/*
 *  This file is part of the Jikes RVM project (http://jikesrvm.org).
 *
 *  This file is licensed to You under the Eclipse Public License (EPL);
 *  You may not use this file except in compliance with the License. You
 *  may obtain a copy of the License at
 *
 *      http://www.opensource.org/licenses/eclipse-1.0.php
 *
 *  See the COPYRIGHT.txt file distributed with this work for information
 *  regarding copyright ownership.
 */
package org.jikesrvm.compilers.opt.util;

import java.util.ArrayList;
import java.util.Iterator;

/**
 * Stack is a smaller implementation of java.util.Stack, that uses a linked
 * list rather than a vector.
 */
public class Stack<T> implements Iterable<T> {
  private final ArrayList<T> stack = new ArrayList<T>();

  public Stack() {
  }

  public Stack(T e) {
    push(e);
  }

  public final T push(T e) {
    stack.add(e);
    return e;
  }

  public final T pop() {
    return stack.remove(stack.size() - 1);
  }

  public final T getTOS() {
    return stack.get(stack.size() - 1);
  }

  public final T peek() {
    return getTOS();
  }

  public final boolean isEmpty() {
    return stack.isEmpty();
  }

  public final boolean empty() {
    return isEmpty();
  }

  public final boolean compare(Stack<T> s2) {
    Iterator<T> i1 = iterator();
    Iterator<T> i2 = s2.iterator();
    if (isEmpty() && s2.isEmpty()) {
      return true;
    } else if (isEmpty() || s2.isEmpty()) {
      return false;
    }
    for (T t1 = i1.next(), t2 = i2.next(); i1.hasNext() && i2.hasNext();) {
      if (t1 != t2) {
        return false;
      }
      t1 = i1.next();
      t2 = i2.next();
    }
    return !i1.hasNext() && !i2.hasNext();
  }

  public final Stack<T> copy() {
    Stack<T> s = new Stack<T>();
    s.stack.addAll(stack);
    return s;
  }

  public final Stack<T> shallowCopy() {
    Stack<T> s = new Stack<T>();
    s.stack.addAll(stack);
    return s;
  }

  @Override
  public final Iterator<T> iterator() {
    return stack.iterator();
  }

  @Override
  public String toString() {
    StringBuilder sb = new StringBuilder(" --> ");
    for (T t : stack) {
      sb.append(t.toString());
      sb.append(' ');
    }
    return sb.toString();
  }
}