pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / contrib / grouping / src / java / org / apache / lucene / search / grouping / SentinelIntSet.java

diff --git a/lucene-java-3.5.0/lucene/contrib/grouping/src/java/org/apache/lucene/search/grouping/SentinelIntSet.java b/lucene-java-3.5.0/lucene/contrib/grouping/src/java/org/apache/lucene/search/grouping/SentinelIntSet.java
new file mode 100644 (file)
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+++ b/lucene-java-3.5.0/lucene/contrib/grouping/src/java/org/apache/lucene/search/grouping/SentinelIntSet.java
@@ -0,0 +1,116 @@
+/**
+ * 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.
+ */
+
+package org.apache.lucene.search.grouping;
+
+import java.util.Arrays;
+
+/** A native int set where one value is reserved to mean "EMPTY" */
+class SentinelIntSet {
+  public int[] keys;
+  public int count;
+  public final int emptyVal;
+  public int rehashCount;   // the count at which a rehash should be done
+
+  public SentinelIntSet(int size, int emptyVal) {
+    this.emptyVal = emptyVal;
+    int tsize = Math.max(org.apache.lucene.util.BitUtil.nextHighestPowerOfTwo(size), 1);
+    rehashCount = tsize - (tsize>>2);
+    if (size >= rehashCount) {  // should be able to hold "size" w/o rehashing
+      tsize <<= 1;
+      rehashCount = tsize - (tsize>>2);
+    }
+    keys = new int[tsize];
+    if (emptyVal != 0)
+      clear();
+  }
+
+  public void clear() {
+    Arrays.fill(keys, emptyVal);
+    count = 0;
+  }
+
+  public int hash(int key) {
+    return key;
+  }
+
+  public int size() { return count; }
+
+  /** returns the slot for this key */
+  public int getSlot(int key) {
+    assert key != emptyVal;
+    int h = hash(key);
+    int s = h & (keys.length-1);
+    if (keys[s] == key || keys[s]== emptyVal) return s;
+
+    int increment = (h>>7)|1;
+    do {
+      s = (s + increment) & (keys.length-1);
+    } while (keys[s] != key && keys[s] != emptyVal);
+    return s;
+  }
+
+  /** returns the slot for this key, or -slot-1 if not found */
+  public int find(int key) {
+    assert key != emptyVal;
+    int h = hash(key);
+    int s = h & (keys.length-1);
+    if (keys[s] == key) return s;
+    if (keys[s] == emptyVal) return -s-1;
+
+    int increment = (h>>7)|1;
+    for(;;) {
+      s = (s + increment) & (keys.length-1);
+      if (keys[s] == key) return s;
+      if (keys[s] == emptyVal) return -s-1;
+    }
+  }
+
+  public boolean exists(int key) {
+    return find(key) >= 0;
+  }
+
+  public int put(int key) {
+    int s = find(key);
+    if (s < 0) {
+      if (count >= rehashCount) {
+        rehash();
+        s = getSlot(key);
+      } else {
+        s = -s-1;
+      }
+      count++;
+      keys[s] = key;
+    }
+    return s;
+  }
+
+  public void rehash() {
+    int newSize = keys.length << 1;
+    int[] oldKeys = keys;
+    keys = new int[newSize];
+    if (emptyVal != 0) Arrays.fill(keys, emptyVal);
+
+    for (int i=0; i<oldKeys.length; i++) {
+      int key = oldKeys[i];
+      if (key == emptyVal) continue;
+      int newSlot = getSlot(key);
+      keys[newSlot] = key;
+    }
+    rehashCount = newSize - (newSize>>2);
+  }
+}