Mega Code Archive
Stack for boolean values
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/*
* 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: BoolStack.java 468655 2006-10-28 07:12:06Z minchau $
*/
/**
* 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();
}
}
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