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 * 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
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 * Unless required by applicable law or agreed to in writing, software
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/*
 * $Id: ObjectStack.java 1225426 2011-12-29 04:13:08Z mrglavas $
 */
package org.apache.xml.utils;

import java.util.EmptyStackException;

Implement a stack of simple integers. %OPT% This is currently based on ObjectVector, which permits fast acess but pays a heavy recopying penalty if/when its size is increased. If we expect deep stacks, we should consider a version based on ChunkedObjectVector.
@xsl.usageinternal
/** * Implement a stack of simple integers. * * %OPT% * This is currently based on ObjectVector, which permits fast acess but pays a * heavy recopying penalty if/when its size is increased. If we expect deep * stacks, we should consider a version based on ChunkedObjectVector. * @xsl.usage internal */
public class ObjectStack extends ObjectVector {
Default constructor. Note that the default block size is very small, for small lists.
/** * Default constructor. Note that the default * block size is very small, for small lists. */
public ObjectStack() { super(); }
Construct a ObjectVector, using the given block size.
Params:
  • blocksize – Size of block to allocate
/** * Construct a ObjectVector, using the given block size. * * @param blocksize Size of block to allocate */
public ObjectStack(int blocksize) { super(blocksize); }
Copy constructor for ObjectStack
Params:
  • v – ObjectStack to copy
/** * Copy constructor for ObjectStack * * @param v ObjectStack to copy */
public ObjectStack (ObjectStack v) { super(v); }
Pushes an item onto the top of this stack.
Params:
  • i – the int to be pushed onto this stack.
Returns: the item argument.
/** * Pushes an item onto the top of this stack. * * @param i the int to be pushed onto this stack. * @return the <code>item</code> argument. */
public Object push(Object i) { if ((m_firstFree + 1) >= m_mapSize) { m_mapSize += m_blocksize; Object newMap[] = new Object[m_mapSize]; System.arraycopy(m_map, 0, newMap, 0, m_firstFree + 1); m_map = newMap; } m_map[m_firstFree] = i; m_firstFree++; return i; }
Removes the object at the top of this stack and returns that object as the value of this function.
Returns: The object at the top of this stack.
/** * 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. */
public Object pop() { Object val = m_map[--m_firstFree]; m_map[m_firstFree] = null; return val; }
Quickly pops a number of items from the stack.
/** * Quickly pops a number of items from the stack. */
public void quickPop(int n) { m_firstFree -= n; }
Looks at the object at the top of this stack without removing it from the stack.
Throws:
Returns: the object at the top of this stack.
/** * 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 Object peek() { try { return m_map[m_firstFree - 1]; } catch (ArrayIndexOutOfBoundsException e) { throw new EmptyStackException(); } }
Looks at the object at the position the stack counting down n items.
Params:
  • n – The number of items down, indexed from zero.
Throws:
Returns: the object at n items down.
/** * Looks at the object at the position the stack counting down n items. * * @param n The number of items down, indexed from zero. * @return the object at n items down. * @throws EmptyStackException if this stack is empty. */
public Object peek(int n) { try { return m_map[m_firstFree-(1+n)]; } catch (ArrayIndexOutOfBoundsException e) { throw new EmptyStackException(); } }
Sets an object at a the top of the statck
Params:
  • val – object to set at the top
Throws:
/** * Sets an object at a the top of the statck * * * @param val object to set at the top * @throws EmptyStackException if this stack is empty. */
public void setTop(Object val) { try { m_map[m_firstFree - 1] = val; } catch (ArrayIndexOutOfBoundsException e) { throw new EmptyStackException(); } }
Tests if this stack is empty.
Returns: true if this stack is empty; false otherwise.
Since: JDK1.0
/** * Tests if this stack is empty. * * @return <code>true</code> if this stack is empty; * <code>false</code> otherwise. * @since JDK1.0 */
public boolean empty() { return m_firstFree == 0; }
Returns where an object is on this stack.
Params:
  • o – the desired object.
Returns: the distance from the top of the stack where the object is] located; the return value -1 indicates that the object is not on the stack.
Since: JDK1.0
/** * Returns where an object is on this stack. * * @param o the desired object. * @return the distance from the top of the stack where the object is] * located; the return value <code>-1</code> indicates that the * object is not on the stack. * @since JDK1.0 */
public int search(Object o) { int i = lastIndexOf(o); if (i >= 0) { return size() - i; } return -1; }
Returns clone of current ObjectStack
Returns:clone of current ObjectStack
/** * Returns clone of current ObjectStack * * @return clone of current ObjectStack */
public Object clone() throws CloneNotSupportedException { return (ObjectStack) super.clone(); } }