/*
* Copyright (c) 2009, 2011, 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.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.lang.invoke;
import sun.invoke.util.*;
import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
/**
* Adapters which manage inexact MethodHandle.invoke calls.
* The JVM calls one of these when the exact type match fails.
* @author jrose
*/
class InvokeGeneric {
// erased type for the call, which originates from an inexact invoke site
private final MethodType erasedCallerType;
// an invoker of type (MT, MH; A...) -> R
private final MethodHandle initialInvoker;
/** Compute and cache information for this adapter, so that it can
* call out to targets of the erasure-family of the given erased type.
*/
/*non-public*/ InvokeGeneric(MethodType erasedCallerType) throws ReflectiveOperationException {
assert(erasedCallerType.equals(erasedCallerType.erase()));
this.erasedCallerType = erasedCallerType;
this.initialInvoker = makeInitialInvoker();
assert initialInvoker.type().equals(erasedCallerType
.insertParameterTypes(0, MethodType.class, MethodHandle.class))
: initialInvoker.type();
}
private static MethodHandles.Lookup lookup() {
return IMPL_LOOKUP;
}
/** Return the adapter information for this type's erasure. */
/*non-public*/ static MethodHandle generalInvokerOf(MethodType erasedCallerType) throws ReflectiveOperationException {
InvokeGeneric gen = new InvokeGeneric(erasedCallerType);
return gen.initialInvoker;
}
private MethodHandle makeInitialInvoker() throws ReflectiveOperationException {
// postDispatch = #(MH'; MT, MH; A...){MH'(MT, MH; A)}
MethodHandle postDispatch = makePostDispatchInvoker();
MethodHandle invoker;
if (returnConversionPossible()) {
invoker = MethodHandles.foldArguments(postDispatch,
dispatcher("dispatchWithConversion"));
} else {
invoker = MethodHandles.foldArguments(postDispatch, dispatcher("dispatch"));
}
return invoker;
}
private static final Class<?>[] EXTRA_ARGS = { MethodType.class, MethodHandle.class };
private MethodHandle makePostDispatchInvoker() {
// Take (MH'; MT, MH; A...) and run MH'(MT, MH; A...).
MethodType invokerType = erasedCallerType.insertParameterTypes(0, EXTRA_ARGS);
return invokerType.invokers().exactInvoker();
}
private MethodHandle dropDispatchArguments(MethodHandle targetInvoker) {
assert(targetInvoker.type().parameterType(0) == MethodHandle.class);
return MethodHandles.dropArguments(targetInvoker, 1, EXTRA_ARGS);
}
private MethodHandle dispatcher(String dispatchName) throws ReflectiveOperationException {
return lookup().bind(this, dispatchName,
MethodType.methodType(MethodHandle.class,
MethodType.class, MethodHandle.class));
}
static final boolean USE_AS_TYPE_PATH = true;
/** Return a method handle to invoke on the callerType, target, and remaining arguments.
* The method handle must finish the call.
* This is the first look at the caller type and target.
*/
private MethodHandle dispatch(MethodType callerType, MethodHandle target) {
MethodType targetType = target.type();
if (USE_AS_TYPE_PATH || target.isVarargsCollector()) {
MethodHandle newTarget = target.asType(callerType);
targetType = callerType;
Invokers invokers = targetType.invokers();
MethodHandle invoker = invokers.erasedInvokerWithDrops;
if (invoker == null) {
invokers.erasedInvokerWithDrops = invoker =
dropDispatchArguments(invokers.erasedInvoker());
}
return invoker.bindTo(newTarget);
}
throw new RuntimeException("NYI");
}
private MethodHandle dispatchWithConversion(MethodType callerType, MethodHandle target) {
MethodHandle finisher = dispatch(callerType, target);
if (returnConversionNeeded(callerType, target))
finisher = addReturnConversion(finisher, callerType.returnType()); //FIXME: slow
return finisher;
}
private boolean returnConversionPossible() {
Class<?> needType = erasedCallerType.returnType();
return !needType.isPrimitive();
}
private boolean returnConversionNeeded(MethodType callerType, MethodHandle target) {
Class<?> needType = callerType.returnType();
if (needType == erasedCallerType.returnType())
return false; // no conversions possible, since must be primitive or Object
Class<?> haveType = target.type().returnType();
if (VerifyType.isNullConversion(haveType, needType) && !needType.isInterface())
return false;
return true;
}
private MethodHandle addReturnConversion(MethodHandle finisher, Class<?> type) {
// FIXME: This is slow because it creates a closure node on every call that requires a return cast.
MethodType finisherType = finisher.type();
MethodHandle caster = ValueConversions.identity(type);
caster = caster.asType(caster.type().changeParameterType(0, finisherType.returnType()));
finisher = MethodHandles.filterReturnValue(finisher, caster);
return finisher.asType(finisherType);
}
public String toString() {
return "InvokeGeneric"+erasedCallerType;
}
}