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Diffstat (limited to 'src/share/classes/javax/swing/text/SegmentCache.java')
-rw-r--r-- | src/share/classes/javax/swing/text/SegmentCache.java | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/src/share/classes/javax/swing/text/SegmentCache.java b/src/share/classes/javax/swing/text/SegmentCache.java new file mode 100644 index 000000000..a2bf89f91 --- /dev/null +++ b/src/share/classes/javax/swing/text/SegmentCache.java @@ -0,0 +1,127 @@ +/* + * Copyright 2001 Sun Microsystems, Inc. All Rights Reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. Sun designates this + * particular file as subject to the "Classpath" exception as provided + * by Sun in the LICENSE file that accompanied this code. + * + * This code 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 + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + */ +package javax.swing.text; + +import java.util.ArrayList; +import java.util.List; + +/** + * SegmentCache caches <code>Segment</code>s to avoid continually creating + * and destroying of <code>Segment</code>s. A common use of this class would + * be: + * <pre> + * Segment segment = segmentCache.getSegment(); + * // do something with segment + * ... + * segmentCache.releaseSegment(segment); + * </pre> + * + */ +class SegmentCache { + /** + * A global cache. + */ + private static SegmentCache sharedCache = new SegmentCache(); + + /** + * A list of the currently unused Segments. + */ + private List segments; + + + /** + * Returns the shared SegmentCache. + */ + public static SegmentCache getSharedInstance() { + return sharedCache; + } + + /** + * A convenience method to get a Segment from the shared + * <code>SegmentCache</code>. + */ + public static Segment getSharedSegment() { + return getSharedInstance().getSegment(); + } + + /** + * A convenience method to release a Segment to the shared + * <code>SegmentCache</code>. + */ + public static void releaseSharedSegment(Segment segment) { + getSharedInstance().releaseSegment(segment); + } + + + + /** + * Creates and returns a SegmentCache. + */ + public SegmentCache() { + segments = new ArrayList(11); + } + + /** + * Returns a <code>Segment</code>. When done, the <code>Segment</code> + * should be recycled by invoking <code>releaseSegment</code>. + */ + public Segment getSegment() { + synchronized(this) { + int size = segments.size(); + + if (size > 0) { + return (Segment)segments.remove(size - 1); + } + } + return new CachedSegment(); + } + + /** + * Releases a Segment. You should not use a Segment after you release it, + * and you should NEVER release the same Segment more than once, eg: + * <pre> + * segmentCache.releaseSegment(segment); + * segmentCache.releaseSegment(segment); + * </pre> + * Will likely result in very bad things happening! + */ + public void releaseSegment(Segment segment) { + if (segment instanceof CachedSegment) { + synchronized(this) { + segment.array = null; + segment.count = 0; + segments.add(segment); + } + } + } + + + /** + * CachedSegment is used as a tagging interface to determine if + * a Segment can successfully be shared. + */ + private static class CachedSegment extends Segment { + } +} |