/*
* Copyright 2007, 2008 Duncan McGregor
*
* This file is part of Rococoa, a library to allow Java to talk to Cocoa.
*
* Rococoa is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Rococoa 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with Rococoa. If not, see <http://www.gnu.org/licenses/>.
*/
package org.rococoa.internal;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
import org.rococoa.ID;
import org.rococoa.RococoaException;
import org.rococoa.Selector;
import com.sun.jna.Function;
import com.sun.jna.Library;
import com.sun.jna.NativeLong;
import com.sun.jna.Structure;
/**
* Very special case InvocationHandler that invokes the correct message dispatch
* function for different return types.
*
* Either objc_msgSend or objc_msgSend_stret should be called, depending on the
* return type. The latter is usually for struct by value, but the former is
* used for small structs on Intel! Oh and the call has to be mangled in all
* cases as the result is returned on the stack, but is different sizes
* depending on its type. Luckily jna and libffi take care of the details -
* provided they know what the return type is.
*
* This InvocationHandler is passed the return type as the first arg to the method call that it
* intercepts, it uses it to determine which function to call, and removes it before
* calling invoking.
*
* @see "http://www.cocoabuilder.com/archive/message/cocoa/2006/6/25/166236"
* @see "http://developer.apple.com/mac/library/documentation/DeveloperTools/Conceptual/LowLevelABI/Mac_OS_X_ABI_Function_Calls.pdf"
* @see "http://www.sealiesoftware.com/blog/archive/2008/10/30/objc_explain_objc_msgSend_stret.html"
*
* Note also that there is a objc_msgSend_fret that is used supposed to be for
* floating point return types, but that I haven't (yet) had to use.
*
* @see "http://www.sealiesoftware.com/blog/archive/2008/11/16/objc_explain_objc_msgSend_fpret.html"
*
* @author duncan
*
*/
class MsgSendHandler implements InvocationHandler {
/**
* @see com.sun.jna.Function#OPTION_INVOKING_METHOD
*/
private final String OPTION_INVOKING_METHOD = "invoking-method";
// TODO - use JNA string when made public
private final static int I386_STRET_CUTOFF = 9;
private final static int IA64_STRET_CUTOFF = 17;
private final static int stretCutoff = NativeLong.SIZE == 8 ? IA64_STRET_CUTOFF : I386_STRET_CUTOFF;
private final static boolean ppc = System.getProperty("os.arch").trim().equalsIgnoreCase("ppc");
private final static Method OBJC_MSGSEND;
private final static Method OBJC_MSGSEND_STRET;
static {
try {
OBJC_MSGSEND = MsgSendLibrary.class.getDeclaredMethod("objc_msgSend",
ID.class, Selector.class, Object[].class);
OBJC_MSGSEND_STRET = MsgSendLibrary.class.getDeclaredMethod("objc_msgSend_stret",
ID.class, Selector.class, Object[].class);
}
catch (NoSuchMethodException x) {
throw new RococoaException(x);
}
}
private final Pair<Method, Function> objc_msgSend_stret_Pair;
private final Pair<Method, Function> objc_msgSend_Pair;
public MsgSendHandler(Function objc_msgSend_Function, Function objc_msgSend_stret_Function) {
this.objc_msgSend_Pair = new Pair<Method, Function>(OBJC_MSGSEND, objc_msgSend_Function);
this.objc_msgSend_stret_Pair = new Pair<Method, Function>(OBJC_MSGSEND_STRET, objc_msgSend_stret_Function);
}
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
Class<?> returnTypeForThisCall = (Class<?>) args[0];
Object[] argsWithoutReturnType = this.removeReturnTypeFrom(args);
Map<String, Object> options = new HashMap<String, Object>(1);
options.put(Library.OPTION_TYPE_MAPPER, new RococoaTypeMapper());
Pair<Method, Function> invocation = this.invocationFor(returnTypeForThisCall);
options.put(OPTION_INVOKING_METHOD, invocation.a);
return invocation.b.invoke(returnTypeForThisCall, argsWithoutReturnType, options);
}
private Object[] removeReturnTypeFrom(Object[] args) {
Object[] result = new Object[args.length - 1];
System.arraycopy(args, 1, result, 0, args.length - 2);
return result;
}
private Pair<Method, Function> invocationFor(Class<?> returnTypeForThisCall) {
boolean isStruct = Structure.class.isAssignableFrom(returnTypeForThisCall);
boolean isStructByValue = isStruct && Structure.ByValue.class.isAssignableFrom(returnTypeForThisCall);
if (!isStructByValue)
return objc_msgSend_Pair;
try {
if(ppc) {
// on ppc32 structs never return in registers
return objc_msgSend_stret_Pair;
}
// on i386 structs with sizeof exactly equal to 1, 2, 4, or 8 return in registers
Structure prototype = (Structure) returnTypeForThisCall.newInstance();
return prototype.size() < stretCutoff ? objc_msgSend_Pair : objc_msgSend_stret_Pair;
}
catch(InstantiationException e) {
throw new RococoaException(e);
}
catch(IllegalAccessException e) {
throw new RococoaException(e);
}
}
}