| // Copyright 2017 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.base.Preconditions; |
| import org.objectweb.asm.Opcodes; |
| import org.objectweb.asm.ClassVisitor; |
| import org.objectweb.asm.Label; |
| import org.objectweb.asm.MethodVisitor; |
| |
| /** |
| * A class scanner to check whether the class has the synthetic method $closeResource(Throwable, |
| * AutoCloseable). |
| */ |
| public class CloseResourceMethodScanner extends ClassVisitor { |
| |
| private boolean hasCloseResourceMethod; |
| private String internalName; |
| private int classFileVersion; |
| |
| public CloseResourceMethodScanner() { |
| super(Opcodes.ASM9); |
| } |
| |
| @Override |
| public void visit( |
| int version, |
| int access, |
| String name, |
| String signature, |
| String superName, |
| String[] interfaces) { |
| Preconditions.checkState(internalName == null, "This scanner has been used."); |
| this.internalName = name; |
| this.classFileVersion = version; |
| super.visit(version, access, name, signature, superName, interfaces); |
| } |
| |
| public boolean hasCloseResourceMethod() { |
| return hasCloseResourceMethod; |
| } |
| |
| @Override |
| public MethodVisitor visitMethod( |
| int access, String name, String desc, String signature, String[] exceptions) { |
| if (classFileVersion <= 50) { |
| // A Java 6 or below class file should not have $closeResource method. |
| return null; |
| } |
| if (!hasCloseResourceMethod) { |
| hasCloseResourceMethod = |
| TryWithResourcesRewriter.isSyntheticCloseResourceMethod(access, name, desc); |
| } |
| return new StackMapFrameCollector(name, desc); |
| } |
| |
| private class StackMapFrameCollector extends MethodVisitor { |
| |
| private final String methodSignature; |
| private boolean hasCallToCloseResourceMethod; |
| private boolean hasJumpInstructions; |
| private boolean hasStackMapFrame; |
| |
| public StackMapFrameCollector(String name, String desc) { |
| super(Opcodes.ASM9); |
| methodSignature = internalName + '.' + name + desc; |
| } |
| |
| @Override |
| public void visitEnd() { |
| if (!hasCallToCloseResourceMethod) { |
| return; |
| } |
| if (hasJumpInstructions && !hasStackMapFrame) { |
| throw new UnsupportedOperationException( |
| "The method " |
| + methodSignature |
| + " calls $closeResource(Throwable, AutoCloseable), " |
| + "and Desugar thus needs to perform type inference for it " |
| + "to rewrite $closeResourceMethod. " |
| + "However, this method has jump instructions, but does not have stack map frames. " |
| + "Please recompile this class with stack map frames."); |
| } |
| } |
| |
| @Override |
| public void visitMethodInsn(int opcode, String owner, String name, String desc, boolean itf) { |
| if (!hasCallToCloseResourceMethod |
| && TryWithResourcesRewriter.isCallToSyntheticCloseResource( |
| internalName, opcode, owner, name, desc)) { |
| hasCallToCloseResourceMethod = true; |
| } |
| } |
| |
| @Override |
| public void visitFrame(int type, int nLocal, Object[] local, int nStack, Object[] stack) { |
| hasStackMapFrame = true; |
| } |
| |
| @Override |
| public void visitJumpInsn(int opcode, Label label) { |
| hasJumpInstructions = true; |
| } |
| } |
| } |