content: /*
   *  This file is part of AndroidIDE.
   *
   *  AndroidIDE is free software: you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License as published by
   *  the Free Software Foundation, either version 3 of the License, or
   *  (at your option) any later version.
   *
   *  AndroidIDE is distributed in the hope that it will be useful,
   *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *  GNU General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License
   *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
   */
  
  /*
   * reserved comment block
   * DO NOT REMOVE OR ALTER!
   */
  package jaxp.sun.org.apache.bcel.internal.generic;
  
  /* ====================================================================
   * The Apache Software License, Version 1.1
   *
   * Copyright (c) 2001 The Apache Software Foundation.  All rights
   * reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. The end-user documentation included with the redistribution,
   *    if any, must include the following acknowledgment:
   *       "This product includes software developed by the
   *        Apache Software Foundation (http://www.apache.org/)."
   *    Alternately, this acknowledgment may appear in the software itself,
   *    if and wherever such third-party acknowledgments normally appear.
   *
   * 4. The names "Apache" and "Apache Software Foundation" and
   *    "Apache BCEL" must not be used to endorse or promote products
   *    derived from this software without prior written permission. For
   *    written permission, please contact apache@apache.org.
   *
   * 5. Products derived from this software may not be called "Apache",
   *    "Apache BCEL", nor may "Apache" appear in their name, without
   *    prior written permission of the Apache Software Foundation.
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   */
  
  import jaxp.sun.org.apache.bcel.internal.classfile.Utility;
  import java.util.HashSet;
  import java.util.Collection;
  import java.util.HashMap;
  
  /**
   * Instances of this class give users a handle to the instructions contained in
   * an InstructionList. Instruction objects may be used more than once within a
   * list, this is useful because it saves memory and may be much faster.
   *
   * Within an InstructionList an InstructionHandle object is wrapped
   * around all instructions, i.e., it implements a cell in a
   * doubly-linked list. From the outside only the next and the
   * previous instruction (handle) are accessible. One
   * can traverse the list via an Enumeration returned by
   * InstructionList.elements().
   *
   * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
   * @see Instruction
   * @see BranchHandle
   * @see InstructionList
   */
  public class InstructionHandle implements java.io.Serializable {
    InstructionHandle next, prev;  // Will be set from the outside
    Instruction       instruction;
    protected int     i_position = -1; // byte code offset of instruction
    private HashSet   targeters;
    private HashMap   attributes;
  
    public final InstructionHandle getNext()        { return next; }
    public final InstructionHandle getPrev()        { return prev; }
    public final Instruction       getInstruction() { return instruction; }
  
    /**
     * Replace current instruction contained in this handle.
     * Old instruction is disposed using Instruction.dispose().
     */
    public void setInstruction(Instruction i) { // Overridden in BranchHandle
      if(i == null)
        throw new ClassGenException("Assigning null to handle");
  
      if((this.getClass() != BranchHandle.class) && (i instanceof BranchInstruction))
        throw new ClassGenException("Assigning branch instruction " + i + " to plain handle");
  
      if(instruction != null)
        instruction.dispose();
  
      instruction = i;
    }
  
    /**
     * Temporarily swap the current instruction, without disturbing
     * anything. Meant to be used by a debugger, implementing
     * breakpoints. Current instruction is returned.
     */
    public Instruction swapInstruction(Instruction i) {
      Instruction oldInstruction = instruction;
      instruction = i;
      return oldInstruction;
    }
  
    /*private*/ protected InstructionHandle(Instruction i) {
      setInstruction(i);
    }
  
    private static InstructionHandle ih_list = null; // List of reusable handles
  
    /** Factory method.
     */
    static final InstructionHandle getInstructionHandle(Instruction i) {
      if(ih_list == null)
        return new InstructionHandle(i);
      else {
        InstructionHandle ih = ih_list;
        ih_list = ih.next;
  
        ih.setInstruction(i);
  
        return ih;
      }
    }
  
    /**
     * Called by InstructionList.setPositions when setting the position for every
     * instruction. In the presence of variable length instructions `setPositions()'
     * performs multiple passes over the instruction list to calculate the
     * correct (byte) positions and offsets by calling this function.
     *
     * @param offset additional offset caused by preceding (variable length) instructions
     * @param max_offset the maximum offset that may be caused by these instructions
     * @return additional offset caused by possible change of this instruction's length
     */
    protected int updatePosition(int offset, int max_offset) {
      i_position += offset;
      return 0;
    }
  
    /** @return the position, i.e., the byte code offset of the contained
     * instruction. This is accurate only after
     * InstructionList.setPositions() has been called.
     */
    public int getPosition() { return i_position; }
  
    /** Set the position, i.e., the byte code offset of the contained
     * instruction.
     */
    void setPosition(int pos) { i_position = pos; }
  
    /** Overridden in BranchHandle
     */
    protected void addHandle() {
      next    = ih_list;
      ih_list = this;
    }
  
    /**
     * Delete contents, i.e., remove user access and make handle reusable.
     */
    void dispose() {
      next = prev = null;
      instruction.dispose();
      instruction = null;
      i_position = -1;
      attributes = null;
      removeAllTargeters();
      addHandle();
    }
  
    /** Remove all targeters, if any.
     */
    public void removeAllTargeters() {
      if(targeters != null)
        targeters.clear();
    }
  
    /**
     * Denote this handle isn't referenced anymore by t.
     */
    public void removeTargeter(InstructionTargeter t) {
      targeters.remove(t);
    }
  
    /**
     * Denote this handle is being referenced by t.
     */
    public void addTargeter(InstructionTargeter t) {
      if(targeters == null)
        targeters = new HashSet();
  
      //if(!targeters.contains(t))
      targeters.add(t);
    }
  
    public boolean hasTargeters() {
      return (targeters != null) && (targeters.size() > 0);
    }
  
    /**
     * @return null, if there are no targeters
     */
    public InstructionTargeter[] getTargeters() {
      if(!hasTargeters())
        return null;
  
      InstructionTargeter[] t = new InstructionTargeter[targeters.size()];
      targeters.toArray(t);
      return t;
    }
  
    /** @return a (verbose) string representation of the contained instruction.
     */
    public String toString(boolean verbose) {
      return Utility.format(i_position, 4, false, ' ') + ": " + instruction.toString(verbose);
    }
  
    /** @return a string representation of the contained instruction.
     */
    public String toString() {
      return toString(true);
    }
  
    /** Add an attribute to an instruction handle.
     *
     * @param key the key object to store/retrieve the attribute
     * @param attr the attribute to associate with this handle
     */
    public void addAttribute(Object key, Object attr) {
      if(attributes == null)
        attributes = new HashMap(3);
  
      attributes.put(key, attr);
    }
  
    /** Delete an attribute of an instruction handle.
     *
     * @param key the key object to retrieve the attribute
     */
    public void removeAttribute(Object key) {
      if(attributes != null)
        attributes.remove(key);
    }
  
    /** Get attribute of an instruction handle.
     *
     * @param key the key object to store/retrieve the attribute
     */
    public Object getAttribute(Object key) {
      if(attributes != null)
        return attributes.get(key);
  
      return null;
    }
  
    /** @return all attributes associated with this handle
     */
    public Collection getAttributes() {
      return attributes.values();
    }
  
    /** Convenience method, simply calls accept() on the contained instruction.
     *
     * @param v Visitor object
     */
    public void accept(Visitor v) {
      instruction.accept(v);
    }
  }
  