javamembers.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):
 *   Norris Boyd
 *   Cameron McCormack
 *   Frank Mitchell
 *   Mike Shaver
 *   Kurt Westerfeld
 *
 * 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.util.*;

/**
 *
 * @author Mike Shaver
 * @author Norris Boyd
 * @see NativeJavaObject
 * @see NativeJavaClass
 */
class JavaMembers
{
    JavaMembers(Scriptable scope, Class cl)
    {
        this(scope, cl, false);
    }

    JavaMembers(Scriptable scope, Class cl, boolean includeProtected)
    {
        try {
            Context cx = ContextFactory.getGlobal().enterContext();
            ClassShutter shutter = cx.getClassShutter();
            if (shutter != null && !shutter.visibleToScripts(cl.getName())) {
                throw Context.reportRuntimeError1("msg.access.prohibited",
                                                  cl.getName());
            }
            this.includePrivate = cx.hasFeature(
                Context.FEATURE_ENHANCED_JAVA_ACCESS);
            this.members = new Hashtable(23);
            this.staticMembers = new Hashtable(7);
            this.cl = cl;
            reflect(scope, includeProtected);
        } finally {
            Context.exit();
        }
    }

    boolean has(String name, boolean isStatic)
    {
        Hashtable ht = isStatic ? staticMembers : members;
        Object obj = ht.get(name);
        if (obj != null) {
            return true;
        }
        return findExplicitFunction(name, isStatic) != null;
    }

    Object get(Scriptable scope, String name, Object javaObject,
               boolean isStatic)
    {
        Hashtable ht = isStatic ? staticMembers : members;
        Object member = ht.get(name);
        if (!isStatic && member == null) {
            // Try to get static member from instance (LC3)
            member = staticMembers.get(name);
        }
        if (member == null) {
            member = this.getExplicitFunction(scope, name,
                                              javaObject, isStatic);
            if (member == null)
                return Scriptable.NOT_FOUND;
        }
        if (member instanceof Scriptable) {
            return member;
        }
        Context cx = Context.getContext();
        Object rval;
        Class type;
        try {
            if (member instanceof BeanProperty) {
                BeanProperty bp = (BeanProperty) member;
                if (bp.getter == null)
                    return Scriptable.NOT_FOUND;
                rval = bp.getter.invoke(javaObject, Context.emptyArgs);
                type = bp.getter.method().getReturnType();
            } else {
                Field field = (Field) member;
                rval = field.get(isStatic ? null : javaObject);
                type = field.getType();
            }
        } catch (Exception ex) {
            throw Context.throwAsScriptRuntimeEx(ex);
        }
        // Need to wrap the object before we return it.
        scope = ScriptableObject.getTopLevelScope(scope);
        return cx.getWrapFactory().wrap(cx, scope, rval, type);
    }

    void put(Scriptable scope, String name, Object javaObject,
             Object value, boolean isStatic)
    {
        Hashtable ht = isStatic ? staticMembers : members;
        Object member = ht.get(name);
        if (!isStatic && member == null) {
            // Try to get static member from instance (LC3)
            member = staticMembers.get(name);
        }
        if (member == null)
            throw reportMemberNotFound(name);
        if (member instanceof FieldAndMethods) {
            FieldAndMethods fam = (FieldAndMethods) ht.get(name);
            member = fam.field;
        }

        // Is this a bean property "set"?
        if (member instanceof BeanProperty) {
            BeanProperty bp = (BeanProperty)member;
            if (bp.setter == null) {
                throw reportMemberNotFound(name);
            }
            // If there's only one setter or if the value is null, use the
            // main setter. Otherwise, let the NativeJavaMethod decide which
            // setter to use:
            if (bp.setters == null || value == null) {
                Class setType = bp.setter.argTypes[0];
                Object[] args = { Context.jsToJava(value, setType) };
                try {
                    bp.setter.invoke(javaObject, args);
                } catch (Exception ex) {
                  throw Context.throwAsScriptRuntimeEx(ex);
                }
            } else {
                Object[] args = { value };
                bp.setters.call(Context.getContext(),
                                ScriptableObject.getTopLevelScope(scope),
                                scope, args);
            }
        }
        else {
            if (!(member instanceof Field)) {
                String str = (member == null) ? "msg.java.internal.private"
                                              : "msg.java.method.assign";
                throw Context.reportRuntimeError1(str, name);
            }
            Field field = (Field)member;
            Object javaValue = Context.jsToJava(value, field.getType());
            try {
                field.set(javaObject, javaValue);
            } catch (IllegalAccessException accessEx) {
                if ((field.getModifiers() & Modifier.FINAL) != 0) {
                    // treat Java final the same as JavaScript [[READONLY]]
                    return;
                }
                throw Context.throwAsScriptRuntimeEx(accessEx);
            } catch (IllegalArgumentException argEx) {
                throw Context.reportRuntimeError3(
                    "msg.java.internal.field.type",
                    value.getClass().getName(), field,
                    javaObject.getClass().getName());
            }
        }
    }

    Object[] getIds(boolean isStatic)
    {
        Hashtable ht = isStatic ? staticMembers : members;
        int len = ht.size();
        Object[] result = new Object[len];
        Enumeration keys = ht.keys();
        for (int i=0; i < len; i++)
            result[i] = keys.nextElement();
        return result;
    }

    static String javaSignature(Class type)
    {
        if (!type.isArray()) {
            return type.getName();
        } else {
            int arrayDimension = 0;
            do {
                ++arrayDimension;
                type = type.getComponentType();
            } while (type.isArray());
            String name = type.getName();
            String suffix = "[]";
            if (arrayDimension == 1) {
                return name.concat(suffix);
            } else {
                int length = name.length() + arrayDimension * suffix.length();
                StringBuffer sb = new StringBuffer(length);
                sb.append(name);
                while (arrayDimension != 0) {
                    --arrayDimension;
                    sb.append(suffix);
                }
                return sb.toString();
            }
        }
    }

    static String liveConnectSignature(Class[] argTypes)
    {
        int N = argTypes.length;
        if (N == 0) { return "()"; }
        StringBuffer sb = new StringBuffer();
        sb.append('(');
        for (int i = 0; i != N; ++i) {
            if (i != 0) {
                sb.append(',');
            }
            sb.append(javaSignature(argTypes[i]));
        }
        sb.append(')');
        return sb.toString();
    }

    private MemberBox findExplicitFunction(String name, boolean isStatic)
    {
        int sigStart = name.indexOf('(');
        if (sigStart < 0) { return null; }

        Hashtable ht = isStatic ? staticMembers : members;
        MemberBox[] methodsOrCtors = null;
        boolean isCtor = (isStatic && sigStart == 0);

        if (isCtor) {
            // Explicit request for an overloaded constructor
            methodsOrCtors = ctors;
        } else {
            // Explicit request for an overloaded method
            String trueName = name.substring(0,sigStart);
            Object obj = ht.get(trueName);
            if (!isStatic && obj == null) {
                // Try to get static member from instance (LC3)
                obj = staticMembers.get(trueName);
            }
            if (obj instanceof NativeJavaMethod) {
                NativeJavaMethod njm = (NativeJavaMethod)obj;
                methodsOrCtors = njm.methods;
            }
        }

        if (methodsOrCtors != null) {
            for (int i = 0; i < methodsOrCtors.length; i++) {
                Class[] type = methodsOrCtors[i].argTypes;
                String sig = liveConnectSignature(type);
                if (sigStart + sig.length() == name.length()
                    && name.regionMatches(sigStart, sig, 0, sig.length()))
                {
                    return methodsOrCtors[i];
                }
            }
        }

        return null;
    }

    private Object getExplicitFunction(Scriptable scope, String name,
                                       Object javaObject, boolean isStatic)
    {
        Hashtable ht = isStatic ? staticMembers : members;
        Object member = null;
        MemberBox methodOrCtor = findExplicitFunction(name, isStatic);

        if (methodOrCtor != null) {
            Scriptable prototype =
                ScriptableObject.getFunctionPrototype(scope);

            if (methodOrCtor.isCtor()) {
                NativeJavaConstructor fun =
                    new NativeJavaConstructor(methodOrCtor);
                fun.setPrototype(prototype);
                member = fun;
                ht.put(name, fun);
            } else {
                String trueName = methodOrCtor.getName();
                member = ht.get(trueName);