/**
* 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.
*/
package org.apache.lucene.search.function;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.FieldCache;
import java.io.IOException;
/**
* Expert: obtains the ordinal of the field value from the default Lucene
* {@link org.apache.lucene.search.FieldCache Fieldcache} using getStringIndex().
* <p>
* The native lucene index order is used to assign an ordinal value for each field value.
* <p
* Field values (terms) are lexicographically ordered by unicode value, and numbered starting at 1.
* <p>
* Example:
* <br>If there were only three field values: "apple","banana","pear"
* <br>then ord("apple")=1, ord("banana")=2, ord("pear")=3
* <p>
* WARNING:
* ord() depends on the position in an index and can thus change
* when other documents are inserted or deleted,
* or if a MultiSearcher is used.
*
* @lucene.experimental
*
* <p><b>NOTE</b>: with the switch in 2.9 to segment-based
* searching, if {@link #getValues} is invoked with a
* composite (multi-segment) reader, this can easily cause
* double RAM usage for the values in the FieldCache. It's
* best to switch your application to pass only atomic
* (single segment) readers to this API.</p>
*/
public class OrdFieldSource extends ValueSource {
protected String field;
/**
* Constructor for a certain field.
* @param field field whose values order is used.
*/
public OrdFieldSource(String field) {
this.field = field;
}
/*(non-Javadoc) @see org.apache.lucene.search.function.ValueSource#description() */
@Override
public String description() {
return "ord(" + field + ')';
}
/*(non-Javadoc) @see org.apache.lucene.search.function.ValueSource#getValues(org.apache.lucene.index.IndexReader) */
@Override
public DocValues getValues(IndexReader reader) throws IOException {
final int[] arr = FieldCache.DEFAULT.getStringIndex(reader, field).order;
return new DocValues() {
/*(non-Javadoc) @see org.apache.lucene.search.function.DocValues#floatVal(int) */
@Override
public float floatVal(int doc) {
return arr[doc];
}
/*(non-Javadoc) @see org.apache.lucene.search.function.DocValues#strVal(int) */
@Override
public String strVal(int doc) {
// the string value of the ordinal, not the string itself
return Integer.toString(arr[doc]);
}
/*(non-Javadoc) @see org.apache.lucene.search.function.DocValues#toString(int) */
@Override
public String toString(int doc) {
return description() + '=' + intVal(doc);
}
/*(non-Javadoc) @see org.apache.lucene.search.function.DocValues#getInnerArray() */
@Override
Object getInnerArray() {
return arr;
}
};
}
/*(non-Javadoc) @see java.lang.Object#equals(java.lang.Object) */
@Override
public boolean equals(Object o) {
if (o == this) return true;
if (o == null) return false;
if (o.getClass() != OrdFieldSource.class) return false;
OrdFieldSource other = (OrdFieldSource)o;
return this.field.equals(other.field);
}
private static final int hcode = OrdFieldSource.class.hashCode();
/*(non-Javadoc) @see java.lang.Object#hashCode() */
@Override
public int hashCode() {
return hcode + field.hashCode();
}
}