org.apache.lucene.search.highlight

Class TokenSources

java.lang.Object

org.apache.lucene.search.highlight.TokenSources

public class TokenSources
extends Object

Convenience methods for obtaining a TokenStream for use with the Highlighter - can obtain from term vectors with offsets and positions or from an Analyzer re-parsing the stored content.

See Also:

TokenStreamFromTermVector

Method Summary

Modifier and Type	Method and Description
static TokenStream	getAnyTokenStream(IndexReader reader, int docId, String field, Analyzer analyzer) Deprecated.
static TokenStream	getAnyTokenStream(IndexReader reader, int docId, String field, Document document, Analyzer analyzer) Deprecated.
static TokenStream	getTermVectorTokenStreamOrNull(String field, Fields tvFields, int maxStartOffset) Get a token stream by un-inverting the term vector.
static TokenStream	getTokenStream(Document doc, String field, Analyzer analyzer) Deprecated.
static TokenStream	getTokenStream(IndexReader reader, int docId, String field, Analyzer analyzer) Deprecated.
static TokenStream	getTokenStream(String field, Fields tvFields, String text, Analyzer analyzer, int maxStartOffset) Get a token stream from either un-inverting a term vector if possible, or by analyzing the text.
static TokenStream	getTokenStream(String field, String contents, Analyzer analyzer) Deprecated.
static TokenStream	getTokenStream(Terms tpv) Deprecated.
static TokenStream	getTokenStream(Terms vector, boolean tokenPositionsGuaranteedContiguous) Deprecated.
static TokenStream	getTokenStreamWithOffsets(IndexReader reader, int docId, String field) Deprecated.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getTokenStream

public static TokenStream getTokenStream(String field,
                                         Fields tvFields,
                                         String text,
                                         Analyzer analyzer,
                                         int maxStartOffset)
                                  throws IOException

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.

Parameters:

field - The field to either get term vectors from or to analyze the text from.

tvFields - from IndexReader.getTermVectors(int). Possibly null. For performance, this instance should be re-used for the same document (e.g. when highlighting multiple fields).

text - the text to analyze, failing term vector un-inversion

analyzer - the analyzer to analyze text with, failing term vector un-inversion

maxStartOffset - Terms with a startOffset greater than this aren't returned. Use -1 for no limit. Suggest using Highlighter.getMaxDocCharsToAnalyze() - 1.

Returns:

a token stream from either term vectors, or from analyzing the text. Never null.

Throws:

IOException

getTermVectorTokenStreamOrNull

public static TokenStream getTermVectorTokenStreamOrNull(String field,
                                                         Fields tvFields,
                                                         int maxStartOffset)
                                                  throws IOException

Get a token stream by un-inverting the term vector. This method returns null if 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.

Parameters:

field - The field to get term vectors from.

tvFields - from IndexReader.getTermVectors(int). Possibly null. For performance, this instance should be re-used for the same document (e.g. when highlighting multiple fields).

maxStartOffset - Terms with a startOffset greater than this aren't returned. Use -1 for no limit. Suggest using Highlighter.getMaxDocCharsToAnalyze() - 1

Returns:

a token stream from term vectors. Null if no term vectors with the right options.

Throws:

IOException

getAnyTokenStream

@Deprecated
public static TokenStream getAnyTokenStream(IndexReader reader,
                                                        int docId,
                                                        String field,
                                                        Document document,
                                                        Analyzer analyzer)
                                                 throws IOException

Deprecated.

A convenience method that tries to first get a TokenStreamFromTermVector for the specified docId, then, falls back to using the passed in Document to retrieve the TokenStream. This is useful when you already have the document, but would prefer to use the vector first.

Parameters:

reader - The IndexReader to use to try and get the vector from

docId - The docId to retrieve.

field - The field to retrieve on the document

document - The document to fall back on

analyzer - The analyzer to use for creating the TokenStream if the vector doesn't exist

Returns:

The TokenStream for the IndexableField on the Document

Throws:

IOException - if there was an error loading

getAnyTokenStream

@Deprecated
public static TokenStream getAnyTokenStream(IndexReader reader,
                                                        int docId,
                                                        String field,
                                                        Analyzer analyzer)
                                                 throws IOException

Deprecated.

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

Returns:

null if field not stored correctly

Throws:

IOException - If there is a low-level I/O error

getTokenStream

@Deprecated
public static TokenStream getTokenStream(Terms vector,
                                                     boolean tokenPositionsGuaranteedContiguous)
                                              throws IOException

Deprecated.

Simply calls getTokenStream(org.apache.lucene.index.Terms) now.

Throws:

IOException

getTokenStream

@Deprecated
public static TokenStream getTokenStream(Terms tpv)
                                              throws IOException

Deprecated.

Returns a token stream generated from a Terms. This can be used to feed the highlighter with a pre-parsed token stream. The 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

IOException

getTokenStreamWithOffsets

@Deprecated
public static TokenStream getTokenStreamWithOffsets(IndexReader reader,
                                                                int docId,
                                                                String field)
                                                         throws IOException

Deprecated.

Returns a 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 getTokenStream(org.apache.lucene.index.Terms) for an explanation of what happens when positions aren't present.

Parameters:

reader - the IndexReader to retrieve term vectors from

docId - the document to retrieve termvectors for

field - the field to retrieve termvectors for

Returns:

a TokenStream, or null if offsets are not available

Throws:

IOException - If there is a low-level I/O error

See Also:

getTokenStream(org.apache.lucene.index.Terms)

getTokenStream

@Deprecated
public static TokenStream getTokenStream(IndexReader reader,
                                                     int docId,
                                                     String field,
                                                     Analyzer analyzer)
                                              throws IOException

Deprecated.

Throws:

IOException

getTokenStream

@Deprecated
public static TokenStream getTokenStream(Document doc,
                                                     String field,
                                                     Analyzer analyzer)

Deprecated.

getTokenStream

@Deprecated
public static TokenStream getTokenStream(String field,
                                                     String contents,
                                                     Analyzer analyzer)

Deprecated.