pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / src / java / org / apache / lucene / search / FieldDocSortedHitQueue.java

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/FieldDocSortedHitQueue.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/FieldDocSortedHitQueue.java
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+++ b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/FieldDocSortedHitQueue.java
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+package org.apache.lucene.search;
+
+/**
+ * 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 org.apache.lucene.util.PriorityQueue;
+import java.io.IOException;
+import java.text.Collator;
+import java.util.Locale;
+
+/**
+ * Expert: Collects sorted results from Searchable's and collates them.
+ * The elements put into this queue must be of type FieldDoc.
+ *
+ * <p>Created: Feb 11, 2004 2:04:21 PM
+ *
+ * @since   lucene 1.4
+ */
+class FieldDocSortedHitQueue extends PriorityQueue<FieldDoc> {
+
+  volatile SortField[] fields = null;
+
+  // used in the case where the fields are sorted by locale
+  // based strings
+  volatile Collator[] collators = null;
+
+  volatile FieldComparator[] comparators = null;
+
+
+  /**
+   * Creates a hit queue sorted by the given list of fields.
+   * @param fields Fieldable names, in priority order (highest priority first).
+   * @param size  The number of hits to retain.  Must be greater than zero.
+   */
+  FieldDocSortedHitQueue (int size) {
+    initialize (size);
+  }
+
+
+  /**
+   * Allows redefinition of sort fields if they are <code>null</code>.
+   * This is to handle the case using ParallelMultiSearcher where the
+   * original list contains AUTO and we don't know the actual sort
+   * type until the values come back.  The fields can only be set once.
+   * This method should be synchronized external like all other PQ methods.
+   * @param fields
+   */
+  void setFields (SortField[] fields) throws IOException {
+    this.fields = fields;
+    this.collators = hasCollators (fields);
+    comparators = new FieldComparator[fields.length];
+    for(int fieldIDX=0;fieldIDX<fields.length;fieldIDX++) {
+      comparators[fieldIDX] = fields[fieldIDX].getComparator(1, fieldIDX);
+    }
+  }
+
+
+  /** Returns the fields being used to sort. */
+  SortField[] getFields() {
+    return fields;
+  }
+
+
+  /** Returns an array of collators, possibly <code>null</code>.  The collators
+   * correspond to any SortFields which were given a specific locale.
+   * @param fields Array of sort fields.
+   * @return Array, possibly <code>null</code>.
+   */
+  private Collator[] hasCollators (final SortField[] fields) {
+    if (fields == null) return null;
+    Collator[] ret = new Collator[fields.length];
+    for (int i=0; i<fields.length; ++i) {
+      Locale locale = fields[i].getLocale();
+      if (locale != null)
+        ret[i] = Collator.getInstance (locale);
+    }
+    return ret;
+  }
+
+
+  /**
+   * Returns whether <code>a</code> is less relevant than <code>b</code>.
+   * @param a ScoreDoc
+   * @param b ScoreDoc
+   * @return <code>true</code> if document <code>a</code> should be sorted after document <code>b</code>.
+   */
+  @SuppressWarnings("unchecked") @Override
+  protected final boolean lessThan(final FieldDoc docA, final FieldDoc docB) {
+    final int n = fields.length;
+    int c = 0;
+    for (int i=0; i<n && c==0; ++i) {
+      final int type = fields[i].getType();
+      if (type == SortField.STRING) {
+        final String s1 = (String) docA.fields[i];
+        final String s2 = (String) docB.fields[i];
+        // null values need to be sorted first, because of how FieldCache.getStringIndex()
+        // works - in that routine, any documents without a value in the given field are
+        // put first.  If both are null, the next SortField is used
+        if (s1 == null) {
+          c = (s2 == null) ? 0 : -1;
+        } else if (s2 == null) {
+          c = 1;
+        } else if (fields[i].getLocale() == null) {
+          c = s1.compareTo(s2);
+        } else {
+          c = collators[i].compare(s1, s2);
+        }
+      } else {
+        c = comparators[i].compareValues(docA.fields[i], docB.fields[i]);
+      }
+      // reverse sort
+      if (fields[i].getReverse()) {
+        c = -c;
+      }
+    }
+
+    // avoid random sort order that could lead to duplicates (bug #31241):
+    if (c == 0)
+      return docA.doc > docB.doc;
+
+    return c > 0;
+  }
+}