StubMethodAdapter.java revision b798689749c64baba81f02e10cf2157c747d6b46 
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.AnnotationVisitor;
20import org.objectweb.asm.Attribute;
21import org.objectweb.asm.Label;
22import org.objectweb.asm.MethodVisitor;
23import org.objectweb.asm.Opcodes;
24import org.objectweb.asm.Type;
25
26/**
27 * This method adapter rewrites a method by discarding the original code and generating
28 * a stub depending on the return type. Original annotations are passed along unchanged.
29 */
30class StubMethodAdapter implements MethodVisitor {
31
32    private static String CONSTRUCTOR = "<init>";
33    private static String CLASS_INIT = "<clinit>";
34
35    /** The parent method writer */
36    private MethodVisitor mParentVisitor;
37    /** The method return type. Can be null. */
38    private Type mReturnType;
39    /** Message to be printed by stub methods. */
40    private String mInvokeSignature;
41    /** Flag to output the first line number. */
42    private boolean mOutputFirstLineNumber = true;
43    /** Flag that is true when implementing a constructor, to accept all original
44     *  code calling the original super constructor. */
45    private boolean mIsInitMethod = false;
46
47    private boolean mMessageGenerated;
48    private final boolean mIsStatic;
49    private final boolean mIsNative;
50
51    public StubMethodAdapter(MethodVisitor mv, String methodName, Type returnType,
52            String invokeSignature, boolean isStatic, boolean isNative) {
53        mParentVisitor = mv;
54        mReturnType = returnType;
55        mInvokeSignature = invokeSignature;
56        mIsStatic = isStatic;
57        mIsNative = isNative;
58
59        if (CONSTRUCTOR.equals(methodName) || CLASS_INIT.equals(methodName)) {
60            mIsInitMethod = true;
61        }
62    }
63
64    private void generateInvoke() {
65        /* Generates the code:
66         *  OverrideMethod.invoke("signature", mIsNative ? true : false, null or this);
67         */
68        mParentVisitor.visitLdcInsn(mInvokeSignature);
69        // push true or false
70        mParentVisitor.visitInsn(mIsNative ? Opcodes.ICONST_1 : Opcodes.ICONST_0);
71        // push null or this
72        if (mIsStatic) {
73            mParentVisitor.visitInsn(Opcodes.ACONST_NULL);
74        } else {
75            mParentVisitor.visitVarInsn(Opcodes.ALOAD, 0);
76        }
77
78        int sort = mReturnType != null ? mReturnType.getSort() : Type.VOID;
79        switch(sort) {
80        case Type.VOID:
81            mParentVisitor.visitMethodInsn(Opcodes.INVOKESTATIC,
82                    "com/android/tools/layoutlib/create/OverrideMethod",
83                    "invokeV",
84                    "(Ljava/lang/String;ZLjava/lang/Object;)V");
85            mParentVisitor.visitInsn(Opcodes.RETURN);
86            break;
87        case Type.BOOLEAN:
88        case Type.CHAR:
89        case Type.BYTE:
90        case Type.SHORT:
91        case Type.INT:
92            mParentVisitor.visitMethodInsn(Opcodes.INVOKESTATIC,
93                    "com/android/tools/layoutlib/create/OverrideMethod",
94                    "invokeI",
95                    "(Ljava/lang/String;ZLjava/lang/Object;)I");
96            switch(sort) {
97            case Type.BOOLEAN:
98                Label l1 = new Label();
99                mParentVisitor.visitJumpInsn(Opcodes.IFEQ, l1);
100                mParentVisitor.visitInsn(Opcodes.ICONST_1);
101                mParentVisitor.visitInsn(Opcodes.IRETURN);
102                mParentVisitor.visitLabel(l1);
103                mParentVisitor.visitInsn(Opcodes.ICONST_0);
104                break;
105            case Type.CHAR:
106                mParentVisitor.visitInsn(Opcodes.I2C);
107                break;
108            case Type.BYTE:
109                mParentVisitor.visitInsn(Opcodes.I2B);
110                break;
111            case Type.SHORT:
112                mParentVisitor.visitInsn(Opcodes.I2S);
113                break;
114            }
115            mParentVisitor.visitInsn(Opcodes.IRETURN);
116            break;
117        case Type.LONG:
118            mParentVisitor.visitMethodInsn(Opcodes.INVOKESTATIC,
119                    "com/android/tools/layoutlib/create/OverrideMethod",
120                    "invokeL",
121                    "(Ljava/lang/String;ZLjava/lang/Object;)J");
122            mParentVisitor.visitInsn(Opcodes.LRETURN);
123            break;
124        case Type.FLOAT:
125            mParentVisitor.visitMethodInsn(Opcodes.INVOKESTATIC,
126                    "com/android/tools/layoutlib/create/OverrideMethod",
127                    "invokeF",
128                    "(Ljava/lang/String;ZLjava/lang/Object;)F");
129            mParentVisitor.visitInsn(Opcodes.FRETURN);
130            break;
131        case Type.DOUBLE:
132            mParentVisitor.visitMethodInsn(Opcodes.INVOKESTATIC,
133                    "com/android/tools/layoutlib/create/OverrideMethod",
134                    "invokeD",
135                    "(Ljava/lang/String;ZLjava/lang/Object;)D");
136            mParentVisitor.visitInsn(Opcodes.DRETURN);
137            break;
138        case Type.ARRAY:
139        case Type.OBJECT:
140            mParentVisitor.visitMethodInsn(Opcodes.INVOKESTATIC,
141                    "com/android/tools/layoutlib/create/OverrideMethod",
142                    "invokeA",
143                    "(Ljava/lang/String;ZLjava/lang/Object;)Ljava/lang/Object;");
144            mParentVisitor.visitTypeInsn(Opcodes.CHECKCAST, mReturnType.getInternalName());
145            mParentVisitor.visitInsn(Opcodes.ARETURN);
146            break;
147        }
148
149    }
150
151    private void generatePop() {
152        /* Pops the stack, depending on the return type.
153         */
154        switch(mReturnType != null ? mReturnType.getSort() : Type.VOID) {
155        case Type.VOID:
156            break;
157        case Type.BOOLEAN:
158        case Type.CHAR:
159        case Type.BYTE:
160        case Type.SHORT:
161        case Type.INT:
162        case Type.FLOAT:
163        case Type.ARRAY:
164        case Type.OBJECT:
165            mParentVisitor.visitInsn(Opcodes.POP);
166            break;
167        case Type.LONG:
168        case Type.DOUBLE:
169            mParentVisitor.visitInsn(Opcodes.POP2);
170            break;
171        }
172    }
173
174    /* Pass down to visitor writer. In this implementation, either do nothing. */
175    public void visitCode() {
176        mParentVisitor.visitCode();
177    }
178
179    /*
180     * visitMaxs is called just before visitEnd if there was any code to rewrite.
181     * For non-constructor, generate the messaging code and the return statement
182     * if it hasn't been done before.
183     */
184    public void visitMaxs(int maxStack, int maxLocals) {
185        if (!mIsInitMethod && !mMessageGenerated) {
186            generateInvoke();
187            mMessageGenerated = true;
188        }
189        mParentVisitor.visitMaxs(maxStack, maxLocals);
190    }
191
192    /**
193     * End of visiting.
194     * For non-constructor, generate the messaging code and the return statement
195     * if it hasn't been done before.
196     */
197    public void visitEnd() {
198        if (!mIsInitMethod && !mMessageGenerated) {
199            generateInvoke();
200            mMessageGenerated = true;
201            mParentVisitor.visitMaxs(1, 1);
202        }
203        mParentVisitor.visitEnd();
204    }
205
206    /* Writes all annotation from the original method. */
207    public AnnotationVisitor visitAnnotation(String desc, boolean visible) {
208        return mParentVisitor.visitAnnotation(desc, visible);
209    }
210
211    /* Writes all annotation default values from the original method. */
212    public AnnotationVisitor visitAnnotationDefault() {
213        return mParentVisitor.visitAnnotationDefault();
214    }
215
216    public AnnotationVisitor visitParameterAnnotation(int parameter, String desc,
217            boolean visible) {
218        return mParentVisitor.visitParameterAnnotation(parameter, desc, visible);
219    }
220
221    /* Writes all attributes from the original method. */
222    public void visitAttribute(Attribute attr) {
223        mParentVisitor.visitAttribute(attr);
224    }
225
226    /*
227     * Only writes the first line number present in the original code so that source
228     * viewers can direct to the correct method, even if the content doesn't match.
229     */
230    public void visitLineNumber(int line, Label start) {
231        if (mIsInitMethod || mOutputFirstLineNumber) {
232            mParentVisitor.visitLineNumber(line, start);
233            mOutputFirstLineNumber = false;
234        }
235    }
236
237    /**
238     * For non-constructor, rewrite existing "return" instructions to write the message.
239     */
240    public void visitInsn(int opcode) {
241        if (mIsInitMethod) {
242            switch (opcode) {
243            case Opcodes.RETURN:
244            case Opcodes.ARETURN:
245            case Opcodes.DRETURN:
246            case Opcodes.FRETURN:
247            case Opcodes.IRETURN:
248            case Opcodes.LRETURN:
249                // Pop the last word from the stack since invoke will generate its own return.
250                generatePop();
251                generateInvoke();
252                mMessageGenerated = true;
253            default:
254                mParentVisitor.visitInsn(opcode);
255            }
256        }
257    }
258
259    public void visitLabel(Label label) {
260        if (mIsInitMethod) {
261            mParentVisitor.visitLabel(label);
262        }
263    }
264
265    public void visitTryCatchBlock(Label start, Label end, Label handler, String type) {
266        if (mIsInitMethod) {
267            mParentVisitor.visitTryCatchBlock(start, end, handler, type);
268        }
269    }
270
271    public void visitMethodInsn(int opcode, String owner, String name, String desc) {
272        if (mIsInitMethod) {
273            mParentVisitor.visitMethodInsn(opcode, owner, name, desc);
274        }
275    }
276
277    public void visitFieldInsn(int opcode, String owner, String name, String desc) {
278        if (mIsInitMethod) {
279            mParentVisitor.visitFieldInsn(opcode, owner, name, desc);
280        }
281    }
282
283    public void visitFrame(int type, int nLocal, Object[] local, int nStack, Object[] stack) {
284        if (mIsInitMethod) {
285            mParentVisitor.visitFrame(type, nLocal, local, nStack, stack);
286        }
287    }
288
289    public void visitIincInsn(int var, int increment) {
290        if (mIsInitMethod) {
291            mParentVisitor.visitIincInsn(var, increment);
292        }
293    }
294
295    public void visitIntInsn(int opcode, int operand) {
296        if (mIsInitMethod) {
297            mParentVisitor.visitIntInsn(opcode, operand);
298        }
299    }
300
301    public void visitJumpInsn(int opcode, Label label) {
302        if (mIsInitMethod) {
303            mParentVisitor.visitJumpInsn(opcode, label);
304        }
305    }
306
307    public void visitLdcInsn(Object cst) {
308        if (mIsInitMethod) {
309            mParentVisitor.visitLdcInsn(cst);
310        }
311    }
312
313    public void visitLocalVariable(String name, String desc, String signature,
314            Label start, Label end, int index) {
315        if (mIsInitMethod) {
316            mParentVisitor.visitLocalVariable(name, desc, signature, start, end, index);
317        }
318    }
319
320    public void visitLookupSwitchInsn(Label dflt, int[] keys, Label[] labels) {
321        if (mIsInitMethod) {
322            mParentVisitor.visitLookupSwitchInsn(dflt, keys, labels);
323        }
324    }
325
326    public void visitMultiANewArrayInsn(String desc, int dims) {
327        if (mIsInitMethod) {
328            mParentVisitor.visitMultiANewArrayInsn(desc, dims);
329        }
330    }
331
332    public void visitTableSwitchInsn(int min, int max, Label dflt, Label[] labels) {
333        if (mIsInitMethod) {
334            mParentVisitor.visitTableSwitchInsn(min, max, dflt, labels);
335        }
336    }
337
338    public void visitTypeInsn(int opcode, String type) {
339        if (mIsInitMethod) {
340            mParentVisitor.visitTypeInsn(opcode, type);
341        }
342    }
343
344    public void visitVarInsn(int opcode, int var) {
345        if (mIsInitMethod) {
346            mParentVisitor.visitVarInsn(opcode, var);
347        }
348    }
349
350}
351