-\u196d\u19b0-\u19c0\u19c8-\u19c9\u19d0-\u19d9\u1a00-\u1a15\u1a20-\u1a53\u1a60-\u1a7c\u1a7f-\u1a89\u1a90-\u1a99\u1b46-\u1b4b\u1b50-\u1b59\u1b6b-\u1b73\u1bb0-\u1bb9\u1be6-\u1bf3\u1c00-\u1c22\u1c40-\u1c49\u1c5b-\u1c7d\u1cd0-\u1cd2\u1d00-\u1dbe\u1e01-\u1f15\u200c\u200d\u203f\u2040\u2054\u20d0-\u20dc\u20e1\u20e5-\u20f0\u2d81-\u2d96\u2de0-\u2dff\u3021-\u3028\u3099\u309a\ua640-\ua66d\ua674-\ua67d\ua69f\ua6f0-\ua6f1\ua7f8-\ua800\ua806\ua80b\ua823-\ua827\ua880-\ua881\ua8b4-\ua8c4\ua8d0-\ua8d9\ua8f3-\ua8f7\ua900-\ua909\ua926-\ua92d\ua930-\ua945\ua980-\ua983\ua9b3-\ua9c0\uaa00-\uaa27\uaa40-\uaa41\uaa4c-\uaa4d\uaa50-\uaa59\uaa7b\uaae0-\uaae9\uaaf2-\uaaf3\uabc0-\uabe1\uabec\uabed\uabf0-\uabf9\ufb20-\ufb28\ufe00-\ufe0f\ufe20-\ufe26\ufe33\ufe34\ufe4d-\ufe4f\uff10-\uff19\uff3f";
    var nonASCIIidentifierStart = new RegExp("[" + nonASCIIidentifierStartChars + "]");
    var nonASCIIidentifier = new RegExp("[" + nonASCIIidentifierStartChars + nonASCIIidentifierChars + "]");
  
    // Whether a single character denotes a newline.
  
    var newline = /[\n\r\u2028\u2029]/;
  
    // Matches a whole line break (where CRLF is considered a single
    // line break). Used to count lines.
  
    var lineBreak = /\r\n|[\n\r\u2028\u2029]/g;
  
    // Test whether a given character code starts an identifier.
  
    var isIdentifierStart = exports.isIdentifierStart = function(code) {
      if (code < 65) return code === 36;
      if (code < 91) return true;
      if (code < 97) return code === 95;
      if (code < 123)return true;
      return code >= 0xaa && nonASCIIidentifierStart.test(String.fromCharCode(code));
    };
  
    // Test whether a given character is part of an identifier.
  
    var isIdentifierChar = exports.isIdentifierChar = function(code) {
      if (code < 48) return code === 36;
      if (code < 58) return true;
      if (code < 65) return false;
      if (code < 91) return true;
      if (code < 97) return code === 95;
      if (code < 123)return true;
      return code >= 0xaa && nonASCIIidentifier.test(String.fromCharCode(code));
    };
  
    // ## Tokenizer
  
    // These are used when `options.locations` is on, for the
    // `tokStartLoc` and `tokEndLoc` properties.
  
    function line_loc_t() {
      this.line = tokCurLine;
      this.column = tokPos - tokLineStart;
    }
  
    // Reset the token state. Used at the start of a parse.
  
    function initTokenState() {
      tokCurLine = 1;
      tokPos = tokLineStart = 0;
      tokRegexpAllowed = true;
      skipSpace();
    }
  
    // Called at the end of every token. Sets `tokEnd`, `tokVal`, and
    // `tokRegexpAllowed`, and skips the space after the token, so that
    // the next one's `tokStart` will point at the right position.
  
    function finishToken(type, val) {
      tokEnd = tokPos;
      if (options.locations) tokEndLoc = new line_loc_t;
      tokType = type;
      skipSpace();
      tokVal = val;
      tokRegexpAllowed = type.beforeExpr;
    }
  
    function skipBlockComment() {
      var startLoc = options.onComment && options.locations && new line_loc_t;
      var start = tokPos, end = input.indexOf("*/", tokPos += 2);
      if (end === -1) raise(tokPos - 2, "Unterminated comment");
      tokPos = end + 2;
      if (options.locations) {
        lineBreak.lastIndex = start;
        var match;
        while ((match = lineBreak.exec(input)) && match.index < tokPos) {
          ++tokCurLine;
          tokLineStart = match.index + match[0].length;
        }
      }
      if (options.onComment)
        options.onComment(true, input.slice(start + 2, end), start, tokPos,
                          startLoc, options.locations && new line_loc_t);
    }
  
    function skipLineComment() {
      var start = tokPos;
      var startLoc = options.onComment && options.locations && new line_loc_t;
      var ch = input.charCodeAt(tokPos+=2);
      while (tokPos < inputLen && ch !== 10 && ch !== 13 && ch !== 8232 && ch !== 8233) {
        ++tokPos;
        ch = input.charCodeAt(tokPos);
      }
      if (options.onComment)
        options.onComment(false, input.slice(start + 2, tokPos), start, tokPos,
                          startLoc, options.locations && new line_loc_t);
    }
  
    // Called at the start of the parse and after every token. Skips
    // whitespace and comments, and.
  
    function skipSpace() {
      while (tokPos < inputLen) {
        var ch = input.charCodeAt(tokPos);
        if (ch === 32) { // ' '
          ++tokPos;
        } else if (ch === 13) {
          ++tokPos;
          var next = input.charCodeAt(tokPos);
          if (next === 10) {
            ++tokPos;
          }
          if (options.locations) {
            ++tokCurLine;
            tokLineStart = tokPos;
          }
        } else if (ch === 10 || ch === 8232 || ch === 8233) {
          ++tokPos;
          if (options.locations) {
            ++tokCurLine;
            tokLineStart = tokPos;
          }
        } else if (ch > 8 && ch < 14) {
          ++tokPos;
        } else if (ch === 47) { // '/'
          var next = input.charCodeAt(tokPos + 1);
          if (next === 42) { // '*'
            skipBlockComment();
          } else if (next === 47) { // '/'
            skipLineComment();
          } else break;
        } else if (ch === 160) { // '\xa0'
          ++tokPos;
        } else if (ch >= 5760 && nonASCIIwhitespace.test(String.fromCharCode(ch))) {
          ++tokPos;
        } else {
          break;
        }
      }
    }
  
    // ### Token reading
  
    // This is the function that is called to fetch the next token. It
    // is somewhat obscure, because it works in character codes rather
    // than characters, and because operator parsing has been inlined
    // into it.
    //
    // All in the name of speed.
    //
    // The `forceRegexp` parameter is used in the one case where the
    // `tokRegexpAllowed` trick does not work. See `parseStatement`.
  
    function readToken_dot() {
      var next = input.charCodeAt(tokPos + 1);
      if (next >= 48 && next <= 57) return readNumber(true);
      ++tokPos;
      return finishToken(_dot);
    }
  
    function readToken_slash() { // '/'
      var next = input.charCodeAt(tokPos + 1);
      if (tokRegexpAllowed) {++tokPos; return readRegexp();}
      if (next === 61) return finishOp(_assign, 2);
      return finishOp(_slash, 1);
    }
  
    function readToken_mult_modulo() { // '%*'
      var next = input.charCodeAt(tokPos + 1);
      if (next === 61) return finishOp(_assign, 2);
      return finishOp(_multiplyModulo, 1);
    }
  
    function readToken_pipe_amp(code) { // '|&'
      var next = input.charCodeAt(tokPos + 1);
      if (next === code) return finishOp(code === 124 ? _logicalOR : _logicalAND, 2);
      if (next === 61) return finishOp(_assign, 2);
      return finishOp(code === 124 ? _bitwiseOR : _bitwiseAND, 1);
    }
  
    function readToken_caret() { // '^'
      var next = input.charCodeAt(tokPos + 1);
      if (next === 61) return finishOp(_assign, 2);
      return finishOp(_bitwiseXOR, 1);
    }
  
    function readToken_plus_min(code) { // '+-'
      var next = input.charCodeAt(tokPos + 1);
      if (next === code) {
        if (next == 45 && input.charCodeAt(tokPos + 2) == 62 &&
            newline.test(input.slice(lastEnd, tokPos))) {
          // A `-->` line comment
          tokPos += 3;
          skipLineComment();
          skipSpace();
          return readToken();
        }
        return finishOp(_incDec, 2);
      }
      if (next === 61) return finishOp(_assign, 2);
      return finishOp(_plusMin, 1);
    }
  
    function readToken_lt_gt(code) { // '<>'
      var next = input.charCodeAt(tokPos + 1);
      var size = 1;
      if (next === code) {
        size = code === 62 && input.charCodeAt(tokPos + 2) === 62 ? 3 : 2;
        if (input.charCodeAt(tokPos + size) === 61) return finishOp(_assign, size + 1);
        return finishOp(_bitShift, size);
      }
      if (next == 33 && code == 60 && input.charCodeAt(tokPos + 2) == 45 &&
          input.charCodeAt(tokPos + 3) == 45) {
        // `<!--`, an XML-style comment that should be interpreted as a line comment
        tokPos += 4;
        skipLineComment();
        skipSpace();
        return readToken();
      }
      if (next === 61)
        size = input.charCodeAt(tokPos + 2) === 61 ? 3 : 2;
      return finishOp(_relational, size);
    }
  
    function readToken_eq_excl(code) { // '=!'
      var next = input.charCodeAt(tokPos + 1);
      if (next === 61) return finishOp(_equality, input.charCodeAt(tokPos + 2) === 61 ? 3 : 2);
      return finishOp(code === 61 ? _eq : _prefix, 1);
    }
  
    function getTokenFromCode(code) {
      switch(code) {
        // The interpretation of a dot depends on whether it is followed
        // by a digit.
      case 46: // '.'
        return readToken_dot();
  
        // Punctuation tokens.
      case 40: ++tokPos; return finishToken(_parenL);
      case 41: ++tokPos; return finishToken(_parenR);
      case 59: ++tokPos; return finishToken(_semi);
      case 44: ++tokPos; return finishToken(_comma);
      case 91: ++tokPos; return finishToken(_bracketL);
      case 93: ++tokPos; return finishToken(_bracketR);
      case 123: ++tokPos; return finishToken(_braceL);
      case 125: ++tokPos; return finishToken(_braceR);
      case 58: ++tokPos; return finishToken(_colon);
      case 63: ++tokPos; return finishToken(_question);
  
        // '0x' is a hexadecimal number.
      case 48: // '0'
        var next = input.charCodeAt(tokPos + 1);
        if (next === 120 || next === 88) return readHexNumber();
        // Anything else beginning with a digit is an integer, octal
        // number, or float.
      case 49: case 50: case 51: case 52: case 53: case 54: case 55: case 56: case 57: // 1-9
        return readNumber(false);
  
        // Quotes produce strings.
      case 34: case 39: // '"', "'"
        return readString(code);
  
      // Operators are parsed inline in tiny state machines. '=' (61) is
      // often referred to. `finishOp` simply skips the amount of
      // characters it is given as second argument, and returns a token
      // of the type given by its first argument.
  
      case 47: // '/'
        return readToken_slash(code);
  
      case 37: case 42: // '%*'
        return readToken_mult_modulo();
  
      case 124: case 38: // '|&'
        return readToken_pipe_amp(code);
  
      case 94: // '^'
        return readToken_caret();
  
      case 43: case 45: // '+-'
        return readToken_plus_min(code);
  
      case 60: case 62: // '<>'
        return readToken_lt_gt(code);
  
      case 61: case 33: // '=!'
        return readToken_eq_excl(code);
  
      case 126: // '~'
        return finishOp(_prefix, 1);
      }
  
      return false;
    }
  
    function readToken(forceRegexp) {
      if (!forceRegexp) tokStart = tokPos;
      else tokPos = tokStart + 1;
      if (options.locations) tokStartLoc = new line_loc_t;
      if (forceRegexp) return readRegexp();
      if (tokPos >= inputLen) return finishToken(_eof);
  
      var code = input.charCodeAt(tokPos);
      // Identifier or keyword. '\uXXXX' sequences are allowed in
      // identifiers, so '\' also dispatches to that.
      if (isIdentifierStart(code) || code === 92 /* '\' */) return readWord();
  
      var tok = getTokenFromCode(code);
  
      if (tok === false) {
        // If we are here, we either found a non-ASCII identifier
        // character, or something that's entirely disallowed.
        var ch = String.fromCharCode(code);
        if (ch === "\\" || nonASCIIidentifierStart.test(ch)) return readWord();
        raise(tokPos, "Unexpected character '" + ch + "'");
      }
      return tok;
    }
  
    function finishOp(type, size) {
      var str = input.slice(tokPos, tokPos + size);
      tokPos += size;
      finishToken(type, str);
    }
  
    // Parse a regular expression. Some context-awareness is necessary,
    // since a '/' inside a '[]' set does not end the expression.
  
    function readRegexp() {
      var content = "", escaped, inClass, start = tokPos;
      for (;;) {
        if (tokPos >= inputLen) raise(start, "Unterminated regular expression");
        var ch = input.charAt(tokPos);
        if (newline.test(ch)) raise(start, "Unterminated regular expression");
        if (!escaped) {
          if (ch === "[") inClass = true;
          else if (ch === "]" && inClass) inClass = false;
          else if (ch === "/" && !inClass) break;
          escaped = ch === "\\";
        } else escaped = false;
        ++tokPos;
      }
      var content = input.slice(start, tokPos);
      ++tokPos;
      // Need to use `readWord1` because '\uXXXX' sequences are allowed
      // here (don't ask).
      var mods = readWord1();
      if (mods && !/^[gmsiy]*$/.test(mods)) raise(start, "Invalid regexp flag");
      try {
        var value = new RegExp(content, mods);
      } catch (e) {
        if (e instanceof SyntaxError) raise(start, e.message);
        raise(e);
      }
      return finishToken(_regexp, value);
    }
  
    // Read an integer in the given radix. Return null if zero digits
    // were read, the integer value otherwise. When `len` is given, this
    // will return `null` unless the integer has exactly `len` digits.
  
    function readInt(radix, len) {
      var start = tokPos, total = 0;
      for (var i = 0, e = len == null ? Infinity : len; i < e; ++i) {
        var code = input.charCodeAt(tokPos), val;
        if (code >= 97) val = code - 97 + 10; // a
        else if (code >= 65) val = code - 65 + 10; // A
        else if (code >= 48 && code <= 57) val = code - 48; // 0-9
        else val = Infinity;
        if (val >= radix) break;
        ++tokPos;
        total = total * radix + val;
      }
      if (tokPos === start || len != null && tokPos - start !== len) return null;
  
      return total;
    }
  
    function readHexNumber() {
      tokPos += 2; // 0x
      var val = readInt(16);
      if (val == null) raise(tokStart + 2, "Expected hexadecimal number");
      if (isIdentifierStart(input.charCodeAt(tokPos))) raise(tokPos, "Identifier directly after number");
      return finishToken(_num, val);
    }
  
    // Read an integer, octal integer, or floating-point number.
  
    function readNumber(startsWithDot) {
      var start = tokPos, isFloat = false, octal = input.charCodeAt(tokPos) === 48;
      if (!startsWithDot && readInt(10) === null) raise(start, "Invalid number");
      if (input.charCodeAt(tokPos) === 46) {
        ++tokPos;
        readInt(10);
        isFloat = true;
      }
      var next = input.charCodeAt(tokPos);
      if (next === 69 || next === 101) { // 'eE'
        next = input.charCodeAt(++tokPos);
        if (next === 43 || next === 45) ++tokPos; // '+-'
        if (readInt(10) === null) raise(start, "Invalid number");
        isFloat = true;
      }
      if (isIdentifierStart(input.charCodeAt(tokPos))) raise(tokPos, "Identifier directly after number");
  
      var str = input.slice(start, tokPos), val;
      if (isFloat) val = parseFloat(str);
      else if (!octal || str.length === 1) val = parseInt(str, 10);
      else if (/[89]/.test(str) || strict) raise(start, "Invalid number");
      else val = parseInt(str, 8);
      return finishToken(_num, val);
    }
  
    // Read a string value, interpreting backslash-escapes.
  
    function readString(quote) {
      tokPos++;
      var out = "";
      for (;;) {
        if (tokPos >= inputLen) raise(tokStart, "Unterminated string constant");
        var ch = input.charCodeAt(tokPos);
        if (ch === quote) {
          ++tokPos;
          return finishToken(_string, out);
        }
        if (ch === 92) { // '\'
          ch = input.charCodeAt(++tokPos);
          var octal = /^[0-7]+/.exec(input.slice(tokPos, tokPos + 3));
          if (octal) octal = octal[0];
          while (octal && parseInt(octal, 8) > 255) octal = octal.slice(0, -1);
          if (octal === "0") octal = null;
          ++tokPos;
          if (octal) {
            if (strict) raise(tokPos - 2, "Octal literal in strict mode");
            out += String.fromCharCode(parseInt(octal, 8));
            tokPos += octal.length - 1;
          } else {
            switch (ch) {
            case 110: out += "\n"; break; // 'n' -> '\n'
            case 114: out += "\r"; break; // 'r' -> '\r'
            case 120: out += String.fromCharCode(readHexChar(2)); break; // 'x'
            case 117: out += String.fromCharCode(readHexChar(4)); break; // 'u'
            case 85: out += String.fromCharCode(readHexChar(8)); break; // 'U'
            case 116: out += "\t"; break; // 't' -> '\t'
            case 98: out += "\b"; break; // 'b' -> '\b'
            case 118: out += "\u000b"; break; // 'v' -> '\u000b'
            case 102: out += "\f"; break; // 'f' -> '\f'
            case 48: out += "\0"; break; // 0 -> '\0'
            case 13: if (input.charCodeAt(tokPos) === 10) ++tokPos; // '\r\n'
            case 10: // ' \n'
              if (options.locations) { tokLineStart = tokPos; ++tokCurLine; }
              break;
            default: out += String.fromCharCode(ch); break;
            }
          }
        } else {
          if (ch === 13 || ch === 10 || ch === 8232 || ch === 8233) raise(tokStart, "Unterminated string constant");
          out += String.fromCharCode(ch); // '\'
          ++tokPos;
        }
      }
    }
  
    // Used to read character escape sequences ('\x', '\u', '\U').
  
    function readHexChar(len) {
      var n = readInt(16, len);
      if (n === null) raise(tokStart, "Bad character escape sequence");
      return n;
    }
  
    // Used to signal to callers of `readWord1` whether the word
    // contained any escape sequences. This is needed because words with
    // escape sequences must not be interpreted as keywords.
  
    var containsEsc;
  
    // Read an identifier, and return it as a string. Sets `containsEsc`
    // to whether the word contained a '\u' escape.
    //
    // Only builds up the word character-by-character when it actually
    // containeds an escape, as a micro-optimization.
  
    function readWord1() {
      containsEsc = false;
      var word, first = true, start = tokPos;
      for (;;) {
        var ch = input.charCodeAt(tokPos);
        if (isIdentifierChar(ch)) {
          if (containsEsc) word += input.charAt(tokPos);
          ++tokPos;
        } else if (ch === 92) { // "\"
          if (!containsEsc) word = input.slice(start, tokPos);
          containsEsc = true;
          if (input.charCodeAt(++tokPos) != 117) // "u"
            raise(tokPos, "Expecting Unicode escape sequence \\uXXXX");
          ++tokPos;
          var esc = readHexChar(4);
          var escStr = String.fromCharCode(esc);
          if (!escStr) raise(tokPos - 1, "Invalid Unicode escape");
          if (!(first ? isIdentifierStart(esc) : isIdentifierChar(esc)))
            raise(tokPos - 4, "Invalid Unicode escape");
          word += escStr;
        } else {
          break;
        }
        first = false;
      }
      return containsEsc ? word : input.slice(start, tokPos);
    }
  
    // Read an identifier or keyword token. Will check for reserved
    // words when necessary.
  
    function readWord() {
      var word = readWord1();
      var type = _name;
      if (!containsEsc && isKeyword(word))
        type = keywordTypes[word];
      return finishToken(type, word);
    }
  
    // ## Parser
  
    // A recursive descent parser operates by defining functions for all
    // syntactic elements, and recursively calling those, each function
    // advancing the input stream and returning an AST node. Precedence
    // of constructs (for example, the fact that `!x[1]` means `!(x[1])`
    // instead of `(!x)[1]` is handled by the fact that the parser
    // function that parses unary prefix operators is called first, and
    // in turn calls the function that parses `[]` subscripts — that
    // way, it'll receive the node for `x[1]` already parsed, and wraps
    // *that* in the unary operator node.
    //
    // Acorn uses an [operator precedence parser][opp] to handle binary
    // operator precedence, because it is much more compact than using
    // the technique outlined above, which uses different, nesting
    // functions to specify precedence, for all of the ten binary
    // precedence levels that JavaScript defines.
    //
    // [opp]: http://en.wikipedia.org/wiki/Operator-precedence_parser
  
    // ### Parser utilities
  
    // Continue to the next token.
  
    function next() {
      lastStart = tokStart;
      lastEnd = tokEnd;
      lastEndLoc = tokEndLoc;
      readToken();
    }
  
    // Enter strict mode. Re-reads the next token to please pedantic
    // tests ("use strict"; 010; -- should fail).
  
    function setStrict(strct) {
      strict = strct;
      tokPos = tokStart;
      if (options.locations) {
        while (tokPos < tokLineStart) {
          tokLineStart = input.lastIndexOf("\n", tokLineStart - 2) + 1;
          --tokCurLine;
        }
      }
      skipSpace();
      readToken();
    }
  
    // Start an AST node, attaching a start offset.
  
    function node_t() {
      this.type = null;
      this.start = tokStart;
      this.end = null;
    }
  
    function node_loc_t() {
      this.start = tokStartLoc;
      this.end = null;
      if (sourceFile !== null) this.source = sourceFile;
    }
  
    function startNode() {
      var node = new node_t();
      if (options.locations)
        node.loc = new node_loc_t();
      if (options.directSourceFile)
        node.sourceFile = options.directSourceFile;
      if (options.ranges)
        node.range = [tokStart, 0];
      return node;
    }
  
    // Start a node whose start offset information should be based on
    // the start of another node. For example, a binary operator node is
    // only started after its left-hand side has already been parsed.
  
    function startNodeFrom(other) {
      var node = new node_t();
      node.start = other.start;
      if (options.locations) {
        node.loc = new node_loc_t();
        node.loc.start = other.loc.start;
      }
      if (options.ranges)
        node.range = [other.range[0], 0];
  
      return node;
    }
  
    // Finish an AST node, adding `type` and `end` properties.
  
    function finishNode(node, type) {
      node.type = type;
      node.end = lastEnd;
      if (options.locations)
        node.loc.end = lastEndLoc;
      if (options.ranges)
        node.range[1] = lastEnd;
      return node;
    }
  
    // Test whether a statement node is the string literal `"use strict"`.
  
    function isUseStrict(stmt) {
      return options.ecmaVersion >= 5 && stmt.type === "ExpressionStatement" &&
        stmt.expression.type === "Literal" && stmt.expression.value === "use strict";
    }
  
    // Predicate that tests whether the next token is of the given
    // type, and if yes, consumes it as a side effect.
  
    function eat(type) {
      if (tokType === type) {
        next();
        return true;
      }
    }
  
    // Test whether a semicolon can be inserted at the current position.
  
    function canInsertSemicolon() {
      return !options.strictSemicolons &&
        (tokType === _eof || tokType === _braceR || newline.test(input.slice(lastEnd, tokStart)));
    }
  
    // Consume a semicolon, or, failing that, see if we are allowed to
    // pretend that there is a semicolon at this position.
  
    function semicolon() {
      if (!eat(_semi) && !canInsertSemicolon()) unexpected();
    }
  
    // Expect a token of a given type. If found, consume it, otherwise,
    // raise an unexpected token error.
  
    function expect(type) {
      if (tokType === type) next();
      else unexpected();
    }
  
    // Raise an unexpected token error.
  
    function unexpected() {
      raise(tokStart, "Unexpected token");
    }
  
    // Verify that a node is an lval — something that can be assigned
    // to.
  
    function checkLVal(expr) {
      if (expr.type !== "Identifier" && expr.type !== "MemberExpression")
        raise(expr.start, "Assigning to rvalue");
      if (strict && expr.type === "Identifier" && isStrictBadIdWord(expr.name))
        raise(expr.start, "Assigning to " + expr.name + " in strict mode");
    }
  
    // ### Statement parsing
  
    // Parse a program. Initializes the parser, reads any number of
    // statements, and wraps them in a Program node.  Optionally takes a
    // `program` argument.  If present, the statements will be appended
    // to its body instead of creating a new node.
  
    function parseTopLevel(program) {
      lastStart = lastEnd = tokPos;
      if (options.locations) lastEndLoc = new line_loc_t;
      inFunction = strict = null;
      labels = [];
      readToken();
  
      var node = program || startNode(), first = true;
      if (!program) node.body = [];
      while (tokType !== _eof) {
        var stmt = parseStatement();
        node.body.push(stmt);
        if (first && isUseStrict(stmt)) setStrict(true);
        first = false;
      }
      return finishNode(node, "Program");
    }
  
    var loopLabel = {kind: "loop"}, switchLabel = {kind: "switch"};
  
    // Parse a single statement.
    //
    // If expecting a statement and finding a slash operator, parse a
    // regular expression literal. This is to handle cases like
    // `if (foo) /blah/.exec(foo);`, where looking at the previous token
    // does not help.
  
    function parseStatement() {
      if (tokType === _slash || tokType === _assign && tokVal == "/=")
        readToken(true);
  
      var starttype = tokType, node = startNode();
  
      // Most types of statements are recognized by the keyword they
      // start with. Many are trivial to parse, some require a bit of
      // complexity.
  
      switch (starttype) {
      case _break: case _continue:
        next();
        var isBreak = starttype === _break;
        if (eat(_semi) || canInsertSemicolon()) node.label = null;
        else if (tokType !== _name) unexpected();
        else {
          node.label = parseIdent();
          semicolon();
        }
  
        // Verify that there is an actual destination to break or
        // continue to.
        for (var i = 0; i < labels.length; ++i) {
          var lab = labels[i];
          if (node.label == null || lab.name === node.label.name) {
            if (lab.kind != null && (isBreak || lab.kind === "loop")) break;
            if (node.label && isBreak) break;
          }
        }
        if (i === labels.length) raise(node.start, "Unsyntactic " + starttype.keyword);
        return finishNode(node, isBreak ? "BreakStatement" : "ContinueStatement");
  
      case _debugger:
        next();
        semicolon();
        return finishNode(node, "DebuggerStatement");
  
      case _do:
        next();
        labels.push(loopLabel);
        node.body = parseStatement();
        labels.pop();
        expect(_while);
        node.test = parseParenExpression();
        semicolon();
        return finishNode(node, "DoWhileStatement");
  
        // Disambiguating between a `for` and a `for`/`in` loop is
        // non-trivial. Basically, we have to parse the init `var`
        // statement or expression, disallowing the `in` operator (see
        // the second parameter to `parseExpression`), and then check
        // whether the next token is `in`. When there is no init part
        // (semicolon immediately after the opening parenthesis), it is
        // a regular `for` loop.
  
      case _for:
        next();
        labels.push(loopLabel);
        expect(_parenL);
        if (tokType === _semi) return parseFor(node, null);
        if (tokType === _var) {
          var init = startNode();
          next();
          parseVar(init, true);
          finishNode(init, "VariableDeclaration");
          if (init.declarations.length === 1 && eat(_in))
            return parseForIn(node, init);
          return parseFor(node, init);
        }
        var init = parseExpression(false, true);
        if (eat(_in)) {checkLVal(init); return parseForIn(node, init);}
        return parseFor(node, init);
  
      case _function:
        next();
        return parseFunction(node, true);
  
      case _if:
        next();
        node.test = parseParenExpression();
        node.consequent = parseStatement();
        node.alternate = eat(_else) ? parseStatement() : null;
        return finishNode(node, "IfStatement");
  
      case _return:
        if (!inFunction && !options.allowReturnOutsideFunction)
          raise(tokStart, "'return' outside of function");
        next();
  
        // In `return` (and `break`/`continue`), the keywords with
        // optional arguments, we eagerly look for a semicolon or the
        // possibility to insert one.
  
        if (eat(_semi) || canInsertSemicolon()) node.argument = null;
        else { node.argument = parseExpression(); semicolon(); }
        return finishNode(node, "ReturnStatement");
  
      case _switch:
        next();
        node.discriminant = parseParenExpression();
        node.cases = [];
        expect(_braceL);
        labels.push(switchLabel);
  
        // Statements under must be grouped (by label) in SwitchCase
        // nodes. `cur` is used to keep the node that we are currently
        // adding statements to.
  
        for (var cur, sawDefault; tokType != _braceR;) {
          if (tokType === _case || tokType === _default) {
            var isCase = tokType === _case;
            if (cur) finishNode(cur, "SwitchCase");
            node.cases.push(cur = startNode());
            cur.consequent = [];
            next();
            if (isCase) cur.test = parseExpression();
            else {
              if (sawDefault) raise(lastStart, "Multiple default clauses"); sawDefault = true;
              cur.test = null;
            }
            expect(_colon);
          } else {
            if (!cur) unexpected();
            cur.consequent.push(parseStatement());
          }
        }
        if (cur) finishNode(cur, "SwitchCase");
        next(); // Closing brace
        labels.pop();
        return finishNode(node, "SwitchStatement");
  
      case _throw:
        next();
        if (newline.test(input.slice(lastEnd, tokStart)))
          raise(lastEnd, "Illegal newline after throw");
        node.argument = parseExpression();
        semicolon();
        return finishNode(node, "ThrowStatement");
  
      case _try:
        next();
        node.block = parseBlock();
        node.handler = null;
        if (tokType === _catch) {
          var clause = startNode();
          next();
          expect(_parenL);
          clause.param = parseIdent();
          if (strict && isStrictBadIdWord(clause.param.name))
            raise(clause.param.start, "Binding " + clause.param.name + " in strict mode");
          expect(_parenR);
          clause.guard = null;
          clause.body = parseBlock();
          node.handler = finishNode(clause, "CatchClause");
        }
        node.guardedHandlers = empty;
        node.finalizer = eat(_finally) ? parseBlock() : null;
        if (!node.handler && !node.finalizer)
          raise(node.start, "Missing catch or finally clause");
        return finishNode(node, "TryStatement");
  
      case _var:
        next();
        parseVar(node);
        semicolon();
        return finishNode(node, "VariableDeclaration");
  
      case _while:
        next();
        node.test = parseParenExpression();
        labels.push(loopLabel);
        node.body = parseStatement();
        labels.pop();
        return finishNode(node, "WhileStatement");
  
      case _with:
        if (strict) raise(tokStart, "'with' in strict mode");
        next();
        node.object = parseParenExpression();
        node.body = parseStatement();
        return finishNode(node, "WithStatement");
  
      case _braceL:
        return parseBlock();
  
      case _semi:
        next();
        return finishNode(node, "EmptyStatement");
  
        // If the statement does not start with a statement keyword or a
        // brace, it's an ExpressionStatement or LabeledStatement. We
        // simply start parsing an expression, and afterwards, if the
        // next token is a colon and the expression was a simple
        // Identifier node, we switch to interpreting it as a label.
  
      default:
        var maybeName = tokVal, expr = parseExpression();
        if (starttype === _name && expr.type === "Identifier" && eat(_colon)) {
          for (var i = 0; i < labels.length; ++i)
            if (labels[i].name === maybeName) raise(expr.start, "Label '" + maybeName + "' is already declared");
          var kind = tokType.isLoop ? "loop" : tokType === _switch ? "switch" : null;
          labels.push({name: maybeName, kind: kind});
          node.body = parseStatement();
          labels.pop();
          node.label = expr;
          return finishNode(node, "LabeledStatement");
        } else {
          node.expression = expr;
          semicolon();
          return finishNode(node, "ExpressionStatement");
        }
      }
    }
  
    // Used for constructs like `switch` and `if` that insist on
    // parentheses around their expression.
  
    function parseParenExpression() {
      expect(_parenL);
      var val = parseExpression();
      expect(_parenR);
      return val;
    }
  
    // Parse a semicolon-enclosed block of statements, handling `"use
    // strict"` declarations when `allowStrict` is true (used for
    // function bodies).
  
    function parseBlock(allowStrict) {
      var node = startNode(), first = true, strict = false, oldStrict;
      node.body = [];
      expect(_braceL);
      while (!eat(_braceR)) {
        var stmt = parseStatement();
        node.body.push(stmt);
        if (first && allowStrict && isUseStrict(stmt)) {
          oldStrict = strict;
          setStrict(strict = true);
        }
        first = false;
      }
      if (strict && !oldStrict) setStrict(false);
      return finishNode(node, "BlockStatement");
    }
  
    // Parse a regular `for` loop. The disambiguation code in
    // `parseStatement` will already have parsed the init statement or
    // expression.
  
    function parseFor(node, init) {
      node.init = init;
      expect(_semi);
      node.test = tokType === _semi ? null : parseExpression();
      expect(_semi);
      node.update = tokType === _parenR ? null : parseExpression();
      expect(_parenR);
      node.body = parseStatement();
      labels.pop();
      return finishNode(node, "ForStatement");
    }
  
    // Parse a `for`/`in` loop.
  
    function parseForIn(node, init) {
      node.left = init;
      node.right = parseExpression();
      expect(_parenR);
      node.body = parseStatement();
      labels.pop();
      return finishNode(node, "ForInStatement");
    }
  
    // Parse a list of variable declarations.
  
    function parseVar(node, noIn) {
      node.declarations = [];
      node.kind = "var";
      for (;;) {
        var decl = startNode();
        decl.id = parseIdent();
        if (strict && isStrictBadIdWord(decl.id.name))
          raise(decl.id.start, "Binding " + decl.id.name + " in strict mode");
        decl.init = eat(_eq) ? parseExpression(true, noIn) : null;
        node.declarations.push(finishNode(decl, "VariableDeclarator"));
        if (!eat(_comma)) break;
      }
      return node;
    }
  
    // ### Expression parsing
  
    // These nest, from the most general expression type at the top to
    // 'atomic', nondivisible expression types at the bottom. Most of
    // the functions will simply let the function(s) below them parse,
    // and, *if* the syntactic construct they handle is present, wrap
    // the AST node that the inner parser gave them in another node.
  
    // Parse a full expression. The arguments are used to forbid comma
    // sequences (in argument lists, array literals, or object literals)
    // or the `in` operator (in for loops initalization expressions).
  
    function parseExpression(noComma, noIn) {
      var expr = parseMaybeAssign(noIn);
      if (!noComma && tokType === _comma) {
        var node = startNodeFrom(expr);
        node.expressions = [expr];
        while (eat(_comma)) node.expressions.push(parseMaybeAssign(noIn));
        return finishNode(node, "SequenceExpression");
      }
      return expr;
    }
  
    // Parse an assignment expression. This includes applications of
    // operators like `+=`.
  
    function parseMaybeAssign(noIn) {
      var left = parseMaybeConditional(noIn);
      if (tokType.isAssign) {
        var node = startNodeFrom(left);
        node.operator = tokVal;
        node.left = left;
        next();
        node.right = parseMaybeAssign(noIn);
        checkLVal(left);
        return finishNode(node, "AssignmentExpression");
      }
      return left;
    }
  
    // Parse a ternary conditional (`?:`) operator.
  
    function parseMaybeConditional(noIn) {
      var expr = parseExprOps(noIn);
      if (eat(_question)) {
        var node = startNodeFrom(expr);
        node.test = expr;
        node.consequent = parseExpression(true);
        expect(_colon);
        node.alternate = parseExpression(true, noIn);
        return finishNode(node, "ConditionalExpression");
      }
      return expr;
    }
  
    // Start the precedence parser.
  
    function parseExprOps(noIn) {
      return parseExprOp(parseMaybeUnary(), -1, noIn);
    }
  
    // Parse binary operators with the operator precedence parsing
    // algorithm. `left` is the left-hand side of the operator.
    // `minPrec` provides context that allows the function to stop and
    // defer further parser to one of its callers when it encounters an
    // operator that has a lower precedence than the set it is parsing.
  
    function parseExprOp(left, minPrec, noIn) {
      var prec = tokType.binop;
      if (prec != null && (!noIn || tokType !== _in)) {
        if (prec > minPrec) {
          var node = startNodeFrom(left);
          node.left = left;
          node.operator = tokVal;
          var op = tokType;
          next();
          node.right = parseExprOp(parseMaybeUnary(), prec, noIn);
          var exprNode = finishNode(node, (op === _logicalOR || op === _logicalAND) ? "LogicalExpression" : "BinaryExpression");
          return parseExprOp(exprNode, minPrec, noIn);
        }
      }
      return left;
    }
  
    // Parse unary operators, both prefix and postfix.
  
    function parseMaybeUnary() {
      if (tokType.prefix) {
        var node = startNode(), update = tokType.isUpdate;
        node.operator = tokVal;
        node.prefix = true;
        tokRegexpAllowed = true;
        next();
        node.argument = parseMaybeUnary();
        if (update) checkLVal(node.argument);
        else if (strict && node.operator === "delete" &&
                 node.argument.type === "Identifier")
          raise(node.start, "Deleting local variable in strict mode");
        return finishNode(node, update ? "UpdateExpression" : "UnaryExpression");
      }
      var expr = parseExprSubscripts();
      while (tokType.postfix && !canInsertSemicolon()) {
        var node = startNodeFrom(expr);
        node.operator = tokVal;
        node.prefix = false;
        node.argument = expr;
        checkLVal(expr);
        next();
        expr = finishNode(node, "UpdateExpression");
      }
      return expr;
    }
  
    // Parse call, dot, and `[]`-subscript expressions.
  
    function parseExprSubscripts() {
      return parseSubscripts(parseExprAtom());
    }
  
    function parseSubscripts(base, noCalls) {
      if (eat(_dot)) {
        var node = startNodeFrom(base);
        node.object = base;
        node.property = parseIdent(true);
        node.computed = false;
        return parseSubscripts(finishNode(node, "MemberExpression"), noCalls);
      } else if (eat(_bracketL)) {
        var node = startNodeFrom(base);
        node.object = base;
        node.property = parseExpression();
        node.computed = true;
        expect(_bracketR);
        return parseSubscripts(finishNode(node, "MemberExpression"), noCalls);
      } else if (!noCalls && eat(_parenL)) {
        var node = startNodeFrom(base);
        node.callee = base;
        node.arguments = parseExprList(_parenR, false);
        return parseSubscripts(finishNode(node, "CallExpression"), noCalls);
      } else return base;
    }
  
    // Parse an atomic expression — either a single token that is an
    // expression, an expression started by a keyword like `function` or
    // `new`, or an expression wrapped in punctuation like `()`, `[]`,
    // or `{}`.
  
    function parseExprAtom() {
      switch (tokType) {
      case _this:
        var node = startNode();
        next();
        return finishNode(node, "ThisExpression");
      case _name:
        return parseIdent();
      case _num: case _string: case _regexp:
        var node = startNode();
        node.value = tokVal;
        node.raw = input.slice(tokStart, tokEnd);
        next();
        return finishNode(node, "Literal");
  
      case _null: case _true: case _false:
        var node = startNode();
        node.value = tokType.atomValue;
        node.raw = tokType.keyword;
        next();
        return finishNode(node, "Literal");
  
      case _parenL:
        var tokStartLoc1 = tokStartLoc, tokStart1 = tokStart;
        next();
        var val = parseExpression();
        val.start = tokStart1;
        val.end = tokEnd;
        if (options.locations) {
          val.loc.start = tokStartLoc1;
          val.loc.end = tokEndLoc;
        }
        if (options.ranges)
          val.range = [tokStart1, tokEnd];
        expect(_parenR);
        return val;
  
      case _bracketL:
        var node = startNode();
        next();
        node.elements = parseExprList(_bracketR, true, true);
        return finishNode(node, "ArrayExpression");
  
      case _braceL:
        return parseObj();
  
      case _function:
        var node = startNode();
        next();
        return parseFunction(node, false);
  
      case _new:
        return parseNew();
  
      default:
        unexpected();
      }
    }
  
    // New's precedence is slightly tricky. It must allow its argument
    // to be a `[]` or dot subscript expression, but not a call — at
    // least, not without wrapping it in parentheses. Thus, it uses the
  
    function parseNew() {
      var node = startNode();
      next();
      node.callee = parseSubscripts(parseExprAtom(), true);
      if (eat(_parenL)) node.arguments = parseExprList(_parenR, false);
      else node.arguments = empty;
      return finishNode(node, "NewExpression");
    }
  
    // Parse an object literal.
  
    function parseObj() {
      var node = startNode(), first = true, sawGetSet = false;
      node.properties = [];
      next();
      while (!eat(_braceR)) {
        if (!first) {
          expect(_comma);
          if (options.allowTrailingCommas && eat(_braceR)) break;
        } else first = false;
  
        var prop = {key: parsePropertyName()}, isGetSet = false, kind;
        if (eat(_colon)) {
          prop.value = parseExpression(true);
          kind = prop.kind = "init";
        } else if (options.ecmaVersion >= 5 && prop.key.type === "Identifier" &&
                   (prop.key.name === "get" || prop.key.name === "set")) {
          isGetSet = sawGetSet = true;
          kind = prop.kind = prop.key.name;
          prop.key = parsePropertyName();
          if (tokType !== _parenL) unexpected();
          prop.value = parseFunction(startNode(), false);
        } else unexpected();
  
        // getters and setters are not allowed to clash — either with
        // each other or with an init property — and in strict mode,
        // init properties are also not allowed to be repeated.
  
        if (prop.key.type === "Identifier" && (strict || sawGetSet)) {
          for (var i = 0; i < node.properties.length; ++i) {
            var other = node.properties[i];
            if (other.key.name === prop.key.name) {
              var conflict = kind == other.kind || isGetSet && other.kind === "init" ||
                kind === "init" && (other.kind === "get" || other.kind === "set");
              if (conflict && !strict && kind === "init" && other.kind === "init") conflict = false;
              if (conflict) raise(prop.key.start, "Redefinition of property");
            }
          }
        }
        node.properties.push(prop);
      }
      return finishNode(node, "ObjectExpression");
    }
  
    function parsePropertyName() {
      if (tokType === _num || tokType === _string) return parseExprAtom();
      return parseIdent(true);
    }
  
    // Parse a function declaration or literal (depending on the
    // `isStatement` parameter).
  
    function parseFunction(node, isStatement) {
      if (tokType === _name) node.id = parseIdent();
      else if (isStatement) unexpected();
      else node.id = null;
      node.params = [];
      var first = true;
      expect(_parenL);
      while (!eat(_parenR)) {
        if (!first) expect(_comma); else first = false;
        node.params.push(parseIdent());
      }
  
      // Start a new scope with regard to labels and the `inFunction`
      // flag (restore them to their old value afterwards).
      var oldInFunc = inFunction, oldLabels = labels;
      inFunction = true; labels = [];
      node.body = parseBlock(true);
      inFunction = oldInFunc; labels = oldLabels;
  
      // If this is a strict mode function, verify that argument names
      // are not repeated, and it does not try to bind the words `eval`
      // or `arguments`.
      if (strict || node.body.body.length && isUseStrict(node.body.body[0])) {
        for (var i = node.id ? -1 : 0; i < node.params.length; ++i) {
          var id = i < 0 ? node.id : node.params[i];
          if (isStrictReservedWord(id.name) || isStrictBadIdWord(id.name))
            raise(id.start, "Defining '" + id.name + "' in strict mode");
          if (i >= 0) for (var j = 0; j < i; ++j) if (id.name === node.params[j].name)
            raise(id.start, "Argument name clash in strict mode");
        }
      }
  
      return finishNode(node, isStatement ? "FunctionDeclaration" : "FunctionExpression");
    }
  
    // Parses a comma-separated list of expressions, and returns them as
    // an array. `close` is the token type that ends the list, and
    // `allowEmpty` can be turned on to allow subsequent commas with
    // nothing in between them to be parsed as `null` (which is needed
    // for array literals).
  
    function parseExprList(close, allowTrailingComma, allowEmpty) {
      var elts = [], first = true;
      while (!eat(close)) {
        if (!first) {
          expect(_comma);
          if (allowTrailingComma && options.allowTrailingCommas && eat(close)) break;
        } else first = false;
  
        if (allowEmpty && tokType === _comma) elts.push(null);
        else elts.push(parseExpression(true));
      }
      return elts;
    }
  
    // Parse the next token as an identifier. If `liberal` is true (used
    // when parsing properties), it will also convert keywords into
    // identifiers.
  
    function parseIdent(liberal) {
      var node = startNode();
      if (liberal && options.forbidReserved == "everywhere") liberal = false;
      if (tokType === _name) {
        if (!liberal &&
            (options.forbidReserved &&
             (options.ecmaVersion === 3 ? isReservedWord3 : isReservedWord5)(tokVal) ||
             strict && isStrictReservedWord(tokVal)) &&
            input.slice(tokStart, tokEnd).indexOf("\\") == -1)
          raise(tokStart, "The keyword '" + tokVal + "' is reserved");
        node.name = tokVal;
      } else if (liberal && tokType.keyword) {
        node.name = tokType.keyword;
      } else {
        unexpected();
      }
      tokRegexpAllowed = false;
      next();
      return finishNode(node, "Identifier");
    }
  
  });
  