/*
* Copyright (c) 2001, 2008, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
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*/
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<Segment> 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<Segment>(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 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 {
}
}