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Common Lisp implementation running on the JVM
/*
* JProxy.java
*
* Copyright (C) 2002-2005 Peter Graves, Andras Simon
* $Id: JProxy.java 13461 2011-08-11 17:01:41Z ehuelsmann $
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program 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 for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* As a special exception, the copyright holders of this library give you
* permission to link this library with independent modules to produce an
* executable, regardless of the license terms of these independent
* modules, and to copy and distribute the resulting executable under
* terms of your choice, provided that you also meet, for each linked
* independent module, the terms and conditions of the license of that
* module. An independent module is a module which is not derived from
* or based on this library. If you modify this library, you may extend
* this exception to your version of the library, but you are not
* obligated to do so. If you do not wish to do so, delete this
* exception statement from your version.
*/
package org.armedbear.lisp;
import static org.armedbear.lisp.Lisp.*;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.HashMap;
import java.util.Map;
import java.util.WeakHashMap;
public final class JProxy
{
static final Map table = new WeakHashMap();
// ### %jnew-proxy interface &rest method-names-and-defs
private static final Primitive _JNEW_PROXY =
new Primitive("%jnew-proxy", PACKAGE_JAVA, false,
"interface &rest method-names-and-defs")
{
@Override
public LispObject execute(LispObject[] args)
{
int length = args.length;
if (length < 3 || length % 2 != 1)
return error(new WrongNumberOfArgumentsException(this));
Map lispDefinedMethods = new HashMap();
for (int i = 1; i < length; i += 2)
lispDefinedMethods.put(args[i].getStringValue(),
(Function) args[i + 1]);
Class iface = (Class) args[0].javaInstance();
Object proxy = Proxy.newProxyInstance(iface.getClassLoader(),
new Class[] { iface },
new LispHandler(table));
table.put(proxy, new Entry(iface, lispDefinedMethods));
return new JavaObject(proxy);
}
};
private static class LispHandler implements InvocationHandler
{
Map table;
LispHandler (Map table)
{
this.table = table;
}
public Object invoke(Object proxy, Method method, Object[] args)
{
String methodName = method.getName();
if (methodName.equals("hashCode"))
return new Integer(System.identityHashCode(proxy));
if (methodName.equals("equals"))
return (proxy == args[0] ? Boolean.TRUE : Boolean.FALSE);
if (methodName.equals("toString"))
return proxy.getClass().getName() + '@' + Integer.toHexString(proxy.hashCode());
if (table.containsKey(proxy))
{
Entry entry = (Entry) table.get(proxy);
Function f = entry.getLispMethod(methodName);
if (f != null)
{
LispObject lispArgs = NIL;
if (args != null)
{
for (int i = args.length - 1 ; 0 <= i ; i--)
lispArgs = lispArgs.push(new JavaObject(args[i]));
}
LispObject result = evalCall(f, lispArgs, new Environment(),
LispThread.currentThread());
return (method.getReturnType() == void.class ? null : result.javaInstance());
}
}
return null;
}
}
private static class Entry
{
Class iface;
Map lispDefinedMethods;
public Entry (Class iface, Map lispDefinedMethods)
{
this.iface = iface;
this.lispDefinedMethods = lispDefinedMethods;
}
public Function getLispMethod(String methodName)
{
if (lispDefinedMethods.containsKey(methodName))
return (Function)lispDefinedMethods.get(methodName);
return null;
}
}
//NEW IMPLEMENTATION by Alessio Stalla
/**
* A weak map associating each proxy instance with a "Lisp-this" object.
*/
static final Map proxyMap = new WeakHashMap();
public static class LispInvocationHandler implements InvocationHandler {
private Function function;
private static Method hashCodeMethod;
private static Method equalsMethod;
private static Method toStringMethod;
static {
try {
hashCodeMethod = Object.class.getMethod("hashCode", new Class[] {});
equalsMethod = Object.class.getMethod("equals", new Class[] { Object.class });
toStringMethod = Object.class.getMethod("toString", new Class[] {});
} catch (Exception e) {
throw new Error("Something got horribly wrong - can't get a method from Object.class", e);
}
}
public LispInvocationHandler(Function function) {
this.function = function;
}
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
if(hashCodeMethod.equals(method)) {
return System.identityHashCode(proxy);
}
if(equalsMethod.equals(method)) {
return proxy == args[0];
}
if(toStringMethod.equals(method)) {
return proxy.getClass().getName() + '@' + Integer.toHexString(proxy.hashCode());
}
if(args == null) {
args = new Object[0];
}
LispObject lispArgs = NIL;
synchronized(proxyMap) {
lispArgs = lispArgs.push(toLispObject(proxyMap.get(proxy)));
}
lispArgs = lispArgs.push(new SimpleString(method.getName()));
for(int i = 0; i < args.length; i++) {
lispArgs = lispArgs.push(toLispObject(args[i]));
}
Object retVal =
LispThread.currentThread().execute
(Symbol.APPLY, function, lispArgs.reverse()).javaInstance();
//(function.execute(lispArgs)).javaInstance();
/* DOES NOT WORK due to autoboxing!
if(retVal != null && !method.getReturnType().isAssignableFrom(retVal.getClass())) {
return error(new TypeError(new JavaObject(retVal), new JavaObject(method.getReturnType())));
}*/
return retVal;
}
}
private static final Primitive _JMAKE_INVOCATION_HANDLER =
new Primitive("%jmake-invocation-handler", PACKAGE_JAVA, false,
"function") {
public LispObject execute(LispObject[] args) {
int length = args.length;
if (length != 1) {
return error(new WrongNumberOfArgumentsException(this, 1));
}
if(!(args[0] instanceof Function)) {
return error(new TypeError(args[0], Symbol.FUNCTION));
}
return new JavaObject(new LispInvocationHandler((Function) args[0]));
}
};
private static final Primitive _JMAKE_PROXY =
new Primitive("%jmake-proxy", PACKAGE_JAVA, false,
"interfaces invocation-handler") {
public LispObject execute(final LispObject[] args) {
int length = args.length;
if (length != 3) {
return error(new WrongNumberOfArgumentsException(this, 3));
}
if(!(args[0] instanceof Cons)) {
return error(new TypeError(args[0], new SimpleString("CONS")));
}
Class[] ifaces = new Class[args[0].length()];
LispObject ifList = args[0];
for(int i = 0; i < ifaces.length; i++) {
ifaces[i] = (Class) ifList.car().javaInstance(Class.class);
ifList = ifList.cdr();
}
InvocationHandler invocationHandler = (InvocationHandler) ((JavaObject) args[1]).javaInstance(InvocationHandler.class);
Object proxy = Proxy.newProxyInstance(
JavaClassLoader.getCurrentClassLoader(),
ifaces,
invocationHandler);
synchronized(proxyMap) {
proxyMap.put(proxy, args[2]);
}
return new JavaObject(proxy);
}
};
static LispObject toLispObject(Object obj) {
return (obj instanceof LispObject) ? (LispObject) obj : new JavaObject(obj);
}
}