package org.apache.lucene.index;
/*
* 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 java.io.IOException;
import java.io.Reader;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.search.similarities.DefaultSimilarity; // javadocs
import org.apache.lucene.search.similarities.Similarity; // javadocs
import org.apache.lucene.util.BytesRef;
// TODO: how to handle versioning here...?
// TODO: we need to break out separate StoredField...
/** Represents a single field for indexing. IndexWriter
* consumes Iterable<IndexableField> as a document.
*
* @lucene.experimental */
public interface IndexableField extends GeneralField {
/**
* 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
* @return TokenStream value for indexing the document. Should always return
* a non-null value if the field is to be indexed
* @throws IOException Can be thrown while creating the TokenStream
*/
public TokenStream tokenStream(Analyzer analyzer) throws IOException;
/**
* Returns the field's index-time boost.
* <p>
* 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.
* <p>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.
* <p>
* It is illegal to return a boost other than 1.0f for a field that is not
* indexed ({@link IndexableFieldType#indexed()} is false) or omits normalization values
* ({@link IndexableFieldType#omitNorms()} returns true).
*
* @see Similarity#computeNorm(FieldInvertState)
* @see DefaultSimilarity#encodeNormValue(float)
*/
public float boost();
}