LocalVariable xref

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    1   /*
    2    * Copyright  2000-2004 The Apache Software Foundation
    3    *
    4    *  Licensed under the Apache License, Version 2.0 (the "License");
    5    *  you may not use this file except in compliance with the License.
    6    *  You may obtain a copy of the License at
    7    *
    8    *      http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   *  Unless required by applicable law or agreed to in writing, software
    11   *  distributed under the License is distributed on an "AS IS" BASIS,
    12   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   *  See the License for the specific language governing permissions and
    14   *  limitations under the License.
    15   *
    16   */
    17  package org.apache.bcel.classfile;
    18
    19  import java.io.DataInputStream;
    20  import java.io.DataOutputStream;
    21  import java.io.IOException;
    22  import java.io.Serializable;
    23  import org.apache.bcel.Constants;
    24
    25  /***
    26   * This class represents a local variable within a method. It contains its
    27   * scope, name, signature and index on the method's frame.
    28   *
    29   * @version $Id: LocalVariable.java 386056 2006-03-15 11:31:56Z tcurdt $
    30   * @author  <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
    31   * @see     LocalVariableTable
    32   */
    33  public final class LocalVariable implements Constants, Cloneable, Node, Serializable {
    34
    35      private int start_pc; // Range in which the variable is valid
    36      private int length;
    37      private int name_index; // Index in constant pool of variable name
    38      private int signature_index; // Index of variable signature
    39      private int index; /* Variable is `index'th local variable on
    40       * this method's frame.
    41       */
    42      private ConstantPool constant_pool;
    43
    44
    45      /***
    46       * Initialize from another object. Note that both objects use the same
    47       * references (shallow copy). Use copy() for a physical copy.
    48       */
    49      public LocalVariable(LocalVariable c) {
    50          this(c.getStartPC(), c.getLength(), c.getNameIndex(), c.getSignatureIndex(), c.getIndex(),
    51                  c.getConstantPool());
    52      }
    53
    54
    55      /***
    56       * Construct object from file stream.
    57       * @param file Input stream
    58       * @throws IOException
    59       */
    60      LocalVariable(DataInputStream file, ConstantPool constant_pool) throws IOException {
    61          this(file.readUnsignedShort(), file.readUnsignedShort(), file.readUnsignedShort(), file
    62                  .readUnsignedShort(), file.readUnsignedShort(), constant_pool);
    63      }
    64
    65
    66      /***
    67       * @param start_pc Range in which the variable
    68       * @param length ... is valid
    69       * @param name_index Index in constant pool of variable name
    70       * @param signature_index Index of variable's signature
    71       * @param index Variable is `index'th local variable on the method's frame
    72       * @param constant_pool Array of constants
    73       */
    74      public LocalVariable(int start_pc, int length, int name_index, int signature_index, int index,
    75              ConstantPool constant_pool) {
    76          this.start_pc = start_pc;
    77          this.length = length;
    78          this.name_index = name_index;
    79          this.signature_index = signature_index;
    80          this.index = index;
    81          this.constant_pool = constant_pool;
    82      }
    83
    84
    85      /***
    86       * Called by objects that are traversing the nodes of the tree implicitely
    87       * defined by the contents of a Java class. I.e., the hierarchy of methods,
    88       * fields, attributes, etc. spawns a tree of objects.
    89       *
    90       * @param v Visitor object
    91       */
    92      public void accept( Visitor v ) {
    93          v.visitLocalVariable(this);
    94      }
    95
    96
    97      /***
    98       * Dump local variable to file stream in binary format.
    99       *
    100      * @param file Output file stream
    101      * @throws IOException
    102      */
    103     public final void dump( DataOutputStream file ) throws IOException {
    104         file.writeShort(start_pc);
    105         file.writeShort(length);
    106         file.writeShort(name_index);
    107         file.writeShort(signature_index);
    108         file.writeShort(index);
    109     }
    110
    111
    112     /***
    113      * @return Constant pool used by this object.
    114      */
    115     public final ConstantPool getConstantPool() {
    116         return constant_pool;
    117     }
    118
    119
    120     /***
    121      * @return Variable is valid within getStartPC() .. getStartPC()+getLength()
    122      */
    123     public final int getLength() {
    124         return length;
    125     }
    126
    127
    128     /***
    129      * @return Variable name.
    130      */
    131     public final String getName() {
    132         ConstantUtf8 c;
    133         c = (ConstantUtf8) constant_pool.getConstant(name_index, CONSTANT_Utf8);
    134         return c.getBytes();
    135     }
    136
    137
    138     /***
    139      * @return Index in constant pool of variable name.
    140      */
    141     public final int getNameIndex() {
    142         return name_index;
    143     }
    144
    145
    146     /***
    147      * @return Signature.
    148      */
    149     public final String getSignature() {
    150         ConstantUtf8 c;
    151         c = (ConstantUtf8) constant_pool.getConstant(signature_index, CONSTANT_Utf8);
    152         return c.getBytes();
    153     }
    154
    155
    156     /***
    157      * @return Index in constant pool of variable signature.
    158      */
    159     public final int getSignatureIndex() {
    160         return signature_index;
    161     }
    162
    163
    164     /***
    165      * @return index of register where variable is stored
    166      */
    167     public final int getIndex() {
    168         return index;
    169     }
    170
    171
    172     /***
    173      * @return Start of range where he variable is valid
    174      */
    175     public final int getStartPC() {
    176         return start_pc;
    177     }
    178
    179
    180     /***
    181      * @param constant_pool Constant pool to be used for this object.
    182      */
    183     public final void setConstantPool( ConstantPool constant_pool ) {
    184         this.constant_pool = constant_pool;
    185     }
    186
    187
    188     /***
    189      * @param length the length of this local variable
    190      */
    191     public final void setLength( int length ) {
    192         this.length = length;
    193     }
    194
    195
    196     /***
    197      * @param name_index the index into the constant pool for the name of this variable
    198      */
    199     public final void setNameIndex( int name_index ) {
    200         this.name_index = name_index;
    201     }
    202
    203
    204     /***
    205      * @param signature_index the index into the constant pool for the signature of this variable
    206      */
    207     public final void setSignatureIndex( int signature_index ) {
    208         this.signature_index = signature_index;
    209     }
    210
    211
    212     /***
    213      * @param index the index in the local variable table of this variable
    214      */
    215     public final void setIndex( int index ) {
    216         this.index = index;
    217     }
    218
    219
    220     /***
    221      * @param start_pc Specify range where the local variable is valid.
    222      */
    223     public final void setStartPC( int start_pc ) {
    224         this.start_pc = start_pc;
    225     }
    226
    227
    228     /***
    229      * @return string representation.
    230      */
    231     public final String toString() {
    232         String name = getName(), signature = Utility.signatureToString(getSignature());
    233         return "LocalVariable(start_pc = " + start_pc + ", length = " + length + ", index = "
    234                 + index + ":" + signature + " " + name + ")";
    235     }
    236
    237
    238     /***
    239      * @return deep copy of this object
    240      */
    241     public LocalVariable copy() {
    242         try {
    243             return (LocalVariable) clone();
    244         } catch (CloneNotSupportedException e) {
    245         }
    246         return null;
    247     }
    248 }