/*
* Created on 28-Oct-2004
*/
/*
* 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.highlight;
import java.io.IOException;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.miscellaneous.LimitTokenOffsetFilter;
import org.apache.lucene.document.Document;
import org.apache.lucene.index.Fields;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Terms;
/**
* Convenience methods for obtaining a {@link TokenStream} for use with the {@link Highlighter} - can obtain from
* term vectors with offsets and positions or from an Analyzer re-parsing the stored content.
*
* @see TokenStreamFromTermVector
*/
public class TokenSources {
private TokenSources() {}
/**
* Get a token stream from either un-inverting a term vector if possible, or by analyzing the text.
*
* WARNING: Don't call this if there is more than one value for this field. If there are, and if there are term
* vectors, then there is a single tokenstream with offsets suggesting all the field values were concatenated.
*
* @param field The field to either get term vectors from or to analyze the text from.
* @param tvFields from {@link IndexReader#getTermVectors(int)}. Possibly null. For performance, this instance should
* be re-used for the same document (e.g. when highlighting multiple fields).
* @param text the text to analyze, failing term vector un-inversion
* @param analyzer the analyzer to analyze {@code text} with, failing term vector un-inversion
* @param maxStartOffset Terms with a startOffset greater than this aren't returned. Use -1 for no limit.
* Suggest using {@link Highlighter#getMaxDocCharsToAnalyze()} - 1.
*
* @return a token stream from either term vectors, or from analyzing the text. Never null.
*/
public static TokenStream getTokenStream(String field, Fields tvFields, String text, Analyzer analyzer,
int maxStartOffset) throws IOException {
TokenStream tokenStream = getTermVectorTokenStreamOrNull(field, tvFields, maxStartOffset);
if (tokenStream != null) {
return tokenStream;
}
tokenStream = analyzer.tokenStream(field, text);
if (maxStartOffset >= 0 && maxStartOffset < text.length() - 1) {
tokenStream = new LimitTokenOffsetFilter(tokenStream, maxStartOffset);
}
return tokenStream;
}
/**
* Get a token stream by un-inverting the term vector. This method returns null if {@code tvFields} is null
* or if the field has no term vector, or if the term vector doesn't have offsets. Positions are recommended on the
* term vector but it isn't strictly required.
*
* @param field The field to get term vectors from.
* @param tvFields from {@link IndexReader#getTermVectors(int)}. Possibly null. For performance, this instance should
* be re-used for the same document (e.g. when highlighting multiple fields).
* @param maxStartOffset Terms with a startOffset greater than this aren't returned. Use -1 for no limit.
* Suggest using {@link Highlighter#getMaxDocCharsToAnalyze()} - 1
* @return a token stream from term vectors. Null if no term vectors with the right options.
*/
public static TokenStream getTermVectorTokenStreamOrNull(String field, Fields tvFields, int maxStartOffset)
throws IOException {
if (tvFields == null) {
return null;
}
final Terms tvTerms = tvFields.terms(field);
if (tvTerms == null || !tvTerms.hasOffsets()) {
return null;
}
return new TokenStreamFromTermVector(tvTerms, maxStartOffset);
}
/**
* A convenience method that tries to first get a {@link TokenStreamFromTermVector} for the
* specified docId, then, falls back to using the passed in
* {@link org.apache.lucene.document.Document} to retrieve the TokenStream.
* This is useful when you already have the document, but would prefer to use
* the vector first.
*
* @param reader The {@link org.apache.lucene.index.IndexReader} to use to try
* and get the vector from
* @param docId The docId to retrieve.
* @param field The field to retrieve on the document
* @param document The document to fall back on
* @param analyzer The analyzer to use for creating the TokenStream if the
* vector doesn't exist
* @return The {@link org.apache.lucene.analysis.TokenStream} for the
* {@link org.apache.lucene.index.IndexableField} on the
* {@link org.apache.lucene.document.Document}
* @throws IOException if there was an error loading
*/
@Deprecated // maintenance reasons LUCENE-6445
public static TokenStream getAnyTokenStream(IndexReader reader, int docId,
String field, Document document, Analyzer analyzer) throws IOException {
TokenStream ts = null;
Fields vectors = reader.getTermVectors(docId);
if (vectors != null) {
Terms vector = vectors.terms(field);
if (vector != null) {
ts = getTokenStream(vector);
}
}
// No token info stored so fall back to analyzing raw content
if (ts == null) {
ts = getTokenStream(document, field, analyzer);
}
return ts;
}
/**
* A convenience method that tries a number of approaches to getting a token
* stream. The cost of finding there are no termVectors in the index is
* minimal (1000 invocations still registers 0 ms). So this "lazy" (flexible?)
* approach to coding is probably acceptable
*
* @return null if field not stored correctly
* @throws IOException If there is a low-level I/O error
*/
@Deprecated // maintenance reasons LUCENE-6445
public static TokenStream getAnyTokenStream(IndexReader reader, int docId,
String field, Analyzer analyzer) throws IOException {
TokenStream ts = null;
Fields vectors = reader.getTermVectors(docId);
if (vectors != null) {
Terms vector = vectors.terms(field);
if (vector != null) {
ts = getTokenStream(vector);
}
}
// No token info stored so fall back to analyzing raw content
if (ts == null) {
ts = getTokenStream(reader, docId, field, analyzer);
}
return ts;
}
/** Simply calls {@link #getTokenStream(org.apache.lucene.index.Terms)} now. */
@Deprecated // maintenance reasons LUCENE-6445
public static TokenStream getTokenStream(Terms vector,
boolean tokenPositionsGuaranteedContiguous) throws IOException {
return getTokenStream(vector);
}
/**
* Returns a token stream generated from a {@link Terms}. This
* can be used to feed the highlighter with a pre-parsed token
* stream. The {@link Terms} must have offsets available. If there are no positions available,
* all tokens will have position increments reflecting adjacent tokens, or coincident when terms
* share a start offset. If there are stopwords filtered from the index, you probably want to ensure
* term vectors have positions so that phrase queries won't match across stopwords.
*
* @throws IllegalArgumentException if no offsets are available
*/
@Deprecated // maintenance reasons LUCENE-6445
public static TokenStream getTokenStream(final Terms tpv) throws IOException {
if (!tpv.hasOffsets()) {
throw new IllegalArgumentException("Highlighting requires offsets from the TokenStream.");
//TokenStreamFromTermVector can handle a lack of offsets if there are positions. But
// highlighters require offsets, so we insist here.
}
return new TokenStreamFromTermVector(tpv, -1); // TODO propagate maxStartOffset; see LUCENE-6445
}
/**
* Returns a {@link TokenStream} with positions and offsets constructed from
* field termvectors. If the field has no termvectors or offsets
* are not included in the termvector, return null. See {@link #getTokenStream(org.apache.lucene.index.Terms)}
* for an explanation of what happens when positions aren't present.
*
* @param reader the {@link IndexReader} to retrieve term vectors from
* @param docId the document to retrieve termvectors for
* @param field the field to retrieve termvectors for
* @return a {@link TokenStream}, or null if offsets are not available
* @throws IOException If there is a low-level I/O error
*
* @see #getTokenStream(org.apache.lucene.index.Terms)
*/
@Deprecated // maintenance reasons LUCENE-6445
public static TokenStream getTokenStreamWithOffsets(IndexReader reader, int docId,
String field) throws IOException {
Fields vectors = reader.getTermVectors(docId);
if (vectors == null) {
return null;
}
Terms vector = vectors.terms(field);
if (vector == null) {
return null;
}
if (!vector.hasOffsets()) {
return null;
}
return getTokenStream(vector);
}
@Deprecated // maintenance reasons LUCENE-6445
public static TokenStream getTokenStream(IndexReader reader, int docId,
String field, Analyzer analyzer) throws IOException {
Document doc = reader.document(docId);
return getTokenStream(doc, field, analyzer);
}
@Deprecated // maintenance reasons LUCENE-6445
public static TokenStream getTokenStream(Document doc, String field,
Analyzer analyzer) {
String contents = doc.get(field);
if (contents == null) {
throw new IllegalArgumentException("Field " + field
+ " in document is not stored and cannot be analyzed");
}
return getTokenStream(field, contents, analyzer);
}
@Deprecated // maintenance reasons LUCENE-6445
public static TokenStream getTokenStream(String field, String contents,
Analyzer analyzer) {
return analyzer.tokenStream(field, contents);
}
}