1   package org.apache.bcel.classfile;
2   
3   /* ====================================================================
4    * The Apache Software License, Version 1.1
5    *
6    * Copyright (c) 2001 The Apache Software Foundation.  All rights
7    * reserved.
8    *
9    * Redistribution and use in source and binary forms, with or without
10   * modification, are permitted provided that the following conditions
11   * are met:
12   *
13   * 1. Redistributions of source code must retain the above copyright
14   *    notice, this list of conditions and the following disclaimer.
15   *
16   * 2. Redistributions in binary form must reproduce the above copyright
17   *    notice, this list of conditions and the following disclaimer in
18   *    the documentation and/or other materials provided with the
19   *    distribution.
20   *
21   * 3. The end-user documentation included with the redistribution,
22   *    if any, must include the following acknowledgment:
23   *       "This product includes software developed by the
24   *        Apache Software Foundation (http://www.apache.org/)."
25   *    Alternately, this acknowledgment may appear in the software itself,
26   *    if and wherever such third-party acknowledgments normally appear.
27   *
28   * 4. The names "Apache" and "Apache Software Foundation" and
29   *    "Apache BCEL" must not be used to endorse or promote products
30   *    derived from this software without prior written permission. For
31   *    written permission, please contact apache@apache.org.
32   *
33   * 5. Products derived from this software may not be called "Apache",
34   *    "Apache BCEL", nor may "Apache" appear in their name, without
35   *    prior written permission of the Apache Software Foundation.
36   *
37   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48   * SUCH DAMAGE.
49   * ====================================================================
50   *
51   * This software consists of voluntary contributions made by many
52   * individuals on behalf of the Apache Software Foundation.  For more
53   * information on the Apache Software Foundation, please see
54   * <http://www.apache.org/>.
55   */
56  import org.apache.bcel.Constants;
57  import org.apache.bcel.generic.Type;
58  import java.io.*;
59  
60  /***
61   * This class represents the method info structure, i.e., the representation 
62   * for a method in the class. See JVM specification for details.
63   * A method has access flags, a name, a signature and a number of attributes.
64   *
65   * @version $Id: Method.java,v 1.5 2002/12/08 16:04:37 mdahm Exp $
66   * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
67   */
68  public final class Method extends FieldOrMethod {
69    /***
70     * Empty constructor, all attributes have to be defined via `setXXX'
71     * methods. Use at your own risk.
72     */
73    public Method() {}
74  
75    /***
76     * Initialize from another object. Note that both objects use the same
77     * references (shallow copy). Use clone() for a physical copy.
78     */
79    public Method(Method c) {
80      super(c);
81    }
82  
83    /***
84     * Construct object from file stream.
85     * @param file Input stream
86     * @throws IOException
87     * @throws ClassFormatException
88     */
89    Method(DataInputStream file, ConstantPool constant_pool)
90      throws IOException, ClassFormatException
91    {
92      super(file, constant_pool);
93    }
94  
95    /***
96     * @param access_flags Access rights of method
97     * @param name_index Points to field name in constant pool
98     * @param signature_index Points to encoded signature
99     * @param attributes Collection of attributes
100    * @param constant_pool Array of constants
101    */
102   public Method(int access_flags, int name_index, int signature_index,
103 		Attribute[] attributes, ConstantPool constant_pool)
104   {
105     super(access_flags, name_index, signature_index, attributes, constant_pool);
106   }
107 
108   /***
109    * Called by objects that are traversing the nodes of the tree implicitely
110    * defined by the contents of a Java class. I.e., the hierarchy of methods,
111    * fields, attributes, etc. spawns a tree of objects.
112    *
113    * @param v Visitor object
114    */
115   public void accept(Visitor v) {
116     v.visitMethod(this);
117   }
118 
119   /***
120    * @return Code attribute of method, if any
121    */   
122   public final Code getCode() {
123     for(int i=0; i < attributes_count; i++)
124       if(attributes[i] instanceof Code)
125 	return (Code)attributes[i];
126 
127     return null;
128   }
129 
130   /***
131    * @return ExceptionTable attribute of method, if any, i.e., list all
132    * exceptions the method may throw not exception handlers!
133    */
134   public final ExceptionTable getExceptionTable() {
135     for(int i=0; i < attributes_count; i++)
136       if(attributes[i] instanceof ExceptionTable)
137 	return (ExceptionTable)attributes[i];
138 
139     return null;
140   }
141 
142   /*** @return LocalVariableTable of code attribute if any, i.e. the call is forwarded
143    * to the Code atribute.
144    */
145   public final LocalVariableTable getLocalVariableTable() {
146     Code code = getCode();
147 
148     if(code != null)
149       return code.getLocalVariableTable();
150     else
151       return null;
152   }
153 
154   /*** @return LineNumberTable of code attribute if any, i.e. the call is forwarded
155    * to the Code atribute.
156    */
157   public final LineNumberTable getLineNumberTable() {
158     Code code = getCode();
159 
160     if(code != null)
161       return code.getLineNumberTable();
162     else
163       return null;
164   }
165 
166   /***
167    * Return string representation close to declaration format,
168    * `public static void main(String[] args) throws IOException', e.g.
169    *
170    * @return String representation of the method.
171    */
172   public final String toString() {
173     ConstantUtf8  c;
174     String        name, signature, access; // Short cuts to constant pool
175     StringBuffer  buf;
176 
177     access = Utility.accessToString(access_flags);
178 
179     // Get name and signature from constant pool
180     c = (ConstantUtf8)constant_pool.getConstant(signature_index, 
181 						Constants.CONSTANT_Utf8);
182     signature = c.getBytes();
183 
184     c = (ConstantUtf8)constant_pool.getConstant(name_index, Constants.CONSTANT_Utf8);
185     name = c.getBytes();
186 
187     signature = Utility.methodSignatureToString(signature, name, access, true,
188 						getLocalVariableTable());
189     buf = new StringBuffer(signature);
190 
191     for(int i=0; i < attributes_count; i++) {
192       Attribute a = attributes[i];
193 
194       if(!((a instanceof Code) || (a instanceof ExceptionTable)))
195 	buf.append(" [" + a.toString() + "]");
196     }
197 
198     ExceptionTable e = getExceptionTable();
199     if(e != null) {
200       String str = e.toString();
201       if(!str.equals(""))
202 	buf.append("\n\t\tthrows " + str);
203     }
204  
205     return buf.toString();
206   }
207 
208   /***
209    * @return deep copy of this method
210    */
211   public final Method copy(ConstantPool constant_pool) {
212     return (Method)copy_(constant_pool);
213   }
214 
215   /***
216    * @return return type of method
217    */
218   public Type getReturnType() {
219     return Type.getReturnType(getSignature());
220   }
221 
222   /***
223    * @return array of method argument types
224    */
225   public Type[] getArgumentTypes() {
226     return Type.getArgumentTypes(getSignature());
227   }
228 }
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