scriptruntime.java

java中比较著名的js引擎当属mozilla开源的rhino

/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0
 *
 * 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 Rhino code, released
 * May 6, 1999.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1997-2000
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Patrick Beard
 *   Norris Boyd
 *   Igor Bukanov
 *   Ethan Hugg
 *   Roger Lawrence
 *   Terry Lucas
 *   Frank Mitchell
 *   Milen Nankov
 *   Andrew Wason
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License Version 2 or later (the "GPL"), in which
 * case the provisions of the GPL are applicable instead of those above. If
 * you wish to allow use of your version of this file only under the terms of
 * the GPL and not to allow others to use your version of this file under the
 * MPL, indicate your decision by deleting the provisions above and replacing
 * them with the notice and other provisions required by the GPL. If you do
 * not delete the provisions above, a recipient may use your version of this
 * file under either the MPL or the GPL.
 *
 * ***** END LICENSE BLOCK ***** */

package org.mozilla.javascript;

import java.lang.reflect.*;
import java.text.MessageFormat;
import java.util.Locale;
import java.util.ResourceBundle;

import org.mozilla.javascript.xml.XMLObject;
import org.mozilla.javascript.xml.XMLLib;
import org.mozilla.javascript.continuations.Continuation;

/**
 * This is the class that implements the runtime.
 *
 * @author Norris Boyd
 */

public class ScriptRuntime {

    /**
     * No instances should be created.
     */
    protected ScriptRuntime() {
    }

    /*
     * There's such a huge space (and some time) waste for the Foo.class
     * syntax: the compiler sticks in a test of a static field in the
     * enclosing class for null and the code for creating the class value.
     * It has to do this since the reference has to get pushed off til
     * executiontime (i.e. can't force an early load), but for the
     * 'standard' classes - especially those in java.lang, we can trust
     * that they won't cause problems by being loaded early.
     */

    public final static Class
        BooleanClass      = Kit.classOrNull("java.lang.Boolean"),
        ByteClass         = Kit.classOrNull("java.lang.Byte"),
        CharacterClass    = Kit.classOrNull("java.lang.Character"),
        ClassClass        = Kit.classOrNull("java.lang.Class"),
        DoubleClass       = Kit.classOrNull("java.lang.Double"),
        FloatClass        = Kit.classOrNull("java.lang.Float"),
        IntegerClass      = Kit.classOrNull("java.lang.Integer"),
        LongClass         = Kit.classOrNull("java.lang.Long"),
        NumberClass       = Kit.classOrNull("java.lang.Number"),
        ObjectClass       = Kit.classOrNull("java.lang.Object"),
        ShortClass        = Kit.classOrNull("java.lang.Short"),
        StringClass       = Kit.classOrNull("java.lang.String"),
        DateClass         = Kit.classOrNull("java.util.Date");

    public final static Class
        ContextClass
            = Kit.classOrNull("org.mozilla.javascript.Context"),
        ContextFactoryClass
            = Kit.classOrNull("org.mozilla.javascript.ContextFactory"),
        FunctionClass
            = Kit.classOrNull("org.mozilla.javascript.Function"),
        ScriptableClass
            = Kit.classOrNull("org.mozilla.javascript.Scriptable"),
        ScriptableObjectClass
            = Kit.classOrNull("org.mozilla.javascript.ScriptableObject");

    private static final String
        XML_INIT_CLASS = "org.mozilla.javascript.xmlimpl.XMLLibImpl";

    private static final String[] lazilyNames = {
        "RegExp",        "org.mozilla.javascript.regexp.NativeRegExp",
        "Packages",      "org.mozilla.javascript.NativeJavaTopPackage",
        "java",          "org.mozilla.javascript.NativeJavaTopPackage",
        "getClass",      "org.mozilla.javascript.NativeJavaTopPackage",
        "JavaAdapter",   "org.mozilla.javascript.JavaAdapter",
        "JavaImporter",  "org.mozilla.javascript.ImporterTopLevel",
        "XML",           XML_INIT_CLASS,
        "XMLList",       XML_INIT_CLASS,
        "Namespace",     XML_INIT_CLASS,
        "QName",         XML_INIT_CLASS,
    };

    private static final Object LIBRARY_SCOPE_KEY = new Object();

    public static boolean isRhinoRuntimeType(Class cl)
    {
        if (cl.isPrimitive()) {
            return (cl != Character.TYPE);
        } else {
            return (cl == StringClass || cl == BooleanClass
                    || NumberClass.isAssignableFrom(cl)
                    || ScriptableClass.isAssignableFrom(cl));
        }
    }

    public static ScriptableObject initStandardObjects(Context cx,
                                                       ScriptableObject scope,
                                                       boolean sealed)
    {
        if (scope == null) {
            scope = new NativeObject();
        }
        scope.associateValue(LIBRARY_SCOPE_KEY, scope);
        (new ClassCache()).associate(scope);

        BaseFunction.init(scope, sealed);
        NativeObject.init(scope, sealed);

        Scriptable objectProto = ScriptableObject.getObjectPrototype(scope);

        // Function.prototype.__proto__ should be Object.prototype
        Scriptable functionProto = ScriptableObject.getFunctionPrototype(scope);
        functionProto.setPrototype(objectProto);

        // Set the prototype of the object passed in if need be
        if (scope.getPrototype() == null)
            scope.setPrototype(objectProto);

        // must precede NativeGlobal since it's needed therein
        NativeError.init(scope, sealed);
        NativeGlobal.init(cx, scope, sealed);

        NativeArray.init(scope, sealed);
        NativeString.init(scope, sealed);
        NativeBoolean.init(scope, sealed);
        NativeNumber.init(scope, sealed);
        NativeDate.init(scope, sealed);
        NativeMath.init(scope, sealed);

        NativeWith.init(scope, sealed);
        NativeCall.init(scope, sealed);
        NativeScript.init(scope, sealed);

        boolean withXml = cx.hasFeature(Context.FEATURE_E4X);

        for (int i = 0; i != lazilyNames.length; i += 2) {
            String topProperty = lazilyNames[i];
            String className = lazilyNames[i + 1];
            if (!withXml && className == XML_INIT_CLASS) {
                continue;
            }
            new LazilyLoadedCtor(scope, topProperty, className, sealed);
        }

        Continuation.init(scope, sealed);

        return scope;
    }

    public static ScriptableObject getLibraryScopeOrNull(Scriptable scope)
    {
        ScriptableObject libScope;
        libScope = (ScriptableObject)ScriptableObject.
                       getTopScopeValue(scope, LIBRARY_SCOPE_KEY);
        return libScope;
    }

    // It is public so NativeRegExp can access it .
    public static boolean isJSLineTerminator(int c)
    {
        // Optimization for faster check for eol character:
        // they do not have 0xDFD0 bits set
        if ((c & 0xDFD0) != 0) {
            return false;
        }
        return c == '\n' || c == '\r' || c == 0x2028 || c == 0x2029;
    }

    public static Boolean wrapBoolean(boolean b)
    {
        return b ? Boolean.TRUE : Boolean.FALSE;
    }

    public static Integer wrapInt(int i)
    {
        return new Integer(i);
    }

    public static Number wrapNumber(double x)
    {
        if (x != x) {
            return ScriptRuntime.NaNobj;
        }
        return new Double(x);
    }

    /**
     * Convert the value to a boolean.
     *
     * See ECMA 9.2.
     */
    public static boolean toBoolean(Object val)
    {
        for (;;) {
            if (val instanceof Boolean)
                return ((Boolean) val).booleanValue();
            if (val == null || val == Undefined.instance)
                return false;
            if (val instanceof String)
                return ((String) val).length() != 0;
            if (val instanceof Number) {
                double d = ((Number) val).doubleValue();
                return (d == d && d != 0.0);
            }
            if (val instanceof Scriptable) {
                if (Context.getContext().isVersionECMA1()) {
                    // pure ECMA
                    return true;
                }
                // ECMA extension
                val = ((Scriptable) val).getDefaultValue(BooleanClass);
                if (val instanceof Scriptable)
                    throw errorWithClassName("msg.primitive.expected", val);
                continue;
            }
            warnAboutNonJSObject(val);
            return true;
        }
    }

    public static boolean toBoolean(Object[] args, int index) {
        return (index < args.length) ? toBoolean(args[index]) : false;
    }

    /**
     * Convert the value to a number.
     *
     * See ECMA 9.3.
     */
    public static double toNumber(Object val)
    {
        for (;;) {
            if (val instanceof Number)
                return ((Number) val).doubleValue();
            if (val == null)
                return +0.0;
            if (val == Undefined.instance)
                return NaN;
            if (val instanceof String)
                return toNumber((String) val);
            if (val instanceof Boolean)
                return ((Boolean) val).booleanValue() ? 1 : +0.0;
            if (val instanceof Scriptable) {
                val = ((Scriptable) val).getDefaultValue(NumberClass);
                if (val instanceof Scriptable)
                    throw errorWithClassName("msg.primitive.expected", val);
                continue;
            }
            warnAboutNonJSObject(val);
            return NaN;
        }
    }

    public static double toNumber(Object[] args, int index) {
        return (index < args.length) ? toNumber(args[index]) : NaN;
    }

    // Can not use Double.NaN defined as 0.0d / 0.0 as under the Microsoft VM,
    // versions 2.01 and 3.0P1, that causes some uses (returns at least) of
    // Double.NaN to be converted to 1.0.
    // So we use ScriptRuntime.NaN instead of Double.NaN.
    public static final double
        NaN = Double.longBitsToDouble(0x7ff8000000000000L);

    // A similar problem exists for negative zero.
    public static final double
        negativeZero = Double.longBitsToDouble(0x8000000000000000L);

    public static final Double NaNobj = new Double(NaN);

    /*
     * Helper function for toNumber, parseInt, and TokenStream.getToken.
     */
    static double stringToNumber(String s, int start, int radix) {
        char digitMax = '9';
        char lowerCaseBound = 'a';
        char upperCaseBound = 'A';
        int len = s.length();
        if (radix < 10) {
            digitMax = (char) ('0' + radix - 1);
        }
        if (radix > 10) {
            lowerCaseBound = (char) ('a' + radix - 10);
            upperCaseBound = (char) ('A' + radix - 10);
        }
        int end;
        double sum = 0.0;
        for (end=start; end < len; end++) {
            char c = s.charAt(end);
            int newDigit;
            if ('0' <= c && c <= digitMax)
                newDigit = c - '0';
            else if ('a' <= c && c < lowerCaseBound)
                newDigit = c - 'a' + 10;
            else if ('A' <= c && c < upperCaseBound)
                newDigit = c - 'A' + 10;
            else
                break;
            sum = sum*radix + newDigit;
        }
        if (start == end) {
            return NaN;
        }
        if (sum >= 9007199254740992.0) {
            if (radix == 10) {
                /* If we're accumulating a decimal number and the number
                 * is >= 2^53, then the result from the repeated multiply-add
                 * above may be inaccurate.  Call Java to get the correct
                 * answer.
                 */
                try {
                    return Double.valueOf(s.substring(start, end)).doubleValue();
                } catch (NumberFormatException nfe) {
                    return NaN;
                }
            } else if (radix == 2 || radix == 4 || radix == 8 ||
                       radix == 16 || radix == 32)
            {
                /* The number may also be inaccurate for one of these bases.
                 * This happens if the addition in value*radix + digit causes
                 * a round-down to an even least significant mantissa bit
                 * when the first dropped bit is a one.  If any of the
                 * following digits in the number (which haven't been added
                 * in yet) are nonzero then the correct action would have
                 * been to round up instead of down.  An example of this
                 * occurs when reading the number 0x1000000000000081, which
                 * rounds to 0x1000000000000000 instead of 0x1000000000000100.
                 */
                int bitShiftInChar = 1;
                int digit = 0;

                final int SKIP_LEADING_ZEROS = 0;
                final int FIRST_EXACT_53_BITS = 1;
                final int AFTER_BIT_53         = 2;
                final int ZEROS_AFTER_54 = 3;
                final int MIXED_AFTER_54 = 4;

                int state = SKIP_LEADING_ZEROS;
                int exactBitsLimit = 53;
                double factor = 0.0;
                boolean bit53 = false;
                // bit54 is the 54th bit (the first dropped from the mantissa)
                boolean bit54 = false;

                for (;;) {
                    if (bitShiftInChar == 1) {
                        if (start == end)
                            break;
                        digit = s.charAt(start++);