SOLR-1302: slight refactoring for common code.

git-svn-id: https://svn.apache.org/repos/asf/lucene/solr/trunk@881037 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/solr/search/function/distance/DistanceUtils.java

@@ -0,0 +1,48 @@
+package org.apache.solr.search.function.distance;
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+/**
+ * Useful distance utiltities
+ *
+ **/
+public class DistanceUtils {
+  /**
+   * @see org.apache.solr.search.function.distance.HaversineFunction
+   * 
+   * @param x1
+   * @param y1
+   * @param x2
+   * @param y2
+   * @param radius
+   * @return
+   */
+  public static double haversine(double x1, double y1, double x2, double y2, double radius){
+    double result = 0;
+    if ((x1 != x2) || (y1 != y2)) {
+      double diffX = x1 - x2;
+      double diffY = y1 - y2;
+      double hsinX = Math.sin(diffX / 2);
+      double hsinY = Math.sin(diffY / 2);
+      double h = hsinX * hsinX +
+              (Math.cos(x1) * Math.cos(x2) * hsinY * hsinY);
+      result = (radius * 2 * Math.atan2(Math.sqrt(h), Math.sqrt(1 - h)));
+    }
+    return result;
+  }
+}

src/java/org/apache/solr/search/function/distance/HaversineFunction.java

@@ -73,15 +73,7 @@ public class HaversineFunction extends ValueSource {
     double y2 = y2DV.doubleVal(doc);
 
     //make sure they aren't all the same, as then we can just return 0
-    if ((x1 != x2) || (y1 != y2)) {
+    result = DistanceUtils.haversine(x1, y1, x2, y2, radius);
-      double diffX = x1 - x2;
-      double diffY = y1 - y2;
-      double hsinX = Math.sin(diffX / 2);
-      double hsinY = Math.sin(diffY / 2);
-      double h = hsinX * hsinX +
-              (Math.cos(x1) * Math.cos(x2) * hsinY * hsinY);
-      result = (radius * 2 * Math.atan2(Math.sqrt(h), Math.sqrt(1 - h)));
-    }
 
     return result;
   }