Import to new git repository

The old repository was using almost 100mb of space because of all
the unnecessary files in the history. So I've imported the code to a
new git repository. Unfortunately the history isn't viewable from this
repository anymore. To see what happened with LibreJS before 2015, see
the old Bazaar repo here: http://bzr.savannah.gnu.org/lh/librejs/

1 files changed, 2042 insertions, 0 deletions

diff --git a/data/chrome_worker/parser/jsparse.js b/data/chrome_worker/parser/jsparse.js
new file mode 100644
index 0000000..b78078c
--- /dev/null
+++ b/data/chrome_worker/parser/jsparse.js
@@ -0,0 +1,2042 @@
+/* -*- Mode: JS; tab-width: 4; indent-tabs-mode: nil; -*-
+ * vim: set sw=4 ts=4 et tw=78:
+ * ***** BEGIN LICENSE BLOCK *****
+ *
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is the Narcissus JavaScript engine.
+ *
+ * The Initial Developer of the Original Code is
+ * Brendan Eich <brendan@mozilla.org>.
+ * Portions created by the Initial Developer are Copyright (C) 2004
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Tom Austin <taustin@ucsc.edu>
+ *   Brendan Eich <brendan@mozilla.org>
+ *   Shu-Yu Guo <shu@rfrn.org>
+ *   Dave Herman <dherman@mozilla.com>
+ *   Dimitris Vardoulakis <dimvar@ccs.neu.edu>
+ *   Patrick Walton <pcwalton@mozilla.com>
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+/**
+ * GNU LibreJS - A browser add-on to block nonfree nontrivial JavaScript.
+ * *
+ * Copyright (C) 2011, 2012, 2014 Loic J. Duros
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see  <http://www.gnu.org/licenses/>.
+ *
+ */
+/*
+ * Narcissus - JS implemented in JS.
+ *
+ * Parser.
+ */
+
+"use strict";
+
+Narcissus.parser = (function() {
+    
+    var lexer = Narcissus.lexer;
+    var definitions = Narcissus.definitions;
+    
+    const StringMap = definitions.StringMap;
+    const Stack = definitions.Stack;
+    
+    var comment;
+    
+		       // Set constants in the local scope.
+		       //eval(definitions.consts);
+		       const END = 0,
+		       NEWLINE = 1,
+		       SEMICOLON = 2,
+		       COMMA = 3,
+		       ASSIGN = 4,
+		       HOOK = 5,
+		       COLON = 6,
+		       CONDITIONAL = 7,
+		       OR = 8,
+		       AND = 9,
+		       BITWISE_OR = 10,
+		       BITWISE_XOR = 11,
+		       BITWISE_AND = 12,
+		       EQ = 13,
+		       NE = 14,
+		       STRICT_EQ = 15,
+		       STRICT_NE = 16,
+		       LT = 17,
+		       LE = 18,
+		       GE = 19,
+		       GT = 20,
+		       LSH = 21,
+		       RSH = 22,
+		       URSH = 23,
+		       PLUS = 24,
+		       MINUS = 25,
+		       MUL = 26,
+		       DIV = 27,
+		       MOD = 28,
+		       NOT = 29,
+		       BITWISE_NOT = 30,
+		       UNARY_PLUS = 31,
+		       UNARY_MINUS = 32,
+		       INCREMENT = 33,
+		       DECREMENT = 34,
+		       DOT = 35,
+		       LEFT_BRACKET = 36,
+		       RIGHT_BRACKET = 37,
+		       LEFT_CURLY = 38,
+		       RIGHT_CURLY = 39,
+		       LEFT_PAREN = 40,
+		       RIGHT_PAREN = 41,
+		       SCRIPT = 42,
+		       BLOCK = 43,
+		       LABEL = 44,
+		       FOR_IN = 45,
+		       CALL = 46,
+		       NEW_WITH_ARGS = 47,
+		       INDEX = 48,
+		       ARRAY_INIT = 49,
+		       OBJECT_INIT = 50,
+		       PROPERTY_INIT = 51,
+		       GETTER = 52,
+		       SETTER = 53,
+		       GROUP = 54,
+		       LIST = 55,
+		       LET_BLOCK = 56,
+		       ARRAY_COMP = 57,
+		       GENERATOR = 58,
+		       COMP_TAIL = 59,
+		       IDENTIFIER = 60,
+		       NUMBER = 61,
+		       STRING = 62,
+		       REGEXP = 63,
+		       BREAK = 64,
+		   CASE = 65,
+		       CATCH = 66,
+		       CONST = 67,
+		       CONTINUE = 68,
+		       DEBUGGER = 69,
+		   DEFAULT = 70,
+		       DELETE = 71,
+		       DO = 72,
+		       ELSE = 73,
+		       EXPORT = 74,
+		       FALSE = 75,
+		       FINALLY = 76,
+		       FOR = 77,
+		       FUNCTION = 78,
+		       IF = 79,
+		       IMPORT = 80,
+			   IN = 81,
+			   INSTANCEOF = 82,
+		       LET = 83,
+		       MODULE = 84,
+		       NEW = 85,
+		       NULL = 86,
+		       RETURN = 87,
+		       SWITCH = 88,
+		       THIS = 89,
+		       THROW = 90,
+		       TRUE = 91,
+		       TRY = 92,
+		       TYPEOF = 93,
+		       VAR = 94,
+		       VOID = 95,
+		       YIELD = 96,
+		       WHILE = 97,
+		       WITH = 98;
+
+    // Banned statement types by language version.
+    const blackLists = { 160: {}, 185: {}, harmony: {} };
+  /*  blackLists[160][IMPORT] = true;
+    blackLists[160][EXPORT] = true;
+    blackLists[160][LET] = true;
+    blackLists[160][MODULE] = true;
+    blackLists[160][YIELD] = true;
+    blackLists[185][IMPORT] = true;
+    blackLists[185][EXPORT] = true;
+    blackLists[185][MODULE] = true;
+    blackLists.harmony[WITH] = true;
+*/
+    /*
+     * pushDestructuringVarDecls :: (node, hoisting node) -> void
+     *
+     * Recursively add all destructured declarations to varDecls.
+     */
+    function pushDestructuringVarDecls(n, s) {
+        for (var i in n) {
+            var sub = n[i];
+            if (sub.type === IDENTIFIER) {
+                s.varDecls.push(sub);
+            } else {
+                pushDestructuringVarDecls(sub, s);
+            }
+        }
+    }
+
+    function StaticContext(parentScript, parentBlock, inModule, inFunction) {
+        this.parentScript = parentScript;
+        this.parentBlock = parentBlock || parentScript;
+        this.inModule = inModule || false;
+        this.inFunction = inFunction || false;
+        this.inForLoopInit = false;
+        this.topLevel = true;
+        this.allLabels = new Stack();
+        this.currentLabels = new Stack();
+        this.labeledTargets = new Stack();
+        this.defaultLoopTarget = null;
+        this.defaultTarget = null;
+        this.blackList = blackLists[Narcissus.options.version];
+        Narcissus.options.ecma3OnlyMode && (this.ecma3OnlyMode = true);
+        Narcissus.options.parenFreeMode && (this.parenFreeMode = true);
+    }
+
+    StaticContext.prototype = {
+        ecma3OnlyMode: false,
+        parenFreeMode: false,
+        // non-destructive update via prototype extension
+        update: function(ext) {
+            var desc = {};
+            for (var key in ext) {
+                desc[key] = {
+                    value: ext[key],
+                    writable: true,
+                    enumerable: true,
+                    configurable: true
+                }
+            }
+            return Object.create(this, desc);
+        },
+        pushLabel: function(label) {
+            return this.update({ currentLabels: this.currentLabels.push(label),
+                                 allLabels: this.allLabels.push(label) });
+        },
+        pushTarget: function(target) {
+            var isDefaultLoopTarget = target.isLoop;
+            var isDefaultTarget = isDefaultLoopTarget || target.type === SWITCH;
+
+            if (this.currentLabels.isEmpty()) {
+                if (isDefaultLoopTarget) this.update({ defaultLoopTarget: target });
+                if (isDefaultTarget) this.update({ defaultTarget: target });
+                return this;
+            }
+
+            target.labels = new StringMap();
+            this.currentLabels.forEach(function(label) {
+                target.labels.set(label, true);
+            });
+            return this.update({ currentLabels: new Stack(),
+                                 labeledTargets: this.labeledTargets.push(target),
+                                 defaultLoopTarget: isDefaultLoopTarget
+                                                    ? target
+                                                    : this.defaultLoopTarget,
+                                 defaultTarget: isDefaultTarget
+                                                ? target
+                                                : this.defaultTarget });
+        },
+        nest: function() {
+            return this.topLevel ? this.update({ topLevel: false }) : this;
+        },
+        allow: function(type) {
+            switch (type) {
+              case EXPORT:
+                if (!this.inModule || this.inFunction || !this.topLevel)
+                    return false;
+                // FALL THROUGH
+
+              case IMPORT:
+                return !this.inFunction && this.topLevel;
+
+              case MODULE:
+                return !this.inFunction && this.topLevel;
+
+              default:
+                return true;
+            }
+        }
+    };
+
+    /*
+     * Script :: (tokenizer, boolean, boolean) -> node
+     *
+     * Parses the toplevel and module/function bodies.
+     */
+    function Script(t, inModule, inFunction) {
+        var n = new Node(t, scriptInit());
+        Statements(t, new StaticContext(n, n, inModule, inFunction), n);
+        return n;
+    }
+
+    // We extend Array slightly with a top-of-stack method.
+    definitions.defineProperty(Array.prototype, "top",
+                               function() {
+                                   return this.length && this[this.length-1];
+                               }, false, false, true);
+
+    /*
+     * Node :: (tokenizer, optional init object) -> node
+     */
+    function Node(t, init) {
+        var token = t.token;
+        if (token) {
+            // If init.type exists it will override token.type.
+            this.type = token.type;
+            this.value = token.value;
+            this.lineno = token.lineno;
+
+            // Start and end are file positions for error handling.
+            this.start = token.start;
+            this.end = token.end;
+        } else {
+            this.lineno = t.lineno;
+        }
+
+        // Node uses a tokenizer for debugging (getSource, filename getter).
+        this.tokenizer = t;
+        this.children = [];
+
+        for (var prop in init)
+            this[prop] = init[prop];
+    }
+
+    /*
+     * SyntheticNode :: (tokenizer, optional init object) -> node
+     */
+    function SyntheticNode(t, init) {
+        // print("SYNTHETIC NODE");
+        // if (init.type === COMMA) {
+        //     print("SYNTHETIC COMMA");
+        //     print(init);
+        // }
+        this.tokenizer = t;
+        this.children = [];
+        for (var prop in init)
+            this[prop] = init[prop];
+        this.synthetic = true;
+    }
+
+    var Np = Node.prototype = SyntheticNode.prototype = {};
+    Np.constructor = Node;
+
+    const TO_SOURCE_SKIP = {
+        type: true,
+        value: true,
+        lineno: true,
+        start: true,
+        end: true,
+        tokenizer: true,
+        assignOp: true
+    };
+    function unevalableConst(code) {
+        var token = definitions.tokens[code];
+        var constName = definitions.opTypeNames.hasOwnProperty(token)
+                      ? definitions.opTypeNames[token]
+                      : token in definitions.keywords
+                      ? token.toUpperCase()
+                      : token;
+        return { toSource: function() { return constName } };
+    }
+    Np.toSource = function toSource() {
+        var mock = {};
+        var self = this;
+        mock.type = unevalableConst(this.type);
+        if ("value" in this)
+            mock.value = this.value;
+        if ("lineno" in this)
+            mock.lineno = this.lineno;
+        if ("start" in this)
+            mock.start = this.start;
+        if ("end" in this)
+            mock.end = this.end;
+        if (this.assignOp)
+            mock.assignOp = unevalableConst(this.assignOp);
+        for (var key in this) {
+            if (this.hasOwnProperty(key) && !(key in TO_SOURCE_SKIP))
+                mock[key] = this[key];
+        }
+        return mock.toSource();
+    };
+
+    // Always use push to add operands to an expression, to update start and end.
+    Np.push = function (kid) {
+        // kid can be null e.g. [1, , 2].
+        if (kid !== null) {
+            if (kid.start < this.start)
+                this.start = kid.start;
+            if (this.end < kid.end)
+                this.end = kid.end;
+        }
+        return this.children.push(kid);
+    }
+
+    Node.indentLevel = 0;
+
+    function tokenString(tt) {
+        var t = definitions.tokens[tt];
+        return /^\W/.test(t) ? definitions.opTypeNames[t] : t.toUpperCase();
+    }
+
+    Np.toString = function () {
+        var a = [];
+        for (var i in this) {
+            if (this.hasOwnProperty(i) && i !== 'type' && i !== 'target')
+                a.push({id: i, value: this[i]});
+        }
+        a.sort(function (a,b) { return (a.id < b.id) ? -1 : 1; });
+        const INDENTATION = "    ";
+        var n = ++Node.indentLevel;
+        var s = "{\n" + INDENTATION.repeat(n) + "type: " + tokenString(this.type);
+        for (i = 0; i < a.length; i++)
+            s += ",\n" + INDENTATION.repeat(n) + a[i].id + ": " + a[i].value;
+        n = --Node.indentLevel;
+        s += "\n" + INDENTATION.repeat(n) + "}";
+        return s;
+    }
+
+    Np.getSource = function () {
+        return this.tokenizer.source.slice(this.start, this.end);
+    };
+
+    /*
+     * Helper init objects for common nodes.
+     */
+
+    const LOOP_INIT = { isLoop: true };
+
+    function blockInit() {
+        return { type: BLOCK, varDecls: [] };
+    }
+
+    function scriptInit() {
+        return { type: SCRIPT,
+                 funDecls: [],
+                 varDecls: [],
+                 modDefns: new StringMap(),
+                 modAssns: new StringMap(),
+                 modDecls: new StringMap(),
+                 modLoads: new StringMap(),
+                 impDecls: [],
+                 expDecls: [],
+                 exports: new StringMap(),
+                 hasEmptyReturn: false,
+                 hasReturnWithValue: false,
+                 isGenerator: false };
+    }
+
+    definitions.defineGetter(Np, "filename",
+                             function() {
+                                 return this.tokenizer.filename;
+                             });
+
+    definitions.defineGetter(Np, "length",
+                             function() {
+                                 throw new Error("Node.prototype.length is gone; " +
+                                                 "use n.children.length instead");
+                             });
+
+    definitions.defineProperty(String.prototype, "repeat",
+                               function(n) {
+                                   var s = "", t = this + s;
+                                   while (--n >= 0)
+                                       s += t;
+                                   return s;
+                               }, false, false, true);
+
+    function MaybeLeftParen(t, x) {
+        if (x.parenFreeMode)
+            return t.match(LEFT_PAREN) ? LEFT_PAREN : END;
+        return t.mustMatch(LEFT_PAREN).type;
+    }
+
+    function MaybeRightParen(t, p) {
+        if (p === LEFT_PAREN)
+            t.mustMatch(RIGHT_PAREN);
+    }
+
+    /*
+     * Statements :: (tokenizer, compiler context, node) -> void
+     *
+     * Parses a sequence of Statements.
+     */
+    function Statements(t, x, n) {
+        try {
+            while (!t.done && t.peek(true) !== RIGHT_CURLY)
+                n.push(Statement(t, x));
+        } catch (e) {
+            if (t.done)
+                t.unexpectedEOF = true;
+            throw e;
+        }
+    }
+
+    function Block(t, x) {
+        t.mustMatch(LEFT_CURLY);
+        var n = new Node(t, blockInit());
+        Statements(t, x.update({ parentBlock: n }).pushTarget(n), n);
+        t.mustMatch(RIGHT_CURLY);
+        return n;
+    }
+
+    const DECLARED_FORM = 0, EXPRESSED_FORM = 1, STATEMENT_FORM = 2;
+
+    /*
+     * Export :: (binding node, boolean) -> Export
+     *
+     * Static semantic representation of a module export.
+     */
+    function Export(node, isDefinition) {
+        this.node = node;                 // the AST node declaring this individual export
+        this.isDefinition = isDefinition; // is the node an 'export'-annotated definition?
+        this.resolved = null;             // resolved pointer to the target of this export
+    }
+
+    /*
+     * registerExport :: (StringMap, EXPORT node) -> void
+     */
+    function registerExport(exports, decl) {
+        function register(name, exp) {
+            if (exports.has(name))
+                throw new SyntaxError("multiple exports of " + name);
+            exports.set(name, exp);
+        }
+
+        switch (decl.type) {
+          case MODULE:
+          case FUNCTION:
+            register(decl.name, new Export(decl, true));
+            break;
+
+          case VAR:
+            for (var i = 0; i < decl.children.length; i++)
+                register(decl.children[i].name, new Export(decl.children[i], true));
+            break;
+
+          case LET:
+          case CONST:
+            throw new Error("NYI: " + definitions.tokens[decl.type]);
+
+          case EXPORT:
+            for (var i = 0; i < decl.pathList.length; i++) {
+                var path = decl.pathList[i];
+                switch (path.type) {
+                  case OBJECT_INIT:
+                    for (var j = 0; j < path.children.length; j++) {
+                        // init :: IDENTIFIER | PROPERTY_INIT
+                        var init = path.children[j];
+                        if (init.type === IDENTIFIER)
+                            register(init.value, new Export(init, false));
+                        else
+                            register(init.children[0].value, new Export(init.children[1], false));
+                    }
+                    break;
+
+                  case DOT:
+                    register(path.children[1].value, new Export(path, false));
+                    break;
+
+                  case IDENTIFIER:
+                    register(path.value, new Export(path, false));
+                    break;
+
+                  default:
+                    throw new Error("unexpected export path: " + definitions.tokens[path.type]);
+                }
+            }
+            break;
+
+          default:
+            throw new Error("unexpected export decl: " + definitions.tokens[exp.type]);
+        }
+    }
+
+    /*
+     * Module :: (node) -> Module
+     *
+     * Static semantic representation of a module.
+     */
+    function Module(node) {
+        var exports = node.body.exports;
+        var modDefns = node.body.modDefns;
+
+        var exportedModules = new StringMap();
+
+        exports.forEach(function(name, exp) {
+            var node = exp.node;
+            if (node.type === MODULE) {
+                exportedModules.set(name, node);
+            } else if (!exp.isDefinition && node.type === IDENTIFIER && modDefns.has(node.value)) {
+                var mod = modDefns.get(node.value);
+                exportedModules.set(name, mod);
+            }
+        });
+
+        this.node = node;
+        this.exports = exports;
+        this.exportedModules = exportedModules;
+    }
+
+    /*
+     * Statement :: (tokenizer, compiler context) -> node
+     *
+     * Parses a Statement.
+     */
+    function Statement(t, x) {
+        var i, label, n, n2, p, c, ss, tt = t.get(true), tt2, x2, x3;
+
+        var comments = t.blockComments;
+
+        if (x.blackList[tt])
+            throw t.newSyntaxError(definitions.tokens[tt] + " statements only allowed in Harmony");
+        if (!x.allow(tt))
+            throw t.newSyntaxError(definitions.tokens[tt] + " statement in illegal context");
+
+        // Cases for statements ending in a right curly return early, avoiding the
+        // common semicolon insertion magic after this switch.
+        switch (tt) {
+          case IMPORT:
+            n = new Node(t);
+            n.pathList = ImportPathList(t, x);
+            x.parentScript.impDecls.push(n);
+            n.blockComments = comments;
+            break;
+
+          case EXPORT:
+            switch (t.peek()) {
+              case MODULE:
+              case FUNCTION:
+              case LET:
+              case VAR:
+              case CONST:
+                n = Statement(t, x);
+                n.blockComments = comments;
+                n.exported = true;
+                x.parentScript.expDecls.push(n);
+                registerExport(x.parentScript.exports, n);
+                return n;
+
+              default:
+                n = new Node(t);
+                n.blockComments = comments;
+                n.pathList = ExportPathList(t, x);
+                break;
+            }
+            x.parentScript.expDecls.push(n);
+            registerExport(x.parentScript.exports, n);
+            break;
+
+          case MODULE:
+            n = new Node(t);
+            n.blockComments = comments;
+            t.mustMatch(IDENTIFIER);
+            label = t.token.value;
+
+            if (t.match(LEFT_CURLY)) {
+                n.name = label;
+                n.body = Script(t, true, false);
+                n.module = new Module(n);
+                t.mustMatch(RIGHT_CURLY);
+                x.parentScript.modDefns.set(n.name, n);
+                return n;
+            }
+
+            t.unget();
+            ModuleVariables(t, x, n);
+            return n;
+
+          case FUNCTION:
+            // DECLARED_FORM extends funDecls of x, STATEMENT_FORM doesn't.
+            return FunctionDefinition(t, x, true, x.topLevel ? DECLARED_FORM : STATEMENT_FORM, comments);
+
+          case LEFT_CURLY:
+            n = new Node(t, blockInit());
+            n.blockComments = comments;
+            Statements(t, x.update({ parentBlock: n }).pushTarget(n).nest(), n);
+            t.mustMatch(RIGHT_CURLY);
+            return n;
+
+          case IF:
+            n = new Node(t);
+            n.blockComments = comments;
+            n.condition = HeadExpression(t, x);
+            x2 = x.pushTarget(n).nest();
+            n.thenPart = Statement(t, x2);
+            n.elsePart = t.match(ELSE, true) ? Statement(t, x2) : null;
+            return n;
+
+          case SWITCH:
+            // This allows CASEs after a DEFAULT, which is in the standard.
+            n = new Node(t, { cases: [], defaultIndex: -1 });
+            n.blockComments = comments;
+            n.discriminant = HeadExpression(t, x);
+            x2 = x.pushTarget(n).nest();
+            t.mustMatch(LEFT_CURLY);
+            while ((tt = t.get()) !== RIGHT_CURLY) {
+                switch (tt) {
+                  case DEFAULT:
+                    if (n.defaultIndex >= 0)
+                        throw t.newSyntaxError("More than one switch default");
+                    // FALL THROUGH
+                  case CASE:
+                    n2 = new Node(t);
+                    if (tt === DEFAULT)
+                        n.defaultIndex = n.cases.length;
+                    else
+                        n2.caseLabel = Expression(t, x2, COLON);
+                    break;
+
+                  default:
+                    throw t.newSyntaxError("Invalid switch case");
+                }
+                t.mustMatch(COLON);
+                n2.statements = new Node(t, blockInit());
+                while ((tt=t.peek(true)) !== CASE && tt !== DEFAULT &&
+                        tt !== RIGHT_CURLY)
+                    n2.statements.push(Statement(t, x2));
+                n.cases.push(n2);
+            }
+            return n;
+
+          case FOR:
+            n = new Node(t, LOOP_INIT);
+            n.blockComments = comments;
+            if (t.match(IDENTIFIER)) {
+                if (t.token.value === "each")
+                    n.isEach = true;
+                else
+                    t.unget();
+            }
+            if (!x.parenFreeMode)
+                t.mustMatch(LEFT_PAREN);
+            x2 = x.pushTarget(n).nest();
+            x3 = x.update({ inForLoopInit: true });
+            n2 = null;
+            if ((tt = t.peek(true)) !== SEMICOLON) {
+                if (tt === VAR || tt === CONST) {
+                    t.get();
+                    n2 = Variables(t, x3);
+                } else if (tt === LET) {
+                    t.get();
+                    if (t.peek() === LEFT_PAREN) {
+                        n2 = LetBlock(t, x3, false);
+                    } else {
+                        // Let in for head, we need to add an implicit block
+                        // around the rest of the for.
+                        x3.parentBlock = n;
+                        n.varDecls = [];
+                        n2 = Variables(t, x3);
+                    }
+                } else {
+                    n2 = Expression(t, x3);
+                }
+            }
+            if (n2 && t.match(IN)) {
+                n.type = FOR_IN;
+                n.object = Expression(t, x3);
+                if (n2.type === VAR || n2.type === LET) {
+                    c = n2.children;
+
+                    // Destructuring turns one decl into multiples, so either
+                    // there must be only one destructuring or only one
+                    // decl.
+                    if (c.length !== 1 && n2.destructurings.length !== 1) {
+                        throw new SyntaxError("Invalid for..in left-hand side",
+                                              t.filename, n2.lineno);
+                    }
+                    if (n2.destructurings.length > 0) {
+                        n.iterator = n2.destructurings[0];
+                    } else {
+                        n.iterator = c[0];
+                    }
+                    n.varDecl = n2;
+                } else {
+                    if (n2.type === ARRAY_INIT || n2.type === OBJECT_INIT) {
+                        n2.destructuredNames = checkDestructuring(t, x3, n2);
+                    }
+                    n.iterator = n2;
+                }
+            } else {
+                x3.inForLoopInit = false;
+                n.setup = n2;
+                t.mustMatch(SEMICOLON);
+                if (n.isEach)
+                    throw t.newSyntaxError("Invalid for each..in loop");
+                n.condition = (t.peek(true) === SEMICOLON)
+                              ? null
+                              : Expression(t, x3);
+                t.mustMatch(SEMICOLON);
+                tt2 = t.peek(true);
+                n.update = (x.parenFreeMode
+                            ? tt2 === LEFT_CURLY || definitions.isStatementStartCode[tt2]
+                            : tt2 === RIGHT_PAREN)
+                           ? null
+                           : Expression(t, x3);
+            }
+            if (!x.parenFreeMode)
+                t.mustMatch(RIGHT_PAREN);
+            n.body = Statement(t, x2);
+            return n;
+
+          case WHILE:
+            n = new Node(t, { isLoop: true });
+            n.blockComments = comments;
+            n.condition = HeadExpression(t, x);
+            n.body = Statement(t, x.pushTarget(n).nest());
+            return n;
+
+          case DO:
+            n = new Node(t, { isLoop: true });
+            n.blockComments = comments;
+            n.body = Statement(t, x.pushTarget(n).nest());
+            t.mustMatch(WHILE);
+            n.condition = HeadExpression(t, x);
+            if (!x.ecmaStrictMode) {
+                // <script language="JavaScript"> (without version hints) may need
+                // automatic semicolon insertion without a newline after do-while.
+                // See http://bugzilla.mozilla.org/show_bug.cgi?id=238945.
+                t.match(SEMICOLON);
+                return n;
+            }
+            break;
+
+          case BREAK:
+          case CONTINUE:
+            n = new Node(t);
+            n.blockComments = comments;
+
+            // handle the |foo: break foo;| corner case
+            x2 = x.pushTarget(n);
+
+            if (t.peekOnSameLine() === IDENTIFIER) {
+                t.get();
+                n.label = t.token.value;
+            }
+
+            if (n.label) {
+                n.target = x2.labeledTargets.find(function(target) { return target.labels.has(n.label) });
+            } else if (tt === CONTINUE) {
+                n.target = x2.defaultLoopTarget;
+            } else {
+                n.target = x2.defaultTarget;
+            }
+
+            if (!n.target)
+                throw t.newSyntaxError("Invalid " + ((tt === BREAK) ? "break" : "continue"));
+            if (!n.target.isLoop && tt === CONTINUE)
+                throw t.newSyntaxError("Invalid continue");
+
+            break;
+
+          case TRY:
+            n = new Node(t, { catchClauses: [] });
+            n.blockComments = comments;
+            n.tryBlock = Block(t, x);
+            while (t.match(CATCH)) {
+                n2 = new Node(t);
+                p = MaybeLeftParen(t, x);
+                switch (t.get()) {
+                  case LEFT_BRACKET:
+                  case LEFT_CURLY:
+                    // Destructured catch identifiers.
+                    t.unget();
+                    n2.varName = DestructuringExpression(t, x, true);
+                    break;
+                  case IDENTIFIER:
+                    n2.varName = t.token.value;
+                    break;
+                  default:
+                    throw t.newSyntaxError("missing identifier in catch");
+                    break;
+                }
+                if (t.match(IF)) {
+                    if (x.ecma3OnlyMode)
+                        throw t.newSyntaxError("Illegal catch guard");
+                    if (n.catchClauses.length && !n.catchClauses.top().guard)
+                        throw t.newSyntaxError("Guarded catch after unguarded");
+                    n2.guard = Expression(t, x);
+                }
+                MaybeRightParen(t, p);
+                n2.block = Block(t, x);
+                n.catchClauses.push(n2);
+            }
+            if (t.match(FINALLY))
+                n.finallyBlock = Block(t, x);
+            if (!n.catchClauses.length && !n.finallyBlock)
+                throw t.newSyntaxError("Invalid try statement");
+            return n;
+
+          case CATCH:
+          case FINALLY:
+            throw t.newSyntaxError(definitions.tokens[tt] + " without preceding try");
+
+          case THROW:
+            n = new Node(t);
+            n.blockComments = comments;
+            n.exception = Expression(t, x);
+            break;
+
+          case RETURN:
+            n = ReturnOrYield(t, x);
+            break;
+
+          case WITH:
+            n = new Node(t);
+            n.blockComments = comments;
+            n.object = HeadExpression(t, x);
+            n.body = Statement(t, x.pushTarget(n).nest());
+            return n;
+
+          case VAR:
+          case CONST:
+            n = Variables(t, x);
+            break;
+
+          case LET:
+            if (t.peek() === LEFT_PAREN)
+                n = LetBlock(t, x, true);
+            else
+                n = Variables(t, x);
+            break;
+
+          case DEBUGGER:
+            n = new Node(t);
+            n.blockComments = comments;
+            break;
+
+          case NEWLINE:
+          case SEMICOLON:
+            n = new Node(t, { type: SEMICOLON });
+            n.blockComments = comments;
+            n.expression = null;
+            return n;
+
+          default:
+            if (tt === IDENTIFIER) {
+                tt = t.peek();
+                // Labeled statement.
+                if (tt === COLON) {
+                    label = t.token.value;
+                    if (x.allLabels.has(label))
+                        throw t.newSyntaxError("Duplicate label");
+                    t.get();
+                    n = new Node(t, { type: LABEL, label: label });
+                    n.blockComments = comments;
+                    n.statement = Statement(t, x.pushLabel(label).nest());
+                    n.target = (n.statement.type === LABEL) ? n.statement.target : n.statement;
+                    return n;
+                }
+            }
+
+            // Expression statement.
+            // We unget the current token to parse the expression as a whole.
+            n = new Node(t, { type: SEMICOLON });
+            t.unget();
+            n.blockComments = comments;
+            n.expression = Expression(t, x);
+            n.end = n.expression.end;
+            break;
+        }
+
+        n.blockComments = comments;
+        MagicalSemicolon(t);
+        return n;
+    }
+
+    /*
+     * MagicalSemicolon :: (tokenizer) -> void
+     */
+    function MagicalSemicolon(t) {
+        var tt;
+        if (t.lineno === t.token.lineno) {
+            tt = t.peekOnSameLine();
+           if (tt !== END && tt !== NEWLINE && tt !== SEMICOLON && tt !== RIGHT_CURLY)
+               throw t.newSyntaxError("missing ; before statement");
+        }
+        t.match(SEMICOLON);
+    }
+
+    /*
+     * ReturnOrYield :: (tokenizer, compiler context) -> (RETURN | YIELD) node
+     */
+    function ReturnOrYield(t, x) {
+        var n, b, tt = t.token.type, tt2;
+
+        var parentScript = x.parentScript;
+
+        if (tt === RETURN) {
+            if (!x.inFunction) {
+                // pass
+                //throw t.newSyntaxError("Return not in function");
+            }
+
+        } else /* if (tt === YIELD) */ {
+            if (!x.inFunction)
+                throw t.newSyntaxError("Yield not in function");
+            parentScript.isGenerator = true;
+        }
+        n = new Node(t, { value: undefined });
+
+        tt2 = (tt === RETURN) ? t.peekOnSameLine(true) : t.peek(true);
+        if (tt2 !== END && tt2 !== NEWLINE &&
+            tt2 !== SEMICOLON && tt2 !== RIGHT_CURLY
+            && (tt !== YIELD ||
+                (tt2 !== tt && tt2 !== RIGHT_BRACKET && tt2 !== RIGHT_PAREN &&
+                 tt2 !== COLON && tt2 !== COMMA))) {
+            if (tt === RETURN) {
+                n.value = Expression(t, x);
+                parentScript.hasReturnWithValue = true;
+            } else {
+                n.value = AssignExpression(t, x);
+            }
+        } else if (tt === RETURN) {
+            parentScript.hasEmptyReturn = true;
+        }
+
+        // Disallow return v; in generator.
+        if (parentScript.hasReturnWithValue && parentScript.isGenerator)
+            throw t.newSyntaxError("Generator returns a value");
+
+        return n;
+    }
+
+    /*
+     * ModuleExpression :: (tokenizer, compiler context) -> (STRING | IDENTIFIER | DOT) node
+     */
+    function ModuleExpression(t, x) {
+        return t.match(STRING) ? new Node(t) : QualifiedPath(t, x);
+    }
+
+    /*
+     * ImportPathList :: (tokenizer, compiler context) -> Array[DOT node]
+     */
+    function ImportPathList(t, x) {
+        var a = [];
+        do {
+            a.push(ImportPath(t, x));
+        } while (t.match(COMMA));
+        return a;
+    }
+
+    /*
+     * ImportPath :: (tokenizer, compiler context) -> DOT node
+     */
+    function ImportPath(t, x) {
+        var n = QualifiedPath(t, x);
+        if (!t.match(DOT)) {
+            if (n.type === IDENTIFIER)
+                throw t.newSyntaxError("cannot import local variable");
+            return n;
+        }
+
+        var n2 = new Node(t);
+        n2.push(n);
+        n2.push(ImportSpecifierSet(t, x));
+        return n2;
+    }
+
+    /*
+     * ExplicitSpecifierSet :: (tokenizer, compiler context, (tokenizer, compiler context) -> node)
+     *                      -> OBJECT_INIT node
+     */
+    function ExplicitSpecifierSet(t, x, SpecifierRHS) {
+        var n, n2, id, tt;
+
+        n = new Node(t, { type: OBJECT_INIT });
+        t.mustMatch(LEFT_CURLY);
+
+        if (!t.match(RIGHT_CURLY)) {
+            do {
+                id = Identifier(t, x);
+                if (t.match(COLON)) {
+                    n2 = new Node(t, { type: PROPERTY_INIT });
+                    n2.push(id);
+                    n2.push(SpecifierRHS(t, x));
+                    n.push(n2);
+                } else {
+                    n.push(id);
+                }
+            } while (!t.match(RIGHT_CURLY) && t.mustMatch(COMMA));
+        }
+
+        return n;
+    }
+
+    /*
+     * ImportSpecifierSet :: (tokenizer, compiler context) -> (IDENTIFIER | OBJECT_INIT) node
+     */
+    function ImportSpecifierSet(t, x) {
+        return t.match(MUL)
+             ? new Node(t, { type: IDENTIFIER, name: "*" })
+             : ExplicitSpecifierSet(t, x, Identifier);
+    }
+
+    /*
+     * Identifier :: (tokenizer, compiler context) -> IDENTIFIER node
+     */
+    function Identifier(t, x) {
+        t.mustMatch(IDENTIFIER);
+        return new Node(t, { type: IDENTIFIER });
+    }
+
+    /*
+     * IdentifierName :: (tokenizer) -> IDENTIFIER node
+     */
+    function IdentifierName(t) {
+        if (t.match(IDENTIFIER))
+            return new Node(t, { type: IDENTIFIER });
+        t.get();
+        if (t.token.value in definitions.keywords)
+            return new Node(t, { type: IDENTIFIER });
+        throw t.newSyntaxError("missing IdentifierName");
+    }
+
+    /*
+     * QualifiedPath :: (tokenizer, compiler context) -> (IDENTIFIER | DOT) node
+     */
+    function QualifiedPath(t, x) {
+        var n, n2;
+
+        n = Identifier(t, x);
+
+        while (t.match(DOT)) {
+            if (t.peek() !== IDENTIFIER) {
+                // Unget the '.' token, which isn't part of the QualifiedPath.
+                t.unget();
+                break;
+            }
+            n2 = new Node(t);
+            n2.push(n);
+            n2.push(Identifier(t, x));
+            n = n2;
+        }
+
+        return n;
+    }
+
+    /*
+     * ExportPath :: (tokenizer, compiler context) -> (IDENTIFIER | DOT | OBJECT_INIT) node
+     */
+    function ExportPath(t, x) {
+        if (t.peek() === LEFT_CURLY)
+            return ExplicitSpecifierSet(t, x, QualifiedPath);
+        return QualifiedPath(t, x);
+    }
+
+    /*
+     * ExportPathList :: (tokenizer, compiler context)
+     *                -> Array[(IDENTIFIER | DOT | OBJECT_INIT) node]
+     */
+    function ExportPathList(t, x) {
+        var a = [];
+        do {
+            a.push(ExportPath(t, x));
+        } while (t.match(COMMA));
+        return a;
+    }
+
+    /*
+     * FunctionDefinition :: (tokenizer, compiler context, boolean,
+     *                        DECLARED_FORM or EXPRESSED_FORM or STATEMENT_FORM,
+     *                        [string] or null or undefined)
+     *                    -> node
+     */
+    function FunctionDefinition(t, x, requireName, functionForm, comments) {
+        var tt;
+        var f = new Node(t, { params: [], paramComments: [] });
+        if (typeof comment === "undefined")
+            comment = null;
+        f.blockComments = comments;
+        if (f.type !== FUNCTION)
+            f.type = (f.value === "get") ? GETTER : SETTER;
+        if (t.match(IDENTIFIER))
+            f.name = t.token.value;
+        else if (requireName)
+            throw t.newSyntaxError("missing function identifier");
+
+        var inModule = x ? x.inModule : false;
+        var x2 = new StaticContext(null, null, inModule, true);
+
+        t.mustMatch(LEFT_PAREN);
+        if (!t.match(RIGHT_PAREN)) {
+            do {
+                tt = t.get();
+                f.paramComments.push(t.lastBlockComment());
+                switch (tt) {
+                  case LEFT_BRACKET:
+                  case LEFT_CURLY:
+                    // Destructured formal parameters.
+                    t.unget();
+                    f.params.push(DestructuringExpression(t, x2));
+                    break;
+                  case IDENTIFIER:
+                    f.params.push(t.token.value);
+                    break;
+                  default:
+                    throw t.newSyntaxError("missing formal parameter");
+                    break;
+                }
+            } while (t.match(COMMA));
+            t.mustMatch(RIGHT_PAREN);
+        }
+
+        // Do we have an expression closure or a normal body?
+        tt = t.get();
+        if (tt !== LEFT_CURLY)
+            t.unget();
+
+        if (tt !== LEFT_CURLY) {
+            f.body = AssignExpression(t, x2);
+            if (f.body.isGenerator)
+                throw t.newSyntaxError("Generator returns a value");
+        } else {
+            f.body = Script(t, inModule, true);
+        }
+
+        if (tt === LEFT_CURLY)
+            t.mustMatch(RIGHT_CURLY);
+
+        f.end = t.token.end;
+        f.functionForm = functionForm;
+        if (functionForm === DECLARED_FORM)
+            x.parentScript.funDecls.push(f);
+        return f;
+    }
+
+    /*
+     * ModuleVariables :: (tokenizer, compiler context, MODULE node) -> void
+     *
+     * Parses a comma-separated list of module declarations (and maybe
+     * initializations).
+     */
+    function ModuleVariables(t, x, n) {
+        var n1, n2;
+        do {
+            n1 = Identifier(t, x);
+            if (t.match(ASSIGN)) {
+                n2 = ModuleExpression(t, x);
+                n1.initializer = n2;
+                if (n2.type === STRING)
+                    x.parentScript.modLoads.set(n1.value, n2.value);
+                else
+                    x.parentScript.modAssns.set(n1.value, n1);
+            }
+            n.push(n1);
+        } while (t.match(COMMA));
+    }
+
+    /*
+     * Variables :: (tokenizer, compiler context) -> node
+     *
+     * Parses a comma-separated list of var declarations (and maybe
+     * initializations).
+     */
+    function Variables(t, x, letBlock) {
+        var n, n2, ss, i, s, tt;
+
+        tt = t.token.type;
+        switch (tt) {
+          case VAR:
+          case CONST:
+            s = x.parentScript;
+            break;
+          case LET:
+            s = x.parentBlock;
+            break;
+          case LEFT_PAREN:
+            tt = LET;
+            s = letBlock;
+            break;
+        }
+
+        n = new Node(t, { type: tt, destructurings: [] });
+
+        do {
+            tt = t.get();
+            if (tt === LEFT_BRACKET || tt === LEFT_CURLY) {
+                // Need to unget to parse the full destructured expression.
+                t.unget();
+
+                var dexp = DestructuringExpression(t, x, true);
+
+                n2 = new Node(t, { type: IDENTIFIER,
+                                   name: dexp,
+                                   readOnly: n.type === CONST });
+                n.push(n2);
+                pushDestructuringVarDecls(n2.name.destructuredNames, s);
+                n.destructurings.push({ exp: dexp, decl: n2 });
+
+                if (x.inForLoopInit && t.peek() === IN) {
+                    continue;
+                }
+
+                t.mustMatch(ASSIGN);
+                if (t.token.assignOp)
+                    throw t.newSyntaxError("Invalid variable initialization");
+
+                n2.blockComment = t.lastBlockComment();
+                n2.initializer = AssignExpression(t, x);
+
+                continue;
+            }
+
+            if (tt !== IDENTIFIER)
+                throw t.newSyntaxError("missing variable name");
+
+            n2 = new Node(t, { type: IDENTIFIER,
+                               name: t.token.value,
+                               readOnly: n.type === CONST });
+            n.push(n2);
+            s.varDecls.push(n2);
+
+            if (t.match(ASSIGN)) {
+                var comment = t.lastBlockComment();
+                if (t.token.assignOp)
+                    throw t.newSyntaxError("Invalid variable initialization");
+
+                n2.initializer = AssignExpression(t, x);
+            } else {
+                var comment = t.lastBlockComment();
+            }
+            n2.blockComment = comment;
+        } while (t.match(COMMA));
+
+        return n;
+    }
+
+    /*
+     * LetBlock :: (tokenizer, compiler context, boolean) -> node
+     *
+     * Does not handle let inside of for loop init.
+     */
+    function LetBlock(t, x, isStatement) {
+        var n, n2;
+
+        // t.token.type must be LET
+        n = new Node(t, { type: LET_BLOCK, varDecls: [] });
+        t.mustMatch(LEFT_PAREN);
+        n.variables = Variables(t, x, n);
+        t.mustMatch(RIGHT_PAREN);
+
+        if (isStatement && t.peek() !== LEFT_CURLY) {
+            /*
+             * If this is really an expression in let statement guise, then we
+             * need to wrap the LET_BLOCK node in a SEMICOLON node so that we pop
+             * the return value of the expression.
+             */
+            n2 = new Node(t, { type: SEMICOLON,
+                               expression: n });
+            isStatement = false;
+        }
+
+        if (isStatement)
+            n.block = Block(t, x);
+        else
+            n.expression = AssignExpression(t, x);
+
+        return n;
+    }
+
+    function checkDestructuring(t, x, n, simpleNamesOnly) {
+        if (n.type === ARRAY_COMP)
+            throw t.newSyntaxError("Invalid array comprehension left-hand side");
+        if (n.type !== ARRAY_INIT && n.type !== OBJECT_INIT)
+            return undefined;
+
+        var lhss = {};
+        var nn, n2, idx, sub, cc, c = n.children;
+        for (var i = 0, j = c.length; i < j; i++) {
+            if (!(nn = c[i]))
+                continue;
+            if (nn.type === PROPERTY_INIT) {
+                cc = nn.children;
+                sub = cc[1];
+                idx = cc[0].value;
+            } else if (n.type === OBJECT_INIT) {
+                // Do we have destructuring shorthand {foo, bar}?
+                sub = nn;
+                idx = nn.value;
+            } else {
+                sub = nn;
+                idx = i;
+            }
+
+            if (sub.type === ARRAY_INIT || sub.type === OBJECT_INIT) {
+                lhss[idx] = checkDestructuring(t, x, sub, simpleNamesOnly);
+            } else {
+                if (simpleNamesOnly && sub.type !== IDENTIFIER) {
+                    // In declarations, lhs must be simple names
+                    throw t.newSyntaxError("missing name in pattern");
+                }
+
+                lhss[idx] = sub;
+            }
+        }
+
+        return lhss;
+    }
+
+    function DestructuringExpression(t, x, simpleNamesOnly) {
+        var n = PrimaryExpression(t, x);
+        // Keep the list of lefthand sides for varDecls
+        n.destructuredNames = checkDestructuring(t, x, n, simpleNamesOnly);
+        return n;
+    }
+
+    function GeneratorExpression(t, x, e) {
+        return new Node(t, { type: GENERATOR,
+                             expression: e,
+                             tail: ComprehensionTail(t, x) });
+    }
+
+    function ComprehensionTail(t, x) {
+        var body, n, n2, n3, p;
+
+        // t.token.type must be FOR
+        body = new Node(t, { type: COMP_TAIL });
+
+        do {
+            // Comprehension tails are always for..in loops.
+            n = new Node(t, { type: FOR_IN, isLoop: true });
+            if (t.match(IDENTIFIER)) {
+                // But sometimes they're for each..in.
+                if (t.token.value === "each")
+                    n.isEach = true;
+                else
+                    t.unget();
+            }
+            p = MaybeLeftParen(t, x);
+            switch(t.get()) {
+              case LEFT_BRACKET:
+              case LEFT_CURLY:
+                t.unget();
+                // Destructured left side of for in comprehension tails.
+                n.iterator = DestructuringExpression(t, x);
+                break;
+
+              case IDENTIFIER:
+                n.iterator = n3 = new Node(t, { type: IDENTIFIER });
+                n3.name = n3.value;
+                n.varDecl = n2 = new Node(t, { type: VAR });
+                n2.push(n3);
+                x.parentScript.varDecls.push(n3);
+                // Don't add to varDecls since the semantics of comprehensions is
+                // such that the variables are in their own function when
+                // desugared.
+                break;
+
+              default:
+                throw t.newSyntaxError("missing identifier");
+            }
+            t.mustMatch(IN);
+            n.object = Expression(t, x);
+            MaybeRightParen(t, p);
+            body.push(n);
+        } while (t.match(FOR));
+
+        // Optional guard.
+        if (t.match(IF))
+            body.guard = HeadExpression(t, x);
+
+        return body;
+    }
+
+    function HeadExpression(t, x) {
+        var p = MaybeLeftParen(t, x);
+        var n = ParenExpression(t, x);
+        MaybeRightParen(t, p);
+        if (p === END && !n.parenthesized) {
+            var tt = t.peek();
+            if (tt !== LEFT_CURLY && !definitions.isStatementStartCode[tt])
+                throw t.newSyntaxError("Unparenthesized head followed by unbraced body");
+        }
+        return n;
+    }
+
+    function ParenExpression(t, x) {
+        // Always accept the 'in' operator in a parenthesized expression,
+        // where it's unambiguous, even if we might be parsing the init of a
+        // for statement.
+        var n = Expression(t, x.update({ inForLoopInit: x.inForLoopInit &&
+                                                        (t.token.type === LEFT_PAREN) }));
+
+        if (t.match(FOR)) {
+            if (n.type === YIELD && !n.parenthesized)
+                throw t.newSyntaxError("Yield expression must be parenthesized");
+            if (n.type === COMMA && !n.parenthesized)
+                throw t.newSyntaxError("Generator expression must be parenthesized");
+            n = GeneratorExpression(t, x, n);
+        }
+
+        return n;
+    }
+
+    /*
+     * Expression :: (tokenizer, compiler context) -> node
+     *
+     * Top-down expression parser matched against SpiderMonkey.
+     */
+    function Expression(t, x) {
+        var n, n2;
+
+        n = AssignExpression(t, x);
+        if (t.match(COMMA)) {
+            n2 = new Node(t, { type: COMMA });
+            n2.push(n);
+            n = n2;
+            do {
+                n2 = n.children[n.children.length-1];
+                if (n2.type === YIELD && !n2.parenthesized)
+                    throw t.newSyntaxError("Yield expression must be parenthesized");
+                n.push(AssignExpression(t, x));
+            } while (t.match(COMMA));
+        }
+
+        return n;
+    }
+
+    function AssignExpression(t, x) {
+        var n, lhs;
+
+        // Have to treat yield like an operand because it could be the leftmost
+        // operand of the expression.
+        if (t.match(YIELD, true))
+            return ReturnOrYield(t, x);
+
+        n = new Node(t, { type: ASSIGN });
+        lhs = ConditionalExpression(t, x);
+
+        if (!t.match(ASSIGN)) {
+            return lhs;
+        }
+
+        n.blockComment = t.lastBlockComment();
+
+        switch (lhs.type) {
+          case OBJECT_INIT:
+          case ARRAY_INIT:
+            lhs.destructuredNames = checkDestructuring(t, x, lhs);
+            // FALL THROUGH
+          case IDENTIFIER: case DOT: case INDEX: case CALL:
+            break;
+          default:
+            throw t.newSyntaxError("Bad left-hand side of assignment");
+            break;
+        }
+
+        n.assignOp = lhs.assignOp = t.token.assignOp;
+        n.push(lhs);
+        n.push(AssignExpression(t, x));
+
+        return n;
+    }
+
+    function ConditionalExpression(t, x) {
+        var n, n2;
+
+        n = OrExpression(t, x);
+        if (t.match(HOOK)) {
+            n2 = n;
+            n = new Node(t, { type: HOOK });
+            n.push(n2);
+            /*
+             * Always accept the 'in' operator in the middle clause of a ternary,
+             * where it's unambiguous, even if we might be parsing the init of a
+             * for statement.
+             */
+            n.push(AssignExpression(t, x.update({ inForLoopInit: false })));
+            if (!t.match(COLON))
+                throw t.newSyntaxError("missing : after ?");
+            n.push(AssignExpression(t, x));
+        }
+
+        return n;
+    }
+
+    function OrExpression(t, x) {
+        var n, n2;
+
+        n = AndExpression(t, x);
+        while (t.match(OR)) {
+            n2 = new Node(t);
+            n2.push(n);
+            n2.push(AndExpression(t, x));
+            n = n2;
+        }
+
+        return n;
+    }
+
+    function AndExpression(t, x) {
+        var n, n2;
+
+        n = BitwiseOrExpression(t, x);
+        while (t.match(AND)) {
+            n2 = new Node(t);
+            n2.push(n);
+            n2.push(BitwiseOrExpression(t, x));
+            n = n2;
+        }
+
+        return n;
+    }
+
+    function BitwiseOrExpression(t, x) {
+        var n, n2;
+
+        n = BitwiseXorExpression(t, x);
+        while (t.match(BITWISE_OR)) {
+            n2 = new Node(t);
+            n2.push(n);
+            n2.push(BitwiseXorExpression(t, x));
+            n = n2;
+        }
+
+        return n;
+    }
+
+    function BitwiseXorExpression(t, x) {
+        var n, n2;
+
+        n = BitwiseAndExpression(t, x);
+        while (t.match(BITWISE_XOR)) {
+            n2 = new Node(t);
+            n2.push(n);
+            n2.push(BitwiseAndExpression(t, x));
+            n = n2;
+        }
+
+        return n;
+    }
+
+    function BitwiseAndExpression(t, x) {
+        var n, n2;
+
+        n = EqualityExpression(t, x);
+        while (t.match(BITWISE_AND)) {
+            n2 = new Node(t);
+            n2.push(n);
+            n2.push(EqualityExpression(t, x));
+            n = n2;
+        }
+
+        return n;
+    }
+
+    function EqualityExpression(t, x) {
+        var n, n2;
+
+        n = RelationalExpression(t, x);
+        while (t.match(EQ) || t.match(NE) ||
+               t.match(STRICT_EQ) || t.match(STRICT_NE)) {
+            n2 = new Node(t);
+            n2.push(n);
+            n2.push(RelationalExpression(t, x));
+            n = n2;
+        }
+
+        return n;
+    }
+
+    function RelationalExpression(t, x) {
+        var n, n2;
+
+        /*
+         * Uses of the in operator in shiftExprs are always unambiguous,
+         * so unset the flag that prohibits recognizing it.
+         */
+        var x2 = x.update({ inForLoopInit: false });
+        n = ShiftExpression(t, x2);
+        while ((t.match(LT) || t.match(LE) || t.match(GE) || t.match(GT) ||
+               (!x.inForLoopInit && t.match(IN)) ||
+               t.match(INSTANCEOF))) {
+            n2 = new Node(t);
+            n2.push(n);
+            n2.push(ShiftExpression(t, x2));
+            n = n2;
+        }
+
+        return n;
+    }
+
+    function ShiftExpression(t, x) {
+        var n, n2;
+
+        n = AddExpression(t, x);
+        while (t.match(LSH) || t.match(RSH) || t.match(URSH)) {
+            n2 = new Node(t);
+            n2.push(n);
+            n2.push(AddExpression(t, x));
+            n = n2;
+        }
+
+        return n;
+    }
+
+    function AddExpression(t, x) {
+        var n, n2;
+
+        n = MultiplyExpression(t, x);
+        while (t.match(PLUS) || t.match(MINUS)) {
+            n2 = new Node(t);
+            n2.push(n);
+            n2.push(MultiplyExpression(t, x));
+            n = n2;
+        }
+
+        return n;
+    }
+
+    function MultiplyExpression(t, x) {
+        var n, n2;
+
+        n = UnaryExpression(t, x);
+        while (t.match(MUL) || t.match(DIV) || t.match(MOD)) {
+            n2 = new Node(t);
+            n2.push(n);
+            n2.push(UnaryExpression(t, x));
+            n = n2;
+        }
+
+        return n;
+    }
+
+    function UnaryExpression(t, x) {
+        var n, n2, tt;
+
+        switch (tt = t.get(true)) {
+          case DELETE: case VOID: case TYPEOF:
+          case NOT: case BITWISE_NOT: case PLUS: case MINUS:
+            if (tt === PLUS)
+                n = new Node(t, { type: UNARY_PLUS });
+            else if (tt === MINUS)
+                n = new Node(t, { type: UNARY_MINUS });
+            else
+                n = new Node(t);
+            n.push(UnaryExpression(t, x));
+            break;
+
+          case INCREMENT:
+          case DECREMENT:
+            // Prefix increment/decrement.
+            n = new Node(t);
+            n.push(MemberExpression(t, x, true));
+            break;
+
+          default:
+            t.unget();
+            n = MemberExpression(t, x, true);
+
+            // Don't look across a newline boundary for a postfix {in,de}crement.
+            if (t.tokens[(t.tokenIndex + t.lookahead - 1) & 3].lineno ===
+                t.lineno) {
+                if (t.match(INCREMENT) || t.match(DECREMENT)) {
+                    n2 = new Node(t, { postfix: true });
+                    n2.push(n);
+                    n = n2;
+                }
+            }
+            break;
+        }
+
+        return n;
+    }
+
+    function MemberExpression(t, x, allowCallSyntax) {
+        var n, n2, name, tt;
+
+        if (t.match(NEW)) {
+            n = new Node(t);
+            n.push(MemberExpression(t, x, false));
+            if (t.match(LEFT_PAREN)) {
+                n.type = NEW_WITH_ARGS;
+                n.push(ArgumentList(t, x));
+            }
+        } else {
+            n = PrimaryExpression(t, x);
+        }
+
+        while ((tt = t.get()) !== END) {
+            switch (tt) {
+              case DOT:
+                n2 = new Node(t);
+                n2.push(n);
+                n2.push(IdentifierName(t));
+                break;
+
+              case LEFT_BRACKET:
+                n2 = new Node(t, { type: INDEX });
+                n2.push(n);
+                n2.push(Expression(t, x));
+                t.mustMatch(RIGHT_BRACKET);
+                break;
+
+              case LEFT_PAREN:
+                if (allowCallSyntax) {
+                    n2 = new Node(t, { type: CALL });
+                    n2.push(n);
+                    n2.push(ArgumentList(t, x));
+                    break;
+                }
+
+                // FALL THROUGH
+              default:
+                t.unget();
+                return n;
+            }
+
+            n = n2;
+        }
+
+        return n;
+    }
+
+    function ArgumentList(t, x) {
+        var n, n2;
+
+        n = new Node(t, { type: LIST });
+        if (t.match(RIGHT_PAREN, true))
+            return n;
+        do {
+            n2 = AssignExpression(t, x);
+            if (n2.type === YIELD && !n2.parenthesized && t.peek() === COMMA)
+                throw t.newSyntaxError("Yield expression must be parenthesized");
+            if (t.match(FOR)) {
+                n2 = GeneratorExpression(t, x, n2);
+                if (n.children.length > 1 || t.peek(true) === COMMA)
+                    throw t.newSyntaxError("Generator expression must be parenthesized");
+            }
+            n.push(n2);
+        } while (t.match(COMMA));
+        t.mustMatch(RIGHT_PAREN);
+
+        return n;
+    }
+
+    function PrimaryExpression(t, x) {
+        var n, n2, tt = t.get(true);
+
+        switch (tt) {
+          case FUNCTION:
+            n = FunctionDefinition(t, x, false, EXPRESSED_FORM);
+            break;
+
+          case LEFT_BRACKET:
+            n = new Node(t, { type: ARRAY_INIT });
+            while ((tt = t.peek(true)) !== RIGHT_BRACKET) {
+                if (tt === COMMA) {
+                    t.get();
+                    n.push(null);
+                    continue;
+                }
+                n.push(AssignExpression(t, x));
+                if (tt !== COMMA && !t.match(COMMA))
+                    break;
+            }
+
+            // If we matched exactly one element and got a FOR, we have an
+            // array comprehension.
+            if (n.children.length === 1 && t.match(FOR)) {
+                n2 = new Node(t, { type: ARRAY_COMP,
+                                   expression: n.children[0],
+                                   tail: ComprehensionTail(t, x) });
+                n = n2;
+            }
+            t.mustMatch(RIGHT_BRACKET);
+            break;
+
+          case LEFT_CURLY:
+            var id, fd;
+            n = new Node(t, { type: OBJECT_INIT });
+
+          object_init:
+            if (!t.match(RIGHT_CURLY)) {
+                do {
+                    tt = t.get();
+                    if ((t.token.value === "get" || t.token.value === "set") &&
+                        t.peek() === IDENTIFIER) {
+                        if (x.ecma3OnlyMode)
+                            throw t.newSyntaxError("Illegal property accessor");
+                        n.push(FunctionDefinition(t, x, true, EXPRESSED_FORM));
+                    } else {
+                        var comments = t.blockComments;
+                        switch (tt) {
+                          case IDENTIFIER: case NUMBER: case STRING:
+                            id = new Node(t, { type: IDENTIFIER });
+                            break;
+                          case RIGHT_CURLY:
+                            if (x.ecma3OnlyMode)
+                                throw t.newSyntaxError("Illegal trailing ,");
+                            break object_init;
+                          default:
+                            if (t.token.value in definitions.keywords) {
+                                id = new Node(t, { type: IDENTIFIER });
+                                break;
+                            }
+                            throw t.newSyntaxError("Invalid property name");
+                        }
+                        if (t.match(COLON)) {
+                            n2 = new Node(t, { type: PROPERTY_INIT });
+                            n2.push(id);
+                            n2.push(AssignExpression(t, x));
+                            n2.blockComments = comments;
+                            n.push(n2);
+                        } else {
+                            // Support, e.g., |var {x, y} = o| as destructuring shorthand
+                            // for |var {x: x, y: y} = o|, per proposed JS2/ES4 for JS1.8.
+                            if (t.peek() !== COMMA && t.peek() !== RIGHT_CURLY)
+                                throw t.newSyntaxError("missing : after property");
+                            n.push(id);
+                        }
+                    }
+                } while (t.match(COMMA));
+                t.mustMatch(RIGHT_CURLY);
+            }
+            break;
+
+          case LEFT_PAREN:
+            n = ParenExpression(t, x);
+            t.mustMatch(RIGHT_PAREN);
+            n.parenthesized = true;
+            break;
+
+          case LET:
+            n = LetBlock(t, x, false);
+            break;
+
+          case NULL: case THIS: case TRUE: case FALSE:
+          case IDENTIFIER: case NUMBER: case STRING: case REGEXP:
+            n = new Node(t);
+            break;
+
+          default:
+            n = new Node(t);
+            // don't throw an error by default. Just make it a node and forget it :-}
+            //throw t.newSyntaxError("missing operand"); 
+            break;
+        }
+        
+        return n;
+    }
+
+    /*
+     * parse :: (source, filename, line number) -> node
+     */
+    function parse(s, f, l) {
+        var t = new lexer.Tokenizer(s, f, l);
+        var n = Script(t, false, false);
+        if (!t.done)
+            throw t.newSyntaxError("Syntax error");
+
+        return n;
+    }
+
+    /*
+     * parseStdin :: (source, {line number}, string, (string) -> boolean) -> program node
+     */
+    function parseStdin(s, ln, prefix, isCommand) {
+        // the special .begin command is only recognized at the beginning
+        if (s.match(/^[\s]*\.begin[\s]*$/)) {
+            ++ln.value;
+            return parseMultiline(ln, prefix);
+        }
+
+        // commands at the beginning are treated as the entire input
+        if (isCommand(s.trim()))
+            s = "";
+
+        for (;;) {
+            try {
+                var t = new lexer.Tokenizer(s, "stdin", ln.value);
+                var n = Script(t, false, false);
+                ln.value = t.lineno;
+                return n;
+            } catch (e) {
+                if (!t.unexpectedEOF)
+                    throw e;
+
+                // commands in the middle are not treated as part of the input
+                var more;
+                do {
+                    if (prefix)
+                        putstr(prefix);
+                    more = readline();
+                    if (!more)
+                        throw e;
+                } while (isCommand(more.trim()));
+
+                s += "\n" + more;
+            }
+        }
+    }
+
+    /*
+     * parseMultiline :: ({line number}, string | null) -> program node
+     */
+    function parseMultiline(ln, prefix) {
+        var s = "";
+        for (;;) {
+            if (prefix)
+                putstr(prefix);
+            var more = readline();
+            if (more === null)
+                return null;
+            // the only command recognized in multiline mode is .end
+            if (more.match(/^[\s]*\.end[\s]*$/))
+                break;
+            s += "\n" + more;
+        }
+        var t = new lexer.Tokenizer(s, "stdin", ln.value);
+        var n = Script(t, false, false);
+        ln.value = t.lineno;
+        return n;
+    }
+
+    return {
+        parse: parse,
+        parseStdin: parseStdin,
+        Node: Node,
+        SyntheticNode: SyntheticNode,
+        DECLARED_FORM: DECLARED_FORM,
+        EXPRESSED_FORM: EXPRESSED_FORM,
+        STATEMENT_FORM: STATEMENT_FORM,
+        Tokenizer: lexer.Tokenizer,
+        FunctionDefinition: FunctionDefinition,
+        Module: Module,
+        Export: Export
+    };
+
+}());