TransformClassAdapter.java revision 54b6cfa9a9e5b861a9930af873580d6dc20f773c 
1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.tools.layoutlib.create;
18
19import org.objectweb.asm.ClassAdapter;
20import org.objectweb.asm.ClassVisitor;
21import org.objectweb.asm.FieldVisitor;
22import org.objectweb.asm.MethodVisitor;
23import org.objectweb.asm.Opcodes;
24import org.objectweb.asm.Type;
25
26import java.util.Set;
27
28/**
29 * Class adapter that can stub some or all of the methods of the class.
30 */
31class TransformClassAdapter extends ClassAdapter {
32
33    /** True if all methods should be stubbed, false if only native ones must be stubbed. */
34    private final boolean mStubAll;
35    /** True if the class is an interface. */
36    private boolean mIsInterface;
37    private final String mClassName;
38    private final Log mLog;
39    private final Set<String> mStubMethods;
40    private Set<String> mDeleteReturns;
41
42    /**
43     * Creates a new class adapter that will stub some or all methods.
44     * @param logger
45     * @param stubMethods
46     * @param deleteReturns list of types that trigger the deletion of methods returning them.
47     * @param className The name of the class being modified
48     * @param cv The parent class writer visitor
49     * @param stubNativesOnly True if only native methods should be stubbed. False if all
50     *                        methods should be stubbed.
51     * @param hasNative True if the method has natives, in which case its access should be
52     *                  changed.
53     */
54    public TransformClassAdapter(Log logger, Set<String> stubMethods,
55            Set<String> deleteReturns, String className, ClassVisitor cv,
56            boolean stubNativesOnly, boolean hasNative) {
57        super(cv);
58        mLog = logger;
59        mStubMethods = stubMethods;
60        mClassName = className;
61        mStubAll = !stubNativesOnly;
62        mIsInterface = false;
63        mDeleteReturns = deleteReturns;
64    }
65
66    /* Visits the class header. */
67    @Override
68    public void visit(int version, int access, String name,
69            String signature, String superName, String[] interfaces) {
70
71        // This class might be being renamed.
72        name = mClassName;
73
74        // remove protected or private and set as public
75        access = access & ~(Opcodes.ACC_PRIVATE | Opcodes.ACC_PROTECTED);
76        access |= Opcodes.ACC_PUBLIC;
77        // remove final
78        access = access & ~Opcodes.ACC_FINAL;
79        // note: leave abstract classes as such
80        // don't try to implement stub for interfaces
81
82        mIsInterface = ((access & Opcodes.ACC_INTERFACE) != 0);
83        super.visit(version, access, name, signature, superName, interfaces);
84    }
85
86    /* Visits the header of an inner class. */
87    @Override
88    public void visitInnerClass(String name, String outerName, String innerName, int access) {
89        // remove protected or private and set as public
90        access = access & ~(Opcodes.ACC_PRIVATE | Opcodes.ACC_PROTECTED);
91        access |= Opcodes.ACC_PUBLIC;
92        // remove final
93        access = access & ~Opcodes.ACC_FINAL;
94        // note: leave abstract classes as such
95        // don't try to implement stub for interfaces
96
97        super.visitInnerClass(name, outerName, innerName, access);
98    }
99
100    /* Visits a method. */
101    @Override
102    public MethodVisitor visitMethod(int access, String name, String desc,
103            String signature, String[] exceptions) {
104
105        if (mDeleteReturns != null) {
106            Type t = Type.getReturnType(desc);
107            if (t.getSort() == Type.OBJECT) {
108                String returnType = t.getInternalName();
109                if (returnType != null) {
110                    if (mDeleteReturns.contains(returnType)) {
111                        return null;
112                    }
113                }
114            }
115        }
116
117        String methodSignature = mClassName.replace('/', '.') + "#" + name;
118
119        // change access to public
120        access &= ~(Opcodes.ACC_PROTECTED | Opcodes.ACC_PRIVATE);
121        access |= Opcodes.ACC_PUBLIC;
122
123        // remove final
124        access = access & ~Opcodes.ACC_FINAL;
125
126        // stub this method if they are all to be stubbed or if it is a native method
127        // and don't try to stub interfaces nor abstract non-native methods.
128        if (!mIsInterface &&
129            ((access & (Opcodes.ACC_ABSTRACT | Opcodes.ACC_NATIVE)) != Opcodes.ACC_ABSTRACT) &&
130            (mStubAll ||
131             (access & Opcodes.ACC_NATIVE) != 0) ||
132             mStubMethods.contains(methodSignature)) {
133
134            // remove abstract, final and native
135            access = access & ~(Opcodes.ACC_ABSTRACT | Opcodes.ACC_FINAL | Opcodes.ACC_NATIVE);
136
137            boolean isStatic = (access & Opcodes.ACC_STATIC) != 0;
138
139            String invokeSignature = methodSignature + desc;
140            mLog.debug("  Stub: %s", invokeSignature);
141
142            MethodVisitor mw = super.visitMethod(access, name, desc, signature, exceptions);
143            return new StubMethodAdapter(mw, name, returnType(desc), invokeSignature, isStatic);
144
145        } else {
146            mLog.debug("  Keep: %s %s", name, desc);
147            return super.visitMethod(access, name, desc, signature, exceptions);
148        }
149    }
150
151    /* Visits a field. Makes it public. */
152    @Override
153    public FieldVisitor visitField(int access, String name, String desc, String signature,
154            Object value) {
155        // change access to public
156        access &= ~(Opcodes.ACC_PROTECTED | Opcodes.ACC_PRIVATE);
157        access |= Opcodes.ACC_PUBLIC;
158
159        return super.visitField(access, name, desc, signature, value);
160    }
161
162    /**
163     * Extracts the return {@link Type} of this descriptor.
164     */
165    Type returnType(String desc) {
166        if (desc != null) {
167            try {
168                return Type.getReturnType(desc);
169            } catch (ArrayIndexOutOfBoundsException e) {
170                // ignore, not a valid type.
171            }
172        }
173        return null;
174    }
175}
176