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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 static org.objectweb.asm.Opcodes.ASM6;
import static org.objectweb.asm.Opcodes.DUP;
import static org.objectweb.asm.Opcodes.INVOKESTATIC;
import static org.objectweb.asm.Opcodes.INVOKEVIRTUAL;
import static org.objectweb.asm.Opcodes.POP;
import com.google.devtools.build.android.desugar.io.CoreLibraryRewriter;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.MethodVisitor;
/**
* This class desugars any call to Objects.requireNonNull(Object o), Objects.requireNonNull(Object
* o, String msg), and Objects.requireNonNull(Object o, Supplier msg), by replacing the call with
* o.getClass().
*/
public class ObjectsRequireNonNullMethodRewriter extends ClassVisitor {
private final CoreLibraryRewriter rewriter;
public ObjectsRequireNonNullMethodRewriter(ClassVisitor cv, CoreLibraryRewriter rewriter) {
super(ASM6, cv);
this.rewriter = rewriter;
}
@Override
public MethodVisitor visitMethod(
int access, String name, String desc, String signature, String[] exceptions) {
MethodVisitor visitor = super.cv.visitMethod(access, name, desc, signature, exceptions);
return visitor == null ? visitor : new ObjectsMethodInlinerMethodVisitor(visitor);
}
private class ObjectsMethodInlinerMethodVisitor extends MethodVisitor {
public ObjectsMethodInlinerMethodVisitor(MethodVisitor mv) {
super(ASM6, mv);
}
@Override
public void visitMethodInsn(int opcode, String owner, String name, String desc, boolean itf) {
if (opcode == INVOKESTATIC
&& rewriter.unprefix(owner).equals("java/util/Objects")
&& name.equals("requireNonNull")
&& desc.equals("(Ljava/lang/Object;)Ljava/lang/Object;")) {
// a call to Objects.requireNonNull(Object o)
// duplicate the first argument 'o', as this method returns 'o'.
super.visitInsn(DUP);
super.visitMethodInsn(
INVOKEVIRTUAL, "java/lang/Object", "getClass", "()Ljava/lang/Class;", false);
super.visitInsn(POP);
} else {
super.visitMethodInsn(opcode, owner, name, desc, itf);
}
}
}
}
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