--- /dev/null
+/* 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;
+ }
+}
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