pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / contrib / facet / src / java / org / apache / lucene / facet / search / FacetsCollector.java

diff --git a/lucene-java-3.5.0/lucene/contrib/facet/src/java/org/apache/lucene/facet/search/FacetsCollector.java b/lucene-java-3.5.0/lucene/contrib/facet/src/java/org/apache/lucene/facet/search/FacetsCollector.java
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+package org.apache.lucene.facet.search;
+
+import java.io.IOException;
+import java.util.List;
+
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.search.Collector;
+import org.apache.lucene.search.Scorer;
+
+import org.apache.lucene.facet.search.params.FacetRequest;
+import org.apache.lucene.facet.search.params.FacetSearchParams;
+import org.apache.lucene.facet.search.results.FacetResult;
+import org.apache.lucene.facet.taxonomy.TaxonomyReader;
+
+/**
+ * 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.
+ */
+
+/**
+ * Collector for facet accumulation. *
+ * 
+ * @lucene.experimental
+ */
+public class FacetsCollector extends Collector {
+
+  protected final FacetsAccumulator facetsAccumulator;
+  private ScoredDocIdCollector scoreDocIdCollector;
+  private List<FacetResult> results;
+  private Object resultsGuard;
+
+  /**
+   * Create a collector for accumulating facets while collecting documents
+   * during search.
+   * 
+   * @param facetSearchParams
+   *          faceted search parameters defining which facets are required and
+   *          how.
+   * @param indexReader
+   *          searched index.
+   * @param taxonomyReader
+   *          taxonomy containing the facets.
+   */
+  public FacetsCollector(FacetSearchParams facetSearchParams,
+                          IndexReader indexReader, TaxonomyReader taxonomyReader) {
+    facetsAccumulator = initFacetsAccumulator(facetSearchParams, indexReader, taxonomyReader);
+    scoreDocIdCollector = initScoredDocCollector(facetSearchParams, indexReader, taxonomyReader);
+    resultsGuard = new Object();
+  }
+
+  /**
+   * Create a {@link ScoredDocIdCollector} to be used as the first phase of
+   * the facet collection. If all facetRequests are do not require the
+   * document score, a ScoredDocIdCollector which does not store the document
+   * scores would be returned. Otherwise a SDIC which does store the documents
+   * will be returned, having an initial allocated space for 1000 such
+   * documents' scores.
+   */
+  protected ScoredDocIdCollector initScoredDocCollector(
+      FacetSearchParams facetSearchParams, IndexReader indexReader,
+      TaxonomyReader taxonomyReader) {
+    for (FacetRequest frq : facetSearchParams.getFacetRequests()) {
+      if (frq.requireDocumentScore()) {
+        return ScoredDocIdCollector.create(1000, true);
+      }
+    }
+    return ScoredDocIdCollector.create(indexReader.maxDoc(), false);
+  }
+
+  /**
+   * Create the {@link FacetsAccumulator} to be used. Default is 
+   * {@link StandardFacetsAccumulator}. Called once at the constructor of the collector.
+   * 
+   * @param facetSearchParams
+   *            The search params.
+   * @param indexReader
+   *            A reader to the index to search in.
+   * @param taxonomyReader
+   *            A reader to the active taxonomy.
+   * @return The {@link FacetsAccumulator} to use.
+   */
+  protected FacetsAccumulator initFacetsAccumulator(FacetSearchParams facetSearchParams,
+                                                    IndexReader indexReader,
+                                                    TaxonomyReader taxonomyReader) {
+    return new StandardFacetsAccumulator(facetSearchParams, indexReader, taxonomyReader);
+  }
+
+  /**
+   * Return accumulated facets results (according to faceted search parameters) 
+   * for collected documents.
+   * @throws IOException on error
+   */
+  public List<FacetResult> getFacetResults() throws IOException {
+    synchronized (resultsGuard) { // over protection 
+      if (results == null) {
+        // lazy creation but just once
+        results = facetsAccumulator.accumulate(scoreDocIdCollector.getScoredDocIDs());
+        scoreDocIdCollector = null;
+      }
+      return results;
+    }
+  }
+
+  @Override
+  public boolean acceptsDocsOutOfOrder() {
+    return false;
+  }
+
+  @Override
+  public void collect(int doc) throws IOException {
+    scoreDocIdCollector.collect(doc);
+  }
+
+  @Override
+  public void setNextReader(IndexReader reader, int docBase) throws IOException {
+    scoreDocIdCollector.setNextReader(reader, docBase);
+  }
+
+  @Override
+  public void setScorer(Scorer scorer) throws IOException {
+    scoreDocIdCollector.setScorer(scorer);
+  }
+
+}