1   package org.apache.bcel.generic;
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  
57  import org.apache.bcel.Constants;
58  import org.apache.bcel.classfile.*;
59  import java.util.ArrayList;
60  import java.util.Iterator;
61  
62  /*** 
63   * Template class for building up a field.  The only extraordinary thing
64   * one can do is to add a constant value attribute to a field (which must of
65   * course be compatible with to the declared type).
66   *
67   * @version $Id: FieldGen.java,v 1.1.1.1 2001/10/29 20:00:12 jvanzyl Exp $
68   * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
69   * @see Field
70   */
71  public class FieldGen extends FieldGenOrMethodGen {
72    private Object value = null;
73  
74    /***
75     * Declare a field. If it is static (isStatic() == true) and has a
76     * basic type like int or String it may have an initial value
77     * associated with it as defined by setInitValue().
78     *
79     * @param access_flags access qualifiers
80     * @param type  field type
81     * @param name field name
82     * @param cp constant pool
83     */
84    public FieldGen(int access_flags, Type type, String name, ConstantPoolGen cp) {
85      setAccessFlags(access_flags);
86      setType(type);
87      setName(name);
88      setConstantPool(cp);
89    }
90  
91    /***
92     * Instantiate from existing field.
93     *
94     * @param field Field object
95     * @param cp constant pool (must contain the same entries as the field's constant pool)
96     */
97    public FieldGen(Field field, ConstantPoolGen cp) {
98      this(field.getAccessFlags(), Type.getType(field.getSignature()), field.getName(), cp);
99  
100     Attribute[] attrs = field.getAttributes();
101 
102     for(int i=0; i < attrs.length; i++) {
103       if(attrs[i] instanceof ConstantValue)
104 	setValue(((ConstantValue)attrs[i]).getConstantValueIndex());
105       else
106 	addAttribute(attrs[i]);
107     }
108   }
109 
110   private void setValue(int index) {
111     ConstantPool cp  = this.cp.getConstantPool();
112     Constant     c   = cp.getConstant(index);
113     value = ((ConstantObject)c).getConstantValue(cp);
114   }
115 
116   /***
117    * Set (optional) initial value of field, otherwise it will be set to null/0/false
118    * by the JVM automatically.
119    */
120   public void setInitValue(String str) {
121     checkType(new ObjectType("java.lang.String"));
122 
123     if(str != null)
124       value = str;
125   }
126 
127   public void setInitValue(long l) {
128     checkType(Type.LONG);
129 
130     if(l != 0L)
131       value = new Long(l);
132   }
133 
134   public void setInitValue(int i) {
135     checkType(Type.INT);
136 
137     if(i != 0)
138       value = new Integer(i);
139   }
140 
141   public void setInitValue(short s) {
142     checkType(Type.SHORT);
143 
144     if(s != 0)
145       value = new Integer(s);
146   }
147 
148   public void setInitValue(char c) {
149     checkType(Type.CHAR);
150 
151     if(c != 0)
152       value = new Integer(c);
153   }
154 
155   public void setInitValue(byte b) {
156     checkType(Type.BYTE);
157 
158     if(b != 0)
159       value = new Integer(b);
160   }
161 
162   public void setInitValue(boolean b) {
163     checkType(Type.BOOLEAN);
164 
165     if(b)
166       value = new Integer(1);
167   }
168 
169   public void setInitValue(float f) {
170     checkType(Type.FLOAT);
171 
172     if(f != 0.0)
173       value = new Float(f);
174   }
175 
176   public void setInitValue(double d) {
177     checkType(Type.DOUBLE);
178 
179     if(d != 0.0)
180       value = new Double(d);
181   }
182 
183   /*** Remove any initial value.
184    */
185   public void cancelInitValue() {
186     value = null;
187   }
188 
189   private void checkType(Type atype) {
190     if(type == null)
191       throw new ClassGenException("You haven't defined the type of the field yet");
192     
193     if(!isFinal())
194       throw new ClassGenException("Only final fields may have an initial value!");
195 
196     if(!type.equals(atype))
197       throw new ClassGenException("Types are not compatible: " + type + " vs. " + atype);
198   }
199 
200   /***
201    * Get field object after having set up all necessary values.
202    */
203   public Field getField() {
204     String      signature       = getSignature();
205     int         name_index      = cp.addUtf8(name);
206     int         signature_index = cp.addUtf8(signature);
207 
208     if(value != null) {
209       checkType(type);
210       int index = addConstant();
211       addAttribute(new ConstantValue(cp.addUtf8("ConstantValue"),
212 				     2, index, cp.getConstantPool()));
213     }
214 
215     return new Field(access_flags, name_index, signature_index, getAttributes(),
216 		     cp.getConstantPool());
217   }
218 
219   private int addConstant() {
220     switch(type.getType()) {
221     case Constants.T_INT: case Constants.T_CHAR: case Constants.T_BYTE:
222     case Constants.T_BOOLEAN: case Constants.T_SHORT:
223       return cp.addInteger(((Integer)value).intValue());
224       
225     case Constants.T_FLOAT:
226       return cp.addFloat(((Float)value).floatValue());
227 
228     case Constants.T_DOUBLE:
229       return cp.addDouble(((Double)value).doubleValue());
230 
231     case Constants.T_LONG:
232       return cp.addLong(((Long)value).longValue());
233 
234     case Constants.T_REFERENCE:
235       return cp.addString(((String)value));
236 
237     default:
238       throw new RuntimeException("Oops: Unhandled : " + type.getType());
239     }
240   }
241 
242   public String  getSignature()  { return type.getSignature(); }
243 
244   private ArrayList observers;
245 
246   /*** Add observer for this object.
247    */
248   public void addObserver(FieldObserver o) {
249     if(observers == null)
250       observers = new ArrayList();
251 
252     observers.add(o);
253   }
254 
255   /*** Remove observer for this object.
256    */
257   public void removeObserver(FieldObserver o) {
258     if(observers != null)
259       observers.remove(o);
260   }
261 
262   /*** Call notify() method on all observers. This method is not called
263    * automatically whenever the state has changed, but has to be
264    * called by the user after he has finished editing the object.
265    */
266   public void update() {
267     if(observers != null)
268       for(Iterator e = observers.iterator(); e.hasNext(); )
269 	((FieldObserver)e.next()).notify(this);
270   }
271 
272   public String getInitValue() {
273     if(value != null) {
274       return value.toString();
275     } else
276       return null;
277   }
278 
279   /***
280    * Return string representation close to declaration format,
281    * `public static final short MAX = 100', e.g..
282    *
283    * @return String representation of field
284    */
285   public final String toString() {
286     String name, signature, access; // Short cuts to constant pool
287 
288     access    = Utility.accessToString(access_flags);
289     access    = access.equals("")? "" : (access + " ");
290     signature = type.toString();
291     name      = getName();
292 
293     StringBuffer buf = new StringBuffer(access + signature + " " + name);
294     String value = getInitValue();
295 
296     if(value != null)
297       buf.append(" = " + value);
298 
299     return buf.toString();
300   }
301 
302   /*** @return deep copy of this field
303    */
304   public FieldGen copy(ConstantPoolGen cp) {
305     FieldGen fg = (FieldGen)clone();
306 
307     fg.setConstantPool(cp);
308     return fg;
309   }
310 }
This page was automatically generated by Maven