--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hg4j/src/main/java/org/tmatesoft/hg/util/PathPool.java	Tue May 10 10:52:53 2011 +0200
@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2011 TMate Software Ltd
+ *  
+ * This program 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; version 2 of the License.
+ *
+ * This program 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.
+ *
+ * For information on how to redistribute this software under
+ * the terms of a license other than GNU General Public License
+ * contact TMate Software at support@hg4j.com
+ */
+package org.tmatesoft.hg.util;
+
+import java.lang.ref.SoftReference;
+import java.util.WeakHashMap;
+
+
+/**
+ * Produces path from strings and caches result for reuse
+ * 
+ * @author Artem Tikhomirov
+ * @author TMate Software Ltd.
+ */
+public class PathPool implements Path.Source {
+	private final WeakHashMap<String, SoftReference<Path>> cache;
+	private final PathRewrite pathRewrite;
+	
+	public PathPool(PathRewrite rewrite) {
+		pathRewrite = rewrite;
+		cache = new WeakHashMap<String, SoftReference<Path>>();
+	}
+
+	public Path path(String p) {
+		p = pathRewrite.rewrite(p);
+		return get(p, true);
+	}
+
+	// pipes path object through cache to reuse instance, if possible
+	public Path path(Path p) {
+		String s = pathRewrite.rewrite(p.toString());
+		Path cached = get(s, false);
+		if (cached == null) {
+			cache.put(s, new SoftReference<Path>(cached = p));
+		}
+		return cached;
+	}
+
+	// XXX what would be parent of an empty path?
+	// Path shall have similar functionality
+	public Path parent(Path path) {
+		if (path.length() == 0) {
+			throw new IllegalArgumentException();
+		}
+		for (int i = path.length() - 2 /*if path represents a dir, trailing char is slash, skip*/; i >= 0; i--) {
+			if (path.charAt(i) == '/') {
+				return get(path.subSequence(0, i+1).toString(), true);
+			}
+		}
+		return get("", true);
+	}
+
+	private Path get(String p, boolean create) {
+		SoftReference<Path> sr = cache.get(p);
+		Path path = sr == null ? null : sr.get();
+		if (path == null) {
+			if (create) {
+				path = Path.create(p);
+				cache.put(p, new SoftReference<Path>(path));
+			} else if (sr != null) {
+				// cached path no longer used, clear cache entry - do not wait for RefQueue to step in
+				cache.remove(p);
+			}
+		} 
+		return path;
+	}
+}