pylucene 3.5.0-3

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

diff --git a/lucene-java-3.5.0/lucene/contrib/grouping/src/java/org/apache/lucene/search/grouping/TermFirstPassGroupingCollector.java b/lucene-java-3.5.0/lucene/contrib/grouping/src/java/org/apache/lucene/search/grouping/TermFirstPassGroupingCollector.java
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+++ b/lucene-java-3.5.0/lucene/contrib/grouping/src/java/org/apache/lucene/search/grouping/TermFirstPassGroupingCollector.java
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+package org.apache.lucene.search.grouping;
+
+/**
+ * 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 org.apache.lucene.index.IndexReader;
+import org.apache.lucene.search.FieldCache;
+import org.apache.lucene.search.Sort;
+
+/**
+ * Concrete implementation of {@link AbstractFirstPassGroupingCollector} that groups based on
+ * field values and more specifically uses {@link org.apache.lucene.search.FieldCache.StringIndex}
+ * to collect groups.
+ *
+ * @lucene.experimental
+ */
+public class TermFirstPassGroupingCollector extends AbstractFirstPassGroupingCollector<String> {
+
+  private FieldCache.StringIndex index;
+
+  private String groupField;
+
+  /**
+   * Create the first pass collector.
+   *
+   *  @param groupField The field used to group
+   *    documents. This field must be single-valued and
+   *    indexed (FieldCache is used to access its value
+   *    per-document).
+   *  @param groupSort The {@link Sort} used to sort the
+   *    groups.  The top sorted document within each group
+   *    according to groupSort, determines how that group
+   *    sorts against other groups.  This must be non-null,
+   *    ie, if you want to groupSort by relevance use
+   *    Sort.RELEVANCE.
+   *  @param topNGroups How many top groups to keep.
+   *  @throws IOException When I/O related errors occur
+   */
+  public TermFirstPassGroupingCollector(String groupField, Sort groupSort, int topNGroups) throws IOException {
+    super(groupSort, topNGroups);
+    this.groupField = groupField;
+  }
+
+  @Override
+  protected String getDocGroupValue(int doc) {
+    final int ord = index.order[doc];
+    return ord == 0 ? null : index.lookup[ord];
+  }
+
+  @Override
+  protected String copyDocGroupValue(String groupValue, String reuse) {
+    return groupValue;
+  }
+
+  @Override
+  public void setNextReader(IndexReader reader, int docBase) throws IOException {
+    super.setNextReader(reader, docBase);
+    index = FieldCache.DEFAULT.getStringIndex(reader, groupField);
+  }
+}