| // Copyright 2018 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.devtools.build.android.desugar.ClassSignatureParser.ClassSignature; |
| import com.google.devtools.build.android.desugar.io.BitFlags; |
| import java.util.Collections; |
| import java.util.LinkedHashSet; |
| import org.objectweb.asm.ClassVisitor; |
| import org.objectweb.asm.Opcodes; |
| |
| /** |
| * Visitor that renames emulated interfaces and marks classes that extend emulated interfaces to |
| * also implement the renamed interfaces. {@link DefaultMethodClassFixer} makes sure the requisite |
| * methods are present in all classes implementing the renamed interface. Doing this helps with |
| * dynamic dispatch on emulated interfaces. |
| */ |
| public class EmulatedInterfaceRewriter extends ClassVisitor { |
| |
| private static final String[] EMPTY_ARRAY = new String[0]; |
| |
| private final CoreLibrarySupport support; |
| |
| public EmulatedInterfaceRewriter(ClassVisitor dest, CoreLibrarySupport support) { |
| super(Opcodes.ASM7, dest); |
| this.support = support; |
| } |
| |
| @Override |
| public void visit( |
| int version, |
| int access, |
| String name, |
| String signature, |
| String superName, |
| String[] interfaces) { |
| boolean emulated = support.isEmulatedCoreClassOrInterface(name); |
| { |
| // If signature is already broken (if it is null), we can't salvage it. Bail out. |
| ClassSignature classSignature = |
| signature != null |
| ? ClassSignatureParser.readTypeParametersForInterfaces( |
| name, signature, superName, interfaces) |
| : null; |
| |
| StringBuilder signatureAdditions = new StringBuilder(); |
| |
| // 1. see if we should implement any additional interfaces. |
| // Use LinkedHashSet to dedupe but maintain deterministic order |
| LinkedHashSet<String> newInterfaces = new LinkedHashSet<>(); |
| if (interfaces != null && interfaces.length > 0) { |
| // Make classes implementing emulated interfaces also implement the renamed interfaces we |
| // create below. This includes making the renamed interfaces extends each other as needed. |
| Collections.addAll(newInterfaces, interfaces); |
| for (int i = 0; i < interfaces.length; i++) { |
| String itf = interfaces[i]; |
| |
| if (support.isEmulatedCoreClassOrInterface(itf)) { |
| String newInterface = support.renameCoreLibrary(itf); |
| newInterfaces.add(newInterface); |
| |
| if (classSignature != null) { |
| signatureAdditions |
| .append("L") |
| .append(newInterface) |
| .append(classSignature.interfaceTypeParameters().get(i)) |
| .append(";"); |
| } |
| } |
| } |
| } |
| |
| if (!emulated) { |
| // For an immediate subclass of an emulated class, also fill in any interfaces implemented |
| // by superclasses, similar to the additional default method stubbing performed in |
| // DefaultMethodClassFixer in this situation. |
| Class<?> superclass = support.getEmulatedCoreClassOrInterface(superName); |
| while (superclass != null) { |
| for (Class<?> implemented : superclass.getInterfaces()) { |
| String itf = implemented.getName().replace('.', '/'); |
| if (support.isEmulatedCoreClassOrInterface(itf)) { |
| String newInterface = support.renameCoreLibrary(itf); |
| boolean added = newInterfaces.add(newInterface); |
| |
| // Make sure we don't generate the same signature for an interface implemented in |
| // multiple superclasses |
| if (classSignature != null && added) { |
| signatureAdditions |
| .append("L") |
| .append(newInterface) |
| // TODO(b/137073683): Handle the case where superclass has additional type |
| // parameters not used in the emulated interface. |
| .append(classSignature.superClassSignature().typeParameters()) |
| .append(";"); |
| } |
| } |
| } |
| superclass = superclass.getSuperclass(); |
| } |
| } |
| // Update implemented interfaces and signature if we did anything above |
| if (interfaces == null |
| ? !newInterfaces.isEmpty() |
| : interfaces.length != newInterfaces.size()) { |
| interfaces = newInterfaces.toArray(EMPTY_ARRAY); |
| if (signature != null) { |
| // If we had no previous interfaces but have new interfaces from the super class, which |
| // should still append this additions. Per the specification, it is valid to add these |
| // interfaces after the superclass signature. |
| signature += signatureAdditions; |
| } |
| } |
| } |
| |
| // 2. see if we need to rename this interface itself |
| if (BitFlags.isInterface(access) && emulated) { |
| name = support.renameCoreLibrary(name); |
| } |
| super.visit(version, access, name, signature, superName, interfaces); |
| } |
| } |