// Acorn is a tiny, fast JavaScript parser written in JavaScript.
//
// Acorn was written by Marijn Haverbeke and various contributors 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 = "0.12.1";

  // 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 inline XML 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();
    var startPos = options.locations ? [tokPos, curPosition()] : tokPos;
    initParserState();
    return parseTopLevel(options.program || startNodeAt(startPos));
  };

  // 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, or 6. This influences support for strict
    // mode, the set of reserved words, support for getters and
    // setters and other features.
    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 enabled, import/export statements are not constrained to
    // appearing at the top of the program.
    allowImportExportEverywhere: false,
    // When enabled, hashbang directive in the beginning of file
    // is allowed and treated as a line comment.
    allowHashBang: 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 `onToken` option, which will
    // cause Acorn to call that function with object in the same
    // format as tokenize() returns. Note that you are not
    // allowed to call the parser from the callback—that will
    // corrupt its internal state.
    onToken: null,
    // 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,
    // When enabled, parenthesized expressions are represented by
    // (non-standard) ParenthesizedExpression nodes
    preserveParens: false
  };

  // This function tries to parse a single expression at a given
  // offset in a string. Useful for parsing mixed-language formats
  // that embed JavaScript expressions.

  exports.parseExpressionAt = function(inpt, pos, opts) {
    input = String(inpt); inputLen = input.length;
    setOptions(opts);
    initTokenState(pos);
    initParserState();
    return parseExpression();
  };

  var isArray = function (obj) {
    return Object.prototype.toString.call(obj) === "[object Array]";
  };

  function setOptions(opts) {
    options = {};
    for (var opt in defaultOptions)
      options[opt] = opts && has(opts, opt) ? opts[opt] : defaultOptions[opt];
    sourceFile = options.sourceFile || null;
    if (isArray(options.onToken)) {
      var tokens = options.onToken;
      options.onToken = function (token) {
        tokens.push(token);
      };
    }
    if (isArray(options.onComment)) {
      var comments = options.onComment;
      options.onComment = function (block, text, start, end, startLoc, endLoc) {
        var comment = {
          type: block ? 'Block' : 'Line',
          value: text,
          start: start,
          end: end
        };
        if (options.locations) {
          comment.loc = new SourceLocation();
          comment.loc.start = startLoc;
          comment.loc.end = endLoc;
        }
        if (options.ranges)
          comment.range = [start, end];
        comments.push(comment);
      };
    }
    isKeyword = options.ecmaVersion >= 6 ? isEcma6Keyword : isEcma5AndLessKeyword;
  }

  // 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};
  };

  function Token() {
    this.type = tokType;
    this.value = tokVal;
    this.start = tokStart;
    this.end = tokEnd;
    if (options.locations) {
      this.loc = new SourceLocation();
      this.loc.end = tokEndLoc;
    }
    if (options.ranges)
      this.range = [tokStart, tokEnd];
  }

  exports.Token = Token;

  // 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();
    skipSpace();

    function getToken() {
      lastEnd = tokEnd;
      readToken();
      return new Token();
    }
    getToken.jumpTo = function(pos, exprAllowed) {
      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;
        }
      }
      tokExprAllowed = !!exprAllowed;
      skipSpace();
    };
    getToken.current = function() { return new Token(); };
    if (typeof Symbol !== 'undefined') {
      getToken[Symbol.iterator] = function () {
        return {
          next: function () {
            var token = getToken();
            return {
              done: token.type === _eof,
              value: token
            };
          }
        };
      };
    }
    getToken.options = options;
    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;

  // Internal 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. In
  // some cases, notably after ')' or '}' tokens, the situation
  // depends on the context before the matching opening bracket, so
  // tokContext keeps a stack of information about current bracketed
  // forms.

  var tokContext, tokExprAllowed;

  // 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, `inGenerator` to
  // reject `yield`s outside of generators, `labels` to verify
  // that `break` and `continue` have somewhere to jump to, and
  // `strict` indicates whether strict mode is on.

  var inFunction, inGenerator, labels, strict;

  function initParserState() {
    lastStart = lastEnd = tokPos;
    if (options.locations) lastEndLoc = curPosition();
    inFunction = inGenerator = false;
    labels = [];
    skipSpace();
    readToken();
  }

  // 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;
  }

  function fullCharCodeAtPos() {
    var code = input.charCodeAt(tokPos);
    if (code <= 0xd7ff || code >= 0xe000) return code;
    var next = input.charCodeAt(tokPos + 1);
    return (code << 10) + next - 0x35fdc00;
  }

  function skipChar(code) {
    if (code <= 0xffff) tokPos++;
    else tokPos += 2;
  }

  // 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 _let = {keyword: "let"}, _const = {keyword: "const"};
  var _while = {keyword: "while", isLoop: true}, _with = {keyword: "with"}, _new = {keyword: "new", beforeExpr: true};
  var _this = {keyword: "this"};
  var _class = {keyword: "class"}, _extends = {keyword: "extends", beforeExpr: true};
  var _export = {keyword: "export"}, _import = {keyword: "import"};
  var _yield = {keyword: "yield", beforeExpr: true};

  // 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, "let": _let, "const": _const,
                      "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},
                      "class": _class, "extends": _extends,
                      "export": _export, "import": _import, "yield": _yield};

  // 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};
  var _arrow = {type: "=>", beforeExpr: true}, _template = {type: "template"};
  var _ellipsis = {type: "...", beforeExpr: true};
  var _backQuote = {type: "`"}, _dollarBraceL = {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 _modulo = {binop: 10, beforeExpr: true};

  // '*' may be multiply or have special meaning in ES6
  var _star = {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, ellipsis: _ellipsis, question: _question, slash: _slash, eq: _eq,
                      name: _name, eof: _eof, num: _num, regexp: _regexp, string: _string,
                      arrow: _arrow, template: _template, star: _star, assign: _assign,
                      backQuote: _backQuote, dollarBraceL: _dollarBraceL};
  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 ecma5AndLessKeywords = "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";

  var isEcma5AndLessKeyword = makePredicate(ecma5AndLessKeywords);

  var isEcma6Keyword = makePredicate(ecma5AndLessKeywords + " let const class extends export import yield");

  var isKeyword = isEcma5AndLessKeyword;

  // ## 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.
  // Generated by `tools/generate-identifier-regex.js`.

  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\u037f\u0386\u0388-\u038a\u038c\u038e-\u03a1\u03a3-\u03f5\u03f7-\u0481\u048a-\u052f\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-\u08b2\u0904-\u0939\u093d\u0950\u0958-\u0961\u0971-\u0980\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-\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-\u16f8\u1700-\u170c\u170e-\u1711\u1720-\u1731\u1740-\u1751\u1760-\u176c\u176e-\u1770\u1780-\u17b3\u17d7\u17dc\u1820-\u1877\u1880-\u18a8\u18aa\u18b0-\u18f5\u1900-\u191e\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\u2118-\u211d\u2124\u2126\u2128\u212a-\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\u3005-\u3007\u3021-\u3029\u3031-\u3035\u3038-\u303c\u3041-\u3096\u309b-\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-\ua69d\ua6a0-\ua6ef\ua717-\ua71f\ua722-\ua788\ua78b-\ua78e\ua790-\ua7ad\ua7b0\ua7b1\ua7f7-\ua801\ua803-\ua805\ua807-\ua80a\ua80c-\ua822\ua840-\ua873\ua882-\ua8b3\ua8f2-\ua8f7\ua8fb\ua90a-\ua925\ua930-\ua946\ua960-\ua97c\ua984-\ua9b2\ua9cf\ua9e0-\ua9e4\ua9e6-\ua9ef\ua9fa-\ua9fe\uaa00-\uaa28\uaa40-\uaa42\uaa44-\uaa4b\uaa60-\uaa76\uaa7a\uaa7e-\uaaaf\uaab1\uaab5\uaab6\uaab9-\uaabd\uaac0\uaac2\uaadb-\uaadd\uaae0-\uaaea\uaaf2-\uaaf4\uab01-\uab06\uab09-\uab0e\uab11-\uab16\uab20-\uab26\uab28-\uab2e\uab30-\uab5a\uab5c-\uab5f\uab64\uab65\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 = "\u200c\u200d\xb7\u0300-\u036f\u0387\u0483-\u0487\u0591-\u05bd\u05bf\u05c1\u05c2\u05c4\u05c5\u05c7\u0610-\u061a\u064b-\u0669\u0670\u06d6-\u06dc\u06df-\u06e4\u06e7\u06e8\u06ea-\u06ed\u06f0-\u06f9\u0711\u0730-\u074a\u07a6-\u07b0\u07c0-\u07c9\u07eb-\u07f3\u0816-\u0819\u081b-\u0823\u0825-\u0827\u0829-\u082d\u0859-\u085b\u08e4-\u0903\u093a-\u093c\u093e-\u094f\u0951-\u0957\u0962\u0963\u0966-\u096f\u0981-\u0983\u09bc\u09be-\u09c4\u09c7\u09c8\u09cb-\u09cd\u09d7\u09e2\u09e3\u09e6-\u09ef\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\u0b62\u0b63\u0b66-\u0b6f\u0b82\u0bbe-\u0bc2\u0bc6-\u0bc8\u0bca-\u0bcd\u0bd7\u0be6-\u0bef\u0c00-\u0c03\u0c3e-\u0c44\u0c46-\u0c48\u0c4a-\u0c4d\u0c55\u0c56\u0c62\u0c63\u0c66-\u0c6f\u0c81-\u0c83\u0cbc\u0cbe-\u0cc4\u0cc6-\u0cc8\u0cca-\u0ccd\u0cd5\u0cd6\u0ce2\u0ce3\u0ce6-\u0cef\u0d01-\u0d03\u0d3e-\u0d44\u0d46-\u0d48\u0d4a-\u0d4d\u0d57\u0d62\u0d63\u0d66-\u0d6f\u0d82\u0d83\u0dca\u0dcf-\u0dd4\u0dd6\u0dd8-\u0ddf\u0de6-\u0def\u0df2\u0df3\u0e31\u0e34-\u0e3a\u0e47-\u0e4e\u0e50-\u0e59\u0eb1\u0eb4-\u0eb9\u0ebb\u0ebc\u0ec8-\u0ecd\u0ed0-\u0ed9\u0f18\u0f19\u0f20-\u0f29\u0f35\u0f37\u0f39\u0f3e\u0f3f\u0f71-\u0f84\u0f86\u0f87\u0f8d-\u0f97\u0f99-\u0fbc\u0fc6\u102b-\u103e\u1040-\u1049\u1056-\u1059\u105e-\u1060\u1062-\u1064\u1067-\u106d\u1071-\u1074\u1082-\u108d\u108f-\u109d\u135d-\u135f\u1369-\u1371\u1712-\u1714\u1732-\u1734\u1752\u1753\u1772\u1773\u17b4-\u17d3\u17dd\u17e0-\u17e9\u180b-\u180d\u1810-\u1819\u18a9\u1920-\u192b\u1930-\u193b\u1946-\u194f\u19b0-\u19c0\u19c8\u19c9\u19d0-\u19da\u1a17-\u1a1b\u1a55-\u1a5e\u1a60-\u1a7c\u1a7f-\u1a89\u1a90-\u1a99\u1ab0-\u1abd\u1b00-\u1b04\u1b34-\u1b44\u1b50-\u1b59\u1b6b-\u1b73\u1b80-\u1b82\u1ba1-\u1bad\u1bb0-\u1bb9\u1be6-\u1bf3\u1c24-\u1c37\u1c40-\u1c49\u1c50-\u1c59\u1cd0-\u1cd2\u1cd4-\u1ce8\u1ced\u1cf2-\u1cf4\u1cf8\u1cf9\u1dc0-\u1df5\u1dfc-\u1dff\u203f\u2040\u2054\u20d0-\u20dc\u20e1\u20e5-\u20f0\u2cef-\u2cf1\u2d7f\u2de0-\u2dff\u302a-\u302f\u3099\u309a\ua620-\ua629\ua66f\ua674-\ua67d\ua69f\ua6f0\ua6f1\ua802\ua806\ua80b\ua823-\ua827\ua880\ua881\ua8b4-\ua8c4\ua8d0-\ua8d9\ua8e0-\ua8f1\ua900-\ua909\ua926-\ua92d\ua947-\ua953\ua980-\ua983\ua9b3-\ua9c0\ua9d0-\ua9d9\ua9e5\ua9f0-\ua9f9\uaa29-\uaa36\uaa43\uaa4c\uaa4d\uaa50-\uaa59\uaa7b-\uaa7d\uaab0\uaab2-\uaab4\uaab7\uaab8\uaabe\uaabf\uaac1\uaaeb-\uaaef\uaaf5\uaaf6\uabe3-\uabea\uabec\uabed\uabf0-\uabf9\ufb1e\ufe00-\ufe0f\ufe20-\ufe2d\ufe33\ufe34\ufe4d-\ufe4f\uff10-\uff19\uff3f";

  var nonASCIIidentifierStart = new RegExp("[" + nonASCIIidentifierStartChars + "]");
  var nonASCIIidentifier = new RegExp("[" + nonASCIIidentifierStartChars + nonASCIIidentifierChars + "]");
  nonASCIIidentifierStartChars = nonASCIIidentifierChars = null;

  // These are a run-length and offset encoded representation of the
  // >0xffff code points that are a valid part of identifiers. The
  // offset starts at 0x10000, and each pair of numbers represents an
  // offset to the next range, and then a size of the range. They were
  // generated by tools/generate-identifier-regex.js
  var astralIdentifierStartCodes = [0,11,2,25,2,18,2,1,2,14,3,13,35,122,70,52,268,28,4,48,48,31,17,26,6,37,11,29,3,35,5,7,2,4,43,157,99,39,9,51,157,310,10,21,11,7,153,5,3,0,2,43,2,1,4,0,3,22,11,22,10,30,98,21,11,25,71,55,7,1,65,0,16,3,2,2,2,26,45,28,4,28,36,7,2,27,28,53,11,21,11,18,14,17,111,72,955,52,76,44,33,24,27,35,42,34,4,0,13,47,15,3,22,0,38,17,2,24,133,46,39,7,3,1,3,21,2,6,2,1,2,4,4,0,32,4,287,47,21,1,2,0,185,46,82,47,21,0,60,42,502,63,32,0,449,56,1288,920,104,110,2962,1070,13266,568,8,30,114,29,19,47,17,3,32,20,6,18,881,68,12,0,67,12,16481,1,3071,106,6,12,4,8,8,9,5991,84,2,70,2,1,3,0,3,1,3,3,2,11,2,0,2,6,2,64,2,3,3,7,2,6,2,27,2,3,2,4,2,0,4,6,2,339,3,24,2,24,2,30,2,24,2,30,2,24,2,30,2,24,2,30,2,24,2,7,4149,196,1340,3,2,26,2,1,2,0,3,0,2,9,2,3,2,0,2,0,7,0,5,0,2,0,2,0,2,2,2,1,2,0,3,0,2,0,2,0,2,0,2,0,2,1,2,0,3,3,2,6,2,3,2,3,2,0,2,9,2,16,6,2,2,4,2,16,4421,42710,42,4148,12,221,16355,541];
  var astralIdentifierCodes = [509,0,227,0,150,4,294,9,1368,2,2,1,6,3,41,2,5,0,166,1,1306,2,54,14,32,9,16,3,46,10,54,9,7,2,37,13,2,9,52,0,13,2,49,13,16,9,83,11,168,11,6,9,8,2,57,0,2,6,3,1,3,2,10,0,11,1,3,6,4,4,316,19,13,9,214,6,3,8,112,16,16,9,82,12,9,9,535,9,20855,9,135,4,60,6,26,9,1016,45,17,3,19723,1,5319,4,4,5,9,7,3,6,31,3,149,2,1418,49,4305,6,792618,239];

  // This has a complexity linear to the value of the code. The
  // assumption is that looking up astral identifier characters is
  // rare.
  function isInAstralSet(code, set) {
    var pos = 0x10000;
    for (var i = 0; i < set.length; i += 2) {
      pos += set[i];
      if (pos > code) return false;
      pos += set[i + 1];
      if (pos >= code) return true;
    }
  }

  // Whether a single character denotes a newline.

  var newline = /[\n\r\u2028\u2029]/;

  function isNewLine(code) {
    return code === 10 || code === 13 || code === 0x2028 || code == 0x2029;
  }

  // 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, astral) {
    if (code < 65) return code === 36;
    if (code < 91) return true;
    if (code < 97) return code === 95;
    if (code < 123) return true;
    if (code <= 0xffff) return code >= 0xaa && nonASCIIidentifierStart.test(String.fromCharCode(code));
    if (astral === false) return false;
    return isInAstralSet(code, astralIdentifierStartCodes);
  };

  // Test whether a given character is part of an identifier.

  var isIdentifierChar = exports.isIdentifierChar = function(code, astral) {
    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;
    if (code <= 0xffff) return code >= 0xaa && nonASCIIidentifier.test(String.fromCharCode(code));
    if (astral === false) return false;
    return isInAstralSet(code, astralIdentifierStartCodes) || isInAstralSet(code, astralIdentifierCodes);
  };

  // ## Tokenizer

  // These are used when `options.locations` is on, for the
  // `tokStartLoc` and `tokEndLoc` properties.

  function Position(line, col) {
    this.line = line;
    this.column = col;
  }

  Position.prototype.offset = function(n) {
    return new Position(this.line, this.column + n);
  };

  function curPosition() {
    return new Position(tokCurLine, tokPos - tokLineStart);
  }

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

  function initTokenState(pos) {
    if (pos) {
      tokPos = pos;
      tokLineStart = Math.max(0, input.lastIndexOf("\n", pos));
      tokCurLine = input.slice(0, tokLineStart).split(newline).length;
    } else {
      tokCurLine = 1;
      tokPos = tokLineStart = 0;
    }
    tokType = _eof;
    tokContext = [b_stat];
    tokExprAllowed = true;
    strict = false;
    if (tokPos === 0 && options.allowHashBang && input.slice(0, 2) === '#!') {
      skipLineComment(2);
    }
  }

  // The algorithm used to determine whether a regexp can appear at a
  // given point in the program is loosely based on sweet.js' approach.
  // See https://github.com/mozilla/sweet.js/wiki/design

  var b_stat = {token: "{", isExpr: false}, b_expr = {token: "{", isExpr: true}, b_tmpl = {token: "${", isExpr: true};
  var p_stat = {token: "(", isExpr: false}, p_expr = {token: "(", isExpr: true};
  var q_tmpl = {token: "`", isExpr: true}, f_expr = {token: "function", isExpr: true};

  function curTokContext() {
    return tokContext[tokContext.length - 1];
  }

  function braceIsBlock(prevType) {
    var parent;
    if (prevType === _colon && (parent = curTokContext()).token == "{")
      return !parent.isExpr;
    if (prevType === _return)
      return newline.test(input.slice(lastEnd, tokStart));
    if (prevType === _else || prevType === _semi || prevType === _eof)
      return true;
    if (prevType == _braceL)
      return curTokContext() === b_stat;
    return !tokExprAllowed;
  }

  // Called at the end of every token. Sets `tokEnd`, `tokVal`, and
  // maintains `tokContext` and `tokExprAllowed`, 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 = curPosition();
    var prevType = tokType, preserveSpace = false;
    tokType = type;
    tokVal = val;

    // Update context info
    if (type === _parenR || type === _braceR) {
      var out = tokContext.pop();
      if (out === b_tmpl) {
        preserveSpace = true;
      } else if (out === b_stat && curTokContext() === f_expr) {
        tokContext.pop();
        tokExprAllowed = false;
      } else {
        tokExprAllowed = !(out && out.isExpr);
      }
    } else if (type === _braceL) {
      tokContext.push(braceIsBlock(prevType) ? b_stat : b_expr);
      tokExprAllowed = true;
    } else if (type === _dollarBraceL) {
      tokContext.push(b_tmpl);
      tokExprAllowed = true;
    } else if (type == _parenL) {
      var statementParens = prevType === _if || prevType === _for || prevType === _with || prevType === _while;
      tokContext.push(statementParens ? p_stat : p_expr);
      tokExprAllowed = true;
    } else if (type == _incDec) {
      // tokExprAllowed stays unchanged
    } else if (type.keyword && prevType == _dot) {
      tokExprAllowed = false;
    } else if (type == _function) {
      if (curTokContext() !== b_stat) {
        tokContext.push(f_expr);
      }
      tokExprAllowed = false;
    } else if (type === _backQuote) {
      if (curTokContext() === q_tmpl) {
        tokContext.pop();
      } else {
        tokContext.push(q_tmpl);
        preserveSpace = true;
      }
      tokExprAllowed = false;
    } else {
      tokExprAllowed = type.beforeExpr;
    }

    if (!preserveSpace) skipSpace();
  }

  function skipBlockComment() {
    var startLoc = options.onComment && options.locations && curPosition();
    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 && curPosition());
  }

  function skipLineComment(startSkip) {
    var start = tokPos;
    var startLoc = options.onComment && options.locations && curPosition();
    var ch = input.charCodeAt(tokPos+=startSkip);
    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 + startSkip, tokPos), start, tokPos,
                        startLoc, options.locations && curPosition());
  }

  // 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(2);
        } 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.
  //
  function readToken_dot() {
    var next = input.charCodeAt(tokPos + 1);
    if (next >= 48 && next <= 57) return readNumber(true);
    var next2 = input.charCodeAt(tokPos + 2);
    if (options.ecmaVersion >= 6 && next === 46 && next2 === 46) { // 46 = dot '.'
      tokPos += 3;
      return finishToken(_ellipsis);
    } else {
      ++tokPos;
      return finishToken(_dot);
    }
  }

  function readToken_slash() { // '/'
    var next = input.charCodeAt(tokPos + 1);
    if (tokExprAllowed) {++tokPos; return readRegexp();}
    if (next === 61) return finishOp(_assign, 2);
    return finishOp(_slash, 1);
  }

  function readToken_mult_modulo(code) { // '%*'
    var next = input.charCodeAt(tokPos + 1);
    if (next === 61) return finishOp(_assign, 2);
    return finishOp(code === 42 ? _star : _modulo, 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
        skipLineComment(3);
        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
      skipLineComment(4);
      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);
    if (code === 61 && next === 62 && options.ecmaVersion >= 6) { // '=>'
      tokPos += 2;
      return finishToken(_arrow);
    }
    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 or another two dots.
    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);

    case 96: // '`'
      if (options.ecmaVersion < 6) break;
      ++tokPos;
      return finishToken(_backQuote);

    case 48: // '0'
      var next = input.charCodeAt(tokPos + 1);
      if (next === 120 || next === 88) return readRadixNumber(16); // '0x', '0X' - hex number
      if (options.ecmaVersion >= 6) {
        if (next === 111 || next === 79) return readRadixNumber(8); // '0o', '0O' - octal number
        if (next === 98 || next === 66) return readRadixNumber(2); // '0b', '0B' - binary number
      }
    // 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();

    case 37: case 42: // '%*'
      return readToken_mult_modulo(code);

    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);
    }

    raise(tokPos, "Unexpected character '" + codePointToString(code) + "'");
  }

  function readToken() {
    tokStart = tokPos;
    if (options.locations) tokStartLoc = curPosition();
    if (tokPos >= inputLen) return finishToken(_eof);

    if (curTokContext() === q_tmpl) {
      return readTmplToken();
    }

    var code = fullCharCodeAtPos();

    // Identifier or keyword. '\uXXXX' sequences are allowed in
    // identifiers, so '\' also dispatches to that.
    if (isIdentifierStart(code, options.ecmaVersion >= 6) || code === 92 /* '\' */) return readWord();

    return getTokenFromCode(code);
  }

  function finishOp(type, size) {
    var str = input.slice(tokPos, tokPos + size);
    tokPos += size;
    finishToken(type, str);
  }

  var regexpUnicodeSupport = false;
  try { new RegExp("\uffff", "u"); regexpUnicodeSupport = true; }
  catch(e) {}

  // 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();
    var tmp = content;
    if (mods) {
      var validFlags = /^[gmsiy]*$/;
      if (options.ecmaVersion >= 6) validFlags = /^[gmsiyu]*$/;
      if (!validFlags.test(mods)) raise(start, "Invalid regular expression flag");
      if (mods.indexOf('u') >= 0 && !regexpUnicodeSupport) {
        // Replace each astral symbol and every Unicode code point
        // escape sequence that represents such a symbol with a single
        // ASCII symbol to avoid throwing on regular expressions that
        // are only valid in combination with the `/u` flag.
        tmp = tmp
          .replace(/\\u\{([0-9a-fA-F]{5,6})\}/g, "x")
          .replace(/[\uD800-\uDBFF][\uDC00-\uDFFF]/g, "x");
      }
    }
    // Detect invalid regular expressions.
    try {
      new RegExp(tmp);
    } catch (e) {
      if (e instanceof SyntaxError) raise(start, "Error parsing regular expression: " + e.message);
      raise(e);
    }
    // Get a regular expression object for this pattern-flag pair, or `null` in
    // case the current environment doesn't support the flags it uses.
    try {
      var value = new RegExp(content, mods);
    } catch (err) {
      value = null;
    }
    return finishToken(_regexp, {pattern: content, flags: mods, value: 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 readRadixNumber(radix) {
    tokPos += 2; // 0x
    var val = readInt(radix);
    if (val == null) raise(tokStart + 2, "Expected number in radix " + radix);
    if (isIdentifierStart(fullCharCodeAtPos())) 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(fullCharCodeAtPos())) 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 readCodePoint() {
    var ch = input.charCodeAt(tokPos), code;

    if (ch === 123) {
      if (options.ecmaVersion < 6) unexpected();
      ++tokPos;
      code = readHexChar(input.indexOf('}', tokPos) - tokPos);
      ++tokPos;
      if (code > 0x10FFFF) unexpected();
    } else {
      code = readHexChar(4);
    }
    return code;
  }

  function codePointToString(code) {
    // UTF-16 Encoding
    if (code <= 0xFFFF) return String.fromCharCode(code);
    return String.fromCharCode(((code - 0x10000) >> 10) + 0xD800,
                               ((code - 0x10000) & 1023) + 0xDC00);
  }

  function readString(quote) {
    var out = "", chunkStart = ++tokPos;
    for (;;) {
      if (tokPos >= inputLen) raise(tokStart, "Unterminated string constant");
      var ch = input.charCodeAt(tokPos);
      if (ch === quote) break;
      if (ch === 92) { // '\'
        out += input.slice(chunkStart, tokPos);
        out += readEscapedChar();
        chunkStart = tokPos;
      } else {
        if (isNewLine(ch)) raise(tokStart, "Unterminated string constant");
        ++tokPos;
      }
    }
    out += input.slice(chunkStart, tokPos++);
    return finishToken(_string, out);
  }

  // Reads template string tokens.

  function readTmplToken() {
    var out = "", chunkStart = tokPos;
    for (;;) {
      if (tokPos >= inputLen) raise(tokStart, "Unterminated template");
      var ch = input.charCodeAt(tokPos);
      if (ch === 96 || ch === 36 && input.charCodeAt(tokPos + 1) === 123) { // '`', '${'
        if (tokPos === tokStart && tokType === _template) {
          if (ch === 36) {
            tokPos += 2;
            return finishToken(_dollarBraceL);
          } else {
            ++tokPos;
            return finishToken(_backQuote);
          }
        }
        out += input.slice(chunkStart, tokPos);
        return finishToken(_template, out);
      }
      if (ch === 92) { // '\'
        out += input.slice(chunkStart, tokPos);
        out += readEscapedChar();
        chunkStart = tokPos;
      } else if (isNewLine(ch)) {
        out += input.slice(chunkStart, tokPos);
        ++tokPos;
        if (ch === 13 && input.charCodeAt(tokPos) === 10) {
          ++tokPos;
          out += "\n";
        } else {
          out += String.fromCharCode(ch);
        }
        if (options.locations) {
          ++tokCurLine;
          tokLineStart = tokPos;
        }
        chunkStart = tokPos;
      } else {
        ++tokPos;
      }
    }
  }

  // Used to read escaped characters

  function readEscapedChar() {
    var 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");
      tokPos += octal.length - 1;
      return String.fromCharCode(parseInt(octal, 8));
    } else {
      switch (ch) {
        case 110: return "\n"; // 'n' -> '\n'
        case 114: return "\r"; // 'r' -> '\r'
        case 120: return String.fromCharCode(readHexChar(2)); // 'x'
        case 117: return codePointToString(readCodePoint()); // 'u'
        case 116: return "\t"; // 't' -> '\t'
        case 98: return "\b"; // 'b' -> '\b'
        case 118: return "\u000b"; // 'v' -> '\u000b'
        case 102: return "\f"; // 'f' -> '\f'
        case 48: return "\0"; // 0 -> '\0'
        case 13: if (input.charCodeAt(tokPos) === 10) ++tokPos; // '\r\n'
        case 10: // ' \n'
          if (options.locations) { tokLineStart = tokPos; ++tokCurLine; }
          return "";
        default: return String.fromCharCode(ch);
      }
    }
  }

  // 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.
  //
  // Incrementally adds only escaped chars, adding other chunks as-is
  // as a micro-optimization.

  function readWord1() {
    containsEsc = false;
    var word = "", first = true, chunkStart = tokPos;
    var astral = options.ecmaVersion >= 6;
    while (tokPos < inputLen) {
      var ch = fullCharCodeAtPos();
      if (isIdentifierChar(ch, astral)) {
        skipChar(ch);
      } else if (ch === 92) { // "\"
        containsEsc = true;
        word += input.slice(chunkStart, tokPos);
        var escStart = tokPos;
        if (input.charCodeAt(++tokPos) != 117) // "u"
          raise(tokPos, "Expecting Unicode escape sequence \\uXXXX");
        ++tokPos;
        var esc = readCodePoint();
        if (!(first ? isIdentifierStart : isIdentifierChar)(esc, astral))
          raise(escStart, "Invalid Unicode escape");
        word += codePointToString(esc);
        chunkStart = tokPos;
      } else {
        break;
      }
      first = false;
    }
    return word + input.slice(chunkStart, tokPos);
  }

  // Read an identifier or keyword token. Will check for reserved
  // words when necessary.

  function readWord() {
    var word = readWord1();
    var type = _name;
    if ((options.ecmaVersion >= 6 || !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() {
    if (options.onToken)
      options.onToken(new Token());

    lastStart = tokStart;
    lastEnd = tokEnd;
    lastEndLoc = tokEndLoc;
    readToken();
  }

  // Enter strict mode. Re-reads the next number or string to
  // please pedantic tests ("use strict"; 010; -- should fail).

  function setStrict(strct) {
    strict = strct;
    if (tokType !== _num && tokType !== _string) return;
    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() {
    this.type = null;
    this.start = tokStart;
    this.end = null;
  }

  exports.Node = Node;

  function SourceLocation() {
    this.start = tokStartLoc;
    this.end = null;
    if (sourceFile !== null) this.source = sourceFile;
  }

  function startNode() {
    var node = new Node();
    if (options.locations)
      node.loc = new SourceLocation();
    if (options.directSourceFile)
      node.sourceFile = options.directSourceFile;
    if (options.ranges)
      node.range = [tokStart, 0];
    return node;
  }

  // Sometimes, a node is only started *after* the token stream passed
  // its start position. The functions below help storing a position
  // and creating a node from a previous position.

  function storeCurrentPos() {
    return options.locations ? [tokStart, tokStartLoc] : tokStart;
  }

  function startNodeAt(pos) {
    var node = new Node(), start = pos;
    if (options.locations) {
      node.loc = new SourceLocation();
      node.loc.start = start[1];
      start = pos[0];
    }
    node.start = start;
    if (options.directSourceFile)
      node.sourceFile = options.directSourceFile;
    if (options.ranges)
      node.range = [start, 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;
  }

  // Finish node at given position

  function finishNodeAt(node, type, pos) {
    if (options.locations) { node.loc.end = pos[1]; pos = pos[0]; }
    node.type = type;
    node.end = pos;
    if (options.ranges)
      node.range[1] = pos;
    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;
    } else {
      return false;
    }
  }

  // Tests whether parsed token is a contextual keyword.

  function isContextual(name) {
    return tokType === _name && tokVal === name;
  }

  // Consumes contextual keyword if possible.

  function eatContextual(name) {
    return tokVal === name && eat(_name);
  }

  // Asserts that following token is given contextual keyword.

  function expectContextual(name) {
    if (!eatContextual(name)) unexpected();
  }

  // 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) {
    eat(type) || unexpected();
  }

  // Raise an unexpected token error.

  function unexpected(pos) {
    raise(pos != null ? pos : tokStart, "Unexpected token");
  }

  // Checks if hash object has a property.

  function has(obj, propName) {
    return Object.prototype.hasOwnProperty.call(obj, propName);
  }

  // Convert existing expression atom to assignable pattern
  // if possible.

  function toAssignable(node, isBinding) {
    if (options.ecmaVersion >= 6 && node) {
      switch (node.type) {
        case "Identifier":
        case "ObjectPattern":
        case "ArrayPattern":
        case "AssignmentPattern":
          break;

        case "ObjectExpression":
          node.type = "ObjectPattern";
          for (var i = 0; i < node.properties.length; i++) {
            var prop = node.properties[i];
            if (prop.kind !== "init") raise(prop.key.start, "Object pattern can't contain getter or setter");
            toAssignable(prop.value, isBinding);
          }
          break;

        case "ArrayExpression":
          node.type = "ArrayPattern";
          toAssignableList(node.elements, isBinding);
          break;

        case "AssignmentExpression":
          if (node.operator === "=") {
            node.type = "AssignmentPattern";
          } else {
            raise(node.left.end, "Only '=' operator can be used for specifying default value.");
          }
          break;

        case "MemberExpression":
          if (!isBinding) break;

        default:
          raise(node.start, "Assigning to rvalue");
      }
    }
    return node;
  }

  // Convert list of expression atoms to binding list.

  function toAssignableList(exprList, isBinding) {
    if (exprList.length) {
      for (var i = 0; i < exprList.length - 1; i++) {
        toAssignable(exprList[i], isBinding);
      }
      var last = exprList[exprList.length - 1];
      switch (last.type) {
        case "RestElement":
          break;
        case "SpreadElement":
          last.type = "RestElement";
          var arg = last.argument;
          toAssignable(arg, isBinding);
          if (arg.type !== "Identifier" && arg.type !== "MemberExpression" && arg.type !== "ArrayPattern")
            unexpected(arg.start);
          break;
        default:
          toAssignable(last, isBinding);
      }
    }
    return exprList;
  }

  // Parses spread element.

  function parseSpread(refShorthandDefaultPos) {
    var node = startNode();
    next();
    node.argument = parseMaybeAssign(refShorthandDefaultPos);
    return finishNode(node, "SpreadElement");
  }

  function parseRest() {
    var node = startNode();
    next();
    node.argument = tokType === _name || tokType === _bracketL ? parseBindingAtom() : unexpected();
    return finishNode(node, "RestElement");
  }

  // Parses lvalue (assignable) atom.

  function parseBindingAtom() {
    if (options.ecmaVersion < 6) return parseIdent();
    switch (tokType) {
      case _name:
        return parseIdent();

      case _bracketL:
        var node = startNode();
        next();
        node.elements = parseBindingList(_bracketR, true);
        return finishNode(node, "ArrayPattern");

      case _braceL:
        return parseObj(true);

      default:
        unexpected();
    }
  }

  function parseBindingList(close, allowEmpty) {
    var elts = [], first = true;
    while (!eat(close)) {
      first ? first = false : expect(_comma);
      if (tokType === _ellipsis) {
        elts.push(parseRest());
        expect(close);
        break;
      }
      elts.push(allowEmpty && tokType === _comma ? null : parseMaybeDefault());
    }
    return elts;
  }

  // Parses assignment pattern around given atom if possible.

  function parseMaybeDefault(startPos, left) {
    startPos = startPos || storeCurrentPos();
    left = left || parseBindingAtom();
    if (!eat(_eq)) return left;
    var node = startNodeAt(startPos);
    node.operator = "=";
    node.left = left;
    node.right = parseMaybeAssign();
    return finishNode(node, "AssignmentPattern");
  }

  // Verify that argument names are not repeated, and it does not
  // try to bind the words `eval` or `arguments`.

  function checkFunctionParam(param, nameHash) {
    switch (param.type) {
      case "Identifier":
        if (isStrictReservedWord(param.name) || isStrictBadIdWord(param.name))
          raise(param.start, "Defining '" + param.name + "' in strict mode");
        if (has(nameHash, param.name))
          raise(param.start, "Argument name clash in strict mode");
        nameHash[param.name] = true;
        break;

      case "ObjectPattern":
        for (var i = 0; i < param.properties.length; i++)
          checkFunctionParam(param.properties[i].value, nameHash);
        break;

      case "ArrayPattern":
        for (var i = 0; i < param.elements.length; i++) {
          var elem = param.elements[i];
          if (elem) checkFunctionParam(elem, nameHash);
        }
        break;

      case "RestElement":
        return checkFunctionParam(param.argument, nameHash);
    }
  }

  // Check if property name clashes with already added.
  // Object/class 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.

  function checkPropClash(prop, propHash) {
    if (options.ecmaVersion >= 6) return;
    var key = prop.key, name;
    switch (key.type) {
      case "Identifier": name = key.name; break;
      case "Literal": name = String(key.value); break;
      default: return;
    }
    var kind = prop.kind || "init", other;
    if (has(propHash, name)) {
      other = propHash[name];
      var isGetSet = kind !== "init";
      if ((strict || isGetSet) && other[kind] || !(isGetSet ^ other.init))
        raise(key.start, "Redefinition of property");
    } else {
      other = propHash[name] = {
        init: false,
        get: false,
        set: false
      };
    }
    other[kind] = true;
  }

  // Verify that a node is an lval — something that can be assigned
  // to.

  function checkLVal(expr, isBinding) {
    switch (expr.type) {
      case "Identifier":
        if (strict && (isStrictBadIdWord(expr.name) || isStrictReservedWord(expr.name)))
          raise(expr.start, (isBinding ? "Binding " : "Assigning to ") + expr.name + " in strict mode");
        break;

      case "MemberExpression":
        if (isBinding) raise(expr.start, "Binding to member expression");
        break;

      case "ObjectPattern":
        for (var i = 0; i < expr.properties.length; i++)
          checkLVal(expr.properties[i].value, isBinding);
        break;

      case "ArrayPattern":
        for (var i = 0; i < expr.elements.length; i++) {
          var elem = expr.elements[i];
          if (elem) checkLVal(elem, isBinding);
        }
        break;

      case "AssignmentPattern":
        checkLVal(expr.left);
        break;

      case "RestElement":
        checkLVal(expr.argument);
        break;

      default:
        raise(expr.start, "Assigning to rvalue");
    }
  }

  // ### 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(node) {
    var first = true;
    if (!node.body) node.body = [];
    while (tokType !== _eof) {
      var stmt = parseStatement(true, true);
      node.body.push(stmt);
      if (first && isUseStrict(stmt)) setStrict(true);
      first = false;
    }

    next();
    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(declaration, topLevel) {
    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: return parseBreakContinueStatement(node, starttype.keyword);
    case _debugger: return parseDebuggerStatement(node);
    case _do: return parseDoStatement(node);
    case _for: return parseForStatement(node);
    case _function:
      if (!declaration && options.ecmaVersion >= 6) unexpected();
      return parseFunctionStatement(node);
    case _class:
      if (!declaration) unexpected();
      return parseClass(node, true);
    case _if: return parseIfStatement(node);
    case _return: return parseReturnStatement(node);
    case _switch: return parseSwitchStatement(node);
    case _throw: return parseThrowStatement(node);
    case _try: return parseTryStatement(node);
    case _let: case _const: if (!declaration) unexpected(); // NOTE: falls through to _var
    case _var: return parseVarStatement(node, starttype.keyword);
    case _while: return parseWhileStatement(node);
    case _with: return parseWithStatement(node);
    case _braceL: return parseBlock(); // no point creating a function for this
    case _semi: return parseEmptyStatement(node);
    case _export:
    case _import:
      if (!topLevel && !options.allowImportExportEverywhere)
        raise(tokStart, "'import' and 'export' may only appear at the top level");
      return starttype === _import ? parseImport(node) : parseExport(node);

      // 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))
        return parseLabeledStatement(node, maybeName, expr);
      else return parseExpressionStatement(node, expr);
    }
  }

  function parseBreakContinueStatement(node, keyword) {
    var isBreak = keyword == "break";
    next();
    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 " + keyword);
    return finishNode(node, isBreak ? "BreakStatement" : "ContinueStatement");
  }

  function parseDebuggerStatement(node) {
    next();
    semicolon();
    return finishNode(node, "DebuggerStatement");
  }

  function parseDoStatement(node) {
    next();
    labels.push(loopLabel);
    node.body = parseStatement(false);
    labels.pop();
    expect(_while);
    node.test = parseParenExpression();
    if (options.ecmaVersion >= 6)
      eat(_semi);
    else
      semicolon();
    return finishNode(node, "DoWhileStatement");
  }

  // Disambiguating between a `for` and a `for`/`in` or `for`/`of`
  // 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` or `of`. When there is no init
  // part (semicolon immediately after the opening parenthesis), it
  // is a regular `for` loop.

  function parseForStatement(node) {
    next();
    labels.push(loopLabel);
    expect(_parenL);
    if (tokType === _semi) return parseFor(node, null);
    if (tokType === _var || tokType === _let) {
      var init = startNode(), varKind = tokType.keyword, isLet = tokType === _let;
      next();
      parseVar(init, true, varKind);
      finishNode(init, "VariableDeclaration");
      if ((tokType === _in || (options.ecmaVersion >= 6 && isContextual("of"))) && init.declarations.length === 1 &&
          !(isLet && init.declarations[0].init))
        return parseForIn(node, init);
      return parseFor(node, init);
    }
    var refShorthandDefaultPos = {start: 0};
    var init = parseExpression(true, refShorthandDefaultPos);
    if (tokType === _in || (options.ecmaVersion >= 6 && isContextual("of"))) {
      toAssignable(init);
      checkLVal(init);
      return parseForIn(node, init);
    } else if (refShorthandDefaultPos.start) {
      unexpected(refShorthandDefaultPos.start);
    }
    return parseFor(node, init);
  }

  function parseFunctionStatement(node) {
    next();
    return parseFunction(node, true);
  }

  function parseIfStatement(node) {
    next();
    node.test = parseParenExpression();
    node.consequent = parseStatement(false);
    node.alternate = eat(_else) ? parseStatement(false) : null;
    return finishNode(node, "IfStatement");
  }

  function parseReturnStatement(node) {
    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");
  }

  function parseSwitchStatement(node) {
    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(true));
      }
    }
    if (cur) finishNode(cur, "SwitchCase");
    next(); // Closing brace
    labels.pop();
    return finishNode(node, "SwitchStatement");
  }

  function parseThrowStatement(node) {
    next();
    if (newline.test(input.slice(lastEnd, tokStart)))
      raise(lastEnd, "Illegal newline after throw");
    node.argument = parseExpression();
    semicolon();
    return finishNode(node, "ThrowStatement");
  }

  function parseTryStatement(node) {
    next();
    node.block = parseBlock();
    node.handler = null;
    if (tokType === _catch) {
      var clause = startNode();
      next();
      expect(_parenL);
      clause.param = parseBindingAtom();
      checkLVal(clause.param, true);
      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");
  }

  function parseVarStatement(node, kind) {
    next();
    parseVar(node, false, kind);
    semicolon();
    return finishNode(node, "VariableDeclaration");
  }

  function parseWhileStatement(node) {
    next();
    node.test = parseParenExpression();
    labels.push(loopLabel);
    node.body = parseStatement(false);
    labels.pop();
    return finishNode(node, "WhileStatement");
  }

  function parseWithStatement(node) {
    if (strict) raise(tokStart, "'with' in strict mode");
    next();
    node.object = parseParenExpression();
    node.body = parseStatement(false);
    return finishNode(node, "WithStatement");
  }

  function parseEmptyStatement(node) {
    next();
    return finishNode(node, "EmptyStatement");
  }

  function parseLabeledStatement(node, maybeName, expr) {
    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(true);
    labels.pop();
    node.label = expr;
    return finishNode(node, "LabeledStatement");
  }

  function parseExpressionStatement(node, expr) {
    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, oldStrict;
    node.body = [];
    expect(_braceL);
    while (!eat(_braceR)) {
      var stmt = parseStatement(true);
      node.body.push(stmt);
      if (first && allowStrict && isUseStrict(stmt)) {
        oldStrict = strict;
        setStrict(strict = true);
      }
      first = false;
    }
    if (oldStrict === false) 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(false);
    labels.pop();
    return finishNode(node, "ForStatement");
  }

  // Parse a `for`/`in` and `for`/`of` loop, which are almost
  // same from parser's perspective.

  function parseForIn(node, init) {
    var type = tokType === _in ? "ForInStatement" : "ForOfStatement";
    next();
    node.left = init;
    node.right = parseExpression();
    expect(_parenR);
    node.body = parseStatement(false);
    labels.pop();
    return finishNode(node, type);
  }

  // Parse a list of variable declarations.

  function parseVar(node, noIn, kind) {
    node.declarations = [];
    node.kind = kind;
    for (;;) {
      var decl = startNode();
      decl.id = parseBindingAtom();
      checkLVal(decl.id, true);
      decl.init = eat(_eq) ? parseMaybeAssign(noIn) : (kind === _const.keyword ? unexpected() : 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 optional arguments are used to
  // forbid the `in` operator (in for loops initalization expressions)
  // and provide reference for storing '=' operator inside shorthand
  // property assignment in contexts where both object expression
  // and object pattern might appear (so it's possible to raise
  // delayed syntax error at correct position).

  function parseExpression(noIn, refShorthandDefaultPos) {
    var start = storeCurrentPos();
    var expr = parseMaybeAssign(noIn, refShorthandDefaultPos);
    if (tokType === _comma) {
      var node = startNodeAt(start);
      node.expressions = [expr];
      while (eat(_comma)) node.expressions.push(parseMaybeAssign(noIn, refShorthandDefaultPos));
      return finishNode(node, "SequenceExpression");
    }
    return expr;
  }

  // Parse an assignment expression. This includes applications of
  // operators like `+=`.

  function parseMaybeAssign(noIn, refShorthandDefaultPos) {
    var failOnShorthandAssign;
    if (!refShorthandDefaultPos) {
      refShorthandDefaultPos = {start: 0};
      failOnShorthandAssign = true;
    } else {
      failOnShorthandAssign = false;
    }
    var start = storeCurrentPos();
    var left = parseMaybeConditional(noIn, refShorthandDefaultPos);
    if (tokType.isAssign) {
      var node = startNodeAt(start);
      node.operator = tokVal;
      node.left = tokType === _eq ? toAssignable(left) : left;
      refShorthandDefaultPos.start = 0; // reset because shorthand default was used correctly
      checkLVal(left);
      next();
      node.right = parseMaybeAssign(noIn);
      return finishNode(node, "AssignmentExpression");
    } else if (failOnShorthandAssign && refShorthandDefaultPos.start) {
      unexpected(refShorthandDefaultPos.start);
    }
    return left;
  }

  // Parse a ternary conditional (`?:`) operator.

  function parseMaybeConditional(noIn, refShorthandDefaultPos) {
    var start = storeCurrentPos();
    var expr = parseExprOps(noIn, refShorthandDefaultPos);
    if (refShorthandDefaultPos && refShorthandDefaultPos.start) return expr;
    if (eat(_question)) {
      var node = startNodeAt(start);
      node.test = expr;
      node.consequent = parseMaybeAssign();
      expect(_colon);
      node.alternate = parseMaybeAssign(noIn);
      return finishNode(node, "ConditionalExpression");
    }
    return expr;
  }

  // Start the precedence parser.

  function parseExprOps(noIn, refShorthandDefaultPos) {
    var start = storeCurrentPos();
    var expr = parseMaybeUnary(refShorthandDefaultPos);
    if (refShorthandDefaultPos && refShorthandDefaultPos.start) return expr;
    return parseExprOp(expr, start, -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, leftStart, minPrec, noIn) {
    var prec = tokType.binop;
    if (prec != null && (!noIn || tokType !== _in)) {
      if (prec > minPrec) {
        var node = startNodeAt(leftStart);
        node.left = left;
        node.operator = tokVal;
        var op = tokType;
        next();
        var start = storeCurrentPos();
        node.right = parseExprOp(parseMaybeUnary(), start, prec, noIn);
        finishNode(node, (op === _logicalOR || op === _logicalAND) ? "LogicalExpression" : "BinaryExpression");
        return parseExprOp(node, leftStart, minPrec, noIn);
      }
    }
    return left;
  }

  // Parse unary operators, both prefix and postfix.

  function parseMaybeUnary(refShorthandDefaultPos) {
    if (tokType.prefix) {
      var node = startNode(), update = tokType.isUpdate;
      node.operator = tokVal;
      node.prefix = true;
      next();
      node.argument = parseMaybeUnary();
      if (refShorthandDefaultPos && refShorthandDefaultPos.start) unexpected(refShorthandDefaultPos.start);
      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 start = storeCurrentPos();
    var expr = parseExprSubscripts(refShorthandDefaultPos);
    if (refShorthandDefaultPos && refShorthandDefaultPos.start) return expr;
    while (tokType.postfix && !canInsertSemicolon()) {
      var node = startNodeAt(start);
      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(refShorthandDefaultPos) {
    var start = storeCurrentPos();
    var expr = parseExprAtom(refShorthandDefaultPos);
    if (refShorthandDefaultPos && refShorthandDefaultPos.start) return expr;
    return parseSubscripts(expr, start);
  }

  function parseSubscripts(base, start, noCalls) {
    if (eat(_dot)) {
      var node = startNodeAt(start);
      node.object = base;
      node.property = parseIdent(true);
      node.computed = false;
      return parseSubscripts(finishNode(node, "MemberExpression"), start, noCalls);
    } else if (eat(_bracketL)) {
      var node = startNodeAt(start);
      node.object = base;
      node.property = parseExpression();
      node.computed = true;
      expect(_bracketR);
      return parseSubscripts(finishNode(node, "MemberExpression"), start, noCalls);
    } else if (!noCalls && eat(_parenL)) {
      var node = startNodeAt(start);
      node.callee = base;
      node.arguments = parseExprList(_parenR, false);
      return parseSubscripts(finishNode(node, "CallExpression"), start, noCalls);
    } else if (tokType === _backQuote) {
      var node = startNodeAt(start);
      node.tag = base;
      node.quasi = parseTemplate();
      return parseSubscripts(finishNode(node, "TaggedTemplateExpression"), start, noCalls);
    } 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(refShorthandDefaultPos) {
    switch (tokType) {
    case _this:
      var node = startNode();
      next();
      return finishNode(node, "ThisExpression");

    case _yield:
      if (inGenerator) return parseYield();

    case _name:
      var start = storeCurrentPos();
      var id = parseIdent(tokType !== _name);
      if (!canInsertSemicolon() && eat(_arrow)) {
        return parseArrowExpression(startNodeAt(start), [id]);
      }
      return id;

    case _regexp:
      var node = startNode();
      node.regex = {pattern: tokVal.pattern, flags: tokVal.flags};
      node.value = tokVal.value;
      node.raw = input.slice(tokStart, tokEnd);
      next();
      return finishNode(node, "Literal");

    case _num: case _string:
      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:
      return parseParenAndDistinguishExpression();

    case _bracketL:
      var node = startNode();
      next();
      // check whether this is array comprehension or regular array
      if (options.ecmaVersion >= 7 && tokType === _for) {
        return parseComprehension(node, false);
      }
      node.elements = parseExprList(_bracketR, true, true, refShorthandDefaultPos);
      return finishNode(node, "ArrayExpression");

    case _braceL:
      return parseObj(false, refShorthandDefaultPos);

    case _function:
      var node = startNode();
      next();
      return parseFunction(node, false);

    case _class:
      return parseClass(startNode(), false);

    case _new:
      return parseNew();

    case _backQuote:
      return parseTemplate();

    default:
      unexpected();
    }
  }

  function parseParenAndDistinguishExpression() {
    var start = storeCurrentPos(), val;
    if (options.ecmaVersion >= 6) {
      next();

      if (options.ecmaVersion >= 7 && tokType === _for) {
        return parseComprehension(startNodeAt(start), true);
      }

      var innerStart = storeCurrentPos(), exprList = [], first = true;
      var refShorthandDefaultPos = {start: 0}, spreadStart, innerParenStart;
      while (tokType !== _parenR) {
        first ? first = false : expect(_comma);
        if (tokType === _ellipsis) {
          spreadStart = tokStart;
          exprList.push(parseRest());
          break;
        } else {
          if (tokType === _parenL && !innerParenStart) {
            innerParenStart = tokStart;
          }
          exprList.push(parseMaybeAssign(false, refShorthandDefaultPos));
        }
      }
      var innerEnd = storeCurrentPos();
      expect(_parenR);

      if (!canInsertSemicolon() && eat(_arrow)) {
        if (innerParenStart) unexpected(innerParenStart);
        return parseArrowExpression(startNodeAt(start), exprList);
      }

      if (!exprList.length) unexpected(lastStart);
      if (spreadStart) unexpected(spreadStart);
      if (refShorthandDefaultPos.start) unexpected(refShorthandDefaultPos.start);

      if (exprList.length > 1) {
        val = startNodeAt(innerStart);
        val.expressions = exprList;
        finishNodeAt(val, "SequenceExpression", innerEnd);
      } else {
        val = exprList[0];
      }
    } else {
      val = parseParenExpression();
    }

    if (options.preserveParens) {
      var par = startNodeAt(start);
      par.expression = val;
      return finishNode(par, "ParenthesizedExpression");
    } else {
      return val;
    }
  }

  // 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();
    var start = storeCurrentPos();
    node.callee = parseSubscripts(parseExprAtom(), start, true);
    if (eat(_parenL)) node.arguments = parseExprList(_parenR, false);
    else node.arguments = empty;
    return finishNode(node, "NewExpression");
  }

  // Parse template expression.

  function parseTemplateElement() {
    var elem = startNode();
    elem.value = {
      raw: input.slice(tokStart, tokEnd),
      cooked: tokVal
    };
    next();
    elem.tail = tokType === _backQuote;
    return finishNode(elem, "TemplateElement");
  }

  function parseTemplate() {
    var node = startNode();
    next();
    node.expressions = [];
    var curElt = parseTemplateElement();
    node.quasis = [curElt];
    while (!curElt.tail) {
      expect(_dollarBraceL);
      node.expressions.push(parseExpression());
      expect(_braceR);
      node.quasis.push(curElt = parseTemplateElement());
    }
    next();
    return finishNode(node, "TemplateLiteral");
  }

  // Parse an object literal or binding pattern.

  function parseObj(isPattern, refShorthandDefaultPos) {
    var node = startNode(), first = true, propHash = {};
    node.properties = [];
    next();
    while (!eat(_braceR)) {
      if (!first) {
        expect(_comma);
        if (options.allowTrailingCommas && eat(_braceR)) break;
      } else first = false;

      var prop = startNode(), isGenerator, start;
      if (options.ecmaVersion >= 6) {
        prop.method = false;
        prop.shorthand = false;
        if (isPattern || refShorthandDefaultPos) {
          start = storeCurrentPos();
        }
        if (!isPattern) {
          isGenerator = eat(_star);
        }
      }
      parsePropertyName(prop);
      if (eat(_colon)) {
        prop.value = isPattern ? parseMaybeDefault() : parseMaybeAssign(false, refShorthandDefaultPos);
        prop.kind = "init";
      } else if (options.ecmaVersion >= 6 && tokType === _parenL) {
        if (isPattern) unexpected();
        prop.kind = "init";
        prop.method = true;
        prop.value = parseMethod(isGenerator);
      } else if (options.ecmaVersion >= 5 && !prop.computed && prop.key.type === "Identifier" &&
                 (prop.key.name === "get" || prop.key.name === "set") &&
                 (tokType != _comma && tokType != _braceR)) {
        if (isGenerator || isPattern) unexpected();
        prop.kind = prop.key.name;
        parsePropertyName(prop);
        prop.value = parseMethod(false);
      } else if (options.ecmaVersion >= 6 && !prop.computed && prop.key.type === "Identifier") {
        prop.kind = "init";
        if (isPattern) {
          prop.value = parseMaybeDefault(start, prop.key);
        } else if (tokType === _eq && refShorthandDefaultPos) {
          if (!refShorthandDefaultPos.start)
            refShorthandDefaultPos.start = tokStart;
          prop.value = parseMaybeDefault(start, prop.key);
        } else {
          prop.value = prop.key;
        }
        prop.shorthand = true;
      } else unexpected();

      checkPropClash(prop, propHash);
      node.properties.push(finishNode(prop, "Property"));
    }
    return finishNode(node, isPattern ? "ObjectPattern" : "ObjectExpression");
  }

  function parsePropertyName(prop) {
    if (options.ecmaVersion >= 6) {
      if (eat(_bracketL)) {
        prop.computed = true;
        prop.key = parseExpression();
        expect(_bracketR);
        return;
      } else {
        prop.computed = false;
      }
    }
    prop.key = (tokType === _num || tokType === _string) ? parseExprAtom() : parseIdent(true);
  }

  // Initialize empty function node.

  function initFunction(node) {
    node.id = null;
    if (options.ecmaVersion >= 6) {
      node.generator = false;
      node.expression = false;
    }
  }

  // Parse a function declaration or literal (depending on the
  // `isStatement` parameter).

  function parseFunction(node, isStatement, allowExpressionBody) {
    initFunction(node);
    if (options.ecmaVersion >= 6) {
      node.generator = eat(_star);
    }
    if (isStatement || tokType === _name) {
      node.id = parseIdent();
    }
    expect(_parenL);
    node.params = parseBindingList(_parenR, false);
    parseFunctionBody(node, allowExpressionBody);
    return finishNode(node, isStatement ? "FunctionDeclaration" : "FunctionExpression");
  }

  // Parse object or class method.

  function parseMethod(isGenerator) {
    var node = startNode();
    initFunction(node);
    expect(_parenL);
    node.params = parseBindingList(_parenR, false);
    var allowExpressionBody;
    if (options.ecmaVersion >= 6) {
      node.generator = isGenerator;
      allowExpressionBody = true;
    } else {
      allowExpressionBody = false;
    }
    parseFunctionBody(node, allowExpressionBody);
    return finishNode(node, "FunctionExpression");
  }

  // Parse arrow function expression with given parameters.

  function parseArrowExpression(node, params) {
    initFunction(node);
    node.params = toAssignableList(params, true);
    parseFunctionBody(node, true);
    return finishNode(node, "ArrowFunctionExpression");
  }

  // Parse function body and check parameters.

  function parseFunctionBody(node, allowExpression) {
    var isExpression = allowExpression && tokType !== _braceL;

    if (isExpression) {
      node.body = parseMaybeAssign();
      node.expression = true;
    } else {
      // Start a new scope with regard to labels and the `inFunction`
      // flag (restore them to their old value afterwards).
      var oldInFunc = inFunction, oldInGen = inGenerator, oldLabels = labels;
      inFunction = true; inGenerator = node.generator; labels = [];
      node.body = parseBlock(true);
      node.expression = false;
      inFunction = oldInFunc; inGenerator = oldInGen; 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 || !isExpression && node.body.body.length && isUseStrict(node.body.body[0])) {
      var nameHash = {};
      if (node.id)
        checkFunctionParam(node.id, {});
      for (var i = 0; i < node.params.length; i++)
        checkFunctionParam(node.params[i], nameHash);
    }
  }

  // Parse a class declaration or literal (depending on the
  // `isStatement` parameter).

  function parseClass(node, isStatement) {
    next();
    node.id = tokType === _name ? parseIdent() : isStatement ? unexpected() : null;
    node.superClass = eat(_extends) ? parseExprSubscripts() : null;
    var classBody = startNode();
    classBody.body = [];
    expect(_braceL);
    while (!eat(_braceR)) {
      if (eat(_semi)) continue;
      var method = startNode();
      var isGenerator = eat(_star);
      parsePropertyName(method);
      if (tokType !== _parenL && !method.computed && method.key.type === "Identifier" &&
          method.key.name === "static") {
        if (isGenerator) unexpected();
        method['static'] = true;
        isGenerator = eat(_star);
        parsePropertyName(method);
      } else {
        method['static'] = false;
      }
      if (tokType !== _parenL && !method.computed && method.key.type === "Identifier" &&
          (method.key.name === "get" || method.key.name === "set")) {
        if (isGenerator) unexpected();
        method.kind = method.key.name;
        parsePropertyName(method);
      } else {
        method.kind = "";
      }
      method.value = parseMethod(isGenerator);
      classBody.body.push(finishNode(method, "MethodDefinition"));
    }
    node.body = finishNode(classBody, "ClassBody");
    return finishNode(node, isStatement ? "ClassDeclaration" : "ClassExpression");
  }

  // 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, refShorthandDefaultPos) {
    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 {
        if (tokType === _ellipsis)
          elts.push(parseSpread(refShorthandDefaultPos));
        else
          elts.push(parseMaybeAssign(false, refShorthandDefaultPos));
      }
    }
    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();
    }
    next();
    return finishNode(node, "Identifier");
  }

  // Parses module export declaration.

  function parseExport(node) {
    next();
    // export var|const|let|function|class ...;
    if (tokType === _var || tokType === _const || tokType === _let || tokType === _function || tokType === _class) {
      node.declaration = parseStatement(true);
      node['default'] = false;
      node.specifiers = null;
      node.source = null;
    } else
    // export default ...;
    if (eat(_default)) {
      var expr = parseMaybeAssign();
      if (expr.id) {
        switch (expr.type) {
          case "FunctionExpression": expr.type = "FunctionDeclaration"; break;
          case "ClassExpression": expr.type = "ClassDeclaration"; break;
        }
      }
      node.declaration = expr;
      node['default'] = true;
      node.specifiers = null;
      node.source = null;
      semicolon();
    } else {
      // export * from '...';
      // export { x, y as z } [from '...'];
      var isBatch = tokType === _star;
      node.declaration = null;
      node['default'] = false;
      node.specifiers = parseExportSpecifiers();
      if (eatContextual("from")) {
        node.source = tokType === _string ? parseExprAtom() : unexpected();
      } else {
        if (isBatch) unexpected();
        node.source = null;
      }
      semicolon();
    }
    return finishNode(node, "ExportDeclaration");
  }

  // Parses a comma-separated list of module exports.

  function parseExportSpecifiers() {
    var nodes = [], first = true;
    if (tokType === _star) {
      // export * from '...'
      var node = startNode();
      next();
      nodes.push(finishNode(node, "ExportBatchSpecifier"));
    } else {
      // export { x, y as z } [from '...']
      expect(_braceL);
      while (!eat(_braceR)) {
        if (!first) {
          expect(_comma);
          if (options.allowTrailingCommas && eat(_braceR)) break;
        } else first = false;

        var node = startNode();
        node.id = parseIdent(tokType === _default);
        node.name = eatContextual("as") ? parseIdent(true) : null;
        nodes.push(finishNode(node, "ExportSpecifier"));
      }
    }
    return nodes;
  }

  // Parses import declaration.

  function parseImport(node) {
    next();
    // import '...';
    if (tokType === _string) {
      node.specifiers = [];
      node.source = parseExprAtom();
      node.kind = "";
    } else {
      node.specifiers = parseImportSpecifiers();
      expectContextual("from");
      node.source = tokType === _string ? parseExprAtom() : unexpected();
    }
    semicolon();
    return finishNode(node, "ImportDeclaration");
  }

  // Parses a comma-separated list of module imports.

  function parseImportSpecifiers() {
    var nodes = [], first = true;
    if (tokType === _name) {
      // import defaultObj, { x, y as z } from '...'
      var node = startNode();
      node.id = parseIdent();
      checkLVal(node.id, true);
      node.name = null;
      node['default'] = true;
      nodes.push(finishNode(node, "ImportSpecifier"));
      if (!eat(_comma)) return nodes;
    }
    if (tokType === _star) {
      var node = startNode();
      next();
      expectContextual("as");
      node.name = parseIdent();
      checkLVal(node.name, true);
      nodes.push(finishNode(node, "ImportBatchSpecifier"));
      return nodes;
    }
    expect(_braceL);
    while (!eat(_braceR)) {
      if (!first) {
        expect(_comma);
        if (options.allowTrailingCommas && eat(_braceR)) break;
      } else first = false;

      var node = startNode();
      node.id = parseIdent(true);
      node.name = eatContextual("as") ? parseIdent() : null;
      checkLVal(node.name || node.id, true);
      node['default'] = false;
      nodes.push(finishNode(node, "ImportSpecifier"));
    }
    return nodes;
  }

  // Parses yield expression inside generator.

  function parseYield() {
    var node = startNode();
    next();
    if (eat(_semi) || canInsertSemicolon()) {
      node.delegate = false;
      node.argument = null;
    } else {
      node.delegate = eat(_star);
      node.argument = parseMaybeAssign();
    }
    return finishNode(node, "YieldExpression");
  }

  // Parses array and generator comprehensions.

  function parseComprehension(node, isGenerator) {
    node.blocks = [];
    while (tokType === _for) {
      var block = startNode();
      next();
      expect(_parenL);
      block.left = parseBindingAtom();
      checkLVal(block.left, true);
      expectContextual("of");
      block.right = parseExpression();
      expect(_parenR);
      node.blocks.push(finishNode(block, "ComprehensionBlock"));
    }
    node.filter = eat(_if) ? parseParenExpression() : null;
    node.body = parseExpression();
    expect(isGenerator ? _parenR : _bracketR);
    node.generator = isGenerator;
    return finishNode(node, "ComprehensionExpression");
  }
});