Migrated source code from Simantics SVN

[simantics/platform.git] / bundles / org.simantics.databoard / src / org / simantics / databoard / util / IdentityPair.java

diff --git a/bundles/org.simantics.databoard/src/org/simantics/databoard/util/IdentityPair.java b/bundles/org.simantics.databoard/src/org/simantics/databoard/util/IdentityPair.java
new file mode 100644 (file)
index 0000000..a702556
--- /dev/null
+++ b/bundles/org.simantics.databoard/src/org/simantics/databoard/util/IdentityPair.java
@@ -0,0 +1,65 @@
+/*******************************************************************************\r
+ *  Copyright (c) 2010 Association for Decentralized Information Management in\r
+ *  Industry THTH ry.\r
+ *  All rights reserved. This program and the accompanying materials\r
+ *  are made available under the terms of the Eclipse Public License v1.0\r
+ *  which accompanies this distribution, and is available at\r
+ *  http://www.eclipse.org/legal/epl-v10.html\r
+ *\r
+ *  Contributors:\r
+ *      VTT Technical Research Centre of Finland - initial API and implementation\r
+ *******************************************************************************/\r
+package org.simantics.databoard.util;
+
+/**
+ * A generic Pair (2-tuple) structure for containing two object instances of
+ * chosen types. Hash and equals are based on identities.
+ * 
+ * Element order doesn't matter.
+ * 
+ * @param <T1> type of first element
+ * @param <T2> type of second element
+ */
+public final class IdentityPair<T1, T2> {
+    public final T1 first;
+    public final T2 second;
+    private final int hash;
+
+    public static <T1, T2> IdentityPair<T1, T2> make(T1 t1, T2 t2) {
+        return new IdentityPair<T1, T2>(t1, t2);
+    }
+
+    public IdentityPair(T1 first, T2 second) {
+        //assert(first != null);
+        //assert(second != null);
+        this.first = first;
+        this.second = second;
+        this.hash = makeHash();
+    }
+    
+    @Override
+    public boolean equals(Object obj) {        
+        if (obj == null)
+            return false;
+        if (!(obj.getClass().equals(this.getClass())))
+            return false;
+        IdentityPair<?, ?> other = (IdentityPair<?, ?>) obj;
+        return ( (other.first == first) && (other.second == second) ) ||
+        ( (other.first == second) && (other.second == first) );
+    }
+    
+    @Override
+    public int hashCode() {
+        return hash;
+    }
+    
+    @Override
+    public String toString() {
+        return "<"+first+", "+second+">";
+    }
+    
+    private int makeHash() {
+        return (first == null ? 0 : System.identityHashCode(first)) + 
+               (second == null ? 0 : System.identityHashCode(second));
+    }
+}