pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / src / java / org / apache / lucene / index / NoMergePolicy.java

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/index/NoMergePolicy.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/index/NoMergePolicy.java
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+package org.apache.lucene.index;
+
+/**
+ * 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.
+ */
+
+import java.io.IOException;
+import java.util.Map;
+
+/**
+ * A {@link MergePolicy} which never returns merges to execute (hence it's
+ * name). It is also a singleton and can be accessed through
+ * {@link NoMergePolicy#NO_COMPOUND_FILES} if you want to indicate the index
+ * does not use compound files, or through {@link NoMergePolicy#COMPOUND_FILES}
+ * otherwise. Use it if you want to prevent an {@link IndexWriter} from ever
+ * executing merges, without going through the hassle of tweaking a merge
+ * policy's settings to achieve that, such as changing its merge factor.
+ */
+public final class NoMergePolicy extends MergePolicy {
+
+  /**
+   * A singleton {@link NoMergePolicy} which indicates the index does not use
+   * compound files.
+   */
+  public static final MergePolicy NO_COMPOUND_FILES = new NoMergePolicy(false);
+
+  /**
+   * A singleton {@link NoMergePolicy} which indicates the index uses compound
+   * files.
+   */
+  public static final MergePolicy COMPOUND_FILES = new NoMergePolicy(true);
+
+  private final boolean useCompoundFile;
+  
+  private NoMergePolicy(boolean useCompoundFile) {
+    // prevent instantiation
+    this.useCompoundFile = useCompoundFile;
+  }
+
+  @Override
+  public void close() {}
+
+  @Override
+  public MergeSpecification findMerges(SegmentInfos segmentInfos)
+      throws CorruptIndexException, IOException { return null; }
+
+  @Override
+  public MergeSpecification findForcedMerges(SegmentInfos segmentInfos,
+             int maxSegmentCount, Map<SegmentInfo,Boolean> segmentsToMerge)
+      throws CorruptIndexException, IOException { return null; }
+
+  @Override
+  public MergeSpecification findForcedDeletesMerges(SegmentInfos segmentInfos)
+      throws CorruptIndexException, IOException { return null; }
+
+  @Override
+  public boolean useCompoundFile(SegmentInfos segments, SegmentInfo newSegment) { return useCompoundFile; }
+
+  @Override
+  public void setIndexWriter(IndexWriter writer) {}
+
+  @Override
+  public String toString() {
+    return "NoMergePolicy";
+  }
+}