From 90825e2392b2d70e43c7a25b8a3752299a933894 Mon Sep 17 00:00:00 2001
From: toma <toma@283d02a7-25f6-0310-bc7c-ecb5cbfe19da>
Date: Wed, 25 Nov 2009 17:56:58 +0000
Subject: Copy the KDE 3.5 branch to branches/trinity for new KDE 3.5 features.
 BUG:215923

git-svn-id: svn://anonsvn.kde.org/home/kde/branches/trinity/kdebindings@1054174 283d02a7-25f6-0310-bc7c-ecb5cbfe19da
---
 qtjava/javalib/org/kde/qt/WeakValueMap.java | 68 +++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 qtjava/javalib/org/kde/qt/WeakValueMap.java

(limited to 'qtjava/javalib/org/kde/qt/WeakValueMap.java')

diff --git a/qtjava/javalib/org/kde/qt/WeakValueMap.java b/qtjava/javalib/org/kde/qt/WeakValueMap.java
new file mode 100644
index 00000000..4378b7e2
--- /dev/null
+++ b/qtjava/javalib/org/kde/qt/WeakValueMap.java
@@ -0,0 +1,68 @@
+/** From Section 12.5.3, Reference Queues page 324-326
+	of 'The Java Programming Language, Third Edition'.
+	
+	But why wasn't it included in the java.util Collection package?
+	*/
+	
+
+package org.kde.qt;
+
+import java.lang.ref.*;
+import java.util.*;
+
+public class WeakValueMap extends HashMap {
+	private ReferenceQueue reaped = new ReferenceQueue();
+	
+	private static class ValueRef extends WeakReference  {
+		private final Object key;		// key for value
+		
+		ValueRef(Object val, Object key, ReferenceQueue q) {
+			super(val, q);
+			this.key = key;
+		}
+	}
+	
+	public Object put(Object key, Object value) {
+		reap();
+		ValueRef vr = new ValueRef(value, key, reaped);
+		return super.put(key, vr);
+	}
+	
+	public Object get(Object key) {
+		reap();
+		ValueRef vr = (ValueRef) super.get(key);
+		if (vr == null) {
+			return null;
+		} else {
+			return vr.get();
+		}
+	}
+	
+	/** Force an entry to be removed if it is known to be invalid,
+		rather than waiting for the garbage collector to put it
+		on the reaped queue.
+	*/
+	public Object remove(Object key) {
+		reap();
+		ValueRef vr = (ValueRef) super.get(key);
+		if (vr == null) {
+			return null;
+		} else {
+			vr.clear();
+			super.remove(key);
+			return null;
+		}
+	}
+	
+	public int size() {
+		reap();
+		return super.size();
+	}
+	
+	public void reap() {
+		ValueRef ref;
+		while ((ref = (ValueRef) reaped.poll()) != null) {
+			super.remove(ref.key);
+		}
+	}
+}
-- 
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