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// Copyright 2016 The Bazel Authors. All rights reserved.
//
// 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.google.devtools.build.android.desugar;
import com.google.common.collect.ImmutableSet;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.Handle;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
/**
* Class visitor to collect all the lambda methods that are used in invokedynamic instructions.
*
* <p>Note that this class only collects lambda methods. If the invokedynamic is used for other
* purposes, the methods used in the instruction are NOT collected.
*/
class InvokeDynamicLambdaMethodCollector extends ClassVisitor {
private final ImmutableSet.Builder<MethodInfo> lambdaMethodsUsedInInvokeDynamic =
ImmutableSet.builder();
private boolean needOuterClassRewrite = false;
public InvokeDynamicLambdaMethodCollector() {
super(Opcodes.ASM6);
}
/**
* Returns whether the visited class is declared in the scope of a lambda. In that case
* {@link LambdaDesugaring} will want to rewrite the EnclosingMethod attribute of the class.
*/
public boolean needOuterClassRewrite() {
return needOuterClassRewrite;
}
/** Returns methods referenced in invokedynamic instructions that use LambdaMetafactory. */
public ImmutableSet<MethodInfo> getLambdaMethodsUsedInInvokeDynamics() {
return lambdaMethodsUsedInInvokeDynamic.build();
}
@Override
public MethodVisitor visitMethod(
int access, String name, String desc, String signature, String[] exceptions) {
MethodVisitor mv = super.visitMethod(access, name, desc, signature, exceptions);
return new LambdaMethodCollector(mv);
}
@Override
public void visitOuterClass(String owner, String name, String desc) {
needOuterClassRewrite = needOuterClassRewrite || (name != null && name.startsWith("lambda$"));
super.visitOuterClass(owner, name, desc);
}
private class LambdaMethodCollector extends MethodVisitor {
public LambdaMethodCollector(MethodVisitor dest) {
super(Opcodes.ASM6, dest);
}
@Override
public void visitInvokeDynamicInsn(String name, String desc, Handle bsm, Object... bsmArgs) {
if (!"java/lang/invoke/LambdaMetafactory".equals(bsm.getOwner())) {
// Not an invokedynamic for a lambda expression
return;
}
Handle handle = (Handle) bsmArgs[1];
lambdaMethodsUsedInInvokeDynamic.add(
MethodInfo.create(handle.getOwner(), handle.getName(), handle.getDesc()));
super.visitInvokeDynamicInsn(name, desc, bsm, bsmArgs);
}
}
}
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