/*
* Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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package com.sun.script.javascript;
import sun.org.mozilla.javascript.internal.*;
import java.util.*;
JSAdapter is java.lang.reflect.Proxy equivalent for JavaScript. JSAdapter
calls specially named JavaScript methods on an adaptee object when property
access is attempted on it.
Example:
var y = {
__get__ : function (name) { ... }
__has__ : function (name) { ... }
__put__ : function (name, value) {...}
__delete__ : function (name) { ... }
__getIds__ : function () { ... }
};
var x = new JSAdapter(y);
x.i; // calls y.__get__
i in x; // calls y.__has__
x.p = 10; // calls y.__put__
delete x.p; // calls y.__delete__
for (i in x) { print(i); } // calls y.__getIds__
If a special JavaScript method is not found in the adaptee, then JSAdapter
forwards the property access to the adaptee itself.
JavaScript caller of adapter object is isolated from the fact that
the property access/mutation/deletion are really calls to
JavaScript methods on adaptee. Use cases include 'smart'
properties, property access tracing/debugging, encaptulation with
easy client access - in short JavaScript becomes more "Self" like.
Note that Rhino already supports special properties like __proto__
(to set, get prototype), __parent__ (to set, get parent scope). We
follow the same double underscore nameing convention here. Similarly
the name JSAdapter is derived from JavaAdapter -- which is a facility
to extend, implement Java classes/interfaces by JavaScript.
Author: A. Sundararajan Since: 1.6
/**
* JSAdapter is java.lang.reflect.Proxy equivalent for JavaScript. JSAdapter
* calls specially named JavaScript methods on an adaptee object when property
* access is attempted on it.
*
* Example:
*
* var y = {
* __get__ : function (name) { ... }
* __has__ : function (name) { ... }
* __put__ : function (name, value) {...}
* __delete__ : function (name) { ... }
* __getIds__ : function () { ... }
* };
*
* var x = new JSAdapter(y);
*
* x.i; // calls y.__get__
* i in x; // calls y.__has__
* x.p = 10; // calls y.__put__
* delete x.p; // calls y.__delete__
* for (i in x) { print(i); } // calls y.__getIds__
*
* If a special JavaScript method is not found in the adaptee, then JSAdapter
* forwards the property access to the adaptee itself.
*
* JavaScript caller of adapter object is isolated from the fact that
* the property access/mutation/deletion are really calls to
* JavaScript methods on adaptee. Use cases include 'smart'
* properties, property access tracing/debugging, encaptulation with
* easy client access - in short JavaScript becomes more "Self" like.
*
* Note that Rhino already supports special properties like __proto__
* (to set, get prototype), __parent__ (to set, get parent scope). We
* follow the same double underscore nameing convention here. Similarly
* the name JSAdapter is derived from JavaAdapter -- which is a facility
* to extend, implement Java classes/interfaces by JavaScript.
*
* @author A. Sundararajan
* @since 1.6
*/
public final class JSAdapter implements Scriptable, Function {
private JSAdapter(Scriptable obj) {
setAdaptee(obj);
}
// initializer to setup JSAdapter prototype in the given scope
public static void init(Context cx, Scriptable scope, boolean sealed)
throws RhinoException {
JSAdapter obj = new JSAdapter(cx.newObject(scope));
obj.setParentScope(scope);
obj.setPrototype(getFunctionPrototype(scope));
obj.isPrototype = true;
ScriptableObject.defineProperty(scope, "JSAdapter", obj,
ScriptableObject.DONTENUM);
}
public String getClassName() {
return "JSAdapter";
}
public Object get(String name, Scriptable start) {
Function func = getAdapteeFunction(GET_PROP);
if (func != null) {
return call(func, new Object[] { name });
} else {
start = getAdaptee();
return start.get(name, start);
}
}
public Object get(int index, Scriptable start) {
Function func = getAdapteeFunction(GET_PROP);
if (func != null) {
return call(func, new Object[] { new Integer(index) });
} else {
start = getAdaptee();
return start.get(index, start);
}
}
public boolean has(String name, Scriptable start) {
Function func = getAdapteeFunction(HAS_PROP);
if (func != null) {
Object res = call(func, new Object[] { name });
return Context.toBoolean(res);
} else {
start = getAdaptee();
return start.has(name, start);
}
}
public boolean has(int index, Scriptable start) {
Function func = getAdapteeFunction(HAS_PROP);
if (func != null) {
Object res = call(func, new Object[] { new Integer(index) });
return Context.toBoolean(res);
} else {
start = getAdaptee();
return start.has(index, start);
}
}
public void put(String name, Scriptable start, Object value) {
if (start == this) {
Function func = getAdapteeFunction(PUT_PROP);
if (func != null) {
call(func, new Object[] { name, value });
} else {
start = getAdaptee();
start.put(name, start, value);
}
} else {
start.put(name, start, value);
}
}
public void put(int index, Scriptable start, Object value) {
if (start == this) {
Function func = getAdapteeFunction(PUT_PROP);
if( func != null) {
call(func, new Object[] { new Integer(index), value });
} else {
start = getAdaptee();
start.put(index, start, value);
}
} else {
start.put(index, start, value);
}
}
public void delete(String name) {
Function func = getAdapteeFunction(DEL_PROP);
if (func != null) {
call(func, new Object[] { name });
} else {
getAdaptee().delete(name);
}
}
public void delete(int index) {
Function func = getAdapteeFunction(DEL_PROP);
if (func != null) {
call(func, new Object[] { new Integer(index) });
} else {
getAdaptee().delete(index);
}
}
public Scriptable getPrototype() {
return prototype;
}
public void setPrototype(Scriptable prototype) {
this.prototype = prototype;
}
public Scriptable getParentScope() {
return parent;
}
public void setParentScope(Scriptable parent) {
this.parent = parent;
}
public Object[] getIds() {
Function func = getAdapteeFunction(GET_PROPIDS);
if (func != null) {
Object val = call(func, new Object[0]);
// in most cases, adaptee would return native JS array
if (val instanceof NativeArray) {
NativeArray array = (NativeArray) val;
Object[] res = new Object[(int)array.getLength()];
for (int index = 0; index < res.length; index++) {
res[index] = mapToId(array.get(index, array));
}
return res;
} else if (val instanceof NativeJavaArray) {
// may be attempt wrapped Java array
Object tmp = ((NativeJavaArray)val).unwrap();
Object[] res;
if (tmp.getClass() == Object[].class) {
Object[] array = (Object[]) tmp;
res = new Object[array.length];
for (int index = 0; index < array.length; index++) {
res[index] = mapToId(array[index]);
}
} else {
// just return an empty array
res = Context.emptyArgs;
}
return res;
} else {
// some other return type, just return empty array
return Context.emptyArgs;
}
} else {
return getAdaptee().getIds();
}
}
public boolean hasInstance(Scriptable scriptable) {
if (scriptable instanceof JSAdapter) {
return true;
} else {
Scriptable proto = scriptable.getPrototype();
while (proto != null) {
if (proto.equals(this)) return true;
proto = proto.getPrototype();
}
return false;
}
}
public Object getDefaultValue(Class hint) {
return getAdaptee().getDefaultValue(hint);
}
public Object call(Context cx, Scriptable scope, Scriptable thisObj,
Object[] args)
throws RhinoException {
if (isPrototype) {
return construct(cx, scope, args);
} else {
Scriptable tmp = getAdaptee();
if (tmp instanceof Function) {
return ((Function)tmp).call(cx, scope, tmp, args);
} else {
throw Context.reportRuntimeError("TypeError: not a function");
}
}
}
public Scriptable construct(Context cx, Scriptable scope, Object[] args)
throws RhinoException {
if (isPrototype) {
Scriptable topLevel = ScriptableObject.getTopLevelScope(scope);
JSAdapter newObj;
if (args.length > 0) {
newObj = new JSAdapter(Context.toObject(args[0], topLevel));
} else {
throw Context.reportRuntimeError("JSAdapter requires adaptee");
}
return newObj;
} else {
Scriptable tmp = getAdaptee();
if (tmp instanceof Function) {
return ((Function)tmp).construct(cx, scope, args);
} else {
throw Context.reportRuntimeError("TypeError: not a constructor");
}
}
}
public Scriptable getAdaptee() {
return adaptee;
}
public void setAdaptee(Scriptable adaptee) {
if (adaptee == null) {
throw new NullPointerException("adaptee can not be null");
}
this.adaptee = adaptee;
}
//-- internals only below this point
// map a property id. Property id can only be an Integer or String
private Object mapToId(Object tmp) {
if (tmp instanceof Double) {
return new Integer(((Double)tmp).intValue());
} else {
return Context.toString(tmp);
}
}
private static Scriptable getFunctionPrototype(Scriptable scope) {
return ScriptableObject.getFunctionPrototype(scope);
}
private Function getAdapteeFunction(String name) {
Object o = ScriptableObject.getProperty(getAdaptee(), name);
return (o instanceof Function)? (Function)o : null;
}
private Object call(Function func, Object[] args) {
Context cx = Context.getCurrentContext();
Scriptable thisObj = getAdaptee();
Scriptable scope = func.getParentScope();
try {
return func.call(cx, scope, thisObj, args);
} catch (RhinoException re) {
throw Context.reportRuntimeError(re.getMessage());
}
}
private Scriptable prototype;
private Scriptable parent;
private Scriptable adaptee;
private boolean isPrototype;
// names of adaptee JavaScript functions
private static final String GET_PROP = "__get__";
private static final String HAS_PROP = "__has__";
private static final String PUT_PROP = "__put__";
private static final String DEL_PROP = "__delete__";
private static final String GET_PROPIDS = "__getIds__";
}