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Java > Open Source Codes > com > vladium > jcd > cls > Method_info


1 /* Copyright (C) 2003 Vladimir Roubtsov. All rights reserved.
2  *
3  * This program and the accompanying materials are made available under
4  * the terms of the Common Public License v1.0 which accompanies this distribution,
5  * and is available at http://www.eclipse.org/legal/cpl-v10.html
6  *
7  * $Id: Method_info.java,v 1.1.1.1 2004/05/09 16:57:47 vlad_r Exp $
8  */
9 package com.vladium.jcd.cls;
10
11 import java.io.IOException JavaDoc;
12
13 import com.vladium.jcd.cls.attribute.*;
14 import com.vladium.jcd.cls.constant.CONSTANT_Utf8_info;
15 import com.vladium.jcd.lib.UDataInputStream;
16 import com.vladium.jcd.lib.UDataOutputStream;
17
18 // ----------------------------------------------------------------------------
19 /**
20  * Each class method, and each instance initialization method <init>, is described
21  * by a variable-length method_info structure. The structure has the following
22  * format:
23  * <PRE>
24  * method_info {
25  * u2 access_flags;
26  * u2 name_index;
27  * u2 descriptor_index;
28  * u2 attributes_count;
29  * attribute_info attributes[attributes_count];
30  * }
31  * </PRE>
32  *
33  * The value of the access_flags item is a mask of modifiers used to describe
34  * access permission to and properties of a method or instance initialization method.<P>
35  *
36  * The value of the name_index item must be a valid index into the constant pool
37  * table. The constant pool entry at that index must be a {@link CONSTANT_Utf8_info}
38  * structure representing either one of the special internal method names, either
39  * &lt;init&gt; or &lt;clinit&gt;, or a valid Java method name, stored as a simple
40  * (not fully qualified) name.<P>
41  *
42  * The value of the descriptor_index item must be a valid index into the constant pool
43  * table. The constant pool entry at that index must be a {@link CONSTANT_Utf8_info}
44  * structure representing a valid Java method descriptor.<P>
45  *
46  * Each value of the attributes table must be a variable-length attribute structure.
47  * A method can have any number of optional attributes associated with it. The only
48  * attributes defined by this specification for the attributes table of a method_info
49  * structure are the Code and Exceptions attributes. See {@link CodeAttribute_info}
50  * and {@link ExceptionsAttribute_info}.
51  *
52  * @author (C) 2001, Vlad Roubtsov
53  */
54 public
55 final class Method_info implements Cloneable JavaDoc, IAccessFlags
56 {
57     // public: ................................................................
58
59     
60     public int m_name_index;
61     public int m_descriptor_index;
62     
63     
64     public Method_info (int access_flags, int name_index, int descriptor_index, IAttributeCollection attributes)
65     {
66         m_access_flags = access_flags;
67         
68         m_name_index = name_index;
69         m_descriptor_index = descriptor_index;
70         
71         m_attributes = attributes;
72     }
73
74
75     public Method_info (final IConstantCollection constants,
76                         final UDataInputStream bytes)
77         throws IOException JavaDoc
78     {
79         m_access_flags = bytes.readU2 ();
80         
81         m_name_index = bytes.readU2 ();
82         m_descriptor_index = bytes.readU2 ();
83         
84         // TODO: put this logic into AttributeCollection
85
86         final int attributes_count = bytes.readU2 ();
87         m_attributes = ElementFactory.newAttributeCollection (attributes_count);
88         
89         for (int i = 0; i < attributes_count; ++ i)
90         {
91             final Attribute_info attribute_info = Attribute_info.new_Attribute_info (constants, bytes);
92             
93             m_attributes.add (attribute_info);
94         }
95     }
96    
97     /**
98      * Returns the method name within the context of 'cls' class definition.
99      *
100      * @param cls class that contains this method
101      * @return method name
102      */
103     public String JavaDoc getName (final ClassDef cls)
104     {
105         return ((CONSTANT_Utf8_info) cls.getConstants ().get (m_name_index)).m_value;
106     }
107     
108     /**
109      * Returns the descriptor string for this method within the context of 'cls'
110      * class definition.
111      *
112      * @param cls class that contains this method
113      * @return field typename descriptor
114      */
115     public String JavaDoc getDescriptor (final ClassDef cls)
116     {
117         return ((CONSTANT_Utf8_info) cls.getConstants ().get (m_descriptor_index)).m_value;
118     }
119     
120     public boolean isNative ()
121     {
122         return (m_access_flags & ACC_NATIVE) != 0;
123     }
124     
125     public boolean isAbstract ()
126     {
127         return (m_access_flags & ACC_ABSTRACT) != 0;
128     }
129     
130     public boolean isSynthetic ()
131     {
132         return m_attributes.hasSynthetic ();
133     }
134     
135     public boolean isBridge ()
136     {
137         return ((m_access_flags & ACC_BRIDGE) != 0) || m_attributes.hasBridge ();
138     }
139     
140     // IAccessFlags:
141
142     public final void setAccessFlags (final int flags)
143     {
144         m_access_flags = flags;
145     }
146
147     public final int getAccessFlags ()
148     {
149         return m_access_flags;
150     }
151     
152     
153     public IAttributeCollection getAttributes ()
154     {
155         return m_attributes;
156     }
157     
158     
159     public String JavaDoc toString ()
160     {
161         StringBuffer JavaDoc s = new StringBuffer JavaDoc ();
162         
163         s.append ("method_info: [modifiers: 0x" + Integer.toHexString(m_access_flags) + ", name_index = " + m_name_index + ", descriptor_index = " + m_descriptor_index + "]\n");
164         for (int i = 0; i < m_attributes.size (); i++)
165         {
166             Attribute_info attribute_info = m_attributes.get (i);
167             
168             s.append ("\t[" + i + "] attribute: " + attribute_info + "\n");
169         }
170
171         return s.toString ();
172     }
173     
174     
175     // Cloneable:
176
177     /**
178      * Performs a deep copy.
179      */
180     public Object JavaDoc clone ()
181     {
182         try
183         {
184             final Method_info _clone = (Method_info) super.clone ();
185             
186             // do deep copy:
187 _clone.m_attributes = (IAttributeCollection) m_attributes.clone ();
188             
189             return _clone;
190         }
191         catch (CloneNotSupportedException JavaDoc e)
192         {
193             throw new InternalError JavaDoc (e.toString ());
194         }
195     }
196     
197     // IClassFormatOutput:
198
199     public void writeInClassFormat (final UDataOutputStream out) throws IOException JavaDoc
200     {
201         out.writeU2 (m_access_flags);
202         
203         out.writeU2 (m_name_index);
204         out.writeU2 (m_descriptor_index);
205         
206         m_attributes.writeInClassFormat (out);
207     }
208     
209     // protected: .............................................................
210
211     // package: ...............................................................
212
213     // private: ...............................................................
214
215     
216     private int m_access_flags;
217     private IAttributeCollection m_attributes;
218
219 } // end of class
220 // ----------------------------------------------------------------------------
221
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