keystack.java

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/*
*  Copyright (c) 2001 Sun Microsystems, Inc.  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 discalimer 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
*  Sun Microsystems, Inc. for Project JXTA."
*  Alternately, this acknowledgment may appear in the software itself,
*  if and wherever such third-party acknowledgments normally appear.
*
*  4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA"
*  must not be used to endorse or promote products derived from this
*  software without prior written permission. For written
*  permission, please contact Project JXTA at http://www.jxta.org.
*
*  5. Products derived from this software may not be called "JXTA",
*  nor may "JXTA" appear in their name, without prior written
*  permission of Sun.
*
*  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 Project JXTA.  For more
*  information on Project JXTA, please see
*  <http://www.jxta.org/>.
*
*  This license is based on the BSD license adopted by the Apache Foundation.
*
*  $Id: KeyStack.java,v 1.1 2004/12/20 06:14:54 gonzo Exp $
*/

package net.jxta.myjxta.misc.eliza;

/**
 *  A stack of keys.
 *  The keys are kept in rank order.
 */
public final class KeyStack {

    /** The stack size */
    final int stackSize = 20;
    /** The key stack */
    final Key[] keyStack = new Key[stackSize];
    /** The top of the key stack */
    int keyTop = 0;

    /**
     *  Prints the key stack.
     */
    public void print() {
        System.out.println("Key stack " + keyTop);
        for (int i = 0; i < keyTop; i++) {
            keyStack[i].printKey(0);
        }
    }

    /**
     *  Get the stack size.
     */
    public int keyTop() {
        return keyTop;
    }

    /**
     *  Reset the key stack.
     */
    public void reset() {
        keyTop = 0;
    }

    /**
     *  Get a key from the stack.
     */
    public Key key(int n) {
        if (n < 0 || n >= keyTop) return null;
        return keyStack[n];
    }

    /**
     *  Push a key in the stack.
     *  Keep the highest rank keys at the bottom.
     */
    public void pushKey(Key key) {
        if (key == null) {
            System.out.println("push null key");
            return;
        }
        int i;
        for (i = keyTop; i > 0; i--) {
            if (key.rank > keyStack[i-1].rank) keyStack[i] = keyStack[i-1];
            else break;
        }
        keyStack[i] = key;
        keyTop++;
    }


}