gecko-dev/js/narcissus/jsdefs.js

/* 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):
 *
 * 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
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 * under the terms of either the GPL or the LGPL, and not to allow others to
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 * 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 ***** */

/*
 * Narcissus - JS implemented in JS.
 *
 * Well-known constants and lookup tables.  Many consts are generated from the
 * tokens table via eval to minimize redundancy, so consumers must be compiled
 * separately to take advantage of the simple switch-case constant propagation
 * done by SpiderMonkey.
 */

Narcissus = {
    options: { version: 185 },
    hostGlobal: this
};

Narcissus.definitions = (function() {

    var tokens = [
        // End of source.
        "END",

        // Operators and punctuators.  Some pair-wise order matters, e.g. (+, -)
        // and (UNARY_PLUS, UNARY_MINUS).
        "\n", ";",
        ",",
        "=",
        "?", ":", "CONDITIONAL",
        "||",
        "&&",
        "|",
        "^",
        "&",
        "==", "!=", "===", "!==",
        "<", "<=", ">=", ">",
        "<<", ">>", ">>>",
        "+", "-",
        "*", "/", "%",
        "!", "~", "UNARY_PLUS", "UNARY_MINUS",
        "++", "--",
        ".",
        "[", "]",
        "{", "}",
        "(", ")",

        // Nonterminal tree node type codes.
        "SCRIPT", "BLOCK", "LABEL", "FOR_IN", "CALL", "NEW_WITH_ARGS", "INDEX",
        "ARRAY_INIT", "OBJECT_INIT", "PROPERTY_INIT", "GETTER", "SETTER",
        "GROUP", "LIST", "LET_BLOCK", "ARRAY_COMP", "GENERATOR", "COMP_TAIL",

        // Terminals.
        "IDENTIFIER", "NUMBER", "STRING", "REGEXP",

        // Keywords.
        "break",
        "case", "catch", "const", "continue",
        "debugger", "default", "delete", "do",
        "else",
        "false", "finally", "for", "function",
        "if", "in", "instanceof",
        "let",
        "new", "null",
        "return",
        "switch",
        "this", "throw", "true", "try", "typeof",
        "var", "void",
        "yield",
        "while", "with",
    ];

    // Operator and punctuator mapping from token to tree node type name.
    // NB: because the lexer doesn't backtrack, all token prefixes must themselves
    // be valid tokens (e.g. !== is acceptable because its prefixes are the valid
    // tokens != and !).
    var opTypeNames = {
        '\n':   "NEWLINE",
        ';':    "SEMICOLON",
        ',':    "COMMA",
        '?':    "HOOK",
        ':':    "COLON",
        '||':   "OR",
        '&&':   "AND",
        '|':    "BITWISE_OR",
        '^':    "BITWISE_XOR",
        '&':    "BITWISE_AND",
        '===':  "STRICT_EQ",
        '==':   "EQ",
        '=':    "ASSIGN",
        '!==':  "STRICT_NE",
        '!=':   "NE",
        '<<':   "LSH",
        '<=':   "LE",
        '<':    "LT",
        '>>>':  "URSH",
        '>>':   "RSH",
        '>=':   "GE",
        '>':    "GT",
        '++':   "INCREMENT",
        '--':   "DECREMENT",
        '+':    "PLUS",
        '-':    "MINUS",
        '*':    "MUL",
        '/':    "DIV",
        '%':    "MOD",
        '!':    "NOT",
        '~':    "BITWISE_NOT",
        '.':    "DOT",
        '[':    "LEFT_BRACKET",
        ']':    "RIGHT_BRACKET",
        '{':    "LEFT_CURLY",
        '}':    "RIGHT_CURLY",
        '(':    "LEFT_PAREN",
        ')':    "RIGHT_PAREN"
    };

    // Hash of keyword identifier to tokens index.  NB: we must null __proto__ to
    // avoid toString, etc. namespace pollution.
    var keywords = {__proto__: null};

    // Define const END, etc., based on the token names.  Also map name to index.
    var tokenIds = {};

    // Building up a string to be eval'd in different contexts.
    var consts = "const ";
    for (var i = 0, j = tokens.length; i < j; i++) {
        if (i > 0)
            consts += ", ";
        var t = tokens[i];
        var name;
        if (/^[a-z]/.test(t)) {
            name = t.toUpperCase();
            keywords[t] = i;
        } else {
            name = (/^\W/.test(t) ? opTypeNames[t] : t);
        }
        consts += name + " = " + i;
        tokenIds[name] = i;
        tokens[t] = i;
    }
    consts += ";";

    // Map assignment operators to their indexes in the tokens array.
    var assignOps = ['|', '^', '&', '<<', '>>', '>>>', '+', '-', '*', '/', '%'];

    for (i = 0, j = assignOps.length; i < j; i++) {
        t = assignOps[i];
        assignOps[t] = tokens[t];
    }

    function defineGetter(obj, prop, fn, dontDelete, dontEnum) {
        Object.defineProperty(obj, prop, { get: fn, configurable: !dontDelete, enumerable: !dontEnum });
    }

    function defineProperty(obj, prop, val, dontDelete, readOnly, dontEnum) {
        Object.defineProperty(obj, prop, { value: val, writable: !readOnly, configurable: !dontDelete, enumerable: !dontEnum });
    }

    // Returns true if fn is a native function.  (Note: SpiderMonkey specific.)
    function isNativeCode(fn) {
        // Relies on the toString method to identify native code.
        return ((typeof fn) === "function") && fn.toString().match(/\[native code\]/);
    }

    function getPropertyDescriptor(obj, name) {
        while (obj) {
            if (({}).hasOwnProperty.call(obj, name))
                return Object.getOwnPropertyDescriptor(obj, name);
            obj = Object.getPrototypeOf(obj);
        }
    }

    function getOwnProperties(obj) {
        var map = {};
        for (var name in Object.getOwnPropertyNames(obj))
            map[name] = Object.getOwnPropertyDescriptor(obj, name);
        return map;
    }

    function makePassthruHandler(obj) {
        // Handler copied from
        // http://wiki.ecmascript.org/doku.php?id=harmony:proxies&s=proxy%20object#examplea_no-op_forwarding_proxy
        return {
            getOwnPropertyDescriptor: function(name) {
                var desc = Object.getOwnPropertyDescriptor(obj, name);

                // a trapping proxy's properties must always be configurable
                desc.configurable = true;
                return desc;
            },
            getPropertyDescriptor: function(name) {
                var desc = getPropertyDescriptor(obj, name);

                // a trapping proxy's properties must always be configurable
                desc.configurable = true;
                return desc;
            },
            getOwnPropertyNames: function() {
                return Object.getOwnPropertyNames(obj);
            },
            defineProperty: function(name, desc) {
                Object.defineProperty(obj, name, desc);
            },
            delete: function(name) { return delete obj[name]; },
            fix: function() {
                if (Object.isFrozen(obj)) {
                    return getOwnProperties(obj);
                }

                // As long as obj is not frozen, the proxy won't allow itself to be fixed.
                return undefined; // will cause a TypeError to be thrown
            },

            has: function(name) { return name in obj; },
            hasOwn: function(name) { return ({}).hasOwnProperty.call(obj, name); },
            get: function(receiver, name) { return obj[name]; },

            // bad behavior when set fails in non-strict mode
            set: function(receiver, name, val) { obj[name] = val; return true; },
            enumerate: function() {
                var result = [];
                for (name in obj) { result.push(name); };
                return result;
            },
            keys: function() { return Object.keys(obj); }
        };
    }

    return {
        tokens: tokens,
        opTypeNames: opTypeNames,
        keywords: keywords,
        tokenIds: tokenIds,
        consts: consts,
        assignOps: assignOps,
        defineGetter: defineGetter,
        defineProperty: defineProperty,
        isNativeCode: isNativeCode,
        makePassthruHandler: makePassthruHandler
    };
}());