001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 *  Unless required by applicable law or agreed to in writing, software
012 *  distributed under the License is distributed on an "AS IS" BASIS,
013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 *  See the License for the specific language governing permissions and
015 *  limitations under the License.
016 *
017 */
018package org.apache.bcel.classfile;
019
020import java.io.DataInput;
021import java.io.IOException;
022import java.util.Objects;
023
024import org.apache.bcel.Const;
025import org.apache.bcel.generic.Type;
026import org.apache.bcel.util.BCELComparator;
027
028/**
029 * This class represents the method info structure, i.e., the representation
030 * for a method in the class. See JVM specification for details.
031 * A method has access flags, a name, a signature and a number of attributes.
032 *
033 * @version $Id$
034 */
035public final class Method extends FieldOrMethod {
036
037    private static BCELComparator bcelComparator = new BCELComparator() {
038
039        @Override
040        public boolean equals( final Object o1, final Object o2 ) {
041            final Method THIS = (Method) o1;
042            final Method THAT = (Method) o2;
043            return Objects.equals(THIS.getName(), THAT.getName())
044                    && Objects.equals(THIS.getSignature(), THAT.getSignature());
045        }
046
047
048        @Override
049        public int hashCode( final Object o ) {
050            final Method THIS = (Method) o;
051            return THIS.getSignature().hashCode() ^ THIS.getName().hashCode();
052        }
053    };
054
055    // annotations defined on the parameters of a method
056    private ParameterAnnotationEntry[] parameterAnnotationEntries;
057
058    /**
059     * Empty constructor, all attributes have to be defined via `setXXX'
060     * methods. Use at your own risk.
061     */
062    public Method() {
063    }
064
065
066    /**
067     * Initialize from another object. Note that both objects use the same
068     * references (shallow copy). Use clone() for a physical copy.
069     */
070    public Method(final Method c) {
071        super(c);
072    }
073
074
075    /**
076     * Construct object from file stream.
077     * @param file Input stream
078     * @throws IOException
079     * @throws ClassFormatException
080     */
081    Method(final DataInput file, final ConstantPool constant_pool) throws IOException,
082            ClassFormatException {
083        super(file, constant_pool);
084    }
085
086
087    /**
088     * @param access_flags Access rights of method
089     * @param name_index Points to field name in constant pool
090     * @param signature_index Points to encoded signature
091     * @param attributes Collection of attributes
092     * @param constant_pool Array of constants
093     */
094    public Method(final int access_flags, final int name_index, final int signature_index, final Attribute[] attributes,
095            final ConstantPool constant_pool) {
096        super(access_flags, name_index, signature_index, attributes, constant_pool);
097    }
098
099
100    /**
101     * Called by objects that are traversing the nodes of the tree implicitely
102     * defined by the contents of a Java class. I.e., the hierarchy of methods,
103     * fields, attributes, etc. spawns a tree of objects.
104     *
105     * @param v Visitor object
106     */
107    @Override
108    public void accept( final Visitor v ) {
109        v.visitMethod(this);
110    }
111
112
113    /**
114     * @return Code attribute of method, if any
115     */
116    public final Code getCode() {
117        for (final Attribute attribute : super.getAttributes()) {
118            if (attribute instanceof Code) {
119                return (Code) attribute;
120            }
121        }
122        return null;
123    }
124
125
126    /**
127     * @return ExceptionTable attribute of method, if any, i.e., list all
128     * exceptions the method may throw not exception handlers!
129     */
130    public final ExceptionTable getExceptionTable() {
131        for (final Attribute attribute : super.getAttributes()) {
132            if (attribute instanceof ExceptionTable) {
133                return (ExceptionTable) attribute;
134            }
135        }
136        return null;
137    }
138
139
140    /** @return LocalVariableTable of code attribute if any, i.e. the call is forwarded
141     * to the Code atribute.
142     */
143    public final LocalVariableTable getLocalVariableTable() {
144        final Code code = getCode();
145        if (code == null) {
146            return null;
147        }
148        return code.getLocalVariableTable();
149    }
150
151
152    /** @return LineNumberTable of code attribute if any, i.e. the call is forwarded
153     * to the Code atribute.
154     */
155    public final LineNumberTable getLineNumberTable() {
156        final Code code = getCode();
157        if (code == null) {
158            return null;
159        }
160        return code.getLineNumberTable();
161    }
162
163
164    /**
165     * Return string representation close to declaration format,
166     * `public static void main(String[] args) throws IOException', e.g.
167     *
168     * @return String representation of the method.
169     */
170    @Override
171    public final String toString() {
172        final String access = Utility.accessToString(super.getAccessFlags());
173        // Get name and signature from constant pool
174        ConstantUtf8 c = (ConstantUtf8) super.getConstantPool().getConstant(super.getSignatureIndex(), Const.CONSTANT_Utf8);
175        String signature = c.getBytes();
176        c = (ConstantUtf8) super.getConstantPool().getConstant(super.getNameIndex(), Const.CONSTANT_Utf8);
177        final String name = c.getBytes();
178        signature = Utility.methodSignatureToString(signature, name, access, true,
179                getLocalVariableTable());
180        final StringBuilder buf = new StringBuilder(signature);
181        for (final Attribute attribute : super.getAttributes()) {
182            if (!((attribute instanceof Code) || (attribute instanceof ExceptionTable))) {
183                buf.append(" [").append(attribute).append("]");
184            }
185        }
186        final ExceptionTable e = getExceptionTable();
187        if (e != null) {
188            final String str = e.toString();
189            if (!str.isEmpty()) {
190                buf.append("\n\t\tthrows ").append(str);
191            }
192        }
193        return buf.toString();
194    }
195
196
197    /**
198     * @return deep copy of this method
199     */
200    public final Method copy( final ConstantPool _constant_pool ) {
201        return (Method) copy_(_constant_pool);
202    }
203
204
205    /**
206     * @return return type of method
207     */
208    public Type getReturnType() {
209        return Type.getReturnType(getSignature());
210    }
211
212
213    /**
214     * @return array of method argument types
215     */
216    public Type[] getArgumentTypes() {
217        return Type.getArgumentTypes(getSignature());
218    }
219
220
221    /**
222     * @return Comparison strategy object
223     */
224    public static BCELComparator getComparator() {
225        return bcelComparator;
226    }
227
228
229    /**
230     * @param comparator Comparison strategy object
231     */
232    public static void setComparator( final BCELComparator comparator ) {
233        bcelComparator = comparator;
234    }
235
236
237    /**
238     * Return value as defined by given BCELComparator strategy.
239     * By default two method objects are said to be equal when
240     * their names and signatures are equal.
241     *
242     * @see java.lang.Object#equals(java.lang.Object)
243     */
244    @Override
245    public boolean equals( final Object obj ) {
246        return bcelComparator.equals(this, obj);
247    }
248
249
250    /**
251     * Return value as defined by given BCELComparator strategy.
252     * By default return the hashcode of the method's name XOR signature.
253     *
254     * @see java.lang.Object#hashCode()
255     */
256    @Override
257    public int hashCode() {
258        return bcelComparator.hashCode(this);
259    }
260
261    /**
262     * @return Annotations on the parameters of a method
263     * @since 6.0
264     */
265    public ParameterAnnotationEntry[] getParameterAnnotationEntries() {
266        if (parameterAnnotationEntries == null) {
267            parameterAnnotationEntries = ParameterAnnotationEntry.createParameterAnnotationEntries(getAttributes());
268        }
269        return parameterAnnotationEntries;
270    }
271}