/*
* Copyright 2012-2014 headius.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.headius.invokebinder.transform;
import com.headius.invokebinder.InvalidTransformException;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.util.Arrays;
/**
* A permutation transform.
*
* Equivalent call: MethodHandles.permuteArguments(MethodHandle, MethodType, int...)
*/
public class Permute extends Transform {
private final MethodType source;
private final int[] reorder;
public Permute(MethodType source, int... reorder) {
this.source = source;
this.reorder = reorder;
}
public MethodHandle up(MethodHandle target) {
return MethodHandles.permuteArguments(target, source, reorder);
}
public MethodType down(MethodType type) {
Class[] types = new Class[reorder.length];
for (int i = 0; i < reorder.length; i++) {
int typeIndex = reorder[i];
if (typeIndex < 0 || typeIndex >= type.parameterCount()) {
throw new InvalidTransformException("one or more permute indices (" + Arrays.toString(reorder) + ") out of bounds for " + source);
}
types[i] = type.parameterType(reorder[i]);
}
return MethodType.methodType(type.returnType(), types);
}
public String toString() {
return "permute " + source + " with " + Arrays.toString(reorder);
}
}