2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
9 * http://www.apache.org/licenses/LICENSE-2.0
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
18 package org.apache.lucene.search.function;
20 import org.apache.lucene.index.IndexReader;
21 import org.apache.lucene.search.FieldCache;
23 import java.io.IOException;
26 * Expert: obtains the ordinal of the field value from the default Lucene
27 * {@link org.apache.lucene.search.FieldCache Fieldcache} using getStringIndex().
29 * The native lucene index order is used to assign an ordinal value for each field value.
31 * Field values (terms) are lexicographically ordered by unicode value, and numbered starting at 1.
34 * <br>If there were only three field values: "apple","banana","pear"
35 * <br>then ord("apple")=1, ord("banana")=2, ord("pear")=3
38 * ord() depends on the position in an index and can thus change
39 * when other documents are inserted or deleted,
40 * or if a MultiSearcher is used.
42 * @lucene.experimental
44 * <p><b>NOTE</b>: with the switch in 2.9 to segment-based
45 * searching, if {@link #getValues} is invoked with a
46 * composite (multi-segment) reader, this can easily cause
47 * double RAM usage for the values in the FieldCache. It's
48 * best to switch your application to pass only atomic
49 * (single segment) readers to this API.</p>
52 public class OrdFieldSource extends ValueSource {
53 protected String field;
56 * Constructor for a certain field.
57 * @param field field whose values order is used.
59 public OrdFieldSource(String field) {
63 /*(non-Javadoc) @see org.apache.lucene.search.function.ValueSource#description() */
65 public String description() {
66 return "ord(" + field + ')';
69 /*(non-Javadoc) @see org.apache.lucene.search.function.ValueSource#getValues(org.apache.lucene.index.IndexReader) */
71 public DocValues getValues(IndexReader reader) throws IOException {
72 final int[] arr = FieldCache.DEFAULT.getStringIndex(reader, field).order;
73 return new DocValues() {
74 /*(non-Javadoc) @see org.apache.lucene.search.function.DocValues#floatVal(int) */
76 public float floatVal(int doc) {
79 /*(non-Javadoc) @see org.apache.lucene.search.function.DocValues#strVal(int) */
81 public String strVal(int doc) {
82 // the string value of the ordinal, not the string itself
83 return Integer.toString(arr[doc]);
85 /*(non-Javadoc) @see org.apache.lucene.search.function.DocValues#toString(int) */
87 public String toString(int doc) {
88 return description() + '=' + intVal(doc);
90 /*(non-Javadoc) @see org.apache.lucene.search.function.DocValues#getInnerArray() */
92 Object getInnerArray() {
98 /*(non-Javadoc) @see java.lang.Object#equals(java.lang.Object) */
100 public boolean equals(Object o) {
101 if (o == this) return true;
102 if (o == null) return false;
103 if (o.getClass() != OrdFieldSource.class) return false;
104 OrdFieldSource other = (OrdFieldSource)o;
105 return this.field.equals(other.field);
108 private static final int hcode = OrdFieldSource.class.hashCode();
110 /*(non-Javadoc) @see java.lang.Object#hashCode() */
112 public int hashCode() {
113 return hcode + field.hashCode();