package org.aspectj.apache.bcel.classfile;

/* ====================================================================
 * 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",
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 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * 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  org.aspectj.apache.bcel.Constants;
import  java.io.*;

/**
 * This class represents collection of local variables in a
 * method. This attribute is contained in the <em>Code</em> attribute.
 *
 * @version $Id: LocalVariableTable.java,v 1.3.6.3 2008/05/08 19:26:47 aclement Exp $
 * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
 * @see     Code
 * @see LocalVariable
 * 
 * Updates: Andy 14Feb06 - Made unpacking of the data lazy, depending on someone
 *          actually asking for it.
 */
public class LocalVariableTable extends Attribute {
	
  // if 'isInPackedState' then this data needs unpacking
  private boolean isInPackedState = false;
  private byte[]  data; 
  
  private int             localVariableTableLength;
  private LocalVariable[] localVariableTable;

  
  /**
   * Initialize from another object. Note that both objects use the same
   * references (shallow copy). Use copy() for a physical copy.
   */
  public LocalVariableTable(LocalVariableTable c) {
    this(c.getNameIndex(), c.getLength(), c.getLocalVariableTable(),c.getConstantPool());
  }

  /**
   * @param name_index Index in constant pool to `LocalVariableTable'
   * @param length Content length in bytes
   * @param local_variable_table Table of local variables
   * @param constant_pool Array of constants
   */
  public LocalVariableTable(int name_index, int length,
			    LocalVariable[] local_variable_table,
			    ConstantPool    constant_pool)
  {
    super(Constants.ATTR_LOCAL_VARIABLE_TABLE, name_index, length, constant_pool);
    setLocalVariableTable(local_variable_table);
  }    

  /**
   * Construct object from file stream.
   * @param name_index Index in constant pool
   * @param length Content length in bytes
   * @param file Input stream
   * @param constant_pool Array of constants
   * @throws IOException
   */
  LocalVariableTable(int name_index, int length, DataInputStream file,
		     ConstantPool constant_pool) throws IOException
  {
    super(Constants.ATTR_LOCAL_VARIABLE_TABLE,name_index, length, constant_pool);
    data = new byte[length];
    int byteReads = file.read(data);
    isInPackedState = true;
    // assert(bytesRead==length)
  }
    
    

  /**
   * Called by objects that are traversing the nodes of the tree implicitely
   * defined by the contents of a Java class. I.e., the hierarchy of methods,
   * fields, attributes, etc. spawns a tree of objects.
   *
   * @param v Visitor object
   */
  public void accept(ClassVisitor v) {
	unpack();
    v.visitLocalVariableTable(this);
  }

  /**
   * Dump local variable table attribute to file stream in binary format.
   *
   * @param file Output file stream
   * @throws IOException
   */ 
  public final void dump(DataOutputStream file) throws IOException
  {
    super.dump(file);
    if (isInPackedState) {
        file.write(data);
    } else {
  	    file.writeShort(localVariableTableLength);
  	    for(int i=0; i < localVariableTableLength; i++)
  	      localVariableTable[i].dump(file);
    }
  }

  /**
   * @return Array of local variables of method.
   */  
  public final LocalVariable[] getLocalVariableTable() {
	unpack();
    return localVariableTable;
  }    

  /** @return first matching variable using index
   */
  public final LocalVariable getLocalVariable(int index) {
	unpack();
    for(int i=0; i < localVariableTableLength; i++)
      if (localVariableTable[i].getIndex() == index) return localVariableTable[i];
    return null;
  }

  public final void setLocalVariableTable(LocalVariable[] local_variable_table)
  {
	data=null;
	isInPackedState=false;
    this.localVariableTable = local_variable_table;
    localVariableTableLength = (local_variable_table == null)? 0 :
      local_variable_table.length;
  }

  /**
   * @return String representation.
   */ 
  public final String toString() {
    StringBuffer buf = new StringBuffer("");
    unpack();
    for(int i=0; i < localVariableTableLength; i++) {
      buf.append(localVariableTable[i].toString());

      if(i < localVariableTableLength - 1)
	buf.append('\n');
    }

    return buf.toString();
  }

  /**
   * @return deep copy of this attribute
   */
  public Attribute copy(ConstantPool constant_pool) {
	unpack();
    LocalVariableTable c = (LocalVariableTable)clone();

    c.localVariableTable = new LocalVariable[localVariableTableLength];
    for(int i=0; i < localVariableTableLength; i++)
      c.localVariableTable[i] = localVariableTable[i].copy();

    c.constantPool = constant_pool;
    return c;
  }

  public final int getTableLength() { 
	  unpack();
	  return localVariableTableLength; 
  }
  
  // ---
  // Unpacks the byte array into the table
  private void unpack() {
	if (!isInPackedState) return;
	try {
  	    ByteArrayInputStream bs = new ByteArrayInputStream(data);
		DataInputStream dis = new DataInputStream(bs);
		localVariableTableLength = (dis.readUnsignedShort());
		localVariableTable = new LocalVariable[localVariableTableLength];
		for (int i=0; i < localVariableTableLength; i++)
		  localVariableTable[i] = new LocalVariable(dis,constantPool);
	    dis.close();
	    data = null; // throw it away now
    } catch (IOException e) {
		throw new RuntimeException("Unpacking of LocalVariableTable attribute failed");
	}
	isInPackedState=false;
  }
}