acorn.js

// 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

(function (root, factory) {
  "use strict";

  // Universal Module Definition (UMD)
  // https://github.com/umdjs/umd/blob/master/commonjsStrict.js
  if (typeof exports === "object") {
    // CommonJS
    factory(exports);
  } else if (typeof define === "function" && define.amd) {
    // AMD. Register as an anonymous module.
    define(["exports"], factory);
  } else {
    // Browser globals
    factory((root.acorn = {}));
  }
}(this, function (exports) {
  "use strict";

  exports.version = "0.0.1";

  // The main exported interface (under `window.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, Syntax;
  
  // Node types
  exports.Syntax = Syntax = {
    AssignmentExpression: "AssignmentExpression",
    ArrayExpression: "ArrayExpression",
    BlockStatement: "BlockStatement",
    BinaryExpression: "BinaryExpression",
    BreakStatement: "BreakStatement",
    CallExpression: "CallExpression",
    CatchClause: "CatchClause",
    ConditionalExpression: "ConditionalExpression",
    ContinueStatement: "ContinueStatement",
    DoWhileStatement: "DoWhileStatement",
    DebuggerStatement: "DebuggerStatement",
    EmptyStatement: "EmptyStatement",
    ExpressionStatement: "ExpressionStatement",
    ForStatement: "ForStatement",
    ForInStatement: "ForInStatement",
    FunctionDeclaration: "FunctionDeclaration",
    FunctionExpression: "FunctionExpression",
    Identifier: "Identifier",
    IfStatement: "IfStatement",
    Literal: "Literal",
    LabeledStatement: "LabeledStatement",
    LogicalExpression: "LogicalExpression",
    MemberExpression: "MemberExpression",
    NewExpression: "NewExpression",
    ObjectExpression: "ObjectExpression",
    Program: "Program",
    Property: "Property",
    ReturnStatement: "ReturnStatement",
    SequenceExpression: "SequenceExpression",
    SwitchStatement: "SwitchStatement",
    SwitchCase: "SwitchCase",
    ThisExpression: "ThisExpression",
    ThrowStatement: "ThrowStatement",
    TryStatement: "TryStatement",
    UnaryExpression: "UnaryExpression",
    UpdateExpression: "UpdateExpression",
    VariableDeclaration: "VariableDeclaration",
    VariableDeclarator: "VariableDeclarator",
    WhileStatement: "WhileStatement",
    WithStatement: "WithStatement"
  };

  exports.parse = function(inpt, opts) {
    input = String(inpt); inputLen = input.length;
    options = opts || {};
    for (var opt in defaultOptions) if (!options.hasOwnProperty(opt))
      options[opt] = defaultOptions[opt];
    sourceFile = options.sourceFile || null;
    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.
    forbidReserved: false,
    // When `trackComments` is turned on, the parser will attach
    // `commentsBefore` and `commentsAfter` properties to AST nodes
    // holding arrays of strings. A single comment may appear in both
    // a `commentsBefore` and `commentsAfter` array (of the nodes
    // after and before it), but never twice in the before (or after)
    // array of different nodes.
    trackComments: 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,
    // 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 `location` is on, you can pass this to record the source
    // file in every node's `loc` object.
    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.
  // Both use (closure-)global variables to keep their state and
  // communicate. We already saw the `options`, `input`, and
  // `inputLen` variables above (set in `parse`).

  // 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;

  // These are used to hold arrays of comments when
  // `options.trackComments` is true.

  var tokCommentsBefore, tokCommentsAfter;

  // 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, tokComments;

  // When `options.locations` is true, these are used to keep
  // track of the current line, and know when a new line has been
  // entered. See the `curLineLoc` function.

  var tokCurLine, tokLineStart, tokLineStartNext;

  // 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 either a `{line, column}` object or an offset integer (into
  // the current `input`) as `pos` argument. It attaches the position
  // to the end of the error message, and then raises a `SyntaxError`
  // with that message.

  function raise(pos, message) {
    if (typeof pos == "number") pos = getLineInfo(input, pos);
    message += " (" + pos.line + ":" + pos.column + ")";
    throw new SyntaxError(message);
  }

  // ## 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}, "this": _this,
                      "typeof": {keyword: "typeof", prefix: true},
                      "void": {keyword: "void", prefix: true},
                      "delete": {keyword: "delete", prefix: 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}, _plusmin = {binop: 9, prefix: true, beforeExpr: true};
  var _incdec = {postfix: true, prefix: true, isUpdate: true}, _prefix = {prefix: true, beforeExpr: true};
  var _bin1 = {binop: 1, beforeExpr: true}, _bin2 = {binop: 2, beforeExpr: true};
  var _bin3 = {binop: 3, beforeExpr: true}, _bin4 = {binop: 4, beforeExpr: true};
  var _bin5 = {binop: 5, beforeExpr: true}, _bin6 = {binop: 6, beforeExpr: true};
  var _bin7 = {binop: 7, beforeExpr: true}, _bin8 = {binop: 8, beforeExpr: true};
  var _bin10 = {binop: 10, beforeExpr: true};

  // 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\u2028\u2029\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 = "\u0371-\u0374\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.

  function isIdentifierStart(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.

  function isIdentifierChar(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, in order to track
  // the current line number and start of line offset, in order to set
  // `tokStartLoc` and `tokEndLoc`.

  function nextLineStart() {
    lineBreak.lastIndex = tokLineStart;
    var match = lineBreak.exec(input);
    return match ? match.index + match[0].length : input.length + 1;
  }

  function curLineLoc() {
    while (tokLineStartNext <= tokPos) {
      ++tokCurLine;
      tokLineStart = tokLineStartNext;
      tokLineStartNext = nextLineStart();
    }
    return {line: tokCurLine, column: tokPos - tokLineStart};
  }

  // Reset the token state. Used at the start of a parse.

  function initTokenState() {
    tokCurLine = 1;
    tokPos = tokLineStart = 0;
    tokLineStartNext = nextLineStart();
    tokRegexpAllowed = true;
    tokComments = null;
    skipSpace();
  }

  // Called at the end of every token. Sets `tokEnd`, `tokVal`,
  // `tokCommentsAfter`, 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 = curLineLoc();
    tokType = type;
    skipSpace();
    tokVal = val;
    tokCommentsAfter = tokComments;
    tokRegexpAllowed = type.beforeExpr;
  }

  function skipBlockComment() {
    var end = input.indexOf("*/", tokPos += 2);
    if (end === -1) raise(tokPos - 2, "Unterminated comment");
    if (options.trackComments)
      (tokComments || (tokComments = [])).push(input.slice(tokPos, end));
    tokPos = end + 2;
  }

  function skipLineComment() {
    var start = tokPos;
    var ch = input.charCodeAt(tokPos+=2);
    while (tokPos < inputLen && ch !== 10 && ch !== 13 && ch !== 8232 && ch !== 8329) {
      ++tokPos;
      ch = input.charCodeAt(tokPos);
    }
    if (options.trackComments)
      (tokComments || (tokComments = [])).push(input.slice(start, tokPos));
  }

  // Called at the start of the parse and after every token. Skips
  // whitespace and comments, and, if `options.trackComments` is on,
  // will store all skipped comments in `tokComments`.

  function skipSpace() {
    tokComments = null;
    while (tokPos < inputLen) {
      var ch = input.charCodeAt(tokPos);
      if (ch === 47) { // '/'
        var next = input.charCodeAt(tokPos+1);
        if (next === 42) { // '*'
          skipBlockComment();
        } else if (next === 47) { // '/'
          skipLineComment();
        } else break;
      } else if (ch < 14 && ch > 8) {
        ++tokPos;
      } else if (ch === 32 || 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(code) {
    var next = input.charCodeAt(tokPos+1);
    if (next >= 48 && next <= 57) return readNumber(String.fromCharCode(code));
    ++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(_bin10, 1);
  }

  function readToken_pipe_amp(code) { // '|&'
    var next = input.charCodeAt(tokPos+1);
    if (next === code) return finishOp(code === 124 ? _bin1 : _bin2, 2);
    if (next === 61) return finishOp(_assign, 2);
    return finishOp(code === 124 ? _bin3 : _bin5, 1);
  }

  function readToken_caret() { // '^'
    var next = input.charCodeAt(tokPos+1);
    if (next === 61) return finishOp(_assign, 2);
    return finishOp(_bin4, 1);    
  }

  function readToken_plus_min(code) { // '+-'
    var next = input.charCodeAt(tokPos+1);
    if (next === code) 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(_bin8, size);
    }
    if (next === 61)
      size = input.charCodeAt(tokPos+2) === 61 ? 3 : 2;
    return finishOp(_bin7, size);
  }
  
  function readToken_eq_excl(code) { // '=!'
    var next = input.charCodeAt(tokPos+1);
    if (next === 61) return finishOp(_bin6, 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(code);

      // 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(String.fromCharCode(code));

      // 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) {
    tokStart = tokPos;
    if (options.locations) tokStartLoc = curLineLoc();
    tokCommentsBefore = tokComments;
    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");
    return finishToken(_regexp, new RegExp(content, mods));
  }

  // 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(ch) {
    var start = tokPos, isFloat = ch === ".";
    if (!isFloat && readInt(10) == null) raise(start, "Invalid number");
    if (isFloat || input.charAt(tokPos) === ".") {
      var next = input.charAt(++tokPos);
      if (next === "-" || next === "+") ++tokPos;
      if (readInt(10) === null && ch === ".") raise(start, "Invalid number");
      isFloat = true;
    }
    if (/e/i.test(input.charAt(tokPos))) {
      var next = input.charAt(++tokPos);
      if (next === "-" || next === "+") ++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 (ch !== "0" || 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 str = [];
    for (;;) {
      if (tokPos >= inputLen) raise(tokStart, "Unterminated string constant");
      var ch = input.charCodeAt(tokPos);
      if (ch === quote) {
        ++tokPos;
        return finishToken(_string, String.fromCharCode.apply(null, str));
      }
      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, octal.length - 1);
        if (octal === "0") octal = null;
        ++tokPos;
        if (octal) {
          if (strict) raise(tokPos - 2, "Octal literal in strict mode");
          str.push(parseInt(octal, 8));
          tokPos += octal.length - 1;
        } else {
          switch (ch) {
          case 110: str.push(10); break; // 'n' -> '\n'
          case 114: str.push(13); break; // 'r' -> '\r'
          case 120: str.push(readHexChar(2)); break; // 'x'
          case 117: str.push(readHexChar(4)); break; // 'u'
          case 85: str.push(readHexChar(8)); break; // 'U'
          case 116: str.push(9); break; // 't' -> '\t'
          case 98: str.push(8); break; // 'b' -> '\b'
          case 118: str.push(11); break; // 'v' -> '\u000b'
          case 102: str.push(12); break; // 'f' -> '\f'
          case 48: str.push(0); break; // 0 -> '\0'
          case 13: if (input.charCodeAt(tokPos) === 10) ++tokPos; // '\r\n'
          case 10: break; // ' \n'
          default: str.push(ch); break;
          }
        }
      } else {
        if (ch === 13 || ch === 10 || ch === 8232 || ch === 8329) raise(tokStart, "Unterminated string constant");
        if (ch !== 92) str.push(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) {
      if (isKeyword(word)) type = keywordTypes[word];
      else if (options.forbidReserved &&
               (options.ecmaVersion === 3 ? isReservedWord3 : isReservedWord5)(word) ||
               strict && isStrictReservedWord(word))
        raise(tokStart, "The keyword '" + word + "' is reserved");
    }
    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 = lastEnd;
    skipSpace();
    readToken();
  }

  // Start an AST node, attaching a start offset and optionally a
  // `commentsBefore` property to it.

  function startNode() {
    var node = {type: null, start: tokStart, end: null};
    if (options.trackComments && tokCommentsBefore) {
      node.commentsBefore = tokCommentsBefore;
      tokCommentsBefore = null;
    }
    if (options.locations)
      node.loc = {start: tokStartLoc, end: null, source: sourceFile};
    if (options.ranges)
      node.range = [tokStart, 0];
    return node;
  }

  // Start a node whose start offset/comments 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 = {type: null, start: other.start};
    if (other.commentsBefore) {
      node.commentsBefore = other.commentsBefore;
      other.commentsBefore = null;
    }
    if (options.locations)
      node.loc = {start: other.loc.start, end: null, source: other.loc.source};
    if (options.ranges)
      node.range = [other.range[0], 0];

    return node;
  }

  // Finish an AST node, adding `type`, `end`, and `commentsAfter`
  // properties.
  //
  // We keep track of the last node that we finished, in order
  // 'bubble' `commentsAfter` properties up to the biggest node. I.e.
  // in '`1 + 1 // foo', the comment should be attached to the binary
  // operator node, not the second literal node.

  var lastFinishedNode;

  function finishNode(node, type) {
    node.type = type;
    node.end = lastEnd;
    if (options.trackComments) {
      if (tokCommentsAfter) {
        node.commentsAfter = tokCommentsAfter;
        tokCommentsAfter = null;
      } else if (lastFinishedNode && lastFinishedNode.end === lastEnd &&
                 lastFinishedNode.commentsAfter) {
        node.commentsAfter = lastFinishedNode.commentsAfter;
        lastFinishedNode.commentsAfter = null;
      }
      lastFinishedNode = node;
    }
    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) {
    initTokenState();
    lastStart = lastEnd = tokPos;
    if (options.locations) lastEndLoc = curLineLoc();
    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, Syntax.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)
      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 ? Syntax.BreakStatement : Syntax.ContinueStatement);

    case _debugger:
      next();
      semicolon();
      return finishNode(node, Syntax.DebuggerStatement);

    case _do:
      next();
      labels.push(loopLabel);
      node.body = parseStatement();
      labels.pop();
      expect(_while);
      node.test = parseParenExpression();
      semicolon();
      return finishNode(node, Syntax.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);
        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, Syntax.IfStatement);

    case _return:
      if (!inFunction) 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, Syntax.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, Syntax.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, Syntax.SwitchCase);
      next(); // Closing brace
      labels.pop();
      return finishNode(node, Syntax.SwitchStatement);

    case _throw:
      next();
      if (newline.test(input.slice(lastEnd, tokStart)))
        raise(lastEnd, "Illegal newline after throw");
      node.argument = parseExpression();
      semicolon();
      return finishNode(node, Syntax.ThrowStatement);

    case _try:
      next();
      node.block = parseBlock();
      node.handlers = [];
      while (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.handlers.push(finishNode(clause, Syntax.CatchClause));
      }
      node.finalizer = eat(_finally) ? parseBlock() : null;
      if (!node.handlers.length && !node.finalizer)
        raise(node.start, "Missing catch or finally clause");
      return finishNode(node, Syntax.TryStatement);

    case _var:
      next();
      node = parseVar(node);
      semicolon();
      return node;

    case _while:
      next();
      node.test = parseParenExpression();
      labels.push(loopLabel);
      node.body = parseStatement();
      labels.pop();
      return finishNode(node, Syntax.WhileStatement);

    case _with:
      if (strict) raise(tokStart, "'with' in strict mode");
      next();
      node.object = parseParenExpression();
      node.body = parseStatement();
      return finishNode(node, Syntax.WithStatement);

    case _braceL:
      return parseBlock();

    case _semi:
      next();
      return finishNode(node, Syntax.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, Syntax.LabeledStatement);
      } else {
        node.expression = expr;
        semicolon();
        return finishNode(node, Syntax.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 && isUseStrict(stmt)) {
        oldStrict = strict;
        setStrict(strict = true);
      }
      first = false
    }
    if (strict && !oldStrict) setStrict(false);
    return finishNode(node, Syntax.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, Syntax.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, Syntax.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, Syntax.VariableDeclarator));
      if (!eat(_comma)) break;
    }
    return finishNode(node, Syntax.VariableDeclaration);
  }

  // ### 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, Syntax.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, Syntax.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, Syntax.ConditionalExpression);
    }
    return expr;
  }

  // Start the precedence parser.

  function parseExprOps(noIn) {
    return parseExprOp(parseMaybeUnary(noIn), -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;
        next();
        node.right = parseExprOp(parseMaybeUnary(noIn), prec, noIn);
        var node = finishNode(node, /&&|\|\|/.test(node.operator) ? Syntax.LogicalExpression : Syntax.BinaryExpression);
        return parseExprOp(node, minPrec, noIn);
      }
    }
    return left;
  }

  // Parse unary operators, both prefix and postfix.

  function parseMaybeUnary(noIn) {
    if (tokType.prefix) {
      var node = startNode(), update = tokType.isUpdate;
      node.operator = tokVal;
      node.prefix = true;
      next();
      node.argument = parseMaybeUnary(noIn);
      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 ? Syntax.UpdateExpression : Syntax.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, Syntax.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, Syntax.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, Syntax.MemberExpression), noCalls);
    } else if (!noCalls && eat(_parenL)) {
      var node = startNodeFrom(base);
      node.callee = base;
      node.arguments = parseExprList(_parenR, false);
      return parseSubscripts(finishNode(node, Syntax.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, Syntax.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, Syntax.Literal);

    case _null: case _true: case _false:
      var node = startNode();
      node.value = tokType.atomValue;
      next();
      return finishNode(node, Syntax.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, Syntax.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(false), true);
    if (eat(_parenL)) node.arguments = parseExprList(_parenR, false);
    else node.arguments = [];
    return finishNode(node, Syntax.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, Syntax.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 ? Syntax.FunctionDeclaration : Syntax.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();
    node.name = tokType === _name ? tokVal : (liberal && !options.forbidReserved && tokType.keyword) || unexpected();
    next();
    return finishNode(node, Syntax.Identifier);
  }

}));