intstack.java

来自「JAVA的一些源码 JAVA2 STANDARD EDITION DEVELO」· Java 代码 · 共 155 行

/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 2000-2002 The Apache Software Foundation.  
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:  
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xerces" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written 
 *    permission, please contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 1999, International
 * Business Machines, Inc., http://www.apache.org.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package com.sun.org.apache.xerces.internal.util;

/**
 * A simple integer based stack.
 *
 * moved to com.sun.org.apache.xerces.internal.util by neilg to support the
 * XPathMatcher.
 * @author  Andy Clark, IBM
 *
 * @version $Id: IntStack.java,v 1.4 2003/10/17 18:14:30 mrglavas Exp $
 */
public final class IntStack {

    //
    // Data
    //

    /** Stack depth. */
    private int fDepth;

    /** Stack data. */
    private int[] fData;

    //
    // Public methods
    //

    /** Returns the size of the stack. */
    public int size() {
        return fDepth;
    }

    /** Pushes a value onto the stack. */
    public void push(int value) {
        ensureCapacity(fDepth + 1);
        fData[fDepth++] = value;
    }

    /** Peeks at the top of the stack. */
    public int peek() {
        return fData[fDepth - 1];
    }

    /** Returns the element at the specified depth in the stack. */
    public int elementAt(int depth) {
        return fData[depth];
    }

    /** Pops a value off of the stack. */
    public int pop() {
        return fData[--fDepth];
    }

    /** Clears the stack. */
    public void clear() {
        fDepth = 0;
    }

    // debugging

    /** Prints the stack. */
    public void print() {
        System.out.print('(');
        System.out.print(fDepth);
        System.out.print(") {");
        for (int i = 0; i < fDepth; i++) {
            if (i == 3) {
                System.out.print(" ...");
                break;
            }
            System.out.print(' ');
            System.out.print(fData[i]);
            if (i < fDepth - 1) {
                System.out.print(',');
            }
        }
        System.out.print(" }");
        System.out.println();
    }

    //
    // Private methods
    //

    /** Ensures capacity. */
    private void ensureCapacity(int size) {
        if (fData == null) {
            fData = new int[32];
        }
        else if (fData.length <= size) {
            int[] newdata = new int[fData.length * 2];
            System.arraycopy(fData, 0, newdata, 0, fData.length);
            fData = newdata;
        }
    }

} // class IntStack