1 /*
   2  * reserved comment block
   3  * DO NOT REMOVE OR ALTER!
   4  */
   5 /*
   6  * Licensed to the Apache Software Foundation (ASF) under one or more
   7  * contributor license agreements.  See the NOTICE file distributed with
   8  * this work for additional information regarding copyright ownership.
   9  * The ASF licenses this file to You under the Apache License, Version 2.0
  10  * (the "License"); you may not use this file except in compliance with
  11  * the License.  You may obtain a copy of the License at
  12  *
  13  *      http://www.apache.org/licenses/LICENSE-2.0
  14  *
  15  * Unless required by applicable law or agreed to in writing, software
  16  * distributed under the License is distributed on an "AS IS" BASIS,
  17  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  18  * See the License for the specific language governing permissions and
  19  * limitations under the License.
  20  */
  21 
  22 package com.sun.org.apache.bcel.internal.classfile;
  23 
  24 import java.io.DataInput;
  25 import java.io.DataOutputStream;
  26 import java.io.IOException;
  27 
  28 import com.sun.org.apache.bcel.internal.Const;
  29 
  30 /**
  31  * This class is derived from the abstract {@link Constant}
  32  * and represents a reference to a (external) class.
  33  *
  34  * @see     Constant
  35  */
  36 public final class ConstantClass extends Constant implements ConstantObject {
  37 
  38     private int name_index; // Identical to ConstantString except for the name
  39 
  40 
  41     /**
  42      * Initialize from another object.
  43      */
  44     public ConstantClass(final ConstantClass c) {
  45         this(c.getNameIndex());
  46     }
  47 
  48 
  49     /**
  50      * Constructs an instance from file data.
  51      *
  52      * @param dataInput Input stream
  53      * @throws IOException if an I/O error occurs reading from the given {@code dataInput}.
  54      */
  55     ConstantClass(final DataInput dataInput) throws IOException {
  56         this(dataInput.readUnsignedShort());
  57     }
  58 
  59 
  60     /**
  61      * @param name_index Name index in constant pool.  Should refer to a
  62      * ConstantUtf8.
  63      */
  64     public ConstantClass(final int name_index) {
  65         super(Const.CONSTANT_Class);
  66         this.name_index = name_index;
  67     }
  68 
  69 
  70     /**
  71      * Called by objects that are traversing the nodes of the tree implicitely
  72      * defined by the contents of a Java class. I.e., the hierarchy of methods,
  73      * fields, attributes, etc. spawns a tree of objects.
  74      *
  75      * @param v Visitor object
  76      */
  77     @Override
  78     public void accept( final Visitor v ) {
  79         v.visitConstantClass(this);
  80     }
  81 
  82 
  83     /**
  84      * Dumps constant class to file stream in binary format.
  85      *
  86      * @param file Output file stream
  87      * @throws IOException if an I/O error occurs writing to the DataOutputStream.
  88      */
  89     @Override
  90     public final void dump( final DataOutputStream file ) throws IOException {
  91         file.writeByte(super.getTag());
  92         file.writeShort(name_index);
  93     }
  94 
  95 
  96     /**
  97      * @return Name index in constant pool of class name.
  98      */
  99     public final int getNameIndex() {
 100         return name_index;
 101     }
 102 
 103 
 104     /**
 105      * @param name_index the name index in the constant pool of this Constant Class
 106      */
 107     public final void setNameIndex( final int name_index ) {
 108         this.name_index = name_index;
 109     }
 110 
 111 
 112     /** @return String object
 113      */
 114     @Override
 115     public Object getConstantValue( final ConstantPool cp ) {
 116         final Constant c = cp.getConstant(name_index, Const.CONSTANT_Utf8);
 117         return ((ConstantUtf8) c).getBytes();
 118     }
 119 
 120 
 121     /** @return dereferenced string
 122      */
 123     public String getBytes( final ConstantPool cp ) {
 124         return (String) getConstantValue(cp);
 125     }
 126 
 127 
 128     /**
 129      * @return String representation.
 130      */
 131     @Override
 132     public final String toString() {
 133         return super.toString() + "(name_index = " + name_index + ")";
 134     }
 135 }