1 files changed, 88 insertions, 0 deletions
diff --git a/src/core/Support/BitSetSupport.cs b/src/core/Support/BitSetSupport.cs
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+++ b/src/core/Support/BitSetSupport.cs
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+/*
+ *
+ * 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.
+ *
+*/
+
+namespace Lucene.Net.Support
+{
+    /// <summary>
+    /// This class provides supporting methods of java.util.BitSet
+    /// that are not present in System.Collections.BitArray.
+    /// </summary>
+    public class BitSetSupport
+    {
+        /// <summary>
+        /// Returns the next set bit at or after index, or -1 if no such bit exists.
+        /// </summary>
+        /// <param name="bitArray"></param>
+        /// <param name="index">the index of bit array at which to start checking</param>
+        /// <returns>the next set bit or -1</returns>
+        public static int NextSetBit(System.Collections.BitArray bitArray, int index)
+        {
+            while (index < bitArray.Length)
+            {
+                // if index bit is set, return it
+                // otherwise check next index bit
+                if (bitArray.Get(index))
+                    return index;
+                else
+                    index++;
+            }
+            // if no bits are set at or after index, return -1
+            return -1;
+        }
+
+        /// <summary>
+        /// Returns the next un-set bit at or after index, or -1 if no such bit exists.
+        /// </summary>
+        /// <param name="bitArray"></param>
+        /// <param name="index">the index of bit array at which to start checking</param>
+        /// <returns>the next set bit or -1</returns>
+        public static int NextClearBit(System.Collections.BitArray bitArray, int index)
+        {
+            while (index < bitArray.Length)
+            {
+                // if index bit is not set, return it
+                // otherwise check next index bit
+                if (!bitArray.Get(index))
+                    return index;
+                else
+                    index++;
+            }
+            // if no bits are set at or after index, return -1
+            return -1;
+        }
+
+        /// <summary>
+        /// Returns the number of bits set to true in this BitSet.
+        /// </summary>
+        /// <param name="bits">The BitArray object.</param>
+        /// <returns>The number of bits set to true in this BitSet.</returns>
+        public static int Cardinality(System.Collections.BitArray bits)
+        {
+            int count = 0;
+            for (int i = 0; i < bits.Count; i++)
+            {
+                if (bits[i])
+                    count++;
+            }
+            return count;
+        }
+    }
+}