aboutsummaryrefslogtreecommitdiffstats
path: root/src/main/javassist/CtNewMethod.java
blob: defafcf692e8db7a1786c231ba1a02b3a28d3cee (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
/*
 * Javassist, a Java-bytecode translator toolkit.
 * Copyright (C) 1999-2003 Shigeru Chiba. All Rights Reserved.
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License.  Alternatively, the contents of this file may be used under
 * the terms of the GNU Lesser General Public License Version 2.1 or later.
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 */

package javassist;

import javassist.bytecode.*;
import javassist.compiler.Javac;
import javassist.compiler.CompileError;
import javassist.CtMethod.ConstParameter;

/**
 * A collection of static methods for creating a <code>CtMethod</code>.
 * An instance of this class does not make any sense.
 *
 * @see CtClass#addMethod(CtMethod)
 */
public class CtNewMethod {

    /**
     * Compiles the given source code and creates a method.
     * The source code must include not only the method body
     * but the whole declaration, for example,
     *
     * <ul><pre>"public Object id(Object obj) { return obj; }"</pre></ul>
     *
     * @param src               the source text. 
     * @param declaring    the class to which the created method is added.
     */
    public static CtMethod make(String src, CtClass declaring)
        throws CannotCompileException
    {
        return make(src, declaring, null, null);
    }

    /**
     * Compiles the given source code and creates a method.
     * The source code must include not only the method body
     * but the whole declaration, for example,
     *
     * <ul><pre>"public Object id(Object obj) { return obj; }"</pre></ul>
     *
     * <p>If the source code includes <code>$proceed()</code>, then
     * it is compiled into a method call on the specified object.
     *
     * @param src               the source text. 
     * @param declaring    the class to which the created method is added.
     * @param delegateObj       the source text specifying the object
     *                          that is called on by <code>$proceed()</code>.
     * @param delegateMethod    the name of the method
     *                          that is called by <code>$proceed()</code>.
     */
    public static CtMethod make(String src, CtClass declaring,
                                String delegateObj, String delegateMethod)
        throws CannotCompileException
    {
        Javac compiler = new Javac(declaring);
        try {
            if (delegateMethod != null)
                compiler.recordProceed(delegateObj, delegateMethod);

            CtMember obj = compiler.compile(src);
            if (obj instanceof CtMethod)
                return (CtMethod)obj;
        }
        catch (CompileError e) {
            throw new CannotCompileException(e);
        }

        throw new CannotCompileException("not a method");
    }

    /**
     * Creates a public method.
     *
     * @param returnType        the type of the returned value.
     * @param mname             the method name.
     * @param parameters        a list of the parameter types.
     * @param exceptions        a list of the exception types.
     * @param body              the source text of the method body.
     *                  It must be a block surrounded by <code>{}</code>.
     *                  If it is <code>null</code>, the created method
     *                  does nothing except returning zero or null.
     * @param declaring    the class to which the created method is added.
     */
    public static CtMethod make(CtClass returnType, String mname,
                                CtClass[] parameters, CtClass[] exceptions,
                                String body, CtClass declaring)
        throws CannotCompileException
    {
        try {
            CtMethod cm
                = new CtMethod(returnType, mname, parameters, declaring);
            cm.setExceptionTypes(exceptions);
            cm.setBody(body);
            return cm;
        }
        catch (NotFoundException e) {
            throw new CannotCompileException(e);
        }
    }

    /**
     * Creates a copy of a method.  This method is provided for creating
     * a new method based on an existing method.
     *
     * @param src       the source method.
     * @param declaring    the class to which the created method is added.
     * @param map       the hashtable associating original class names
     *                  with substituted names.
     *                  It can be <code>null</code>.
     *
     * @see CtMethod#CtMethod(CtMethod,CtClass,ClassMap)
     */
    public static CtMethod copy(CtMethod src, CtClass declaring,
                                ClassMap map) throws CannotCompileException {
        return new CtMethod(src, declaring, map);
    }

    /**
     * Creates a copy of a method with a new name.
     * This method is provided for creating
     * a new method based on an existing method.
     *
     * @param src       the source method.
     * @param name      the name of the created method.
     * @param declaring    the class to which the created method is added.
     * @param map       the hashtable associating original class names
     *                  with substituted names.
     *                  It can be <code>null</code>.
     *
     * @see CtMethod#CtMethod(CtMethod,CtClass,ClassMap)
     */
    public static CtMethod copy(CtMethod src, String name, CtClass declaring,
                                ClassMap map) throws CannotCompileException {
        CtMethod cm = new CtMethod(src, declaring, map);
        cm.setName(name);
        return cm;
    }

    /**
     * Creates a public abstract method.
     *
     * @param returnType        the type of the returned value
     * @param mname             the method name
     * @param parameters        a list of the parameter types
     * @param exceptions        a list of the exception types
     * @param declaring    the class to which the created method is added.
     *
     * @see CtMethod#CtMethod(CtClass,String,CtClass[],CtClass)
     */
    public static CtMethod abstractMethod(CtClass returnType,
                                          String mname,
                                          CtClass[] parameters,
                                          CtClass[] exceptions,
                                          CtClass declaring)
        throws NotFoundException
    {
        CtMethod cm = new CtMethod(returnType, mname, parameters, declaring);
        cm.setExceptionTypes(exceptions);
        return cm;
    }

    /**
     * Creates a public getter method.  The getter method returns the value
     * of the specified field in the class to which this method is added.
     * The created method is initially not static even if the field is
     * static.  Change the modifiers if the method should be static.
     *
     * @param methodName        the name of the getter
     * @param field             the field accessed.
     */
    public static CtMethod getter(String methodName, CtField field)
        throws CannotCompileException
    {
        FieldInfo finfo = field.getFieldInfo2();
        String fieldType = finfo.getDescriptor();
        String desc = "()" + fieldType;
        ConstPool cp = finfo.getConstPool();
        MethodInfo minfo = new MethodInfo(cp, methodName, desc);
        minfo.setAccessFlags(AccessFlag.PUBLIC);

        Bytecode code = new Bytecode(cp, 2, 1);
        try {
            String fieldName = finfo.getName();
            if ((finfo.getAccessFlags() & AccessFlag.STATIC) == 0) {
                code.addAload(0);
                code.addGetfield(Bytecode.THIS, fieldName, fieldType);
            }
            else
                code.addGetstatic(Bytecode.THIS, fieldName, fieldType);

            code.addReturn(field.getType());
        }
        catch (NotFoundException e) {
            throw new CannotCompileException(e);
        }

        minfo.setCodeAttribute(code.toCodeAttribute());
        return new CtMethod(minfo, field.getDeclaringClass());
    }

    /**
     * Creates a public setter method.  The setter method assigns the
     * value of the first parameter to the specified field
     * in the class to which this method is added.
     * The created method is initially not static even if the field is
     * static.  Change the modifiers if the method should be static.
     *
     * @param methodName        the name of the setter
     * @param field             the field accessed.
     */
    public static CtMethod setter(String methodName, CtField field)
        throws CannotCompileException
    {
        FieldInfo finfo = field.getFieldInfo2();
        String fieldType = finfo.getDescriptor();
        String desc = "(" + fieldType + ")V";
        ConstPool cp = finfo.getConstPool();
        MethodInfo minfo = new MethodInfo(cp, methodName, desc);
        minfo.setAccessFlags(AccessFlag.PUBLIC);

        Bytecode code = new Bytecode(cp, 3, 3);
        try {
            String fieldName = finfo.getName();
            if ((finfo.getAccessFlags() & AccessFlag.STATIC) == 0) {
                code.addAload(0);
                code.addLoad(1, field.getType());
                code.addPutfield(Bytecode.THIS, fieldName, fieldType);
            }
            else {
                code.addLoad(0, field.getType());
                code.addPutstatic(Bytecode.THIS, fieldName, fieldType);
            }

            code.addReturn(null);
        }
        catch (NotFoundException e) {
            throw new CannotCompileException(e);
        }

        minfo.setCodeAttribute(code.toCodeAttribute());
        return new CtMethod(minfo, field.getDeclaringClass());
    }

    /**
     * Creates a method forwarding to a delegate in
     * a super class.  The created method calls a method specified
     * by <code>delegate</code> with all the parameters passed to the
     * created method.  If the delegate method returns a value,
     * the created method returns that value to the caller.
     * The delegate method must be declared in a super class.
     *
     * <p>The following method is an example of the created method.
     *
     * <ul><pre>int f(int p, int q) {
     *     return super.f(p, q);
     * }</pre></ul>
     *
     * <p>The name of the created method can be changed by
     * <code>setName()</code>.
     *
     * @param delegate    the method that the created method forwards to.
     * @param declaring         the class to which the created method is
     *                          added.
     */
    public static CtMethod delegator(CtMethod delegate, CtClass declaring)
        throws CannotCompileException
    {
        try {
            return delegator0(delegate, declaring);
        }
        catch (NotFoundException e) {
            throw new CannotCompileException(e);
        }
    }

    private static CtMethod delegator0(CtMethod delegate, CtClass declaring)
        throws CannotCompileException, NotFoundException
    {
        MethodInfo deleInfo = delegate.getMethodInfo2();
        String methodName = deleInfo.getName();
        String desc = deleInfo.getDescriptor();
        ConstPool cp = declaring.getClassFile2().getConstPool();
        MethodInfo minfo = new MethodInfo(cp, methodName, desc);
        minfo.setAccessFlags(deleInfo.getAccessFlags());

        ExceptionsAttribute eattr = deleInfo.getExceptionsAttribute();
        if (eattr != null)
            minfo.setExceptionsAttribute(
                                (ExceptionsAttribute)eattr.copy(cp, null));

        Bytecode code = new Bytecode(cp, 0, 0);
        boolean isStatic = Modifier.isStatic(delegate.getModifiers());
        CtClass deleClass = delegate.getDeclaringClass();
        CtClass[] params = delegate.getParameterTypes();
        int s;
        if (isStatic) {
            s = code.addLoadParameters(params, 0);
            code.addInvokestatic(deleClass, methodName, desc);
        }
        else {
            code.addLoad(0, deleClass);
            s = code.addLoadParameters(params, 1);
            code.addInvokespecial(deleClass, methodName, desc);
        }

        code.addReturn(delegate.getReturnType());
        code.setMaxLocals(++s);
        code.setMaxStack(s < 2 ? 2 : s); // for a 2-word return value
        minfo.setCodeAttribute(code.toCodeAttribute());
        return new CtMethod(minfo, declaring);
    }

    /**
     * Creates a wrapped method.  The wrapped method receives parameters
     * in the form of an array of <code>Object</code>.
     *
     * <p>The body of the created method is a copy of the body of a method
     * specified by <code>body</code>.  However, it is wrapped in
     * parameter-conversion code.
     *
     * <p>The method specified by <code>body</code> must have this singature:
     *
     * <ul><code>Object method(Object[] params, &lt;type&gt; cvalue)
     * </code></ul>
     *
     * <p>The type of the <code>cvalue</code> depends on
     * <code>constParam</code>.
     * If <code>constParam</code> is <code>null</code>, the signature
     * must be:
     *
     * <ul><code>Object method(Object[] params)</code></ul>
     *
     * <p>The method body copied from <code>body</code> is wrapped in
     * parameter-conversion code, which converts parameters specified by
     * <code>parameterTypes</code> into an array of <code>Object</code>.
     * The returned value is also converted from the <code>Object</code>
     * type to the type specified by <code>returnType</code>.  Thus,
     * the resulting method body is as follows:
     *
     * <ul><pre>Object[] params = new Object[] { p0, p1, ... };
     * &lt;<i>type</i>&gt; cvalue = &lt;<i>constant-value</i>&gt;;
     *  <i>... copied method body ...</i>
     * Object result = &lt;<i>returned value</i>&gt;
     * return (<i>&lt;returnType&gt;</i>)result;
     * </pre></ul>
     *
     * <p>The variables <code>p0</code>, <code>p2</code>, ... represent
     * formal parameters of the created method.
     * The value of <code>cvalue</code> is specified by
     * <code>constParam</code>.
     *
     * <p>If the type of a parameter or a returned value is a primitive
     * type, then the value is converted into a wrapper object such as
     * <code>java.lang.Integer</code>.  If the type of the returned value
     * is <code>void</code>, the returned value is discarded.
     *
     * <p><i>Example:</i>
     *
     * <ul><pre>ClassPool pool = ... ;
     * CtClass vec = pool.makeClass("intVector");
     * vec.setSuperclass(pool.get("java.util.Vector"));
     * CtMethod addMethod = pool.getMethod("Sample", "add0");
     *
     * CtClass[] argTypes = { CtClass.intType };
     * CtMethod m = CtNewMethod.wrapped(CtClass.voidType, "add", argTypes,
     *                                  null, addMethod, null, vec);
     * vec.addMethod(m);</pre></ul>
     *
     * <p>where the class <code>Sample</code> is as follows:
     *
     * <ul><pre>public class Sample extends java.util.Vector {
     *     public Object add0(Object[] args) {
     *         super.addElement(args[0]);
     *         return null;
     *     }
     * }</pre></ul>
     *
     * <p>This program produces a class <code>intVector</code>:
     *
     * <ul><pre>public class intVector extends java.util.Vector {
     *     public void add(int p0) {
     *         Object[] args = new Object[] { p0 };
     *         // begin of copied body
     *         super.addElement(args[0]);
     *         Object result = null;
     *         // end
     *     }
     * }</pre></ul>
     *
     * <p>Note that the type of the parameter to <code>add()</code> depends
     * only on the value of <code>argTypes</code> passed to
     * <code>CtNewMethod.wrapped()</code>.  Thus, it is easy to
     * modify this program to produce a
     * <code>StringVector</code> class, which is a vector containing
     * only <code>String</code> objects, and other vector classes.
     *
     * @param returnType        the type of the returned value.
     * @param mname             the method name.
     * @param parameters        a list of the parameter types.
     * @param exceptions        a list of the exception types.
     * @param body              the method body
     *                          (must not be a static method).
     * @param constParam        the constant parameter
     *                          (maybe <code>null</code>).
     * @param declaring         the class to which the created method is
     *                          added.
     */
    public static CtMethod wrapped(CtClass returnType,
                                   String mname,
                                   CtClass[] parameterTypes,
                                   CtClass[] exceptionTypes,
                                   CtMethod body, ConstParameter constParam,
                                   CtClass declaring)
        throws CannotCompileException
    {
        return CtNewWrappedMethod.wrapped(returnType, mname, parameterTypes,
                        exceptionTypes, body, constParam, declaring);
    }
}