+/*******************************************************************************\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));
+ }
+}