TransformClassAdapter.java revision caed59d90db8626462baaec351e66b2a3280dc34 
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  list of method signatures to always stub out
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        if (Main.sOptions.generatePublicAccess) {
76            access = access & ~(Opcodes.ACC_PRIVATE | Opcodes.ACC_PROTECTED);
77            access |= Opcodes.ACC_PUBLIC;
78        }
79        // remove final
80        access = access & ~Opcodes.ACC_FINAL;
81        // note: leave abstract classes as such
82        // don't try to implement stub for interfaces
83
84        mIsInterface = ((access & Opcodes.ACC_INTERFACE) != 0);
85        super.visit(version, access, name, signature, superName, interfaces);
86    }
87
88    /* Visits the header of an inner class. */
89    @Override
90    public void visitInnerClass(String name, String outerName, String innerName, int access) {
91        // remove protected or private and set as public
92        if (Main.sOptions.generatePublicAccess) {
93            access = access & ~(Opcodes.ACC_PRIVATE | Opcodes.ACC_PROTECTED);
94            access |= Opcodes.ACC_PUBLIC;
95        }
96        // remove final
97        access = access & ~Opcodes.ACC_FINAL;
98        // note: leave abstract classes as such
99        // don't try to implement stub for interfaces
100
101        super.visitInnerClass(name, outerName, innerName, access);
102    }
103
104    /* Visits a method. */
105    @Override
106    public MethodVisitor visitMethod(int access, String name, String desc,
107            String signature, String[] exceptions) {
108
109        if (mDeleteReturns != null) {
110            Type t = Type.getReturnType(desc);
111            if (t.getSort() == Type.OBJECT) {
112                String returnType = t.getInternalName();
113                if (returnType != null) {
114                    if (mDeleteReturns.contains(returnType)) {
115                        return null;
116                    }
117                }
118            }
119        }
120
121        String methodSignature = mClassName.replace('/', '.') + "#" + name;
122
123        // change access to public
124        if (Main.sOptions.generatePublicAccess) {
125            access &= ~(Opcodes.ACC_PROTECTED | Opcodes.ACC_PRIVATE);
126            access |= Opcodes.ACC_PUBLIC;
127        }
128
129        // remove final
130        access = access & ~Opcodes.ACC_FINAL;
131
132        // stub this method if they are all to be stubbed or if it is a native method
133        // and don't try to stub interfaces nor abstract non-native methods.
134        if (!mIsInterface &&
135            ((access & (Opcodes.ACC_ABSTRACT | Opcodes.ACC_NATIVE)) != Opcodes.ACC_ABSTRACT) &&
136            (mStubAll ||
137             (access & Opcodes.ACC_NATIVE) != 0) ||
138             mStubMethods.contains(methodSignature)) {
139
140            boolean isStatic = (access & Opcodes.ACC_STATIC) != 0;
141            boolean isNative = (access & Opcodes.ACC_NATIVE) != 0;
142
143            // remove abstract, final and native
144            access = access & ~(Opcodes.ACC_ABSTRACT | Opcodes.ACC_FINAL | Opcodes.ACC_NATIVE);
145
146            String invokeSignature = methodSignature + desc;
147            mLog.debug("  Stub: %s (%s)", invokeSignature, isNative ? "native" : "");
148
149            MethodVisitor mw = super.visitMethod(access, name, desc, signature, exceptions);
150            return new StubMethodAdapter(mw, name, returnType(desc), invokeSignature,
151                    isStatic, isNative);
152
153        } else {
154            mLog.debug("  Keep: %s %s", name, desc);
155            return super.visitMethod(access, name, desc, signature, exceptions);
156        }
157    }
158
159    /* Visits a field. Makes it public. */
160    @Override
161    public FieldVisitor visitField(int access, String name, String desc, String signature,
162            Object value) {
163        // change access to public
164        if (Main.sOptions.generatePublicAccess) {
165            access &= ~(Opcodes.ACC_PROTECTED | Opcodes.ACC_PRIVATE);
166            access |= Opcodes.ACC_PUBLIC;
167        }
168        return super.visitField(access, name, desc, signature, value);
169    }
170
171    /**
172     * Extracts the return {@link Type} of this descriptor.
173     */
174    Type returnType(String desc) {
175        if (desc != null) {
176            try {
177                return Type.getReturnType(desc);
178            } catch (ArrayIndexOutOfBoundsException e) {
179                // ignore, not a valid type.
180            }
181        }
182        return null;
183    }
184}
185