Refactor GeoHashUtils (#40869)

This commit refactors GeoHashUtils class into a new Geohash utility class located in the ES geo library. The intent is to not only better control what geo methods are whitelisted for painless scripting but to clean up the geo utility API in general.

libs/geo/src/main/java/org/elasticsearch/geo/geometry/Rectangle.java

@@ -163,6 +163,14 @@ public boolean crossesDateline() {
         return maxLon < minLon;
     }
 
+    /** returns true if rectangle (defined by minLat, maxLat, minLon, maxLon) contains the lat lon point */
+    public boolean containsPoint(final double lat, final double lon) {
+        if (lat >= minLat && lat <= maxLat) {
+            return crossesDateline() ? lon >= minLon || lon <= maxLon : lon >= minLon && lon <= maxLon;
+        }
+        return false;
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;

libs/geo/src/main/java/org/elasticsearch/geo/utils/BitUtil.java

@@ -0,0 +1,75 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch 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.
+ */
+package org.elasticsearch.geo.utils;
+
+/**
+ * Utilities for common Bit twiddling methods. Borrowed heavily from Lucene (org.apache.lucene.util.BitUtil).
+ */
+public class BitUtil {  // magic numbers for bit interleaving
+    private static final long MAGIC[] = {
+        0x5555555555555555L, 0x3333333333333333L,
+        0x0F0F0F0F0F0F0F0FL, 0x00FF00FF00FF00FFL,
+        0x0000FFFF0000FFFFL, 0x00000000FFFFFFFFL,
+        0xAAAAAAAAAAAAAAAAL
+    };
+    // shift values for bit interleaving
+    private static final short SHIFT[] = {1, 2, 4, 8, 16};
+
+    /**
+     * Interleaves the first 32 bits of each long value
+     *
+     * Adapted from: http://graphics.stanford.edu/~seander/bithacks.html#InterleaveBMN
+     */
+    public static long interleave(int even, int odd) {
+        long v1 = 0x00000000FFFFFFFFL & even;
+        long v2 = 0x00000000FFFFFFFFL & odd;
+        v1 = (v1 | (v1 << SHIFT[4])) & MAGIC[4];
+        v1 = (v1 | (v1 << SHIFT[3])) & MAGIC[3];
+        v1 = (v1 | (v1 << SHIFT[2])) & MAGIC[2];
+        v1 = (v1 | (v1 << SHIFT[1])) & MAGIC[1];
+        v1 = (v1 | (v1 << SHIFT[0])) & MAGIC[0];
+        v2 = (v2 | (v2 << SHIFT[4])) & MAGIC[4];
+        v2 = (v2 | (v2 << SHIFT[3])) & MAGIC[3];
+        v2 = (v2 | (v2 << SHIFT[2])) & MAGIC[2];
+        v2 = (v2 | (v2 << SHIFT[1])) & MAGIC[1];
+        v2 = (v2 | (v2 << SHIFT[0])) & MAGIC[0];
+
+        return (v2<<1) | v1;
+    }
+
+    /**
+     * Extract just the even-bits value as a long from the bit-interleaved value
+     */
+    public static long deinterleave(long b) {
+        b &= MAGIC[0];
+        b = (b ^ (b >>> SHIFT[0])) & MAGIC[1];
+        b = (b ^ (b >>> SHIFT[1])) & MAGIC[2];
+        b = (b ^ (b >>> SHIFT[2])) & MAGIC[3];
+        b = (b ^ (b >>> SHIFT[3])) & MAGIC[4];
+        b = (b ^ (b >>> SHIFT[4])) & MAGIC[5];
+        return b;
+    }
+
+    /**
+     * flip flops odd with even bits
+     */
+    public static final long flipFlop(final long b) {
+        return ((b & MAGIC[6]) >>> 1) | ((b & MAGIC[0]) << 1 );
+    }
+}