/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *   https://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  package org.apache.bcel.generic;
  
  import java.io.DataOutputStream;
  import java.io.IOException;
  
  import org.apache.bcel.classfile.Constant;
  import org.apache.bcel.classfile.ConstantClass;
  import org.apache.bcel.classfile.ConstantPool;
  import org.apache.bcel.classfile.Utility;
  import org.apache.bcel.util.ByteSequence;
  
  /**
   * Abstract super class for instructions that use an index into the constant pool such as LDC, INVOKEVIRTUAL, etc.
   *
   * @see ConstantPoolGen
   * @see LDC
   * @see INVOKEVIRTUAL
   */
  public abstract class CPInstruction extends Instruction implements TypedInstruction, IndexedInstruction {
  
      /**
       * @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
       */
      @Deprecated
      protected int index; // index to constant pool
  
      /**
       * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
       */
      CPInstruction() {
      }
  
      /**
       * Constructs a CPInstruction.
       *
       * @param opcode the opcode.
       * @param index to constant pool.
       */
      protected CPInstruction(final short opcode, final int index) {
          super(opcode, (short) 3);
          setIndex(index);
      }
  
      /**
       * Dumps instruction as byte code to stream out.
       *
       * @param out Output stream.
       */
      @Override
      public void dump(final DataOutputStream out) throws IOException {
          out.writeByte(super.getOpcode());
          out.writeShort(index);
      }
  
      /**
       * @return index in constant pool referred by this instruction.
       */
      @Override
      public final int getIndex() {
          return index;
      }
  
      /**
       * @return type related with this instruction.
       */
      @Override
      public Type getType(final ConstantPoolGen cpg) {
          final ConstantPool cp = cpg.getConstantPool();
          String name = cp.getConstantString(index, org.apache.bcel.Const.CONSTANT_Class);
          if (!name.startsWith("[")) {
              name = "L" + name + ";";
          }
          return Type.getType(name);
      }
  
      /**
       * Reads needed data (that is, index) from file.
       *
       * @param bytes input stream.
       * @param wide wide prefix?.
       */
     @Override
     protected void initFromFile(final ByteSequence bytes, final boolean wide) throws IOException {
         setIndex(bytes.readUnsignedShort());
         super.setLength(3);
     }
 
     /**
      * Sets the index to constant pool.
      *
      * @param index in constant pool.
      */
     @Override
     public void setIndex(final int index) { // TODO could be package-protected?
         if (index < 0) {
             throw new ClassGenException("Negative index value: " + index);
         }
         this.index = index;
     }
 
     /**
      * Long output format:
      *
      * &lt;name of opcode&gt; "["&lt;opcode number&gt;"]" "("&lt;length of instruction&gt;")" "&lt;"&lt; constant pool
      * index&gt;"&gt;"
      *
      * @param verbose long/short format switch.
      * @return mnemonic for instruction.
      */
     @Override
     public String toString(final boolean verbose) {
         return super.toString(verbose) + " " + index;
     }
 
     /**
      * @return mnemonic for instruction with symbolic references resolved.
      */
     @Override
     public String toString(final ConstantPool cp) {
         final Constant c = cp.getConstant(index);
         String str = cp.constantToString(c);
         if (c instanceof ConstantClass) {
             str = Utility.packageToPath(str);
         }
         return org.apache.bcel.Const.getOpcodeName(super.getOpcode()) + " " + str;
     }
 }