/*******************************************************************************
* Copyright (c) 2002 - 2006 IBM Corporation.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package com.ibm.wala.util.collections;
import java.util.EmptyStackException;
/**
* A stack of integer primitives. This should be more efficient than a java.util.Stack
*/
public class IntStack {
/**
* Comment for <code>top</code>
*/
private int top = -1;
/**
* Comment for <code>state</code>
*/
private int state[] = new int[0];
/**
* @param i
*/
public void push(int i) {
if (state.length <= (top+1)) {
int newState[] = new int[ state.length*2 + 1 ];
System.arraycopy(state, 0, newState, 0, state.length);
state = newState;
}
state[++top] = i;
}
/**
* @return the int at the top of the stack
*/
public int peek() throws EmptyStackException {
if (isEmpty()) {
throw new EmptyStackException();
}
return state[top];
}
/**
* pop the stack
* @return the int at the top of the stack
*/
public int pop() throws EmptyStackException{
if (isEmpty()) {
throw new EmptyStackException();
}
return state[top--];
}
/**
* @return true iff the stack is empty
*/
public boolean isEmpty() {
return top == -1;
}
}