| /* Queue.java -- a token queue. |
| Copyright (C) 2005 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package gnu.javax.swing.text.html.parser.support.low; |
| |
| import java.util.Arrays; |
| |
| /** |
| * A token queue. |
| * @author Audrius Meskauskas, Lithuania (AudriusA@Bioinformatics.org) |
| */ |
| public class Queue |
| { |
| Token[] m = new Token[ 64 ]; |
| int a = 0; |
| int b = 0; |
| |
| /** |
| * True for the empty queue. |
| */ |
| public boolean isEmpty() |
| { |
| return size() == 0; |
| } |
| |
| /** |
| * Add this trace to the end of the queue. |
| */ |
| public void add(Token u) |
| { |
| if (a < m.length) |
| { |
| m [ a ] = u; |
| a++; |
| } |
| else // The end of array has been reached. |
| { |
| if (b > 0) // If some elements were deleted from the start of the queue, shift. |
| { |
| int d = b; |
| System.arraycopy(m, b, m, 0, a - b); |
| b = b - d; |
| a = a - d; |
| m [ a ] = u; |
| a++; |
| } |
| else // Enlarge the queue, doubling the size. |
| { |
| int n = m.length * 2; |
| Token[] nm = new Token[ 2 * n ]; |
| System.arraycopy(m, 0, nm, 0, m.length); |
| Arrays.fill(m, null); |
| |
| nm [ a ] = u; |
| m = nm; |
| a++; |
| } |
| } |
| } |
| |
| /** |
| * Clear the queue. |
| */ |
| public void clear() |
| { |
| a = b = 0; |
| Arrays.fill(m, null); |
| } |
| |
| /** |
| * Read the value ahead. 0 is the value that will be returned with |
| * the following next. This method does not remove values from the |
| * queue. To test if there is enough tokens in the queue, size() must |
| * be checked before calling this method. |
| */ |
| public Token get(int ahead) |
| { |
| int p = b + ahead; |
| if (p < a) |
| return m [ p ]; |
| else |
| throw new ArrayIndexOutOfBoundsException("Not enough tokens"); |
| } |
| |
| /** |
| * Read the oldest value from the queue and remove this value from |
| * the queue. |
| */ |
| public Token next() |
| { |
| if (a == b) |
| throw new ArrayIndexOutOfBoundsException("queue empty"); |
| |
| Token r = m [ b ]; |
| m [ b ] = null; |
| b++; |
| return r; |
| } |
| |
| /** |
| * Size of the queue. |
| */ |
| public int size() |
| { |
| return a - b; |
| } |
| } |