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Java > Open Source Codes > com > vladium > jcd > cls > Field_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: Field_info.java,v 1.1.1.1 2004/05/09 16:57:45 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 field is described by a variable-length field_info structure. The
21  * format of this structure is
22  * <PRE>
23  * field_info {
24  * u2 access_flags;
25  * u2 name_index;
26  * u2 descriptor_index;
27  * u2 attributes_count;
28  * attribute_info attributes[attributes_count];
29  * }
30  * </PRE>
31  *
32  * The value of the access_flags item is a mask of modifiers used to describe
33  * access permission to and properties of a field.<P>
34  *
35  * The value of the name_index item must be a valid index into the constant pool
36  * table. The constant pool entry at that index must be a {@link CONSTANT_Utf8_info}
37  * structure which must represent a valid Java field name stored as a simple (not
38  * fully qualified) name, that is, as a Java identifier.<P>
39  *
40  * The value of the descriptor_index item must be a valid index into the constant
41  * pool table. The constant pool entry at that index must be a
42  * {@link CONSTANT_Utf8_info} structure which must represent a valid Java field
43  * descriptor.<P>
44  *
45  * Each value of the attributes table must be a variable-length attribute structure.
46  * A field can have any number of attributes associated with it. The only attribute
47  * defined for the attributes table of a field_info structure at the moment
48  * is the ConstantValue attribute -- see {@link ConstantValueAttribute_info}.
49  *
50  * @author (C) 2001, Vlad Roubtsov
51  */
52 public
53 final class Field_info implements Cloneable JavaDoc, IAccessFlags
54 {
55     // public: ................................................................
56
57     
58     public int m_name_index;
59     public int m_descriptor_index;
60     
61     
62     public Field_info (final int access_flags,
63                        final int name_index, final int descriptor_index,
64                        final 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     public Field_info (final IConstantCollection constants,
75                        final UDataInputStream bytes)
76         throws IOException JavaDoc
77     {
78         m_access_flags = bytes.readU2 ();
79         
80         m_name_index = bytes.readU2 ();
81         m_descriptor_index = bytes.readU2 ();
82         
83         // TODO: put this logic into AttributeCollection
84 final int attributes_count = bytes.readU2 ();
85         m_attributes = ElementFactory.newAttributeCollection (attributes_count);
86         
87         for (int i = 0; i < attributes_count; i++)
88         {
89             final Attribute_info attribute_info = Attribute_info.new_Attribute_info (constants, bytes);
90             if (DEBUG) System.out.println ("\t[" + i + "] attribute: " + attribute_info);
91             
92             m_attributes.add (attribute_info);
93         }
94     }
95     
96     /**
97      * Returns the field name within the context of 'cls' class definition.
98      *
99      * @param cls class that contains this field
100      * @return field name
101      */
102     public String JavaDoc getName (final ClassDef cls)
103     {
104         return ((CONSTANT_Utf8_info) cls.getConstants ().get (m_name_index)).m_value;
105     }
106     
107     /**
108      * Returns the descriptor string for this field within the context of 'cls'
109      * class definition.
110      *
111      * @param cls class that contains this field
112      * @return field typename descriptor
113      */
114     public String JavaDoc getDescriptor (final ClassDef cls)
115     {
116         return ((CONSTANT_Utf8_info) cls.getConstants ().get (m_descriptor_index)).m_value;
117     }
118     
119     public boolean isSynthetic ()
120     {
121         return m_attributes.hasSynthetic ();
122     }
123     
124     // IAccessFlags:
125
126     public final void setAccessFlags (final int flags)
127     {
128         m_access_flags = flags;
129     }
130
131     public final int getAccessFlags ()
132     {
133         return m_access_flags;
134     }
135     
136     public IAttributeCollection getAttributes ()
137     {
138         return m_attributes;
139     }
140     
141     
142     public String JavaDoc toString ()
143     {
144         return "field_info: [modifiers: 0x" + Integer.toHexString(m_access_flags) + ", name_index = " + m_name_index + ", descriptor_index = " + m_descriptor_index + ']';
145     }
146     
147     
148     // Cloneable:
149
150     /**
151      * Performs a deep copy.
152      */
153     public Object JavaDoc clone ()
154     {
155         try
156         {
157             final Field_info _clone = (Field_info) super.clone ();
158             
159             // do deep copy:
160 _clone.m_attributes = (IAttributeCollection) m_attributes.clone ();
161             
162             return _clone;
163         }
164         catch (CloneNotSupportedException JavaDoc e)
165         {
166             throw new InternalError JavaDoc (e.toString ());
167         }
168     }
169     
170     
171     // IClassFormatOutput:
172
173     public void writeInClassFormat (final UDataOutputStream out) throws IOException JavaDoc
174     {
175         out.writeU2 (m_access_flags);
176         
177         out.writeU2 (m_name_index);
178         out.writeU2 (m_descriptor_index);
179         
180         m_attributes.writeInClassFormat (out);
181     }
182     
183     // protected: .............................................................
184
185     // package: ...............................................................
186
187     // private: ...............................................................
188
189     
190     private int m_access_flags;
191     private IAttributeCollection m_attributes; // never null
192
193     
194     private static final boolean DEBUG = false;
195     
196 } // end of class
197 // ----------------------------------------------------------------------------
198
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