code: /*
   * 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
   *
   *     http://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.
   */
  /*
   * $Id$
   */
  package org.apache.xml.utils;
  
  
  /**
   * Simple stack for boolean values.
   * @xsl.usage internal
   */
  public final class BoolStack implements Cloneable
  {
  
    /** Array of boolean values          */
    private boolean m_values[];
  
    /** Array size allocated           */
    private int m_allocatedSize;
  
    /** Index into the array of booleans          */
    private int m_index;
  
    /**
     * Default constructor.  Note that the default
     * block size is very small, for small lists.
     */
    public BoolStack()
    {
      this(32);
    }
  
    /**
     * Construct a IntVector, using the given block size.
     *
     * @param size array size to allocate
     */
    public BoolStack(int size)
    {
  
      m_allocatedSize = size;
      m_values = new boolean[size];
      m_index = -1;
    }
  
    /**
     * Get the length of the list.
     *
     * @return Current length of the list
     */
    public final int size()
    {
      return m_index + 1;
    }
  
    /**
     * Clears the stack.
     *
     */
    public final void clear()
    {
    	m_index = -1;
    }
  
    /**
     * Pushes an item onto the top of this stack.
     *
     *
     * @param val the boolean to be pushed onto this stack.
     * @return  the <code>item</code> argument.
     */
    public final boolean push(boolean val)
    {
  
      if (m_index == m_allocatedSize - 1)
        grow();
  
      return (m_values[++m_index] = val);
    }
  
    /**
     * Removes the object at the top of this stack and returns that
     * object as the value of this function.
     *
     * @return     The object at the top of this stack.
     * @throws  EmptyStackException  if this stack is empty.
     */
    public final boolean pop()
    {
      return m_values[m_index--];
    }
  
    /**
     * Removes the object at the top of this stack and returns the
     * next object at the top as the value of this function.
     *
     *
     * @return Next object to the top or false if none there
     */
    public final boolean popAndTop()
    {
  
      m_index--;
  
      return (m_index >= 0) ? m_values[m_index] : false;
    }
  
    /**
     * Set the item at the top of this stack  
     *
     *
     * @param b Object to set at the top of this stack
     */
    public final void setTop(boolean b)
    {
      m_values[m_index] = b;
    }
  
    /**
     * Looks at the object at the top of this stack without removing it
     * from the stack.
     *
     * @return     the object at the top of this stack.
     * @throws  EmptyStackException  if this stack is empty.
     */
    public final boolean peek()
    {
      return m_values[m_index];
    }
  
    /**
     * Looks at the object at the top of this stack without removing it
     * from the stack.  If the stack is empty, it returns false.
     *
     * @return     the object at the top of this stack.
     */
    public final boolean peekOrFalse()
    {
      return (m_index > -1) ? m_values[m_index] : false;
    }
  
    /**
     * Looks at the object at the top of this stack without removing it
     * from the stack.  If the stack is empty, it returns true.
     *
     * @return     the object at the top of this stack.
     */
    public final boolean peekOrTrue()
    {
      return (m_index > -1) ? m_values[m_index] : true;
    }
  
    /**
     * Tests if this stack is empty.
     *
     * @return  <code>true</code> if this stack is empty;
     *          <code>false</code> otherwise.
     */
    public boolean isEmpty()
    {
      return (m_index == -1);
    }
  
    /**
     * Grows the size of the stack
     *
     */
    private void grow()
    {
  
      m_allocatedSize *= 2;
  
      boolean newVector[] = new boolean[m_allocatedSize];
  
      System.arraycopy(m_values, 0, newVector, 0, m_index + 1);
  
      m_values = newVector;
    }
    
    public Object clone() 
      throws CloneNotSupportedException
    {
      return super.clone();
    }
  
  }
  