1 files changed, 97 insertions, 0 deletions

diff --git a/subprojects/interpreter-rete/src/main/java/tools/refinery/interpreter/rete/util/OrderingCompareAgent.java b/subprojects/interpreter-rete/src/main/java/tools/refinery/interpreter/rete/util/OrderingCompareAgent.java
new file mode 100644
index 00000000..20fd35dd
--- /dev/null
+++ b/subprojects/interpreter-rete/src/main/java/tools/refinery/interpreter/rete/util/OrderingCompareAgent.java
@@ -0,0 +1,97 @@
+/*******************************************************************************
+ * Copyright (c) 2004-2010 Gabor Bergmann 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.interpreter.rete.util;
+
+import java.util.Comparator;
+
+/**
+ * Comparing agent for an ordering. Terminology: the "preferred" item will register as LESS.
+ *
+ * @author Gabor Bergmann
+ *
+ */
+public abstract class OrderingCompareAgent<T> {
+    protected T a;
+    protected T b;
+
+    /**
+     * @param a
+     * @param b
+     */
+    protected OrderingCompareAgent(T a, T b) {
+        super();
+        this.a = a;
+        this.b = b;
+    }
+
+    int result = 0;
+
+    protected abstract void doCompare();
+
+    /**
+     * @return the result
+     */
+    public int compare() {
+        doCompare();
+        return result;
+    }
+
+    // COMPARISON HELPERS
+    protected boolean isUnknown() {
+        return result == 0;
+    }
+
+    /**
+     * @pre result == 0
+     */
+    protected boolean consider(int partial) {
+        if (isUnknown())
+            result = partial;
+        return isUnknown();
+    }
+
+    protected boolean swallowBoolean(boolean x) {
+        return x;
+    }
+
+    // PREFERENCE FUNCTIONS
+    protected static int dontCare() {
+        return 0;
+    }
+
+    protected static int preferTrue(boolean b1, boolean b2) {
+        return (b1 ^ b2) ? (b1 ? -1 : +1) : 0;
+    }
+
+    protected static int preferFalse(boolean b1, boolean b2) {
+        return (b1 ^ b2) ? (b2 ? -1 : +1) : 0;
+    }
+
+    protected static <U> int preferLess(Comparable<U> c1, U c2) {
+        return c1.compareTo(c2);
+    }
+
+    protected static <U> int preferLess(U c1, U c2, Comparator<U> comp) {
+        return comp.compare(c1, c2);
+    }
+
+    protected static <U> int preferMore(Comparable<U> c1, U c2) {
+        return reverse(c1.compareTo(c2));
+    }
+
+    protected static <U> int preferMore(U c1, U c2, Comparator<U> comp) {
+        return reverse(comp.compare(c1, c2));
+    }
+
+        private static int reverse(int value) {
+                return Integer.compare(0, value);
+        }
+
+}