org.apache.lucene.index.IndexableField Maven / Gradle / Ivy
/*
* 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.index;
import java.io.Reader;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.search.similarities.DefaultSimilarity;
import org.apache.lucene.search.similarities.Similarity;
import org.apache.lucene.util.BytesRef;
// TODO: how to handle versioning here...?
/** Represents a single field for indexing. IndexWriter
* consumes Iterable<IndexableField> as a document.
*
* @lucene.experimental */
public interface IndexableField {
/** Field name */
public String name();
/** {@link IndexableFieldType} describing the properties
* of this field. */
public IndexableFieldType fieldType();
/**
* Returns the field's index-time boost.
*
* Only fields can have an index-time boost, if you want to simulate
* a "document boost", then you must pre-multiply it across all the
* relevant fields yourself.
*
The boost is used to compute the norm factor for the field. By
* default, in the {@link Similarity#computeNorm(FieldInvertState)} method,
* the boost value is multiplied by the length normalization factor and then
* rounded by {@link DefaultSimilarity#encodeNormValue(float)} before it is stored in the
* index. One should attempt to ensure that this product does not overflow
* the range of that encoding.
*
* It is illegal to return a boost other than 1.0f for a field that is not
* indexed ({@link IndexableFieldType#indexOptions()} is IndexOptions.NONE) or
* omits normalization values ({@link IndexableFieldType#omitNorms()} returns true).
*
* @see Similarity#computeNorm(FieldInvertState)
* @see DefaultSimilarity#encodeNormValue(float)
*/
public float boost();
/** Non-null if this field has a binary value */
public BytesRef binaryValue();
/** Non-null if this field has a string value */
public String stringValue();
/** Non-null if this field has a Reader value */
public Reader readerValue();
/** Non-null if this field has a numeric value */
public Number numericValue();
/**
* Creates the TokenStream used for indexing this field. If appropriate,
* implementations should use the given Analyzer to create the TokenStreams.
*
* @param analyzer Analyzer that should be used to create the TokenStreams from
* @param reuse TokenStream for a previous instance of this field name. This allows
* custom field types (like StringField and NumericField) that do not use
* the analyzer to still have good performance. Note: the passed-in type
* may be inappropriate, for example if you mix up different types of Fields
* for the same field name. So its the responsibility of the implementation to
* check.
* @return TokenStream value for indexing the document. Should always return
* a non-null value if the field is to be indexed
*/
public TokenStream tokenStream(Analyzer analyzer, TokenStream reuse);
}