/*!
 * JSHint, by JSHint Community.
 *
 * This file (and this file only) is licensed under the same slightly modified
 * MIT license that JSLint is. It stops evil-doers everywhere:
 *
 *   Copyright (c) 2002 Douglas Crockford  (www.JSLint.com)
 *
 *   Permission is hereby granted, free of charge, to any person obtaining
 *   a copy of this software and associated documentation files (the "Software"),
 *   to deal in the Software without restriction, including without limitation
 *   the rights to use, copy, modify, merge, publish, distribute, sublicense,
 *   and/or sell copies of the Software, and to permit persons to whom
 *   the Software is furnished to do so, subject to the following conditions:
 *
 *   The above copyright notice and this permission notice shall be included
 *   in all copies or substantial portions of the Software.
 *
 *   The Software shall be used for Good, not Evil.
 *
 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 *   DEALINGS IN THE SOFTWARE.
 *
 */

/*jshint quotmark:double */
/*global console:true */
/*exported console */

var _            = require("lodash");
var events       = require("events");
var vars         = require("./vars.js");
var messages     = require("./messages.js");
var Lexer        = require("./lex.js").Lexer;
var reg          = require("./reg.js");
var state        = require("./state.js").state;
var style        = require("./style.js");
var options      = require("./options.js");
var scopeManager = require("./scope-manager.js");

// We need this module here because environments such as IE and Rhino
// don't necessarilly expose the 'console' API and browserify uses
// it to log things. It's a sad state of affair, really.
var console = require("console-browserify");

// We build the application inside a function so that we produce only a singleton
// variable. That function will be invoked immediately, and its return value is
// the JSHINT function itself.

var JSHINT = (function() {
  "use strict";

  var api, // Extension API

    // These are operators that should not be used with the ! operator.
    bang = {
      "<"  : true,
      "<=" : true,
      "==" : true,
      "===": true,
      "!==": true,
      "!=" : true,
      ">"  : true,
      ">=" : true,
      "+"  : true,
      "-"  : true,
      "*"  : true,
      "/"  : true,
      "%"  : true
    },

    declared, // Globals that were declared using /*global ... */ syntax.

    functionicity = [
      "closure", "exception", "global", "label",
      "outer", "unused", "var"
    ],

    functions, // All of the functions

    inblock,
    indent,
    lookahead,
    lex,
    member,
    membersOnly,
    predefined,    // Global variables defined by option

    stack,
    urls,

    extraModules = [],
    emitter = new events.EventEmitter();

  function checkOption(name, t) {
    name = name.trim();

    if (/^[+-]W\d{3}$/g.test(name)) {
      return true;
    }

    if (options.validNames.indexOf(name) === -1) {
      if (t.type !== "jslint" && !_.has(options.removed, name)) {
        error("E001", t, name);
        return false;
      }
    }

    return true;
  }

  function isString(obj) {
    return Object.prototype.toString.call(obj) === "[object String]";
  }

  function isIdentifier(tkn, value) {
    if (!tkn)
      return false;

    if (!tkn.identifier || tkn.value !== value)
      return false;

    return true;
  }

  function isReserved(token) {
    if (!token.reserved) {
      return false;
    }
    var meta = token.meta;

    if (meta && meta.isFutureReservedWord) {
      if (meta.moduleOnly && !state.option.module) {
        return false;
      }

      if (state.inES5()) {
        // ES3 FutureReservedWord in an ES5 environment.
        if (!meta.es5) {
          return false;
        }

        // Some ES5 FutureReservedWord identifiers are active only
        // within a strict mode environment.
        if (meta.strictOnly) {
          if (!state.option.strict && !state.isStrict()) {
            return false;
          }
        }

        if (token.isProperty) {
          return false;
        }
      }
    }

    return true;
  }

  function supplant(str, data) {
    return str.replace(/\{([^{}]*)\}/g, function(a, b) {
      var r = data[b];
      return typeof r === "string" || typeof r === "number" ? r : a;
    });
  }

  function combine(dest, src) {
    Object.keys(src).forEach(function(name) {
      if (_.has(JSHINT.blacklist, name)) return;
      dest[name] = src[name];
    });
  }

  function processenforceall() {
    if (state.option.enforceall) {
      for (var enforceopt in options.bool.enforcing) {
        if (state.option[enforceopt] === undefined &&
            !options.noenforceall[enforceopt]) {
          state.option[enforceopt] = true;
        }
      }
      for (var relaxopt in options.bool.relaxing) {
        if (state.option[relaxopt] === undefined) {
          state.option[relaxopt] = false;
        }
      }
    }
  }

  function assume() {
    var badESOpt = null;
    processenforceall();

    /**
     * TODO: Remove in JSHint 3
     */
    badESOpt = state.inferEsVersion();
    if (badESOpt) {
      quit("E059", state.tokens.next, "esversion", badESOpt);
    }

    if (state.inES5()) {
      combine(predefined, vars.ecmaIdentifiers[5]);
    }

    if (state.inES6()) {
      combine(predefined, vars.ecmaIdentifiers[6]);
    }

    /**
     * Use `in` to check for the presence of any explicitly-specified value for
     * `globalstrict` because both `true` and `false` should trigger an error.
     */
    if (state.option.strict === "global" && "globalstrict" in state.option) {
      quit("E059", state.tokens.next, "strict", "globalstrict");
    }

    if (state.option.module) {
      /**
       * TODO: Extend this restriction to *all* ES6-specific options.
       */
      if (!state.inES6()) {
        warning("W134", state.tokens.next, "module", 6);
      }
    }

    if (state.option.couch) {
      combine(predefined, vars.couch);
    }

    if (state.option.qunit) {
      combine(predefined, vars.qunit);
    }

    if (state.option.rhino) {
      combine(predefined, vars.rhino);
    }

    if (state.option.shelljs) {
      combine(predefined, vars.shelljs);
      combine(predefined, vars.node);
    }
    if (state.option.typed) {
      combine(predefined, vars.typed);
    }

    if (state.option.phantom) {
      combine(predefined, vars.phantom);
    }

    if (state.option.prototypejs) {
      combine(predefined, vars.prototypejs);
    }

    if (state.option.node) {
      combine(predefined, vars.node);
      combine(predefined, vars.typed);
    }

    if (state.option.devel) {
      combine(predefined, vars.devel);
    }

    if (state.option.dojo) {
      combine(predefined, vars.dojo);
    }

    if (state.option.browser) {
      combine(predefined, vars.browser);
      combine(predefined, vars.typed);
    }

    if (state.option.browserify) {
      combine(predefined, vars.browser);
      combine(predefined, vars.typed);
      combine(predefined, vars.browserify);
    }

    if (state.option.nonstandard) {
      combine(predefined, vars.nonstandard);
    }

    if (state.option.jasmine) {
      combine(predefined, vars.jasmine);
    }

    if (state.option.jquery) {
      combine(predefined, vars.jquery);
    }

    if (state.option.mootools) {
      combine(predefined, vars.mootools);
    }

    if (state.option.worker) {
      combine(predefined, vars.worker);
    }

    if (state.option.wsh) {
      combine(predefined, vars.wsh);
    }

    if (state.option.yui) {
      combine(predefined, vars.yui);
    }

    if (state.option.mocha) {
      combine(predefined, vars.mocha);
    }
  }

  // Produce an error warning.
  function quit(code, token, a, b) {
    var percentage = Math.floor((token.line / state.lines.length) * 100);
    var message = messages.errors[code].desc;

    var exception = {
      name: "JSHintError",
      line: token.line,
      character: token.from,
      message: message + " (" + percentage + "% scanned).",
      raw: message,
      code: code,
      a: a,
      b: b
    };

    exception.reason = supplant(message, exception) + " (" + percentage +
      "% scanned).";

    throw exception;
  }

  function removeIgnoredMessages() {
    var ignored = state.ignoredLines;

    if (_.isEmpty(ignored)) return;
    JSHINT.errors = _.reject(JSHINT.errors, function(err) { return ignored[err.line] });
  }

  function warning(code, t, a, b, c, d) {
    var ch, l, w, msg;

    if (/^W\d{3}$/.test(code)) {
      if (state.ignored[code])
        return;

      msg = messages.warnings[code];
    } else if (/E\d{3}/.test(code)) {
      msg = messages.errors[code];
    } else if (/I\d{3}/.test(code)) {
      msg = messages.info[code];
    }

    t = t || state.tokens.next || {};
    if (t.id === "(end)") {  // `~
      t = state.tokens.curr;
    }

    l = t.line;
    ch = t.from;

    w = {
      id: "(error)",
      raw: msg.desc,
      code: msg.code,
      evidence: state.lines[l - 1] || "",
      line: l,
      character: ch,
      scope: JSHINT.scope,
      a: a,
      b: b,
      c: c,
      d: d
    };

    w.reason = supplant(msg.desc, w);
    JSHINT.errors.push(w);

    removeIgnoredMessages();

    if (JSHINT.errors.length >= state.option.maxerr)
      quit("E043", t);

    return w;
  }

  function warningAt(m, l, ch, a, b, c, d) {
    return warning(m, {
      line: l,
      from: ch
    }, a, b, c, d);
  }

  function error(m, t, a, b, c, d) {
    warning(m, t, a, b, c, d);
  }

  function errorAt(m, l, ch, a, b, c, d) {
    return error(m, {
      line: l,
      from: ch
    }, a, b, c, d);
  }

  // Tracking of "internal" scripts, like eval containing a static string
  function addInternalSrc(elem, src) {
    var i;
    i = {
      id: "(internal)",
      elem: elem,
      value: src
    };
    JSHINT.internals.push(i);
    return i;
  }

  function doOption() {
    var nt = state.tokens.next;
    var body = nt.body.split(",").map(function(s) { return s.trim(); });

    var predef = {};
    if (nt.type === "globals") {
      body.forEach(function(g, idx) {
        g = g.split(":");
        var key = (g[0] || "").trim();
        var val = (g[1] || "").trim();

        if (key === "-" || !key.length) {
          // Ignore trailing comma
          if (idx > 0 && idx === body.length - 1) {
            return;
          }
          error("E002", nt);
          return;
        }

        if (key.charAt(0) === "-") {
          key = key.slice(1);
          val = false;

          JSHINT.blacklist[key] = key;
          delete predefined[key];
        } else {
          predef[key] = (val === "true");
        }
      });

      combine(predefined, predef);

      for (var key in predef) {
        if (_.has(predef, key)) {
          declared[key] = nt;
        }
      }
    }

    if (nt.type === "exported") {
      body.forEach(function(e, idx) {
        if (!e.length) {
          // Ignore trailing comma
          if (idx > 0 && idx === body.length - 1) {
            return;
          }
          error("E002", nt);
          return;
        }

        state.funct["(scope)"].addExported(e);
      });
    }

    if (nt.type === "members") {
      membersOnly = membersOnly || {};

      body.forEach(function(m) {
        var ch1 = m.charAt(0);
        var ch2 = m.charAt(m.length - 1);

        if (ch1 === ch2 && (ch1 === "\"" || ch1 === "'")) {
          m = m
            .substr(1, m.length - 2)
            .replace("\\\"", "\"");
        }

        membersOnly[m] = false;
      });
    }

    var numvals = [
      "maxstatements",
      "maxparams",
      "maxdepth",
      "maxcomplexity",
      "maxerr",
      "maxlen",
      "indent"
    ];

    if (nt.type === "jshint" || nt.type === "jslint") {
      body.forEach(function(g) {
        g = g.split(":");
        var key = (g[0] || "").trim();
        var val = (g[1] || "").trim();

        if (!checkOption(key, nt)) {
          return;
        }

        if (numvals.indexOf(key) >= 0) {
          // GH988 - numeric options can be disabled by setting them to `false`
          if (val !== "false") {
            val = +val;

            if (typeof val !== "number" || !isFinite(val) || val <= 0 || Math.floor(val) !== val) {
              error("E032", nt, g[1].trim());
              return;
            }

            state.option[key] = val;
          } else {
            state.option[key] = key === "indent" ? 4 : false;
          }

          return;
        }

        if (key === "validthis") {
          // `validthis` is valid only within a function scope.

          if (state.funct["(global)"])
            return void error("E009");

          if (val !== "true" && val !== "false")
            return void error("E002", nt);

          state.option.validthis = (val === "true");
          return;
        }

        if (key === "quotmark") {
          switch (val) {
          case "true":
          case "false":
            state.option.quotmark = (val === "true");
            break;
          case "double":
          case "single":
            state.option.quotmark = val;
            break;
          default:
            error("E002", nt);
          }
          return;
        }

        if (key === "shadow") {
          switch (val) {
          case "true":
            state.option.shadow = true;
            break;
          case "outer":
            state.option.shadow = "outer";
            break;
          case "false":
          case "inner":
            state.option.shadow = "inner";
            break;
          default:
            error("E002", nt);
          }
          return;
        }

        if (key === "unused") {
          switch (val) {
          case "true":
            state.option.unused = true;
            break;
          case "false":
            state.option.unused = false;
            break;
          case "vars":
          case "strict":
            state.option.unused = val;
            break;
          default:
            error("E002", nt);
          }
          return;
        }

        if (key === "latedef") {
          switch (val) {
          case "true":
            state.option.latedef = true;
            break;
          case "false":
            state.option.latedef = false;
            break;
          case "nofunc":
            state.option.latedef = "nofunc";
            break;
          default:
            error("E002", nt);
          }
          return;
        }

        if (key === "ignore") {
          switch (val) {
          case "line":
            state.ignoredLines[nt.line] = true;
            removeIgnoredMessages();
            break;
          default:
            error("E002", nt);
          }
          return;
        }

        if (key === "strict") {
          switch (val) {
          case "true":
            state.option.strict = true;
            break;
          case "false":
            state.option.strict = false;
            break;
          case "global":
          case "implied":
            state.option.strict = val;
            break;
          default:
            error("E002", nt);
          }
          return;
        }

        if (key === "module") {
          /**
           * TODO: Extend this restriction to *all* "environmental" options.
           */
          if (!hasParsedCode(state.funct)) {
            error("E055", state.tokens.next, "module");
          }
        }

        if (key === "esversion") {
          switch (val) {
          case "3":
          case "5":
          case "6":
            state.option.moz = false;
            state.option.esversion = +val;
            break;
          case "2015":
            state.option.moz = false;
            state.option.esversion = 6;
            break;
          default:
            error("E002", nt);
          }
          if (!hasParsedCode(state.funct)) {
            error("E055", state.tokens.next, "esversion");
          }
          return;
        }

        var match = /^([+-])(W\d{3})$/g.exec(key);
        if (match) {
          // ignore for -W..., unignore for +W...
          state.ignored[match[2]] = (match[1] === "-");
          return;
        }

        var tn;
        if (val === "true" || val === "false") {
          if (nt.type === "jslint") {
            tn = options.renamed[key] || key;
            state.option[tn] = (val === "true");

            if (options.inverted[tn] !== undefined) {
              state.option[tn] = !state.option[tn];
            }
          } else {
            state.option[key] = (val === "true");
          }

          return;
        }

        error("E002", nt);
      });

      assume();
    }
  }

  // We need a peek function. If it has an argument, it peeks that much farther
  // ahead. It is used to distinguish
  //     for ( var i in ...
  // from
  //     for ( var i = ...

  function peek(p) {
    var i = p || 0, j = lookahead.length, t;

    if (i < j) {
      return lookahead[i];
    }

    while (j <= i) {
      t = lookahead[j];
      if (!t) {
        t = lookahead[j] = lex.token();
      }
      j += 1;
    }

    // Peeking past the end of the program should produce the "(end)" token.
    if (!t && state.tokens.next.id === "(end)") {
      return state.tokens.next;
    }

    return t;
  }

  function peekIgnoreEOL() {
    var i = 0;
    var t;
    do {
      t = peek(i++);
    } while (t.id === "(endline)");
    return t;
  }

  // Produce the next token. It looks for programming errors.

  function advance(id, t) {

    switch (state.tokens.curr.id) {
    case "(number)":
      if (state.tokens.next.id === ".") {
        warning("W005", state.tokens.curr);
      }
      break;
    case "-":
      if (state.tokens.next.id === "-" || state.tokens.next.id === "--") {
        warning("W006");
      }
      break;
    case "+":
      if (state.tokens.next.id === "+" || state.tokens.next.id === "++") {
        warning("W007");
      }
      break;
    }

    if (id && state.tokens.next.id !== id) {
      if (t) {
        if (state.tokens.next.id === "(end)") {
          error("E019", t, t.id);
        } else {
          error("E020", state.tokens.next, id, t.id, t.line, state.tokens.next.value);
        }
      } else if (state.tokens.next.type !== "(identifier)" || state.tokens.next.value !== id) {
        warning("W116", state.tokens.next, id, state.tokens.next.value);
      }
    }

    state.tokens.prev = state.tokens.curr;
    state.tokens.curr = state.tokens.next;
    for (;;) {
      state.tokens.next = lookahead.shift() || lex.token();

      if (!state.tokens.next) { // No more tokens left, give up
        quit("E041", state.tokens.curr);
      }

      if (state.tokens.next.id === "(end)" || state.tokens.next.id === "(error)") {
        return;
      }

      if (state.tokens.next.check) {
        state.tokens.next.check();
      }

      if (state.tokens.next.isSpecial) {
        if (state.tokens.next.type === "falls through") {
          state.tokens.curr.caseFallsThrough = true;
        } else {
          doOption();
        }
      } else {
        if (state.tokens.next.id !== "(endline)") {
          break;
        }
      }
    }
  }

  function isInfix(token) {
    return token.infix || (!token.identifier && !token.template && !!token.led);
  }

  function isEndOfExpr() {
    var curr = state.tokens.curr;
    var next = state.tokens.next;
    if (next.id === ";" || next.id === "}" || next.id === ":") {
      return true;
    }
    if (isInfix(next) === isInfix(curr) || (curr.id === "yield" && state.inMoz())) {
      return curr.line !== startLine(next);
    }
    return false;
  }

  function isBeginOfExpr(prev) {
    return !prev.left && prev.arity !== "unary";
  }

  // This is the heart of JSHINT, the Pratt parser. In addition to parsing, it
  // is looking for ad hoc lint patterns. We add .fud to Pratt's model, which is
  // like .nud except that it is only used on the first token of a statement.
  // Having .fud makes it much easier to define statement-oriented languages like
  // JavaScript. I retained Pratt's nomenclature.

  // .nud  Null denotation
  // .fud  First null denotation
  // .led  Left denotation
  //  lbp  Left binding power
  //  rbp  Right binding power

  // They are elements of the parsing method called Top Down Operator Precedence.

  function expression(rbp, initial) {
    var left, isArray = false, isObject = false, isLetExpr = false;

    state.nameStack.push();

    // if current expression is a let expression
    if (!initial && state.tokens.next.value === "let" && peek(0).value === "(") {
      if (!state.inMoz()) {
        warning("W118", state.tokens.next, "let expressions");
      }
      isLetExpr = true;
      // create a new block scope we use only for the current expression
      state.funct["(scope)"].stack();
      advance("let");
      advance("(");
      state.tokens.prev.fud();
      advance(")");
    }

    if (state.tokens.next.id === "(end)")
      error("E006", state.tokens.curr);

    var isDangerous =
      state.option.asi &&
      state.tokens.prev.line !== startLine(state.tokens.curr) &&
      _.contains(["]", ")"], state.tokens.prev.id) &&
      _.contains(["[", "("], state.tokens.curr.id);

    if (isDangerous)
      warning("W014", state.tokens.curr, state.tokens.curr.id);

    advance();

    if (initial) {
      state.funct["(verb)"] = state.tokens.curr.value;
      state.tokens.curr.beginsStmt = true;
    }

    if (initial === true && state.tokens.curr.fud) {
      left = state.tokens.curr.fud();
    } else {
      if (state.tokens.curr.nud) {
        left = state.tokens.curr.nud();
      } else {
        error("E030", state.tokens.curr, state.tokens.curr.id);
      }

      while (rbp < state.tokens.next.lbp && !isEndOfExpr()) {
        isArray = state.tokens.curr.value === "Array";
        isObject = state.tokens.curr.value === "Object";

        // #527, new Foo.Array(), Foo.Array(), new Foo.Object(), Foo.Object()
        // Line breaks in IfStatement heads exist to satisfy the checkJSHint
        // "Line too long." error.
        if (left && (left.value || (left.first && left.first.value))) {
          // If the left.value is not "new", or the left.first.value is a "."
          // then safely assume that this is not "new Array()" and possibly
          // not "new Object()"...
          if (left.value !== "new" ||
            (left.first && left.first.value && left.first.value === ".")) {
            isArray = false;
            // ...In the case of Object, if the left.value and state.tokens.curr.value
            // are not equal, then safely assume that this not "new Object()"
            if (left.value !== state.tokens.curr.value) {
              isObject = false;
            }
          }
        }

        advance();

        if (isArray && state.tokens.curr.id === "(" && state.tokens.next.id === ")") {
          warning("W009", state.tokens.curr);
        }

        if (isObject && state.tokens.curr.id === "(" && state.tokens.next.id === ")") {
          warning("W010", state.tokens.curr);
        }

        if (left && state.tokens.curr.led) {
          left = state.tokens.curr.led(left);
        } else {
          error("E033", state.tokens.curr, state.tokens.curr.id);
        }
      }
    }
    if (isLetExpr) {
      state.funct["(scope)"].unstack();
    }

    state.nameStack.pop();

    return left;
  }


  // Functions for conformance of style.

  function startLine(token) {
    return token.startLine || token.line;
  }

  function nobreaknonadjacent(left, right) {
    left = left || state.tokens.curr;
    right = right || state.tokens.next;
    if (!state.option.laxbreak && left.line !== startLine(right)) {
      warning("W014", right, right.value);
    }
  }

  function nolinebreak(t) {
    t = t || state.tokens.curr;
    if (t.line !== startLine(state.tokens.next)) {
      warning("E022", t, t.value);
    }
  }

  function nobreakcomma(left, right) {
    if (left.line !== startLine(right)) {
      if (!state.option.laxcomma) {
        if (parseComma.first) {
          warning("I001");
          parseComma.first = false;
        }
        warning("W014", left, right.value);
      }
    }
  }

  function parseComma(opts) {
    opts = opts || {};

    if (!opts.peek) {
      nobreakcomma(state.tokens.curr, state.tokens.next);
      advance(",");
    } else {
      nobreakcomma(state.tokens.prev, state.tokens.curr);
    }

    if (state.tokens.next.identifier && !(opts.property && state.inES5())) {
      // Keywords that cannot follow a comma operator.
      switch (state.tokens.next.value) {
      case "break":
      case "case":
      case "catch":
      case "continue":
      case "default":
      case "do":
      case "else":
      case "finally":
      case "for":
      case "if":
      case "in":
      case "instanceof":
      case "return":
      case "switch":
      case "throw":
      case "try":
      case "var":
      case "let":
      case "while":
      case "with":
        error("E024", state.tokens.next, state.tokens.next.value);
        return false;
      }
    }

    if (state.tokens.next.type === "(punctuator)") {
      switch (state.tokens.next.value) {
      case "}":
      case "]":
      case ",":
        if (opts.allowTrailing) {
          return true;
        }

        /* falls through */
      case ")":
        error("E024", state.tokens.next, state.tokens.next.value);
        return false;
      }
    }
    return true;
  }

  // Functional constructors for making the symbols that will be inherited by
  // tokens.

  function symbol(s, p) {
    var x = state.syntax[s];
    if (!x || typeof x !== "object") {
      state.syntax[s] = x = {
        id: s,
        lbp: p,
        value: s
      };
    }
    return x;
  }

  function delim(s) {
    var x = symbol(s, 0);
    x.delim = true;
    return x;
  }

  function stmt(s, f) {
    var x = delim(s);
    x.identifier = x.reserved = true;
    x.fud = f;
    return x;
  }

  function blockstmt(s, f) {
    var x = stmt(s, f);
    x.block = true;
    return x;
  }

  function reserveName(x) {
    var c = x.id.charAt(0);
    if ((c >= "a" && c <= "z") || (c >= "A" && c <= "Z")) {
      x.identifier = x.reserved = true;
    }
    return x;
  }

  function prefix(s, f) {
    var x = symbol(s, 150);
    reserveName(x);

    x.nud = (typeof f === "function") ? f : function() {
      this.arity = "unary";
      this.right = expression(150);

      if (this.id === "++" || this.id === "--") {
        if (state.option.plusplus) {
          warning("W016", this, this.id);
        } else if (this.right && (!this.right.identifier || isReserved(this.right)) &&
            this.right.id !== "." && this.right.id !== "[") {
          warning("W017", this);
        }

        if (this.right && this.right.isMetaProperty) {
          error("E031", this);
        // detect increment/decrement of a const
        // in the case of a.b, right will be the "." punctuator
        } else if (this.right && this.right.identifier) {
          state.funct["(scope)"].block.modify(this.right.value, this);
        }
      }

      return this;
    };

    return x;
  }

  function type(s, f) {
    var x = delim(s);
    x.type = s;
    x.nud = f;
    return x;
  }

  function reserve(name, func) {
    var x = type(name, func);
    x.identifier = true;
    x.reserved = true;
    return x;
  }

  function FutureReservedWord(name, meta) {
    var x = type(name, (meta && meta.nud) || function() {
      return this;
    });

    meta = meta || {};
    meta.isFutureReservedWord = true;

    x.value = name;
    x.identifier = true;
    x.reserved = true;
    x.meta = meta;

    return x;
  }

  function reservevar(s, v) {
    return reserve(s, function() {
      if (typeof v === "function") {
        v(this);
      }
      return this;
    });
  }

  function infix(s, f, p, w) {
    var x = symbol(s, p);
    reserveName(x);
    x.infix = true;
    x.led = function(left) {
      if (!w) {
        nobreaknonadjacent(state.tokens.prev, state.tokens.curr);
      }
      if ((s === "in" || s === "instanceof") && left.id === "!") {
        warning("W018", left, "!");
      }
      if (typeof f === "function") {
        return f(left, this);
      } else {
        this.left = left;
        this.right = expression(p);
        return this;
      }
    };
    return x;
  }

  function application(s) {
    var x = symbol(s, 42);

    x.led = function(left) {
      nobreaknonadjacent(state.tokens.prev, state.tokens.curr);

      this.left = left;
      this.right = doFunction({ type: "arrow", loneArg: left });
      return this;
    };
    return x;
  }

  function relation(s, f) {
    var x = symbol(s, 100);

    x.led = function(left) {
      nobreaknonadjacent(state.tokens.prev, state.tokens.curr);
      this.left = left;
      var right = this.right = expression(100);

      if (isIdentifier(left, "NaN") || isIdentifier(right, "NaN")) {
        warning("W019", this);
      } else if (f) {
        f.apply(this, [left, right]);
      }

      if (!left || !right) {
        quit("E041", state.tokens.curr);
      }

      if (left.id === "!") {
        warning("W018", left, "!");
      }

      if (right.id === "!") {
        warning("W018", right, "!");
      }

      return this;
    };
    return x;
  }

  function isPoorRelation(node) {
    return node &&
        ((node.type === "(number)" && +node.value === 0) ||
         (node.type === "(string)" && node.value === "") ||
         (node.type === "null" && !state.option.eqnull) ||
        node.type === "true" ||
        node.type === "false" ||
        node.type === "undefined");
  }

  var typeofValues = {};
  typeofValues.legacy = [
    // E4X extended the `typeof` operator to return "xml" for the XML and
    // XMLList types it introduced.
    // Ref: 11.3.2 The typeof Operator
    // http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-357.pdf
    "xml",
    // IE<9 reports "unknown" when the `typeof` operator is applied to an
    // object existing across a COM+ bridge. In lieu of official documentation
    // (which does not exist), see:
    // http://robertnyman.com/2005/12/21/what-is-typeof-unknown/
    "unknown"
  ];
  typeofValues.es3 = [
    "undefined", "boolean", "number", "string", "function", "object",
  ];
  typeofValues.es3 = typeofValues.es3.concat(typeofValues.legacy);
  typeofValues.es6 = typeofValues.es3.concat("symbol");

  // Checks whether the 'typeof' operator is used with the correct
  // value. For docs on 'typeof' see:
  // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/typeof
  function isTypoTypeof(left, right, state) {
    var values;

    if (state.option.notypeof)
      return false;

    if (!left || !right)
      return false;

    values = state.inES6() ? typeofValues.es6 : typeofValues.es3;

    if (right.type === "(identifier)" && right.value === "typeof" && left.type === "(string)")
      return !_.contains(values, left.value);

    return false;
  }

  function isGlobalEval(left, state) {
    var isGlobal = false;

    // permit methods to refer to an "eval" key in their own context
    if (left.type === "this" && state.funct["(context)"] === null) {
      isGlobal = true;
    }
    // permit use of "eval" members of objects
    else if (left.type === "(identifier)") {
      if (state.option.node && left.value === "global") {
        isGlobal = true;
      }

      else if (state.option.browser && (left.value === "window" || left.value === "document")) {
        isGlobal = true;
      }
    }

    return isGlobal;
  }

  function findNativePrototype(left) {
    var natives = [
      "Array", "ArrayBuffer", "Boolean", "Collator", "DataView", "Date",
      "DateTimeFormat", "Error", "EvalError", "Float32Array", "Float64Array",
      "Function", "Infinity", "Intl", "Int16Array", "Int32Array", "Int8Array",
      "Iterator", "Number", "NumberFormat", "Object", "RangeError",
      "ReferenceError", "RegExp", "StopIteration", "String", "SyntaxError",
      "TypeError", "Uint16Array", "Uint32Array", "Uint8Array", "Uint8ClampedArray",
      "URIError"
    ];

    function walkPrototype(obj) {
      if (typeof obj !== "object") return;
      return obj.right === "prototype" ? obj : walkPrototype(obj.left);
    }

    function walkNative(obj) {
      while (!obj.identifier && typeof obj.left === "object")
        obj = obj.left;

      if (obj.identifier && natives.indexOf(obj.value) >= 0 &&
          state.funct["(scope)"].isPredefined(obj.value)) {
        return obj.value;
      }
    }

    var prototype = walkPrototype(left);
    if (prototype) return walkNative(prototype);
  }

  /**
   * Checks the left hand side of an assignment for issues, returns if ok
   * @param {token} left - the left hand side of the assignment
   * @param {token=} assignToken - the token for the assignment, used for reporting
   * @param {object=} options - optional object
   * @param {boolean} options.allowDestructuring - whether to allow destructuting binding
   * @returns {boolean} Whether the left hand side is OK
   */
  function checkLeftSideAssign(left, assignToken, options) {

    var allowDestructuring = options && options.allowDestructuring;

    assignToken = assignToken || left;

    if (state.option.freeze) {
      var nativeObject = findNativePrototype(left);
      if (nativeObject)
        warning("W121", left, nativeObject);
    }
    if (checkPunctuator(left, "...")) {
      left = left.right;
    }

    if (left.identifier && !left.isMetaProperty) {
      // reassign also calls modify
      // but we are specific in order to catch function re-assignment
      // and globals re-assignment
      state.funct["(scope)"].block.reassign(left.value, left);
    }

    if (left.id === ".") {
      if (!left.left || left.left.value === "arguments" && !state.isStrict()) {
        warning("E031", assignToken);
      }

      state.nameStack.set(state.tokens.prev);
      return true;
    } else if (left.id === "{" || left.id === "[") {
      if (allowDestructuring && left.destructAssign) {
        left.destructAssign.forEach(function(t) {
          if (t.id) {
            state.funct["(scope)"].block.modify(t.id, t.token);
          }
        });
      } else {
        if (left.id === "{" || !left.left) {
          warning("E031", assignToken);
        } else if (left.left.value === "arguments" && !state.isStrict()) {
          warning("E031", assignToken);
        }
      }

      if (left.id === "[") {
        state.nameStack.set(left.right);
      }

      return true;
    } else if (left.identifier && !isReserved(left) && !left.isMetaProperty) {
      if (state.funct["(scope)"].labeltype(left.value) === "exception") {
        warning("W022", left);
      }
      state.nameStack.set(left);
      return true;
    }

    if (left === state.syntax["function"]) {
      warning("W023", state.tokens.curr);
    } else {
      error("E031", assignToken);
    }

    return false;
  }

  function assignop(s, f, p) {
    var x = infix(s, typeof f === "function" ? f : function(left, that) {
      that.left = left;

      checkLeftSideAssign(left, that, { allowDestructuring: true });

      that.right = expression(10);

      return that;
    }, p);

    x.exps = true;
    x.assign = true;
    return x;
  }


  function bitwise(s, f, p) {
    var x = symbol(s, p);
    reserveName(x);
    x.led = (typeof f === "function") ? f : function(left) {
      if (state.option.bitwise) {
        warning("W016", this, this.id);
      }
      this.left = left;
      this.right = expression(p);
      return this;
    };
    return x;
  }

  function bitwiseassignop(s) {
    return assignop(s, function(left, that) {
      if (state.option.bitwise) {
        warning("W016", that, that.id);
      }

      checkLeftSideAssign(left, that);

      that.right = expression(10);

      return that;
    }, 20);
  }

  function suffix(s) {
    var x = symbol(s, 150);

    x.led = function(left) {
      // this = suffix e.g. "++" punctuator
      // left = symbol operated e.g. "a" identifier or "a.b" punctuator
      if (state.option.plusplus) {
        warning("W016", this, this.id);
      } else if ((!left.identifier || isReserved(left)) && left.id !== "." && left.id !== "[") {
        warning("W017", this);
      }

      if (left.isMetaProperty) {
        error("E031", this);
      // detect increment/decrement of a const
      // in the case of a.b, left will be the "." punctuator
      } else if (left && left.identifier) {
        state.funct["(scope)"].block.modify(left.value, left);
      }

      this.left = left;
      return this;
    };
    return x;
  }

  // fnparam means that this identifier is being defined as a function
  // argument (see identifier())
  // prop means that this identifier is that of an object property

  function optionalidentifier(fnparam, prop, preserve) {
    if (!state.tokens.next.identifier) {
      return;
    }

    if (!preserve) {
      advance();
    }

    var curr = state.tokens.curr;
    var val  = state.tokens.curr.value;

    if (!isReserved(curr)) {
      return val;
    }

    if (prop) {
      if (state.inES5()) {
        return val;
      }
    }

    if (fnparam && val === "undefined") {
      return val;
    }

    warning("W024", state.tokens.curr, state.tokens.curr.id);
    return val;
  }

  // fnparam means that this identifier is being defined as a function
  // argument
  // prop means that this identifier is that of an object property
  function identifier(fnparam, prop) {
    var i = optionalidentifier(fnparam, prop, false);
    if (i) {
      return i;
    }

    // parameter destructuring with rest operator
    if (state.tokens.next.value === "...") {
      if (!state.inES6(true)) {
        warning("W119", state.tokens.next, "spread/rest operator", "6");
      }
      advance();

      if (checkPunctuator(state.tokens.next, "...")) {
        warning("E024", state.tokens.next, "...");
        while (checkPunctuator(state.tokens.next, "...")) {
          advance();
        }
      }

      if (!state.tokens.next.identifier) {
        warning("E024", state.tokens.curr, "...");
        return;
      }

      return identifier(fnparam, prop);
    } else {
      error("E030", state.tokens.next, state.tokens.next.value);

      // The token should be consumed after a warning is issued so the parser
      // can continue as though an identifier were found. The semicolon token
      // should not be consumed in this way so that the parser interprets it as
      // a statement delimeter;
      if (state.tokens.next.id !== ";") {
        advance();
      }
    }
  }


  function reachable(controlToken) {
    var i = 0, t;
    if (state.tokens.next.id !== ";" || controlToken.inBracelessBlock) {
      return;
    }
    for (;;) {
      do {
        t = peek(i);
        i += 1;
      } while (t.id !== "(end)" && t.id === "(comment)");

      if (t.reach) {
        return;
      }
      if (t.id !== "(endline)") {
        if (t.id === "function") {
          if (state.option.latedef === true) {
            warning("W026", t);
          }
          break;
        }

        warning("W027", t, t.value, controlToken.value);
        break;
      }
    }
  }

  function parseFinalSemicolon() {
    if (state.tokens.next.id !== ";") {
      // don't complain about unclosed templates / strings
      if (state.tokens.next.isUnclosed) return advance();

      var sameLine = startLine(state.tokens.next) === state.tokens.curr.line &&
                     state.tokens.next.id !== "(end)";
      var blockEnd = checkPunctuator(state.tokens.next, "}");

      if (sameLine && !blockEnd) {
        errorAt("E058", state.tokens.curr.line, state.tokens.curr.character);
      } else if (!state.option.asi) {
        // If this is the last statement in a block that ends on
        // the same line *and* option lastsemic is on, ignore the warning.
        // Otherwise, complain about missing semicolon.
        if ((blockEnd && !state.option.lastsemic) || !sameLine) {
          warningAt("W033", state.tokens.curr.line, state.tokens.curr.character);
        }
      }
    } else {
      advance(";");
    }
  }

  function statement() {
    var i = indent, r, t = state.tokens.next, hasOwnScope = false;

    if (t.id === ";") {
      advance(";");
      return;
    }

    // Is this a labelled statement?
    var res = isReserved(t);

    // We're being more tolerant here: if someone uses
    // a FutureReservedWord as a label, we warn but proceed
    // anyway.

    if (res && t.meta && t.meta.isFutureReservedWord && peek().id === ":") {
      warning("W024", t, t.id);
      res = false;
    }

    if (t.identifier && !res && peek().id === ":") {
      advance();
      advance(":");

      hasOwnScope = true;
      state.funct["(scope)"].stack();
      state.funct["(scope)"].block.addBreakLabel(t.value, { token: state.tokens.curr });

      if (!state.tokens.next.labelled && state.tokens.next.value !== "{") {
        warning("W028", state.tokens.next, t.value, state.tokens.next.value);
      }

      state.tokens.next.label = t.value;
      t = state.tokens.next;
    }

    // Is it a lonely block?

    if (t.id === "{") {
      // Is it a switch case block?
      //
      //  switch (foo) {
      //    case bar: { <= here.
      //      ...
      //    }
      //  }
      var iscase = (state.funct["(verb)"] === "case" && state.tokens.curr.value === ":");
      block(true, true, false, false, iscase);
      return;
    }

    // Parse the statement.

    r = expression(0, true);

    if (r && !(r.identifier && r.value === "function") &&
        !(r.type === "(punctuator)" && r.left &&
          r.left.identifier && r.left.value === "function")) {
      if (!state.isStrict() && state.stmtMissingStrict()) {
        warning("E007");
      }
    }

    // Look for the final semicolon.

    if (!t.block) {
      if (!state.option.expr && (!r || !r.exps)) {
        warning("W030", state.tokens.curr);
      } else if (state.option.nonew && r && r.left && r.id === "(" && r.left.id === "new") {
        warning("W031", t);
      }
      parseFinalSemicolon();
    }


    // Restore the indentation.

    indent = i;
    if (hasOwnScope) {
      state.funct["(scope)"].unstack();
    }
    return r;
  }


  function statements() {
    var a = [], p;

    while (!state.tokens.next.reach && state.tokens.next.id !== "(end)") {
      if (state.tokens.next.id === ";") {
        p = peek();

        if (!p || (p.id !== "(" && p.id !== "[")) {
          warning("W032");
        }

        advance(";");
      } else {
        a.push(statement());
      }
    }
    return a;
  }


  /*
   * read all directives
   * recognizes a simple form of asi, but always
   * warns, if it is used
   */
  function directives() {
    var i, p, pn;

    while (state.tokens.next.id === "(string)") {
      p = peek(0);
      if (p.id === "(endline)") {
        i = 1;
        do {
          pn = peek(i++);
        } while (pn.id === "(endline)");
        if (pn.id === ";") {
          p = pn;
        } else if (pn.value === "[" || pn.value === ".") {
          // string -> [ | . is a valid production
          break;
        } else if (!state.option.asi || pn.value === "(") {
          // string -> ( is not a valid production
          warning("W033", state.tokens.next);
        }
      } else if (p.id === "." || p.id === "[") {
        break;
      } else if (p.id !== ";") {
        warning("W033", p);
      }

      advance();
      var directive = state.tokens.curr.value;
      if (state.directive[directive] ||
          (directive === "use strict" && state.option.strict === "implied")) {
        warning("W034", state.tokens.curr, directive);
      }

      // there's no directive negation, so always set to true
      state.directive[directive] = true;

      if (p.id === ";") {
        advance(";");
      }
    }

    if (state.isStrict()) {
      state.option.undef = true;
    }
  }


  /*
   * Parses a single block. A block is a sequence of statements wrapped in
   * braces.
   *
   * ordinary   - true for everything but function bodies and try blocks.
   * stmt       - true if block can be a single statement (e.g. in if/for/while).
   * isfunc     - true if block is a function body
   * isfatarrow - true if its a body of a fat arrow function
   * iscase      - true if block is a switch case block
   */
  function block(ordinary, stmt, isfunc, isfatarrow, iscase) {
    var a,
      b = inblock,
      old_indent = indent,
      m,
      t,
      line,
      d;

    inblock = ordinary;

    t = state.tokens.next;

    var metrics = state.funct["(metrics)"];
    metrics.nestedBlockDepth += 1;
    metrics.verifyMaxNestedBlockDepthPerFunction();

    if (state.tokens.next.id === "{") {
      advance("{");

      // create a new block scope
      state.funct["(scope)"].stack();
      state.funct["(noblockscopedvar)"] = false;

      line = state.tokens.curr.line;
      if (state.tokens.next.id !== "}") {
        indent += state.option.indent;
        while (!ordinary && state.tokens.next.from > indent) {
          indent += state.option.indent;
        }

        if (isfunc) {
          m = {};
          for (d in state.directive) {
            if (_.has(state.directive, d)) {
              m[d] = state.directive[d];
            }
          }
          directives();

          if (state.option.strict && state.funct["(context)"]["(global)"]) {
            if (!m["use strict"] && !state.isStrict()) {
              warning("E007");
            }
          }
        }

        a = statements();

        metrics.statementCount += a.length;

        indent -= state.option.indent;
      }

      advance("}", t);

      if (isfunc) {
        state.funct["(scope)"].validateParams();
        if (m) {
          state.directive = m;
        }
      }

      state.funct["(scope)"].unstack();

      indent = old_indent;
    } else if (!ordinary) {
      if (isfunc) {
        state.funct["(scope)"].stack();

        m = {};
        if (stmt && !isfatarrow && !state.inMoz()) {
          error("W118", state.tokens.curr, "function closure expressions");
        }

        if (!stmt) {
          for (d in state.directive) {
            if (_.has(state.directive, d)) {
              m[d] = state.directive[d];
            }
          }
        }
        expression(10);

        if (state.option.strict && state.funct["(context)"]["(global)"]) {
          if (!m["use strict"] && !state.isStrict()) {
            warning("E007");
          }
        }

        state.funct["(scope)"].unstack();
      } else {
        error("E021", state.tokens.next, "{", state.tokens.next.value);
      }
    } else {

      // check to avoid let declaration not within a block
      // though is fine inside for loop initializer section
      state.funct["(noblockscopedvar)"] = state.tokens.next.id !== "for";
      state.funct["(scope)"].stack();

      if (!stmt || state.option.curly) {
        warning("W116", state.tokens.next, "{", state.tokens.next.value);
      }

      state.tokens.next.inBracelessBlock = true;
      indent += state.option.indent;
      // test indentation only if statement is in new line
      a = [statement()];
      indent -= state.option.indent;

      state.funct["(scope)"].unstack();
      delete state.funct["(noblockscopedvar)"];
    }

    // Don't clear and let it propagate out if it is "break", "return" or similar in switch case
    switch (state.funct["(verb)"]) {
    case "break":
    case "continue":
    case "return":
    case "throw":
      if (iscase) {
        break;
      }

      /* falls through */
    default:
      state.funct["(verb)"] = null;
    }

    inblock = b;
    if (ordinary && state.option.noempty && (!a || a.length === 0)) {
      warning("W035", state.tokens.prev);
    }
    metrics.nestedBlockDepth -= 1;
    return a;
  }


  function countMember(m) {
    if (membersOnly && typeof membersOnly[m] !== "boolean") {
      warning("W036", state.tokens.curr, m);
    }
    if (typeof member[m] === "number") {
      member[m] += 1;
    } else {
      member[m] = 1;
    }
  }

  // Build the syntax table by declaring the syntactic elements of the language.

  type("(number)", function() {
    return this;
  });

  type("(string)", function() {
    return this;
  });

  state.syntax["(identifier)"] = {
    type: "(identifier)",
    lbp: 0,
    identifier: true,

    nud: function() {
      var v = this.value;

      // If this identifier is the lone parameter to a shorthand "fat arrow"
      // function definition, i.e.
      //
      //     x => x;
      //
      // ...it should not be considered as a variable in the current scope. It
      // will be added to the scope of the new function when the next token is
      // parsed, so it can be safely ignored for now.
      if (state.tokens.next.id === "=>") {
        return this;
      }

      if (!state.funct["(comparray)"].check(v)) {
        state.funct["(scope)"].block.use(v, state.tokens.curr);
      }
      return this;
    },

    led: function() {
      error("E033", state.tokens.next, state.tokens.next.value);
    }
  };

  var baseTemplateSyntax = {
    identifier: false,
    template: true,
  };
  state.syntax["(template)"] = _.extend({
    lbp: 155,
    type: "(template)",
    nud: doTemplateLiteral,
    led: doTemplateLiteral,
    noSubst: false
  }, baseTemplateSyntax);

  state.syntax["(template middle)"] = _.extend({
    lbp: 0,
    type: "(template middle)",
    middle: true,
    noSubst: false
  }, baseTemplateSyntax);

  state.syntax["(template tail)"] = _.extend({
    lbp: 0,
    type: "(template tail)",
    tail: true,
    noSubst: false
  }, baseTemplateSyntax);

  state.syntax["(no subst template)"] = _.extend({
    lbp: 155,
    type: "(template)",
    nud: doTemplateLiteral,
    led: doTemplateLiteral,
    noSubst: true,
    tail: true // mark as tail, since it's always the last component
  }, baseTemplateSyntax);

  type("(regexp)", function() {
    return this;
  });

  // ECMAScript parser

  delim("(endline)");
  (function(x) {
    x.line = x.from = 0;
  })(delim("(begin)"));
  delim("(end)").reach = true;
  delim("(error)").reach = true;
  delim("}").reach = true;
  delim(")");
  delim("]");
  delim("\"").reach = true;
  delim("'").reach = true;
  delim(";");
  delim(":").reach = true;
  delim("#");

  reserve("else");
  reserve("case").reach = true;
  reserve("catch");
  reserve("default").reach = true;
  reserve("finally");
  reservevar("arguments", function(x) {
    if (state.isStrict() && state.funct["(global)"]) {
      warning("E008", x);
    }
  });
  reservevar("eval");
  reservevar("false");
  reservevar("Infinity");
  reservevar("null");
  reservevar("this", function(x) {
    if (state.isStrict() && !isMethod() &&
        !state.option.validthis && ((state.funct["(statement)"] &&
        state.funct["(name)"].charAt(0) > "Z") || state.funct["(global)"])) {
      warning("W040", x);
    }
  });
  reservevar("true");
  reservevar("undefined");

  assignop("=", "assign", 20);
  assignop("+=", "assignadd", 20);
  assignop("-=", "assignsub", 20);
  assignop("*=", "assignmult", 20);
  assignop("/=", "assigndiv", 20).nud = function() {
    error("E014");
  };
  assignop("%=", "assignmod", 20);

  bitwiseassignop("&=");
  bitwiseassignop("|=");
  bitwiseassignop("^=");
  bitwiseassignop("<<=");
  bitwiseassignop(">>=");
  bitwiseassignop(">>>=");
  infix(",", function(left, that) {
    var expr;
    that.exprs = [left];

    if (state.option.nocomma) {
      warning("W127");
    }

    if (!parseComma({ peek: true })) {
      return that;
    }
    while (true) {
      if (!(expr = expression(10))) {
        break;
      }
      that.exprs.push(expr);
      if (state.tokens.next.value !== "," || !parseComma()) {
        break;
      }
    }
    return that;
  }, 10, true);

  infix("?", function(left, that) {
    increaseComplexityCount();
    that.left = left;
    that.right = expression(10);
    advance(":");
    that["else"] = expression(10);
    return that;
  }, 30);

  var orPrecendence = 40;
  infix("||", function(left, that) {
    increaseComplexityCount();
    that.left = left;
    that.right = expression(orPrecendence);
    return that;
  }, orPrecendence);
  infix("&&", "and", 50);
  bitwise("|", "bitor", 70);
  bitwise("^", "bitxor", 80);
  bitwise("&", "bitand", 90);
  relation("==", function(left, right) {
    var eqnull = state.option.eqnull &&
      ((left && left.value) === "null" || (right && right.value) === "null");

    switch (true) {
      case !eqnull && state.option.eqeqeq:
        this.from = this.character;
        warning("W116", this, "===", "==");
        break;
      case isPoorRelation(left):
        warning("W041", this, "===", left.value);
        break;
      case isPoorRelation(right):
        warning("W041", this, "===", right.value);
        break;
      case isTypoTypeof(right, left, state):
        warning("W122", this, right.value);
        break;
      case isTypoTypeof(left, right, state):
        warning("W122", this, left.value);
        break;
    }

    return this;
  });
  relation("===", function(left, right) {
    if (isTypoTypeof(right, left, state)) {
      warning("W122", this, right.value);
    } else if (isTypoTypeof(left, right, state)) {
      warning("W122", this, left.value);
    }
    return this;
  });
  relation("!=", function(left, right) {
    var eqnull = state.option.eqnull &&
        ((left && left.value) === "null" || (right && right.value) === "null");

    if (!eqnull && state.option.eqeqeq) {
      this.from = this.character;
      warning("W116", this, "!==", "!=");
    } else if (isPoorRelation(left)) {
      warning("W041", this, "!==", left.value);
    } else if (isPoorRelation(right)) {
      warning("W041", this, "!==", right.value);
    } else if (isTypoTypeof(right, left, state)) {
      warning("W122", this, right.value);
    } else if (isTypoTypeof(left, right, state)) {
      warning("W122", this, left.value);
    }
    return this;
  });
  relation("!==", function(left, right) {
    if (isTypoTypeof(right, left, state)) {
      warning("W122", this, right.value);
    } else if (isTypoTypeof(left, right, state)) {
      warning("W122", this, left.value);
    }
    return this;
  });
  relation("<");
  relation(">");
  relation("<=");
  relation(">=");
  bitwise("<<", "shiftleft", 120);
  bitwise(">>", "shiftright", 120);
  bitwise(">>>", "shiftrightunsigned", 120);
  infix("in", "in", 120);
  infix("instanceof", "instanceof", 120);
  infix("+", function(left, that) {
    var right;
    that.left = left;
    that.right = right = expression(130);

    if (left && right && left.id === "(string)" && right.id === "(string)") {
      left.value += right.value;
      left.character = right.character;
      if (!state.option.scripturl && reg.javascriptURL.test(left.value)) {
        warning("W050", left);
      }
      return left;
    }

    return that;
  }, 130);
  prefix("+", "num");
  prefix("+++", function() {
    warning("W007");
    this.arity = "unary";
    this.right = expression(150);
    return this;
  });
  infix("+++", function(left) {
    warning("W007");
    this.left = left;
    this.right = expression(130);
    return this;
  }, 130);
  infix("-", "sub", 130);
  prefix("-", "neg");
  prefix("---", function() {
    warning("W006");
    this.arity = "unary";
    this.right = expression(150);
    return this;
  });
  infix("---", function(left) {
    warning("W006");
    this.left = left;
    this.right = expression(130);
    return this;
  }, 130);
  infix("*", "mult", 140);
  infix("/", "div", 140);
  infix("%", "mod", 140);

  suffix("++");
  prefix("++", "preinc");
  state.syntax["++"].exps = true;

  suffix("--");
  prefix("--", "predec");
  state.syntax["--"].exps = true;
  prefix("delete", function() {
    var p = expression(10);
    if (!p) {
      return this;
    }

    if (p.id !== "." && p.id !== "[") {
      warning("W051");
    }
    this.first = p;

    // The `delete` operator accepts unresolvable references when not in strict
    // mode, so the operand may be undefined.
    if (p.identifier && !state.isStrict()) {
      p.forgiveUndef = true;
    }
    return this;
  }).exps = true;

  prefix("~", function() {
    if (state.option.bitwise) {
      warning("W016", this, "~");
    }
    this.arity = "unary";
    this.right = expression(150);
    return this;
  });

  prefix("...", function() {
    if (!state.inES6(true)) {
      warning("W119", this, "spread/rest operator", "6");
    }

    // TODO: Allow all AssignmentExpression
    // once parsing permits.
    //
    // How to handle eg. number, boolean when the built-in
    // prototype of may have an @@iterator definition?
    //
    // Number.prototype[Symbol.iterator] = function * () {
    //   yield this.valueOf();
    // };
    //
    // var a = [ ...1 ];
    // console.log(a); // [1];
    //
    // for (let n of [...10]) {
    //    console.log(n);
    // }
    // // 10
    //
    //
    // Boolean.prototype[Symbol.iterator] = function * () {
    //   yield this.valueOf();
    // };
    //
    // var a = [ ...true ];
    // console.log(a); // [true];
    //
    // for (let n of [...false]) {
    //    console.log(n);
    // }
    // // false
    //
    if (!state.tokens.next.identifier &&
        state.tokens.next.type !== "(string)" &&
          !checkPunctuators(state.tokens.next, ["[", "("])) {

      error("E030", state.tokens.next, state.tokens.next.value);
    }
    this.right = expression(150);
    return this;
  });

  prefix("!", function() {
    this.arity = "unary";
    this.right = expression(150);

    if (!this.right) { // '!' followed by nothing? Give up.
      quit("E041", this);
    }

    if (bang[this.right.id] === true) {
      warning("W018", this, "!");
    }
    return this;
  });

  prefix("typeof", (function() {
    var p = expression(150);
    this.first = this.right = p;

    if (!p) { // 'typeof' followed by nothing? Give up.
      quit("E041", this);
    }

    // The `typeof` operator accepts unresolvable references, so the operand
    // may be undefined.
    if (p.identifier) {
      p.forgiveUndef = true;
    }
    return this;
  }));
  prefix("new", function() {
    var mp = metaProperty("target", function() {
      if (!state.inES6(true)) {
        warning("W119", state.tokens.prev, "new.target", "6");
      }
      var inFunction, c = state.funct;
      while (c) {
        inFunction = !c["(global)"];
        if (!c["(arrow)"]) { break; }
        c = c["(context)"];
      }
      if (!inFunction) {
        warning("W136", state.tokens.prev, "new.target");
      }
    });
    if (mp) { return mp; }

    var c = expression(155), i;
    if (c && c.id !== "function") {
      if (c.identifier) {
        c["new"] = true;
        switch (c.value) {
        case "Number":
        case "String":
        case "Boolean":
        case "Math":
        case "JSON":
          warning("W053", state.tokens.prev, c.value);
          break;
        case "Symbol":
          if (state.inES6()) {
            warning("W053", state.tokens.prev, c.value);
          }
          break;
        case "Function":
          if (!state.option.evil) {
            warning("W054");
          }
          break;
        case "Date":
        case "RegExp":
        case "this":
          break;
        default:
          if (c.id !== "function") {
            i = c.value.substr(0, 1);
            if (state.option.newcap && (i < "A" || i > "Z") &&
              !state.funct["(scope)"].isPredefined(c.value)) {
              warning("W055", state.tokens.curr);
            }
          }
        }
      } else {
        if (c.id !== "." && c.id !== "[" && c.id !== "(") {
          warning("W056", state.tokens.curr);
        }
      }
    } else {
      if (!state.option.supernew)
        warning("W057", this);
    }
    if (state.tokens.next.id !== "(" && !state.option.supernew) {
      warning("W058", state.tokens.curr, state.tokens.curr.value);
    }
    this.first = this.right = c;
    return this;
  });
  state.syntax["new"].exps = true;

  prefix("void").exps = true;

  infix(".", function(left, that) {
    var m = identifier(false, true);

    if (typeof m === "string") {
      countMember(m);
    }

    that.left = left;
    that.right = m;

    if (m && m === "hasOwnProperty" && state.tokens.next.value === "=") {
      warning("W001");
    }

    if (left && left.value === "arguments" && (m === "callee" || m === "caller")) {
      if (state.option.noarg)
        warning("W059", left, m);
      else if (state.isStrict())
        error("E008");
    } else if (!state.option.evil && left && left.value === "document" &&
        (m === "write" || m === "writeln")) {
      warning("W060", left);
    }

    if (!state.option.evil && (m === "eval" || m === "execScript")) {
      if (isGlobalEval(left, state)) {
        warning("W061");
      }
    }

    return that;
  }, 160, true);

  infix("(", function(left, that) {
    if (state.option.immed && left && !left.immed && left.id === "function") {
      warning("W062");
    }

    var n = 0;
    var p = [];

    if (left) {
      if (left.type === "(identifier)") {
        if (left.value.match(/^[A-Z]([A-Z0-9_$]*[a-z][A-Za-z0-9_$]*)?$/)) {
          if ("Array Number String Boolean Date Object Error Symbol".indexOf(left.value) === -1) {
            if (left.value === "Math") {
              warning("W063", left);
            } else if (state.option.newcap) {
              warning("W064", left);
            }
          }
        }
      }
    }

    if (state.tokens.next.id !== ")") {
      for (;;) {
        p[p.length] = expression(10);
        n += 1;
        if (state.tokens.next.id !== ",") {
          break;
        }
        parseComma();
      }
    }

    advance(")");

    if (typeof left === "object") {
      if (!state.inES5() && left.value === "parseInt" && n === 1) {
        warning("W065", state.tokens.curr);
      }
      if (!state.option.evil) {
        if (left.value === "eval" || left.value === "Function" ||
            left.value === "execScript") {
          warning("W061", left);

          if (p[0] && [0].id === "(string)") {
            addInternalSrc(left, p[0].value);
          }
        } else if (p[0] && p[0].id === "(string)" &&
             (left.value === "setTimeout" ||
            left.value === "setInterval")) {
          warning("W066", left);
          addInternalSrc(left, p[0].value);

        // window.setTimeout/setInterval
        } else if (p[0] && p[0].id === "(string)" &&
             left.value === "." &&
             left.left.value === "window" &&
             (left.right === "setTimeout" ||
            left.right === "setInterval")) {
          warning("W066", left);
          addInternalSrc(left, p[0].value);
        }
      }
      if (!left.identifier && left.id !== "." && left.id !== "[" && left.id !== "=>" &&
          left.id !== "(" && left.id !== "&&" && left.id !== "||" && left.id !== "?" &&
          !(state.inES6() && left["(name)"])) {
        warning("W067", that);
      }
    }

    that.left = left;
    return that;
  }, 155, true).exps = true;

  prefix("(", function() {
    var pn = state.tokens.next, pn1, i = -1;
    var ret, triggerFnExpr, first, last;
    var parens = 1;
    var opening = state.tokens.curr;
    var preceeding = state.tokens.prev;
    var isNecessary = !state.option.singleGroups;

    do {
      if (pn.value === "(") {
        parens += 1;
      } else if (pn.value === ")") {
        parens -= 1;
      }

      i += 1;
      pn1 = pn;
      pn = peek(i);
    } while (!(parens === 0 && pn1.value === ")") && pn.value !== ";" && pn.type !== "(end)");

    if (state.tokens.next.id === "function") {
      triggerFnExpr = state.tokens.next.immed = true;
    }

    // If the balanced grouping operator is followed by a "fat arrow", the
    // current token marks the beginning of a "fat arrow" function and parsing
    // should proceed accordingly.
    if (pn.value === "=>") {
      return doFunction({ type: "arrow", parsedOpening: true });
    }

    var exprs = [];

    if (state.tokens.next.id !== ")") {
      for (;;) {
        exprs.push(expression(10));

        if (state.tokens.next.id !== ",") {
          break;
        }

        if (state.option.nocomma) {
          warning("W127");
        }

        parseComma();
      }
    }

    advance(")", this);
    if (state.option.immed && exprs[0] && exprs[0].id === "function") {
      if (state.tokens.next.id !== "(" &&
        state.tokens.next.id !== "." && state.tokens.next.id !== "[") {
        warning("W068", this);
      }
    }

    if (!exprs.length) {
      return;
    }
    if (exprs.length > 1) {
      ret = Object.create(state.syntax[","]);
      ret.exprs = exprs;

      first = exprs[0];
      last = exprs[exprs.length - 1];

      if (!isNecessary) {
        isNecessary = preceeding.assign || preceeding.delim;
      }
    } else {
      ret = first = last = exprs[0];

      if (!isNecessary) {
        isNecessary =
          // Used to distinguish from an ExpressionStatement which may not
          // begin with the `{` and `function` tokens
          (opening.beginsStmt && (ret.id === "{" || triggerFnExpr || isFunctor(ret))) ||
          // Used to signal that a function expression is being supplied to
          // some other operator.
          (triggerFnExpr &&
            // For parenthesis wrapping a function expression to be considered
            // necessary, the grouping operator should be the left-hand-side of
            // some other operator--either within the parenthesis or directly
            // following them.
            (!isEndOfExpr() || state.tokens.prev.id !== "}")) ||
          // Used to demarcate an arrow function as the left-hand side of some
          // operator.
          (isFunctor(ret) && !isEndOfExpr()) ||
          // Used as the return value of a single-statement arrow function
          (ret.id === "{" && preceeding.id === "=>") ||
          // Used to delineate an integer number literal from a dereferencing
          // punctuator (otherwise interpreted as a decimal point)
          (ret.type === "(number)" &&
            checkPunctuator(pn, ".") && /^\d+$/.test(ret.value)) ||
          // Used to wrap object destructuring assignment
          (opening.beginsStmt && ret.id === "=" && ret.left.id === "{");
      }
    }

    if (ret) {
      // The operator may be necessary to override the default binding power of
      // neighboring operators (whenever there is an operator in use within the
      // first expression *or* the current group contains multiple expressions)
      if (!isNecessary && (first.left || first.right || ret.exprs)) {
        isNecessary =
          (!isBeginOfExpr(preceeding) && first.lbp <= preceeding.lbp) ||
          (!isEndOfExpr() && last.lbp < state.tokens.next.lbp);
      }

      if (!isNecessary) {
        warning("W126", opening);
      }

      ret.paren = true;
    }

    return ret;
  });

  application("=>");

  infix("[", function(left, that) {
    var e = expression(10), s;
    if (e && e.type === "(string)") {
      if (!state.option.evil && (e.value === "eval" || e.value === "execScript")) {
        if (isGlobalEval(left, state)) {
          warning("W061");
        }
      }

      countMember(e.value);
      if (!state.option.sub && reg.identifier.test(e.value)) {
        s = state.syntax[e.value];
        if (!s || !isReserved(s)) {
          warning("W069", state.tokens.prev, e.value);
        }
      }
    }
    advance("]", that);

    if (e && e.value === "hasOwnProperty" && state.tokens.next.value === "=") {
      warning("W001");
    }

    that.left = left;
    that.right = e;
    return that;
  }, 160, true);

  function comprehensiveArrayExpression() {
    var res = {};
    res.exps = true;
    state.funct["(comparray)"].stack();

    // Handle reversed for expressions, used in spidermonkey
    var reversed = false;
    if (state.tokens.next.value !== "for") {
      reversed = true;
      if (!state.inMoz()) {
        warning("W116", state.tokens.next, "for", state.tokens.next.value);
      }
      state.funct["(comparray)"].setState("use");
      res.right = expression(10);
    }

    advance("for");
    if (state.tokens.next.value === "each") {
      advance("each");
      if (!state.inMoz()) {
        warning("W118", state.tokens.curr, "for each");
      }
    }
    advance("(");
    state.funct["(comparray)"].setState("define");
    res.left = expression(130);
    if (_.contains(["in", "of"], state.tokens.next.value)) {
      advance();
    } else {
      error("E045", state.tokens.curr);
    }
    state.funct["(comparray)"].setState("generate");
    expression(10);

    advance(")");
    if (state.tokens.next.value === "if") {
      advance("if");
      advance("(");
      state.funct["(comparray)"].setState("filter");
      res.filter = expression(10);
      advance(")");
    }

    if (!reversed) {
      state.funct["(comparray)"].setState("use");
      res.right = expression(10);
    }

    advance("]");
    state.funct["(comparray)"].unstack();
    return res;
  }

  prefix("[", function() {
    var blocktype = lookupBlockType();
    if (blocktype.isCompArray) {
      if (!state.option.esnext && !state.inMoz()) {
        warning("W118", state.tokens.curr, "array comprehension");
      }
      return comprehensiveArrayExpression();
    } else if (blocktype.isDestAssign) {
      this.destructAssign = destructuringPattern({ openingParsed: true, assignment: true });
      return this;
    }
    var b = state.tokens.curr.line !== startLine(state.tokens.next);
    this.first = [];
    if (b) {
      indent += state.option.indent;
      if (state.tokens.next.from === indent + state.option.indent) {
        indent += state.option.indent;
      }
    }
    while (state.tokens.next.id !== "(end)") {
      while (state.tokens.next.id === ",") {
        if (!state.option.elision) {
          if (!state.inES5()) {
            // Maintain compat with old options --- ES5 mode without
            // elision=true will warn once per comma
            warning("W070");
          } else {
            warning("W128");
            do {
              advance(",");
            } while (state.tokens.next.id === ",");
            continue;
          }
        }
        advance(",");
      }

      if (state.tokens.next.id === "]") {
        break;
      }

      this.first.push(expression(10));
      if (state.tokens.next.id === ",") {
        parseComma({ allowTrailing: true });
        if (state.tokens.next.id === "]" && !state.inES5()) {
          warning("W070", state.tokens.curr);
          break;
        }
      } else {
        break;
      }
    }
    if (b) {
      indent -= state.option.indent;
    }
    advance("]", this);
    return this;
  });


  function isMethod() {
    return state.funct["(statement)"] && state.funct["(statement)"].type === "class" ||
           state.funct["(context)"] && state.funct["(context)"]["(verb)"] === "class";
  }


  function isPropertyName(token) {
    return token.identifier || token.id === "(string)" || token.id === "(number)";
  }


  function propertyName(preserveOrToken) {
    var id;
    var preserve = true;
    if (typeof preserveOrToken === "object") {
      id = preserveOrToken;
    } else {
      preserve = preserveOrToken;
      id = optionalidentifier(false, true, preserve);
    }

    if (!id) {
      if (state.tokens.next.id === "(string)") {
        id = state.tokens.next.value;
        if (!preserve) {
          advance();
        }
      } else if (state.tokens.next.id === "(number)") {
        id = state.tokens.next.value.toString();
        if (!preserve) {
          advance();
        }
      }
    } else if (typeof id === "object") {
      if (id.id === "(string)" || id.id === "(identifier)") id = id.value;
      else if (id.id === "(number)") id = id.value.toString();
    }

    if (id === "hasOwnProperty") {
      warning("W001");
    }

    return id;
  }

  /**
   * @param {Object} [options]
   * @param {token} [options.loneArg] The argument to the function in cases
   *                                  where it was defined using the
   *                                  single-argument shorthand.
   * @param {bool} [options.parsedOpening] Whether the opening parenthesis has
   *                                       already been parsed.
   * @returns {{ arity: number, params: Array.<string>}}
   */
  function functionparams(options) {
    var next;
    var paramsIds = [];
    var ident;
    var tokens = [];
    var t;
    var pastDefault = false;
    var pastRest = false;
    var arity = 0;
    var loneArg = options && options.loneArg;

    if (loneArg && loneArg.identifier === true) {
      state.funct["(scope)"].addParam(loneArg.value, loneArg);
      return { arity: 1, params: [ loneArg.value ] };
    }

    next = state.tokens.next;

    if (!options || !options.parsedOpening) {
      advance("(");
    }

    if (state.tokens.next.id === ")") {
      advance(")");
      return;
    }

    function addParam(addParamArgs) {
      state.funct["(scope)"].addParam.apply(state.funct["(scope)"], addParamArgs);
    }

    for (;;) {
      arity++;
      // are added to the param scope
      var currentParams = [];

      if (_.contains(["{", "["], state.tokens.next.id)) {
        tokens = destructuringPattern();
        for (t in tokens) {
          t = tokens[t];
          if (t.id) {
            paramsIds.push(t.id);
            currentParams.push([t.id, t.token]);
          }
        }
      } else {
        if (checkPunctuator(state.tokens.next, "...")) pastRest = true;
        ident = identifier(true);
        if (ident) {
          paramsIds.push(ident);
          currentParams.push([ident, state.tokens.curr]);
        } else {
          // Skip invalid parameter.
          while (!checkPunctuators(state.tokens.next, [",", ")"])) advance();
        }
      }

      // It is valid to have a regular argument after a default argument
      // since undefined can be used for missing parameters. Still warn as it is
      // a possible code smell.
      if (pastDefault) {
        if (state.tokens.next.id !== "=") {
          error("W138", state.tokens.current);
        }
      }
      if (state.tokens.next.id === "=") {
        if (!state.inES6()) {
          warning("W119", state.tokens.next, "default parameters", "6");
        }
        advance("=");
        pastDefault = true;
        expression(10);
      }

      // now we have evaluated the default expression, add the variable to the param scope
      currentParams.forEach(addParam);

      if (state.tokens.next.id === ",") {
        if (pastRest) {
          warning("W131", state.tokens.next);
        }
        parseComma();
      } else {
        advance(")", next);
        return { arity: arity, params: paramsIds };
      }
    }
  }

  function functor(name, token, overwrites) {
    var funct = {
      "(name)"      : name,
      "(breakage)"  : 0,
      "(loopage)"   : 0,
      "(tokens)"    : {},
      "(properties)": {},

      "(catch)"     : false,
      "(global)"    : false,

      "(line)"      : null,
      "(character)" : null,
      "(metrics)"   : null,
      "(statement)" : null,
      "(context)"   : null,
      "(scope)"     : null,
      "(comparray)" : null,
      "(generator)" : null,
      "(arrow)"     : null,
      "(params)"    : null
    };

    if (token) {
      _.extend(funct, {
        "(line)"     : token.line,
        "(character)": token.character,
        "(metrics)"  : createMetrics(token)
      });
    }

    _.extend(funct, overwrites);

    if (funct["(context)"]) {
      funct["(scope)"] = funct["(context)"]["(scope)"];
      funct["(comparray)"]  = funct["(context)"]["(comparray)"];
    }

    return funct;
  }

  function isFunctor(token) {
    return "(scope)" in token;
  }

  /**
   * Determine if the parser has begun parsing executable code.
   *
   * @param {Token} funct - The current "functor" token
   *
   * @returns {boolean}
   */
  function hasParsedCode(funct) {
    return funct["(global)"] && !funct["(verb)"];
  }

  function doTemplateLiteral(left) {
    // ASSERT: this.type === "(template)"
    // jshint validthis: true
    var ctx = this.context;
    var noSubst = this.noSubst;
    var depth = this.depth;

    if (!noSubst) {
      while (!end()) {
        if (!state.tokens.next.template || state.tokens.next.depth > depth) {
          expression(0); // should probably have different rbp?
        } else {
          // skip template start / middle
          advance();
        }
      }
    }

    return {
      id: "(template)",
      type: "(template)",
      tag: left
    };

    function end() {
      if (state.tokens.curr.template && state.tokens.curr.tail &&
          state.tokens.curr.context === ctx) return true;
      var complete = (state.tokens.next.template && state.tokens.next.tail &&
                      state.tokens.next.context === ctx);
      if (complete) advance();
      return complete || state.tokens.next.isUnclosed;
    }
  }

  /**
   * @param {Object} [options]
   * @param {token} [options.name] The identifier belonging to the function (if
   *                               any)
   * @param {boolean} [options.statement] The statement that triggered creation
   *                                      of the current function.
   * @param {string} [options.type] If specified, either "generator" or "arrow"
   * @param {token} [options.loneArg] The argument to the function in cases
   *                                  where it was defined using the
   *                                  single-argument shorthand
   * @param {bool} [options.parsedOpening] Whether the opening parenthesis has
   *                                       already been parsed
   * @param {token} [options.classExprBinding] Define a function with this
   *                                           identifier in the new function's
   *                                           scope, mimicking the bahavior of
   *                                           class expression names within
   *                                           the body of member functions.
   */
  function doFunction(options) {
    var f, token, name, statement, classExprBinding, isGenerator, isArrow, ignoreLoopFunc;
    var oldOption = state.option;
    var oldIgnored = state.ignored;

    if (options) {
      name = options.name;
      statement = options.statement;
      classExprBinding = options.classExprBinding;
      isGenerator = options.type === "generator";
      isArrow = options.type === "arrow";
      ignoreLoopFunc = options.ignoreLoopFunc;
    }

    state.option = Object.create(state.option);
    state.ignored = Object.create(state.ignored);

    state.funct = functor(name || state.nameStack.infer(), state.tokens.next, {
      "(statement)": statement,
      "(context)":   state.funct,
      "(arrow)":     isArrow,
      "(generator)": isGenerator
    });

    f = state.funct;
    token = state.tokens.curr;
    token.funct = state.funct;

    functions.push(state.funct);

    // So that the function is available to itself and referencing itself is not
    // seen as a closure, add the function name to a new scope, but do not
    // test for unused (unused: false)
    // it is a new block scope so that params can override it, it can be block scoped
    // but declarations inside the function don't cause already declared error
    state.funct["(scope)"].stack("functionouter");
    var internallyAccessibleName = name || classExprBinding;
    if (internallyAccessibleName) {
      state.funct["(scope)"].block.add(internallyAccessibleName,
        classExprBinding ? "class" : "function", state.tokens.curr, false);
    }

    // create the param scope (params added in functionparams)
    state.funct["(scope)"].stack("functionparams");

    var paramsInfo = functionparams(options);

    if (paramsInfo) {
      state.funct["(params)"] = paramsInfo.params;
      state.funct["(metrics)"].arity = paramsInfo.arity;
      state.funct["(metrics)"].verifyMaxParametersPerFunction();
    } else {
      state.funct["(metrics)"].arity = 0;
    }

    if (isArrow) {
      if (!state.inES6(true)) {
        warning("W119", state.tokens.curr, "arrow function syntax (=>)", "6");
      }

      if (!options.loneArg) {
        advance("=>");
      }
    }

    block(false, true, true, isArrow);

    if (!state.option.noyield && isGenerator &&
        state.funct["(generator)"] !== "yielded") {
      warning("W124", state.tokens.curr);
    }

    state.funct["(metrics)"].verifyMaxStatementsPerFunction();
    state.funct["(metrics)"].verifyMaxComplexityPerFunction();
    state.funct["(unusedOption)"] = state.option.unused;
    state.option = oldOption;
    state.ignored = oldIgnored;
    state.funct["(last)"] = state.tokens.curr.line;
    state.funct["(lastcharacter)"] = state.tokens.curr.character;

    // unstack the params scope
    state.funct["(scope)"].unstack(); // also does usage and label checks

    // unstack the function outer stack
    state.funct["(scope)"].unstack();

    state.funct = state.funct["(context)"];

    if (!ignoreLoopFunc && !state.option.loopfunc && state.funct["(loopage)"]) {
      // If the function we just parsed accesses any non-local variables
      // trigger a warning. Otherwise, the function is safe even within
      // a loop.
      if (f["(isCapturing)"]) {
        warning("W083", token);
      }
    }

    return f;
  }

  function createMetrics(functionStartToken) {
    return {
      statementCount: 0,
      nestedBlockDepth: -1,
      ComplexityCount: 1,
      arity: 0,

      verifyMaxStatementsPerFunction: function() {
        if (state.option.maxstatements &&
          this.statementCount > state.option.maxstatements) {
          warning("W071", functionStartToken, this.statementCount);
        }
      },

      verifyMaxParametersPerFunction: function() {
        if (_.isNumber(state.option.maxparams) &&
          this.arity > state.option.maxparams) {
          warning("W072", functionStartToken, this.arity);
        }
      },

      verifyMaxNestedBlockDepthPerFunction: function() {
        if (state.option.maxdepth &&
          this.nestedBlockDepth > 0 &&
          this.nestedBlockDepth === state.option.maxdepth + 1) {
          warning("W073", null, this.nestedBlockDepth);
        }
      },

      verifyMaxComplexityPerFunction: function() {
        var max = state.option.maxcomplexity;
        var cc = this.ComplexityCount;
        if (max && cc > max) {
          warning("W074", functionStartToken, cc);
        }
      }
    };
  }

  function increaseComplexityCount() {
    state.funct["(metrics)"].ComplexityCount += 1;
  }

  // Parse assignments that were found instead of conditionals.
  // For example: if (a = 1) { ... }

  function checkCondAssignment(expr) {
    var id, paren;
    if (expr) {
      id = expr.id;
      paren = expr.paren;
      if (id === "," && (expr = expr.exprs[expr.exprs.length - 1])) {
        id = expr.id;
        paren = paren || expr.paren;
      }
    }
    switch (id) {
    case "=":
    case "+=":
    case "-=":
    case "*=":
    case "%=":
    case "&=":
    case "|=":
    case "^=":
    case "/=":
      if (!paren && !state.option.boss) {
        warning("W084");
      }
    }
  }

  /**
   * @param {object} props Collection of property descriptors for a given
   *                       object.
   */
  function checkProperties(props) {
    // Check for lonely setters if in the ES5 mode.
    if (state.inES5()) {
      for (var name in props) {
        if (props[name] && props[name].setterToken && !props[name].getterToken) {
          warning("W078", props[name].setterToken);
        }
      }
    }
  }

  function metaProperty(name, c) {
    if (checkPunctuator(state.tokens.next, ".")) {
      var left = state.tokens.curr.id;
      advance(".");
      var id = identifier();
      state.tokens.curr.isMetaProperty = true;
      if (name !== id) {
        error("E057", state.tokens.prev, left, id);
      } else {
        c();
      }
      return state.tokens.curr;
    }
  }

  (function(x) {
    x.nud = function() {
      var b, f, i, p, t, isGeneratorMethod = false, nextVal;
      var props = Object.create(null); // All properties, including accessors

      b = state.tokens.curr.line !== startLine(state.tokens.next);
      if (b) {
        indent += state.option.indent;
        if (state.tokens.next.from === indent + state.option.indent) {
          indent += state.option.indent;
        }
      }

      var blocktype = lookupBlockType();
      if (blocktype.isDestAssign) {
        this.destructAssign = destructuringPattern({ openingParsed: true, assignment: true });
        return this;
      }

      for (;;) {
        if (state.tokens.next.id === "}") {
          break;
        }

        nextVal = state.tokens.next.value;
        if (state.tokens.next.identifier &&
            (peekIgnoreEOL().id === "," || peekIgnoreEOL().id === "}")) {
          if (!state.inES6()) {
            warning("W104", state.tokens.next, "object short notation", "6");
          }
          i = propertyName(true);
          saveProperty(props, i, state.tokens.next);

          expression(10);

        } else if (peek().id !== ":" && (nextVal === "get" || nextVal === "set")) {
          advance(nextVal);

          if (!state.inES5()) {
            error("E034");
          }

          i = propertyName();

          // ES6 allows for get() {...} and set() {...} method
          // definition shorthand syntax, so we don't produce an error
          // if linting ECMAScript 6 code.
          if (!i && !state.inES6()) {
            error("E035");
          }

          // We don't want to save this getter unless it's an actual getter
          // and not an ES6 concise method
          if (i) {
            saveAccessor(nextVal, props, i, state.tokens.curr);
          }

          t = state.tokens.next;
          f = doFunction();
          p = f["(params)"];

          // Don't warn about getter/setter pairs if this is an ES6 concise method
          if (nextVal === "get" && i && p) {
            warning("W076", t, p[0], i);
          } else if (nextVal === "set" && i && f["(metrics)"].arity !== 1) {
            warning("W077", t, i);
          }
        } else {
          if (state.tokens.next.value === "*" && state.tokens.next.type === "(punctuator)") {
            if (!state.inES6()) {
              warning("W104", state.tokens.next, "generator functions", "6");
            }
            advance("*");
            isGeneratorMethod = true;
          } else {
            isGeneratorMethod = false;
          }

          if (state.tokens.next.id === "[") {
            i = computedPropertyName();
            state.nameStack.set(i);
          } else {
            state.nameStack.set(state.tokens.next);
            i = propertyName();
            saveProperty(props, i, state.tokens.next);

            if (typeof i !== "string") {
              break;
            }
          }

          if (state.tokens.next.value === "(") {
            if (!state.inES6()) {
              warning("W104", state.tokens.curr, "concise methods", "6");
            }
            doFunction({ type: isGeneratorMethod ? "generator" : null });
          } else {
            advance(":");
            expression(10);
          }
        }

        countMember(i);

        if (state.tokens.next.id === ",") {
          parseComma({ allowTrailing: true, property: true });
          if (state.tokens.next.id === ",") {
            warning("W070", state.tokens.curr);
          } else if (state.tokens.next.id === "}" && !state.inES5()) {
            warning("W070", state.tokens.curr);
          }
        } else {
          break;
        }
      }
      if (b) {
        indent -= state.option.indent;
      }
      advance("}", this);

      checkProperties(props);

      return this;
    };
    x.fud = function() {
      error("E036", state.tokens.curr);
    };
  }(delim("{")));

  function destructuringPattern(options) {
    var isAssignment = options && options.assignment;

    if (!state.inES6()) {
      warning("W104", state.tokens.curr,
        isAssignment ? "destructuring assignment" : "destructuring binding", "6");
    }

    return destructuringPatternRecursive(options);
  }

  function destructuringPatternRecursive(options) {
    var ids;
    var identifiers = [];
    var openingParsed = options && options.openingParsed;
    var isAssignment = options && options.assignment;
    var recursiveOptions = isAssignment ? { assignment: isAssignment } : null;
    var firstToken = openingParsed ? state.tokens.curr : state.tokens.next;

    var nextInnerDE = function() {
      var ident;
      if (checkPunctuators(state.tokens.next, ["[", "{"])) {
        ids = destructuringPatternRecursive(recursiveOptions);
        for (var id in ids) {
          id = ids[id];
          identifiers.push({ id: id.id, token: id.token });
        }
      } else if (checkPunctuator(state.tokens.next, ",")) {
        identifiers.push({ id: null, token: state.tokens.curr });
      } else if (checkPunctuator(state.tokens.next, "(")) {
        advance("(");
        nextInnerDE();
        advance(")");
      } else {
        var is_rest = checkPunctuator(state.tokens.next, "...");

        if (isAssignment) {
          var assignTarget = expression(20);
          if (assignTarget) {
            checkLeftSideAssign(assignTarget);

            // if the target was a simple identifier, add it to the list to return
            if (assignTarget.identifier) {
              ident = assignTarget.value;
            }
          }
        } else {
          ident = identifier();
        }
        if (ident) {
          identifiers.push({ id: ident, token: state.tokens.curr });
        }
        return is_rest;
      }
      return false;
    };
    var assignmentProperty = function() {
      var id;
      if (checkPunctuator(state.tokens.next, "[")) {
        advance("[");
        expression(10);
        advance("]");
        advance(":");
        nextInnerDE();
      } else if (state.tokens.next.id === "(string)" ||
                 state.tokens.next.id === "(number)") {
        advance();
        advance(":");
        nextInnerDE();
      } else {
        // this id will either be the property name or the property name and the assigning identifier
        id = identifier();
        if (checkPunctuator(state.tokens.next, ":")) {
          advance(":");
          nextInnerDE();
        } else if (id) {
          // in this case we are assigning (not declaring), so check assignment
          if (isAssignment) {
            checkLeftSideAssign(state.tokens.curr);
          }
          identifiers.push({ id: id, token: state.tokens.curr });
        }
      }
    };

    var id, value;
    if (checkPunctuator(firstToken, "[")) {
      if (!openingParsed) {
        advance("[");
      }
      if (checkPunctuator(state.tokens.next, "]")) {
        warning("W137", state.tokens.curr);
      }
      var element_after_rest = false;
      while (!checkPunctuator(state.tokens.next, "]")) {
        if (nextInnerDE() && !element_after_rest &&
            checkPunctuator(state.tokens.next, ",")) {
          warning("W130", state.tokens.next);
          element_after_rest = true;
        }
        if (checkPunctuator(state.tokens.next, "=")) {
          if (checkPunctuator(state.tokens.prev, "...")) {
            advance("]");
          } else {
            advance("=");
          }
          id = state.tokens.prev;
          value = expression(10);
          if (value && value.type === "undefined") {
            warning("W080", id, id.value);
          }
        }
        if (!checkPunctuator(state.tokens.next, "]")) {
          advance(",");
        }
      }
      advance("]");
    } else if (checkPunctuator(firstToken, "{")) {

      if (!openingParsed) {
        advance("{");
      }
      if (checkPunctuator(state.tokens.next, "}")) {
        warning("W137", state.tokens.curr);
      }
      while (!checkPunctuator(state.tokens.next, "}")) {
        assignmentProperty();
        if (checkPunctuator(state.tokens.next, "=")) {
          advance("=");
          id = state.tokens.prev;
          value = expression(10);
          if (value && value.type === "undefined") {
            warning("W080", id, id.value);
          }
        }
        if (!checkPunctuator(state.tokens.next, "}")) {
          advance(",");
          if (checkPunctuator(state.tokens.next, "}")) {
            // Trailing comma
            // ObjectBindingPattern: { BindingPropertyList , }
            break;
          }
        }
      }
      advance("}");
    }
    return identifiers;
  }

  function destructuringPatternMatch(tokens, value) {
    var first = value.first;

    if (!first)
      return;

    _.zip(tokens, Array.isArray(first) ? first : [ first ]).forEach(function(val) {
      var token = val[0];
      var value = val[1];

      if (token && value)
        token.first = value;
      else if (token && token.first && !value)
        warning("W080", token.first, token.first.value);
    });
  }

  function blockVariableStatement(type, statement, context) {
    // used for both let and const statements

    var prefix = context && context.prefix;
    var inexport = context && context.inexport;
    var isLet = type === "let";
    var isConst = type === "const";
    var tokens, lone, value, letblock;

    if (!state.inES6()) {
      warning("W104", state.tokens.curr, type, "6");
    }

    if (isLet && state.tokens.next.value === "(") {
      if (!state.inMoz()) {
        warning("W118", state.tokens.next, "let block");
      }
      advance("(");
      state.funct["(scope)"].stack();
      letblock = true;
    } else if (state.funct["(noblockscopedvar)"]) {
      error("E048", state.tokens.curr, isConst ? "Const" : "Let");
    }

    statement.first = [];
    for (;;) {
      var names = [];
      if (_.contains(["{", "["], state.tokens.next.value)) {
        tokens = destructuringPattern();
        lone = false;
      } else {
        tokens = [ { id: identifier(), token: state.tokens.curr } ];
        lone = true;
      }

      if (!prefix && isConst && state.tokens.next.id !== "=") {
        warning("E012", state.tokens.curr, state.tokens.curr.value);
      }

      for (var t in tokens) {
        if (tokens.hasOwnProperty(t)) {
          t = tokens[t];
          if (state.funct["(scope)"].block.isGlobal()) {
            if (predefined[t.id] === false) {
              warning("W079", t.token, t.id);
            }
          }
          if (t.id && !state.funct["(noblockscopedvar)"]) {
            state.funct["(scope)"].addlabel(t.id, {
              type: type,
              token: t.token });
            names.push(t.token);

            if (lone && inexport) {
              state.funct["(scope)"].setExported(t.token.value, t.token);
            }
          }
        }
      }

      if (state.tokens.next.id === "=") {
        advance("=");
        if (!prefix && peek(0).id === "=" && state.tokens.next.identifier) {
          warning("W120", state.tokens.next, state.tokens.next.value);
        }
        var id = state.tokens.prev;
        // don't accept `in` in expression if prefix is used for ForIn/Of loop.
        value = expression(prefix ? 120 : 10);
        if (!prefix && value && value.type === "undefined") {
          warning("W080", id, id.value);
        }
        if (lone) {
          tokens[0].first = value;
        } else {
          destructuringPatternMatch(names, value);
        }
      }

      statement.first = statement.first.concat(names);

      if (state.tokens.next.id !== ",") {
        break;
      }
      parseComma();
    }
    if (letblock) {
      advance(")");
      block(true, true);
      statement.block = true;
      state.funct["(scope)"].unstack();
    }

    return statement;
  }

  var conststatement = stmt("const", function(context) {
    return blockVariableStatement("const", this, context);
  });
  conststatement.exps = true;

  var letstatement = stmt("let", function(context) {
    return blockVariableStatement("let", this, context);
  });
  letstatement.exps = true;

  var varstatement = stmt("var", function(context) {
    var prefix = context && context.prefix;
    var inexport = context && context.inexport;
    var tokens, lone, value;

    // If the `implied` option is set, bindings are set differently.
    var implied = context && context.implied;
    var report = !(context && context.ignore);

    this.first = [];
    for (;;) {
      var names = [];
      if (_.contains(["{", "["], state.tokens.next.value)) {
        tokens = destructuringPattern();
        lone = false;
      } else {
        tokens = [ { id: identifier(), token: state.tokens.curr } ];
        lone = true;
      }

      if (!(prefix && implied) && report && state.option.varstmt) {
        warning("W132", this);
      }

      this.first = this.first.concat(names);

      for (var t in tokens) {
        if (tokens.hasOwnProperty(t)) {
          t = tokens[t];
          if (!implied && state.funct["(global)"] && !state.impliedClosure()) {
            if (predefined[t.id] === false) {
              warning("W079", t.token, t.id);
            } else if (state.option.futurehostile === false) {
              if ((!state.inES5() && vars.ecmaIdentifiers[5][t.id] === false) ||
                (!state.inES6() && vars.ecmaIdentifiers[6][t.id] === false)) {
                warning("W129", t.token, t.id);
              }
            }
          }
          if (t.id) {
            if (implied === "for") {

              if (!state.funct["(scope)"].has(t.id)) {
                if (report) warning("W088", t.token, t.id);
              }
              state.funct["(scope)"].block.use(t.id, t.token);
            } else {
              state.funct["(scope)"].addlabel(t.id, {
                type: "var",
                token: t.token });

              if (lone && inexport) {
                state.funct["(scope)"].setExported(t.id, t.token);
              }
            }
            names.push(t.token);
          }
        }
      }

      if (state.tokens.next.id === "=") {
        state.nameStack.set(state.tokens.curr);

        advance("=");
        if (peek(0).id === "=" && state.tokens.next.identifier) {
          if (!prefix && report &&
              !state.funct["(params)"] ||
              state.funct["(params)"].indexOf(state.tokens.next.value) === -1) {
            warning("W120", state.tokens.next, state.tokens.next.value);
          }
        }
        var id = state.tokens.prev;
        // don't accept `in` in expression if prefix is used for ForIn/Of loop.
        value = expression(prefix ? 120 : 10);
        if (value && !prefix && report && !state.funct["(loopage)"] && value.type === "undefined") {
          warning("W080", id, id.value);
        }
        if (lone) {
          tokens[0].first = value;
        } else {
          destructuringPatternMatch(names, value);
        }
      }

      if (state.tokens.next.id !== ",") {
        break;
      }
      parseComma();
    }

    return this;
  });
  varstatement.exps = true;

  blockstmt("class", function() {
    return classdef.call(this, true);
  });

  function classdef(isStatement) {

    /*jshint validthis:true */
    if (!state.inES6()) {
      warning("W104", state.tokens.curr, "class", "6");
    }
    if (isStatement) {
      // BindingIdentifier
      this.name = identifier();

      state.funct["(scope)"].addlabel(this.name, {
        type: "class",
        token: state.tokens.curr });
    } else if (state.tokens.next.identifier && state.tokens.next.value !== "extends") {
      // BindingIdentifier(opt)
      this.name = identifier();
      this.namedExpr = true;
    } else {
      this.name = state.nameStack.infer();
    }
    classtail(this);
    return this;
  }

  function classtail(c) {
    var wasInClassBody = state.inClassBody;
    // ClassHeritage(opt)
    if (state.tokens.next.value === "extends") {
      advance("extends");
      c.heritage = expression(10);
    }

    state.inClassBody = true;
    advance("{");
    // ClassBody(opt)
    c.body = classbody(c);
    advance("}");
    state.inClassBody = wasInClassBody;
  }

  function classbody(c) {
    var name;
    var isStatic;
    var isGenerator;
    var getset;
    var props = Object.create(null);
    var staticProps = Object.create(null);
    var computed;
    for (var i = 0; state.tokens.next.id !== "}"; ++i) {
      name = state.tokens.next;
      isStatic = false;
      isGenerator = false;
      getset = null;

      // The ES6 grammar for ClassElement includes the `;` token, but it is
      // defined only as a placeholder to facilitate future language
      // extensions. In ES6 code, it serves no purpose.
      if (name.id === ";") {
        warning("W032");
        advance(";");
        continue;
      }

      if (name.id === "*") {
        isGenerator = true;
        advance("*");
        name = state.tokens.next;
      }
      if (name.id === "[") {
        name = computedPropertyName();
        computed = true;
      } else if (isPropertyName(name)) {
        // Non-Computed PropertyName
        advance();
        computed = false;
        if (name.identifier && name.value === "static") {
          if (checkPunctuator(state.tokens.next, "*")) {
            isGenerator = true;
            advance("*");
          }
          if (isPropertyName(state.tokens.next) || state.tokens.next.id === "[") {
            computed = state.tokens.next.id === "[";
            isStatic = true;
            name = state.tokens.next;
            if (state.tokens.next.id === "[") {
              name = computedPropertyName();
            } else advance();
          }
        }

        if (name.identifier && (name.value === "get" || name.value === "set")) {
          if (isPropertyName(state.tokens.next) || state.tokens.next.id === "[") {
            computed = state.tokens.next.id === "[";
            getset = name;
            name = state.tokens.next;
            if (state.tokens.next.id === "[") {
              name = computedPropertyName();
            } else advance();
          }
        }
      } else {
        warning("W052", state.tokens.next, state.tokens.next.value || state.tokens.next.type);
        advance();
        continue;
      }

      if (!checkPunctuator(state.tokens.next, "(")) {
        // error --- class properties must be methods
        error("E054", state.tokens.next, state.tokens.next.value);
        while (state.tokens.next.id !== "}" &&
               !checkPunctuator(state.tokens.next, "(")) {
          advance();
        }
        if (state.tokens.next.value !== "(") {
          doFunction({ statement: c });
        }
      }

      if (!computed) {
        // We don't know how to determine if we have duplicate computed property names :(
        if (getset) {
          saveAccessor(
            getset.value, isStatic ? staticProps : props, name.value, name, true, isStatic);
        } else {
          if (name.value === "constructor") {
            state.nameStack.set(c);
          } else {
            state.nameStack.set(name);
          }
          saveProperty(isStatic ? staticProps : props, name.value, name, true, isStatic);
        }
      }

      if (getset && name.value === "constructor") {
        var propDesc = getset.value === "get" ? "class getter method" : "class setter method";
        error("E049", name, propDesc, "constructor");
      } else if (name.value === "prototype") {
        error("E049", name, "class method", "prototype");
      }

      propertyName(name);

      doFunction({
        statement: c,
        type: isGenerator ? "generator" : null,
        classExprBinding: c.namedExpr ? c.name : null
      });
    }

    checkProperties(props);
  }

  blockstmt("function", function(context) {
    var inexport = context && context.inexport;
    var generator = false;
    if (state.tokens.next.value === "*") {
      advance("*");
      if (state.inES6(true)) {
        generator = true;
      } else {
        warning("W119", state.tokens.curr, "function*", "6");
      }
    }
    if (inblock) {
      warning("W082", state.tokens.curr);
    }
    var i = optionalidentifier();

    state.funct["(scope)"].addlabel(i, {
      type: "function",
      token: state.tokens.curr });

    if (i === undefined) {
      warning("W025");
    } else if (inexport) {
      state.funct["(scope)"].setExported(i, state.tokens.prev);
    }

    doFunction({
      name: i,
      statement: this,
      type: generator ? "generator" : null,
      ignoreLoopFunc: inblock // a declaration may already have warned
    });
    if (state.tokens.next.id === "(" && state.tokens.next.line === state.tokens.curr.line) {
      error("E039");
    }
    return this;
  });

  prefix("function", function() {
    var generator = false;

    if (state.tokens.next.value === "*") {
      if (!state.inES6()) {
        warning("W119", state.tokens.curr, "function*", "6");
      }
      advance("*");
      generator = true;
    }

    var i = optionalidentifier();
    doFunction({ name: i, type: generator ? "generator" : null });
    return this;
  });

  blockstmt("if", function() {
    var t = state.tokens.next;
    increaseComplexityCount();
    state.condition = true;
    advance("(");
    var expr = expression(0);
    checkCondAssignment(expr);

    // When the if is within a for-in loop, check if the condition
    // starts with a negation operator
    var forinifcheck = null;
    if (state.option.forin && state.forinifcheckneeded) {
      state.forinifcheckneeded = false; // We only need to analyze the first if inside the loop
      forinifcheck = state.forinifchecks[state.forinifchecks.length - 1];
      if (expr.type === "(punctuator)" && expr.value === "!") {
        forinifcheck.type = "(negative)";
      } else {
        forinifcheck.type = "(positive)";
      }
    }

    advance(")", t);
    state.condition = false;
    var s = block(true, true);

    // When the if is within a for-in loop and the condition has a negative form,
    // check if the body contains nothing but a continue statement
    if (forinifcheck && forinifcheck.type === "(negative)") {
      if (s && s[0] && s[0].type === "(identifier)" && s[0].value === "continue") {
        forinifcheck.type = "(negative-with-continue)";
      }
    }

    if (state.tokens.next.id === "else") {
      advance("else");
      if (state.tokens.next.id === "if" || state.tokens.next.id === "switch") {
        statement();
      } else {
        block(true, true);
      }
    }
    return this;
  });

  blockstmt("try", function() {
    var b;

    function doCatch() {
      advance("catch");
      advance("(");

      state.funct["(scope)"].stack("catchparams");

      if (checkPunctuators(state.tokens.next, ["[", "{"])) {
        var tokens = destructuringPattern();
        _.each(tokens, function(token) {
          if (token.id) {
            state.funct["(scope)"].addParam(token.id, token, "exception");
          }
        });
      } else if (state.tokens.next.type !== "(identifier)") {
        warning("E030", state.tokens.next, state.tokens.next.value);
      } else {
        // only advance if we have an identifier so we can continue parsing in the most common error - that no param is given.
        state.funct["(scope)"].addParam(identifier(), state.tokens.curr, "exception");
      }

      if (state.tokens.next.value === "if") {
        if (!state.inMoz()) {
          warning("W118", state.tokens.curr, "catch filter");
        }
        advance("if");
        expression(0);
      }

      advance(")");

      block(false);

      state.funct["(scope)"].unstack();
    }

    block(true);

    while (state.tokens.next.id === "catch") {
      increaseComplexityCount();
      if (b && (!state.inMoz())) {
        warning("W118", state.tokens.next, "multiple catch blocks");
      }
      doCatch();
      b = true;
    }

    if (state.tokens.next.id === "finally") {
      advance("finally");
      block(true);
      return;
    }

    if (!b) {
      error("E021", state.tokens.next, "catch", state.tokens.next.value);
    }

    return this;
  });

  blockstmt("while", function() {
    var t = state.tokens.next;
    state.funct["(breakage)"] += 1;
    state.funct["(loopage)"] += 1;
    increaseComplexityCount();
    advance("(");
    checkCondAssignment(expression(0));
    advance(")", t);
    block(true, true);
    state.funct["(breakage)"] -= 1;
    state.funct["(loopage)"] -= 1;
    return this;
  }).labelled = true;

  blockstmt("with", function() {
    var t = state.tokens.next;
    if (state.isStrict()) {
      error("E010", state.tokens.curr);
    } else if (!state.option.withstmt) {
      warning("W085", state.tokens.curr);
    }

    advance("(");
    expression(0);
    advance(")", t);
    block(true, true);

    return this;
  });

  blockstmt("switch", function() {
    var t = state.tokens.next;
    var g = false;
    var noindent = false;

    state.funct["(breakage)"] += 1;
    advance("(");
    checkCondAssignment(expression(0));
    advance(")", t);
    t = state.tokens.next;
    advance("{");

    if (state.tokens.next.from === indent)
      noindent = true;

    if (!noindent)
      indent += state.option.indent;

    this.cases = [];

    for (;;) {
      switch (state.tokens.next.id) {
      case "case":
        switch (state.funct["(verb)"]) {
        case "yield":
        case "break":
        case "case":
        case "continue":
        case "return":
        case "switch":
        case "throw":
          break;
        default:
          // You can tell JSHint that you don't use break intentionally by
          // adding a comment /* falls through */ on a line just before
          // the next `case`.
          if (!state.tokens.curr.caseFallsThrough) {
            warning("W086", state.tokens.curr, "case");
          }
        }

        advance("case");
        this.cases.push(expression(0));
        increaseComplexityCount();
        g = true;
        advance(":");
        state.funct["(verb)"] = "case";
        break;
      case "default":
        switch (state.funct["(verb)"]) {
        case "yield":
        case "break":
        case "continue":
        case "return":
        case "throw":
          break;
        default:
          // Do not display a warning if 'default' is the first statement or if
          // there is a special /* falls through */ comment.
          if (this.cases.length) {
            if (!state.tokens.curr.caseFallsThrough) {
              warning("W086", state.tokens.curr, "default");
            }
          }
        }

        advance("default");
        g = true;
        advance(":");
        break;
      case "}":
        if (!noindent)
          indent -= state.option.indent;

        advance("}", t);
        state.funct["(breakage)"] -= 1;
        state.funct["(verb)"] = undefined;
        return;
      case "(end)":
        error("E023", state.tokens.next, "}");
        return;
      default:
        indent += state.option.indent;
        if (g) {
          switch (state.tokens.curr.id) {
          case ",":
            error("E040");
            return;
          case ":":
            g = false;
            statements();
            break;
          default:
            error("E025", state.tokens.curr);
            return;
          }
        } else {
          if (state.tokens.curr.id === ":") {
            advance(":");
            error("E024", state.tokens.curr, ":");
            statements();
          } else {
            error("E021", state.tokens.next, "case", state.tokens.next.value);
            return;
          }
        }
        indent -= state.option.indent;
      }
    }
    return this;
  }).labelled = true;

  stmt("debugger", function() {
    if (!state.option.debug) {
      warning("W087", this);
    }
    return this;
  }).exps = true;

  (function() {
    var x = stmt("do", function() {
      state.funct["(breakage)"] += 1;
      state.funct["(loopage)"] += 1;
      increaseComplexityCount();

      this.first = block(true, true);
      advance("while");
      var t = state.tokens.next;
      advance("(");
      checkCondAssignment(expression(0));
      advance(")", t);
      state.funct["(breakage)"] -= 1;
      state.funct["(loopage)"] -= 1;
      return this;
    });
    x.labelled = true;
    x.exps = true;
  }());

  blockstmt("for", function() {
    var s, t = state.tokens.next;
    var letscope = false;
    var foreachtok = null;

    if (t.value === "each") {
      foreachtok = t;
      advance("each");
      if (!state.inMoz()) {
        warning("W118", state.tokens.curr, "for each");
      }
    }

    increaseComplexityCount();
    advance("(");

    // what kind of for(…) statement it is? for(…of…)? for(…in…)? for(…;…;…)?
    var nextop; // contains the token of the "in" or "of" operator
    var i = 0;
    var inof = ["in", "of"];
    var level = 0; // BindingPattern "level" --- level 0 === no BindingPattern
    var comma; // First comma punctuator at level 0
    var initializer; // First initializer at level 0

    // If initial token is a BindingPattern, count it as such.
    if (checkPunctuators(state.tokens.next, ["{", "["])) ++level;
    do {
      nextop = peek(i);
      ++i;
      if (checkPunctuators(nextop, ["{", "["])) ++level;
      else if (checkPunctuators(nextop, ["}", "]"])) --level;
      if (level < 0) break;
      if (level === 0) {
        if (!comma && checkPunctuator(nextop, ",")) comma = nextop;
        else if (!initializer && checkPunctuator(nextop, "=")) initializer = nextop;
      }
    } while (level > 0 || !_.contains(inof, nextop.value) && nextop.value !== ";" &&
    nextop.type !== "(end)"); // Is this a JSCS bug? This looks really weird.

    // if we're in a for (… in|of …) statement
    if (_.contains(inof, nextop.value)) {
      if (!state.inES6() && nextop.value === "of") {
        warning("W104", nextop, "for of", "6");
      }

      var ok = !(initializer || comma);
      if (initializer) {
        error("W133", comma, nextop.value, "initializer is forbidden");
      }

      if (comma) {
        error("W133", comma, nextop.value, "more than one ForBinding");
      }

      if (state.tokens.next.id === "var") {
        advance("var");
        state.tokens.curr.fud({ prefix: true });
      } else if (state.tokens.next.id === "let" || state.tokens.next.id === "const") {
        advance(state.tokens.next.id);
        // create a new block scope
        letscope = true;
        state.funct["(scope)"].stack();
        state.tokens.curr.fud({ prefix: true });
      } else {
        // Parse as a var statement, with implied bindings. Ignore errors if an error
        // was already reported
        Object.create(varstatement).fud({ prefix: true, implied: "for", ignore: !ok });
      }
      advance(nextop.value);
      expression(20);
      advance(")", t);

      if (nextop.value === "in" && state.option.forin) {
        state.forinifcheckneeded = true;

        if (state.forinifchecks === undefined) {
          state.forinifchecks = [];
        }

        // Push a new for-in-if check onto the stack. The type will be modified
        // when the loop's body is parsed and a suitable if statement exists.
        state.forinifchecks.push({
          type: "(none)"
        });
      }

      state.funct["(breakage)"] += 1;
      state.funct["(loopage)"] += 1;

      s = block(true, true);

      if (nextop.value === "in" && state.option.forin) {
        if (state.forinifchecks && state.forinifchecks.length > 0) {
          var check = state.forinifchecks.pop();

          if (// No if statement or not the first statement in loop body
              s && s.length > 0 && (typeof s[0] !== "object" || s[0].value !== "if") ||
              // Positive if statement is not the only one in loop body
              check.type === "(positive)" && s.length > 1 ||
              // Negative if statement but no continue
              check.type === "(negative)") {
            warning("W089", this);
          }
        }

        // Reset the flag in case no if statement was contained in the loop body
        state.forinifcheckneeded = false;
      }

      state.funct["(breakage)"] -= 1;
      state.funct["(loopage)"] -= 1;
    } else {
      if (foreachtok) {
        error("E045", foreachtok);
      }
      if (state.tokens.next.id !== ";") {
        if (state.tokens.next.id === "var") {
          advance("var");
          state.tokens.curr.fud();
        } else if (state.tokens.next.id === "let") {
          advance("let");
          // create a new block scope
          letscope = true;
          state.funct["(scope)"].stack();
          state.tokens.curr.fud();
        } else {
          for (;;) {
            expression(0, "for");
            if (state.tokens.next.id !== ",") {
              break;
            }
            parseComma();
          }
        }
      }
      nolinebreak(state.tokens.curr);
      advance(";");

      // start loopage after the first ; as the next two expressions are executed
      // on every loop
      state.funct["(loopage)"] += 1;
      if (state.tokens.next.id !== ";") {
        checkCondAssignment(expression(0));
      }
      nolinebreak(state.tokens.curr);
      advance(";");
      if (state.tokens.next.id === ";") {
        error("E021", state.tokens.next, ")", ";");
      }
      if (state.tokens.next.id !== ")") {
        for (;;) {
          expression(0, "for");
          if (state.tokens.next.id !== ",") {
            break;
          }
          parseComma();
        }
      }
      advance(")", t);
      state.funct["(breakage)"] += 1;
      block(true, true);
      state.funct["(breakage)"] -= 1;
      state.funct["(loopage)"] -= 1;

    }
    // unstack loop blockscope
    if (letscope) {
      state.funct["(scope)"].unstack();
    }
    return this;
  }).labelled = true;


  stmt("break", function() {
    var v = state.tokens.next.value;

    if (!state.option.asi)
      nolinebreak(this);

    if (state.tokens.next.id !== ";" && !state.tokens.next.reach &&
        state.tokens.curr.line === startLine(state.tokens.next)) {
      if (!state.funct["(scope)"].funct.hasBreakLabel(v)) {
        warning("W090", state.tokens.next, v);
      }
      this.first = state.tokens.next;
      advance();
    } else {
      if (state.funct["(breakage)"] === 0)
        warning("W052", state.tokens.next, this.value);
    }

    reachable(this);

    return this;
  }).exps = true;


  stmt("continue", function() {
    var v = state.tokens.next.value;

    if (state.funct["(breakage)"] === 0)
      warning("W052", state.tokens.next, this.value);
    if (!state.funct["(loopage)"])
      warning("W052", state.tokens.next, this.value);

    if (!state.option.asi)
      nolinebreak(this);

    if (state.tokens.next.id !== ";" && !state.tokens.next.reach) {
      if (state.tokens.curr.line === startLine(state.tokens.next)) {
        if (!state.funct["(scope)"].funct.hasBreakLabel(v)) {
          warning("W090", state.tokens.next, v);
        }
        this.first = state.tokens.next;
        advance();
      }
    }

    reachable(this);

    return this;
  }).exps = true;


  stmt("return", function() {
    if (this.line === startLine(state.tokens.next)) {
      if (state.tokens.next.id !== ";" && !state.tokens.next.reach) {
        this.first = expression(0);

        if (this.first &&
            this.first.type === "(punctuator)" && this.first.value === "=" &&
            !this.first.paren && !state.option.boss) {
          warningAt("W093", this.first.line, this.first.character);
        }
      }
    } else {
      if (state.tokens.next.type === "(punctuator)" &&
        ["[", "{", "+", "-"].indexOf(state.tokens.next.value) > -1) {
        nolinebreak(this); // always warn (Line breaking error)
      }
    }

    reachable(this);

    return this;
  }).exps = true;

  (function(x) {
    x.exps = true;
    x.lbp = 25;
  }(prefix("yield", function() {
    var prev = state.tokens.prev;
    if (state.inES6(true) && !state.funct["(generator)"]) {
      // If it's a yield within a catch clause inside a generator then that's ok
      if (!("(catch)" === state.funct["(name)"] && state.funct["(context)"]["(generator)"])) {
        error("E046", state.tokens.curr, "yield");
      }
    } else if (!state.inES6()) {
      warning("W104", state.tokens.curr, "yield", "6");
    }
    state.funct["(generator)"] = "yielded";
    var delegatingYield = false;

    if (state.tokens.next.value === "*") {
      delegatingYield = true;
      advance("*");
    }

    if (this.line === startLine(state.tokens.next) || !state.inMoz()) {
      if (delegatingYield ||
          (state.tokens.next.id !== ";" && !state.option.asi &&
           !state.tokens.next.reach && state.tokens.next.nud)) {

        nobreaknonadjacent(state.tokens.curr, state.tokens.next);
        this.first = expression(10);

        if (this.first.type === "(punctuator)" && this.first.value === "=" &&
            !this.first.paren && !state.option.boss) {
          warningAt("W093", this.first.line, this.first.character);
        }
      }

      if (state.inMoz() && state.tokens.next.id !== ")" &&
          (prev.lbp > 30 || (!prev.assign && !isEndOfExpr()) || prev.id === "yield")) {
        error("E050", this);
      }
    } else if (!state.option.asi) {
      nolinebreak(this); // always warn (Line breaking error)
    }
    return this;
  })));


  stmt("throw", function() {
    nolinebreak(this);
    this.first = expression(20);

    reachable(this);

    return this;
  }).exps = true;

  stmt("import", function() {
    if (!state.inES6()) {
      warning("W119", state.tokens.curr, "import", "6");
    }

    if (state.tokens.next.type === "(string)") {
      // ModuleSpecifier :: StringLiteral
      advance("(string)");
      return this;
    }

    if (state.tokens.next.identifier) {
      // ImportClause :: ImportedDefaultBinding
      this.name = identifier();
      // Import bindings are immutable (see ES6 8.1.1.5.5)
      state.funct["(scope)"].addlabel(this.name, {
        type: "const",
        token: state.tokens.curr });

      if (state.tokens.next.value === ",") {
        // ImportClause :: ImportedDefaultBinding , NameSpaceImport
        // ImportClause :: ImportedDefaultBinding , NamedImports
        advance(",");
        // At this point, we intentionally fall through to continue matching
        // either NameSpaceImport or NamedImports.
        // Discussion:
        // https://github.com/jshint/jshint/pull/2144#discussion_r23978406
      } else {
        advance("from");
        advance("(string)");
        return this;
      }
    }

    if (state.tokens.next.id === "*") {
      // ImportClause :: NameSpaceImport
      advance("*");
      advance("as");
      if (state.tokens.next.identifier) {
        this.name = identifier();
        // Import bindings are immutable (see ES6 8.1.1.5.5)
        state.funct["(scope)"].addlabel(this.name, {
          type: "const",
          token: state.tokens.curr });
      }
    } else {
      // ImportClause :: NamedImports
      advance("{");
      for (;;) {
        if (state.tokens.next.value === "}") {
          advance("}");
          break;
        }
        var importName;
        if (state.tokens.next.type === "default") {
          importName = "default";
          advance("default");
        } else {
          importName = identifier();
        }
        if (state.tokens.next.value === "as") {
          advance("as");
          importName = identifier();
        }

        // Import bindings are immutable (see ES6 8.1.1.5.5)
        state.funct["(scope)"].addlabel(importName, {
          type: "const",
          token: state.tokens.curr });

        if (state.tokens.next.value === ",") {
          advance(",");
        } else if (state.tokens.next.value === "}") {
          advance("}");
          break;
        } else {
          error("E024", state.tokens.next, state.tokens.next.value);
          break;
        }
      }
    }

    // FromClause
    advance("from");
    advance("(string)");
    return this;
  }).exps = true;

  stmt("export", function() {
    var ok = true;
    var token;
    var identifier;

    if (!state.inES6()) {
      warning("W119", state.tokens.curr, "export", "6");
      ok = false;
    }

    if (!state.funct["(scope)"].block.isGlobal()) {
      error("E053", state.tokens.curr);
      ok = false;
    }

    if (state.tokens.next.value === "*") {
      // ExportDeclaration :: export * FromClause
      advance("*");
      advance("from");
      advance("(string)");
      return this;
    }

    if (state.tokens.next.type === "default") {
      // ExportDeclaration ::
      //      export default [lookahead  { function, class }] AssignmentExpression[In] ;
      //      export default HoistableDeclaration
      //      export default ClassDeclaration
      state.nameStack.set(state.tokens.next);
      advance("default");
      var exportType = state.tokens.next.id;
      if (exportType === "function" || exportType === "class") {
        this.block = true;
      }

      token = peek();

      expression(10);

      identifier = token.value;

      if (this.block) {
        state.funct["(scope)"].addlabel(identifier, {
          type: exportType,
          token: token });

        state.funct["(scope)"].setExported(identifier, token);
      }

      return this;
    }

    if (state.tokens.next.value === "{") {
      // ExportDeclaration :: export ExportClause
      advance("{");
      var exportedTokens = [];
      for (;;) {
        if (!state.tokens.next.identifier) {
          error("E030", state.tokens.next, state.tokens.next.value);
        }
        advance();

        exportedTokens.push(state.tokens.curr);

        if (state.tokens.next.value === "as") {
          advance("as");
          if (!state.tokens.next.identifier) {
            error("E030", state.tokens.next, state.tokens.next.value);
          }
          advance();
        }

        if (state.tokens.next.value === ",") {
          advance(",");
        } else if (state.tokens.next.value === "}") {
          advance("}");
          break;
        } else {
          error("E024", state.tokens.next, state.tokens.next.value);
          break;
        }
      }
      if (state.tokens.next.value === "from") {
        // ExportDeclaration :: export ExportClause FromClause
        advance("from");
        advance("(string)");
      } else if (ok) {
        exportedTokens.forEach(function(token) {
          state.funct["(scope)"].setExported(token.value, token);
        });
      }
      return this;
    }

    if (state.tokens.next.id === "var") {
      // ExportDeclaration :: export VariableStatement
      advance("var");
      state.tokens.curr.fud({ inexport:true });
    } else if (state.tokens.next.id === "let") {
      // ExportDeclaration :: export VariableStatement
      advance("let");
      state.tokens.curr.fud({ inexport:true });
    } else if (state.tokens.next.id === "const") {
      // ExportDeclaration :: export VariableStatement
      advance("const");
      state.tokens.curr.fud({ inexport:true });
    } else if (state.tokens.next.id === "function") {
      // ExportDeclaration :: export Declaration
      this.block = true;
      advance("function");
      state.syntax["function"].fud({ inexport:true });
    } else if (state.tokens.next.id === "class") {
      // ExportDeclaration :: export Declaration
      this.block = true;
      advance("class");
      var classNameToken = state.tokens.next;
      state.syntax["class"].fud();
      state.funct["(scope)"].setExported(classNameToken.value, classNameToken);
    } else {
      error("E024", state.tokens.next, state.tokens.next.value);
    }

    return this;
  }).exps = true;

  // Future Reserved Words

  FutureReservedWord("abstract");
  FutureReservedWord("await", { es5: true, moduleOnly: true });
  FutureReservedWord("boolean");
  FutureReservedWord("byte");
  FutureReservedWord("char");
  FutureReservedWord("class", { es5: true, nud: classdef });
  FutureReservedWord("double");
  FutureReservedWord("enum", { es5: true });
  FutureReservedWord("export", { es5: true });
  FutureReservedWord("extends", { es5: true });
  FutureReservedWord("final");
  FutureReservedWord("float");
  FutureReservedWord("goto");
  FutureReservedWord("implements", { es5: true, strictOnly: true });
  FutureReservedWord("import", { es5: true });
  FutureReservedWord("int");
  FutureReservedWord("interface", { es5: true, strictOnly: true });
  FutureReservedWord("long");
  FutureReservedWord("native");
  FutureReservedWord("package", { es5: true, strictOnly: true });
  FutureReservedWord("private", { es5: true, strictOnly: true });
  FutureReservedWord("protected", { es5: true, strictOnly: true });
  FutureReservedWord("public", { es5: true, strictOnly: true });
  FutureReservedWord("short");
  FutureReservedWord("static", { es5: true, strictOnly: true });
  FutureReservedWord("super", { es5: true });
  FutureReservedWord("synchronized");
  FutureReservedWord("transient");
  FutureReservedWord("volatile");

  // this function is used to determine whether a squarebracket or a curlybracket
  // expression is a comprehension array, destructuring assignment or a json value.

  var lookupBlockType = function() {
    var pn, pn1, prev;
    var i = -1;
    var bracketStack = 0;
    var ret = {};
    if (checkPunctuators(state.tokens.curr, ["[", "{"])) {
      bracketStack += 1;
    }
    do {
      prev = i === -1 ? state.tokens.curr : pn;
      pn = i === -1 ? state.tokens.next : peek(i);
      pn1 = peek(i + 1);
      i = i + 1;
      if (checkPunctuators(pn, ["[", "{"])) {
        bracketStack += 1;
      } else if (checkPunctuators(pn, ["]", "}"])) {
        bracketStack -= 1;
      }
      if (bracketStack === 1 && pn.identifier && pn.value === "for" &&
          !checkPunctuator(prev, ".")) {
        ret.isCompArray = true;
        ret.notJson = true;
        break;
      }
      if (bracketStack === 0 && checkPunctuators(pn, ["}", "]"])) {
        if (pn1.value === "=") {
          ret.isDestAssign = true;
          ret.notJson = true;
          break;
        } else if (pn1.value === ".") {
          ret.notJson = true;
          break;
        }
      }
      if (checkPunctuator(pn, ";")) {
        ret.isBlock = true;
        ret.notJson = true;
      }
    } while (bracketStack > 0 && pn.id !== "(end)");
    return ret;
  };

  function saveProperty(props, name, tkn, isClass, isStatic) {
    var msg = ["key", "class method", "static class method"];
    msg = msg[(isClass || false) + (isStatic || false)];
    if (tkn.identifier) {
      name = tkn.value;
    }

    if (props[name] && name !== "__proto__") {
      warning("W075", state.tokens.next, msg, name);
    } else {
      props[name] = Object.create(null);
    }

    props[name].basic = true;
    props[name].basictkn = tkn;
  }

  /**
   * @param {string} accessorType - Either "get" or "set"
   * @param {object} props - a collection of all properties of the object to
   *                         which the current accessor is being assigned
   * @param {object} tkn - the identifier token representing the accessor name
   * @param {boolean} isClass - whether the accessor is part of an ES6 Class
   *                            definition
   * @param {boolean} isStatic - whether the accessor is a static method
   */
  function saveAccessor(accessorType, props, name, tkn, isClass, isStatic) {
    var flagName = accessorType === "get" ? "getterToken" : "setterToken";
    var msg = "";

    if (isClass) {
      if (isStatic) {
        msg += "static ";
      }
      msg += accessorType + "ter method";
    } else {
      msg = "key";
    }

    state.tokens.curr.accessorType = accessorType;
    state.nameStack.set(tkn);

    if (props[name]) {
      if ((props[name].basic || props[name][flagName]) && name !== "__proto__") {
        warning("W075", state.tokens.next, msg, name);
      }
    } else {
      props[name] = Object.create(null);
    }

    props[name][flagName] = tkn;
  }

  function computedPropertyName() {
    advance("[");
    if (!state.inES6()) {
      warning("W119", state.tokens.curr, "computed property names", "6");
    }
    var value = expression(10);
    advance("]");
    return value;
  }

  /**
   * Test whether a given token is a punctuator matching one of the specified values
   * @param {Token} token
   * @param {Array.<string>} values
   * @returns {boolean}
   */
  function checkPunctuators(token, values) {
    if (token.type === "(punctuator)") {
      return _.contains(values, token.value);
    }
    return false;
  }

  /**
   * Test whether a given token is a punctuator matching the specified value
   * @param {Token} token
   * @param {string} value
   * @returns {boolean}
   */
  function checkPunctuator(token, value) {
    return token.type === "(punctuator)" && token.value === value;
  }

  // Check whether this function has been reached for a destructuring assign with undeclared values
  function destructuringAssignOrJsonValue() {
    // lookup for the assignment (ECMAScript 6 only)
    // if it has semicolons, it is a block, so go parse it as a block
    // or it's not a block, but there are assignments, check for undeclared variables

    var block = lookupBlockType();
    if (block.notJson) {
      if (!state.inES6() && block.isDestAssign) {
        warning("W104", state.tokens.curr, "destructuring assignment", "6");
      }
      statements();
    // otherwise parse json value
    } else {
      state.option.laxbreak = true;
      state.jsonMode = true;
      jsonValue();
    }
  }

  // array comprehension parsing function
  // parses and defines the three states of the list comprehension in order
  // to avoid defining global variables, but keeping them to the list comprehension scope
  // only. The order of the states are as follows:
  //  * "use" which will be the returned iterative part of the list comprehension
  //  * "define" which will define the variables local to the list comprehension
  //  * "filter" which will help filter out values

  var arrayComprehension = function() {
    var CompArray = function() {
      this.mode = "use";
      this.variables = [];
    };
    var _carrays = [];
    var _current;
    function declare(v) {
      var l = _current.variables.filter(function(elt) {
        // if it has, change its undef state
        if (elt.value === v) {
          elt.undef = false;
          return v;
        }
      }).length;
      return l !== 0;
    }
    function use(v) {
      var l = _current.variables.filter(function(elt) {
        // and if it has been defined
        if (elt.value === v && !elt.undef) {
          if (elt.unused === true) {
            elt.unused = false;
          }
          return v;
        }
      }).length;
      // otherwise we warn about it
      return (l === 0);
    }
    return { stack: function() {
          _current = new CompArray();
          _carrays.push(_current);
        },
        unstack: function() {
          _current.variables.filter(function(v) {
            if (v.unused)
              warning("W098", v.token, v.raw_text || v.value);
            if (v.undef)
              state.funct["(scope)"].block.use(v.value, v.token);
          });
          _carrays.splice(-1, 1);
          _current = _carrays[_carrays.length - 1];
        },
        setState: function(s) {
          if (_.contains(["use", "define", "generate", "filter"], s))
            _current.mode = s;
        },
        check: function(v) {
          if (!_current) {
            return;
          }
          // When we are in "use" state of the list comp, we enqueue that var
          if (_current && _current.mode === "use") {
            if (use(v)) {
              _current.variables.push({
                funct: state.funct,
                token: state.tokens.curr,
                value: v,
                undef: true,
                unused: false
              });
            }
            return true;
          // When we are in "define" state of the list comp,
          } else if (_current && _current.mode === "define") {
            // check if the variable has been used previously
            if (!declare(v)) {
              _current.variables.push({
                funct: state.funct,
                token: state.tokens.curr,
                value: v,
                undef: false,
                unused: true
              });
            }
            return true;
          // When we are in the "generate" state of the list comp,
          } else if (_current && _current.mode === "generate") {
            state.funct["(scope)"].block.use(v, state.tokens.curr);
            return true;
          // When we are in "filter" state,
          } else if (_current && _current.mode === "filter") {
            // we check whether current variable has been declared
            if (use(v)) {
              // if not we warn about it
              state.funct["(scope)"].block.use(v, state.tokens.curr);
            }
            return true;
          }
          return false;
        }
        };
  };


  // Parse JSON

  function jsonValue() {
    function jsonObject() {
      var o = {}, t = state.tokens.next;
      advance("{");
      if (state.tokens.next.id !== "}") {
        for (;;) {
          if (state.tokens.next.id === "(end)") {
            error("E026", state.tokens.next, t.line);
          } else if (state.tokens.next.id === "}") {
            warning("W094", state.tokens.curr);
            break;
          } else if (state.tokens.next.id === ",") {
            error("E028", state.tokens.next);
          } else if (state.tokens.next.id !== "(string)") {
            warning("W095", state.tokens.next, state.tokens.next.value);
          }
          if (o[state.tokens.next.value] === true) {
            warning("W075", state.tokens.next, "key", state.tokens.next.value);
          } else if ((state.tokens.next.value === "__proto__" &&
            !state.option.proto) || (state.tokens.next.value === "__iterator__" &&
            !state.option.iterator)) {
            warning("W096", state.tokens.next, state.tokens.next.value);
          } else {
            o[state.tokens.next.value] = true;
          }
          advance();
          advance(":");
          jsonValue();
          if (state.tokens.next.id !== ",") {
            break;
          }
          advance(",");
        }
      }
      advance("}");
    }

    function jsonArray() {
      var t = state.tokens.next;
      advance("[");
      if (state.tokens.next.id !== "]") {
        for (;;) {
          if (state.tokens.next.id === "(end)") {
            error("E027", state.tokens.next, t.line);
          } else if (state.tokens.next.id === "]") {
            warning("W094", state.tokens.curr);
            break;
          } else if (state.tokens.next.id === ",") {
            error("E028", state.tokens.next);
          }
          jsonValue();
          if (state.tokens.next.id !== ",") {
            break;
          }
          advance(",");
        }
      }
      advance("]");
    }

    switch (state.tokens.next.id) {
    case "{":
      jsonObject();
      break;
    case "[":
      jsonArray();
      break;
    case "true":
    case "false":
    case "null":
    case "(number)":
    case "(string)":
      advance();
      break;
    case "-":
      advance("-");
      advance("(number)");
      break;
    default:
      error("E003", state.tokens.next);
    }
  }

  var escapeRegex = function(str) {
    return str.replace(/[-\/\\^$*+?.()|[\]{}]/g, "\\$&");
  };

  // The actual JSHINT function itself.
  var itself = function(s, o, g) {
    var i, k, x, reIgnoreStr, reIgnore;
    var optionKeys;
    var newOptionObj = {};
    var newIgnoredObj = {};

    o = _.clone(o);
    state.reset();

    if (o && o.scope) {
      JSHINT.scope = o.scope;
    } else {
      JSHINT.errors = [];
      JSHINT.undefs = [];
      JSHINT.internals = [];
      JSHINT.blacklist = {};
      JSHINT.scope = "(main)";
    }

    predefined = Object.create(null);
    combine(predefined, vars.ecmaIdentifiers[3]);
    combine(predefined, vars.reservedVars);

    combine(predefined, g || {});

    declared = Object.create(null);
    var exported = Object.create(null); // Variables that live outside the current file

    function each(obj, cb) {
      if (!obj)
        return;

      if (!Array.isArray(obj) && typeof obj === "object")
        obj = Object.keys(obj);

      obj.forEach(cb);
    }

    if (o) {
      each(o.predef || null, function(item) {
        var slice, prop;

        if (item[0] === "-") {
          slice = item.slice(1);
          JSHINT.blacklist[slice] = slice;
          // remove from predefined if there
          delete predefined[slice];
        } else {
          prop = Object.getOwnPropertyDescriptor(o.predef, item);
          predefined[item] = prop ? prop.value : false;
        }
      });

      each(o.exported || null, function(item) {
        exported[item] = true;
      });

      delete o.predef;
      delete o.exported;

      optionKeys = Object.keys(o);
      for (x = 0; x < optionKeys.length; x++) {
        if (/^-W\d{3}$/g.test(optionKeys[x])) {
          newIgnoredObj[optionKeys[x].slice(1)] = true;
        } else {
          var optionKey = optionKeys[x];
          newOptionObj[optionKey] = o[optionKey];
        }
      }
    }

    state.option = newOptionObj;
    state.ignored = newIgnoredObj;

    state.option.indent = state.option.indent || 4;
    state.option.maxerr = state.option.maxerr || 50;

    indent = 1;

    var scopeManagerInst = scopeManager(state, predefined, exported, declared);
    scopeManagerInst.on("warning", function(ev) {
      warning.apply(null, [ ev.code, ev.token].concat(ev.data));
    });

    scopeManagerInst.on("error", function(ev) {
      error.apply(null, [ ev.code, ev.token ].concat(ev.data));
    });

    state.funct = functor("(global)", null, {
      "(global)"    : true,
      "(scope)"     : scopeManagerInst,
      "(comparray)" : arrayComprehension(),
      "(metrics)"   : createMetrics(state.tokens.next)
    });

    functions = [state.funct];
    urls = [];
    stack = null;
    member = {};
    membersOnly = null;
    inblock = false;
    lookahead = [];

    if (!isString(s) && !Array.isArray(s)) {
      errorAt("E004", 0);
      return false;
    }

    api = {
      get isJSON() {
        return state.jsonMode;
      },

      getOption: function(name) {
        return state.option[name] || null;
      },

      getCache: function(name) {
        return state.cache[name];
      },

      setCache: function(name, value) {
        state.cache[name] = value;
      },

      warn: function(code, data) {
        warningAt.apply(null, [ code, data.line, data.char ].concat(data.data));
      },

      on: function(names, listener) {
        names.split(" ").forEach(function(name) {
          emitter.on(name, listener);
        }.bind(this));
      }
    };

    emitter.removeAllListeners();
    (extraModules || []).forEach(function(func) {
      func(api);
    });

    state.tokens.prev = state.tokens.curr = state.tokens.next = state.syntax["(begin)"];

    if (o && o.ignoreDelimiters) {

      if (!Array.isArray(o.ignoreDelimiters)) {
        o.ignoreDelimiters = [o.ignoreDelimiters];
      }

      o.ignoreDelimiters.forEach(function(delimiterPair) {
        if (!delimiterPair.start || !delimiterPair.end)
            return;

        reIgnoreStr = escapeRegex(delimiterPair.start) +
                      "[\\s\\S]*?" +
                      escapeRegex(delimiterPair.end);

        reIgnore = new RegExp(reIgnoreStr, "ig");

        s = s.replace(reIgnore, function(match) {
          return match.replace(/./g, " ");
        });
      });
    }

    lex = new Lexer(s);

    lex.on("warning", function(ev) {
      warningAt.apply(null, [ ev.code, ev.line, ev.character].concat(ev.data));
    });

    lex.on("error", function(ev) {
      errorAt.apply(null, [ ev.code, ev.line, ev.character ].concat(ev.data));
    });

    lex.on("fatal", function(ev) {
      quit("E041", ev);
    });

    lex.on("Identifier", function(ev) {
      emitter.emit("Identifier", ev);
    });

    lex.on("String", function(ev) {
      emitter.emit("String", ev);
    });

    lex.on("Number", function(ev) {
      emitter.emit("Number", ev);
    });

    lex.start();

    // Check options
    for (var name in o) {
      if (_.has(o, name)) {
        checkOption(name, state.tokens.curr);
      }
    }

    try {
      assume();

      // combine the passed globals after we've assumed all our options
      combine(predefined, g || {});

      //reset values
      parseComma.first = true;

      advance();
      switch (state.tokens.next.id) {
      case "{":
      case "[":
        destructuringAssignOrJsonValue();
        break;
      default:
        directives();

        if (state.directive["use strict"]) {
          if (!state.allowsGlobalUsd()) {
            warning("W097", state.tokens.prev);
          }
        }

        statements();
      }

      if (state.tokens.next.id !== "(end)") {
        quit("E041", state.tokens.curr);
      }

      state.funct["(scope)"].unstack();

    } catch (err) {
      if (err && err.name === "JSHintError") {
        var nt = state.tokens.next || {};
        JSHINT.errors.push({
          scope     : "(main)",
          raw       : err.raw,
          code      : err.code,
          reason    : err.reason,
          line      : err.line || nt.line,
          character : err.character || nt.from
        }, null);
      } else {
        throw err;
      }
    }

    // Loop over the listed "internals", and check them as well.

    if (JSHINT.scope === "(main)") {
      o = o || {};

      for (i = 0; i < JSHINT.internals.length; i += 1) {
        k = JSHINT.internals[i];
        o.scope = k.elem;
        itself(k.value, o, g);
      }
    }

    return JSHINT.errors.length === 0;
  };

  // Modules.
  itself.addModule = function(func) {
    extraModules.push(func);
  };

  itself.addModule(style.register);

  // Data summary.
  itself.data = function() {
    var data = {
      functions: [],
      options: state.option
    };

    var fu, f, i, j, n, globals;

    if (itself.errors.length) {
      data.errors = itself.errors;
    }

    if (state.jsonMode) {
      data.json = true;
    }

    var impliedGlobals = state.funct["(scope)"].getImpliedGlobals();
    if (impliedGlobals.length > 0) {
      data.implieds = impliedGlobals;
    }

    if (urls.length > 0) {
      data.urls = urls;
    }

    globals = state.funct["(scope)"].getUsedOrDefinedGlobals();
    if (globals.length > 0) {
      data.globals = globals;
    }

    for (i = 1; i < functions.length; i += 1) {
      f = functions[i];
      fu = {};

      for (j = 0; j < functionicity.length; j += 1) {
        fu[functionicity[j]] = [];
      }

      for (j = 0; j < functionicity.length; j += 1) {
        if (fu[functionicity[j]].length === 0) {
          delete fu[functionicity[j]];
        }
      }

      fu.name = f["(name)"];
      fu.param = f["(params)"];
      fu.line = f["(line)"];
      fu.character = f["(character)"];
      fu.last = f["(last)"];
      fu.lastcharacter = f["(lastcharacter)"];

      fu.metrics = {
        complexity: f["(metrics)"].ComplexityCount,
        parameters: f["(metrics)"].arity,
        statements: f["(metrics)"].statementCount
      };

      data.functions.push(fu);
    }

    var unuseds = state.funct["(scope)"].getUnuseds();
    if (unuseds.length > 0) {
      data.unused = unuseds;
    }

    for (n in member) {
      if (typeof member[n] === "number") {
        data.member = member;
        break;
      }
    }

    return data;
  };

  itself.jshint = itself;

  return itself;
}());

// Make JSHINT a Node module, if possible.
if (typeof exports === "object" && exports) {
  exports.JSHINT = JSHINT;
}