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    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 }

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