/*
* Delegate.java
*
* Copyright (c) 2012 Mike Strobel
*
* This source code is based on the Dynamic Language Runtime from Microsoft,
* Copyright (c) Microsoft Corporation.
*
* This source code is subject to terms and conditions of the Apache License, Version 2.0.
* A copy of the license can be found in the License.html file at the root of this distribution.
* By using this source code in any fashion, you are agreeing to be bound by the terms of the
* Apache License, Version 2.0.
*
* You must not remove this notice, or any other, from this software.
*/
package com.strobel.expressions;
import com.strobel.core.VerifyArgument;
import com.strobel.reflection.MethodInfo;
import com.strobel.reflection.TargetInvocationException;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
/**
* @author Mike Strobel
*/
public final class Delegate<T> {
private final T _instance;
private final MethodInfo _method;
private MethodHandle _methodHandle;
private MethodHandle _spreadInvoker;
Delegate(final T instance, final MethodInfo method) {
_instance = VerifyArgument.notNull(instance, "instance");
_method = VerifyArgument.notNull(method, "method");
}
public final T getInstance() {
return _instance;
}
public final MethodInfo getMethod() {
return _method;
}
public final MethodHandle getMethodHandle() {
if (_methodHandle == null) {
try {
_methodHandle = MethodHandles
.lookup()
.unreflect(_method.getRawMethod())
.bindTo(_instance);
}
catch (IllegalAccessException e) {
throw new IllegalStateException("Could not resolve method handle.");
}
}
return _methodHandle;
}
public final Object invokeDynamic(final Object... args) throws TargetInvocationException {
try {
if (_spreadInvoker == null) {
final MethodHandle methodHandle = getMethodHandle();
_spreadInvoker = methodHandle.asSpreader(Object[].class, _method.getParameters().size());
}
return _spreadInvoker.invoke(args);
}
catch (Throwable t) {
throw new TargetInvocationException(t);
}
}
}