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1 files changed, 48 insertions, 0 deletions

diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/TruthOperator.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/TruthOperator.java
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index 00000000000..26e8b183c21
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+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/TruthOperator.java
@@ -0,0 +1,48 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.searchlib.rankingexpression.rule;
+
+import java.io.Serializable;
+
+/**
+ * A mathematical operator
+ *
+ * @author <a href="mailto:bratseth@yahoo-inc.com">Jon Bratseth</a>
+ */
+public enum TruthOperator  implements Serializable {
+
+    SMALLER("<")   { public boolean evaluate(double x, double y) { return x<y; } },
+    SMALLEREQUAL("<=")  { public boolean evaluate(double x, double y) { return x<=y; } },
+    EQUAL("==")  { public boolean evaluate(double x, double y) { return x==y; } },
+    APPROX_EQUAL("~=") { public boolean evaluate(double x, double y) { return approxEqual(x,y); } },
+    LARGER(">")   { public boolean evaluate(double x, double y) { return x>y; } },
+    LARGEREQUAL(">=")  { public boolean evaluate(double x, double y) { return x>=y; } };
+
+    private final String operatorString;
+
+    TruthOperator(String operatorString) {
+        this.operatorString=operatorString;
+    }
+
+    /** Perform the truth operation on the input */
+    public abstract boolean evaluate(double x, double y);
+
+    public @Override String toString() { return operatorString; }
+
+    public static TruthOperator fromString(String string) {
+        for (TruthOperator operator : values())
+            if (operator.toString().equals(string))
+                return operator;
+        throw new IllegalArgumentException("Illegal truth operator '" + string + "'");
+    }
+
+    private static boolean approxEqual(double x,double y) {
+        if (y < -1.0 || y > 1.0) {
+            x = Math.nextAfter(x/y, 1.0);
+            y = 1.0;
+        } else {
+            x = Math.nextAfter(x, y);
+        }
+        return x==y;
+    }
+
+}
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