scriptruntime.java

這是一個javascript 的 interpreter是了解 web browser的好材料

/* -*- 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
 *   Bob Jervis
 *   Roger Lawrence
 *   Terry Lucas
 *   Frank Mitchell
 *   Milen Nankov
 *   Hannes Wallnoefer
 *   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.io.Serializable;
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;

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

public class ScriptRuntime {

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

    private static class NoSuchMethodShim implements Callable {
        String methodName;
        Callable noSuchMethodMethod;

        NoSuchMethodShim(Callable noSuchMethodMethod, String methodName)
        {
            this.noSuchMethodMethod = noSuchMethodMethod;
            this.methodName = methodName;
        }
        /**
         * Perform the call.
         *
         * @param cx the current Context for this thread
         * @param scope the scope to use to resolve properties.
         * @param thisObj the JavaScript <code>this</code> object
         * @param args the array of arguments
         * @return the result of the call
         */
        public Object call(Context cx, Scriptable scope, Scriptable thisObj,
                           Object[] args)
        {
            Object[] nestedArgs = new Object[2];

            nestedArgs[0] = methodName;
            nestedArgs[1] = newArrayLiteral(args, null, cx, scope);
            return noSuchMethodMethod.call(cx, scope, thisObj, nestedArgs);
        }

    }
    /*
     * 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 until
     * execution time (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[] lazilyNames = {
        "RegExp",        "org.mozilla.javascript.regexp.NativeRegExp",
        "Packages",      "org.mozilla.javascript.NativeJavaTopPackage",
        "java",          "org.mozilla.javascript.NativeJavaTopPackage",
        "javax",         "org.mozilla.javascript.NativeJavaTopPackage",
        "org",           "org.mozilla.javascript.NativeJavaTopPackage",
        "com",           "org.mozilla.javascript.NativeJavaTopPackage",
        "edu",           "org.mozilla.javascript.NativeJavaTopPackage",
        "net",           "org.mozilla.javascript.NativeJavaTopPackage",
        "getClass",      "org.mozilla.javascript.NativeJavaTopPackage",
        "JavaAdapter",   "org.mozilla.javascript.JavaAdapter",
        "JavaImporter",  "org.mozilla.javascript.ImporterTopLevel",
        "Continuation",  "org.mozilla.javascript.continuations.Continuation",
        //	TODO	Grotesque hack using literal string (xml) just to minimize
		//			changes for now
        "XML",           "(xml)",
        "XMLList",       "(xml)",
        "Namespace",     "(xml)",
        "QName",         "(xml)",
    };

    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);
        if (cx.getOptimizationLevel() > 0) {
            // When optimizing, attempt to fulfill all requests for new Array(N)
            // with a higher threshold before switching to a sparse 
            // representation
            NativeArray.setMaximumInitialCapacity(200000);            
        }
        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);
        
        NativeIterator.init(scope, sealed); // Also initializes NativeGenerator

        boolean withXml = cx.hasFeature(Context.FEATURE_E4X) && 
                          cx.getE4xImplementationFactory() != null;

        for (int i = 0; i != lazilyNames.length; i += 2) {
            String topProperty = lazilyNames[i];
            String className = lazilyNames[i + 1];
            if (!withXml && className.equals("(xml)")) {
                continue;
            } else if (withXml && className.equals("(xml)")) {
				className = cx.getE4xImplementationFactory().
                               getImplementationClassName();
			}
            new LazilyLoadedCtor(scope, topProperty, className, 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 (val instanceof ScriptableObject &&
                    ((ScriptableObject) val).avoidObjectDetection())
                {
                    return false;
                }
                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;
        }
    }

    /**
     * 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)