1 files changed, 58 insertions, 0 deletions

diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/util/LexicographicComparator.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/util/LexicographicComparator.java
new file mode 100644
index 00000000..0efc50af
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/util/LexicographicComparator.java
@@ -0,0 +1,58 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2014, Bergmann Gabor, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.util;
+
+import java.util.Comparator;
+import java.util.Iterator;
+
+/**
+ * A comparator that compares two iterables based on the lexicographic sorting induced by a comparator on elements.
+ * @author Bergmann Gabor
+ *
+ */
+public class LexicographicComparator<T> implements Comparator<Iterable<? extends T>> {
+    
+    final Comparator<T> elementComparator;
+    
+    public LexicographicComparator(Comparator<T> elementComparator) {
+        super();
+        this.elementComparator = elementComparator;
+    }
+
+    @Override
+    public int compare(Iterable<? extends T> o1, Iterable<? extends T> o2) {
+        Iterator<? extends T> it1 = o1.iterator();
+        Iterator<? extends T> it2 = o2.iterator();
+        
+        boolean has1, has2, bothHaveNext;
+        do {
+            has1 = it1.hasNext();
+            has2 = it2.hasNext();
+            bothHaveNext = has1 && has2;
+            if (bothHaveNext) {
+                T element1 = it1.next();
+                T element2 = it2.next();
+                int elementComparison = elementComparator.compare(element1, element2);
+                if (elementComparison != 0) 
+                    return elementComparison;
+            }
+        } while (bothHaveNext);
+        if (has1 && !has2) {
+            return +1;
+        } else if (!has1 && has2) {
+            return -1;
+        } else /*if (!has1 && !has2)*/ { 
+            return 0;
+        }
+    }
+
+
+
+
+}