org.apache.lucene.search.highlight

Class TokenStreamFromTermVector

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.search.highlight.TokenStreamFromTermVector

All Implemented Interfaces:

Closeable, AutoCloseable

public final class TokenStreamFromTermVector
extends TokenStream

TokenStream created from a term vector field. The term vector requires positions and/or offsets (either). If you want payloads add PayloadAttributeImpl (as you would normally) but don't assume the attribute is already added just because you know the term vector has payloads, since the first call to incrementToken() will observe if you asked for them and if not then won't get them. This TokenStream supports an efficient reset(), so there's no need to wrap with a caching impl.

The implementation will create an array of tokens indexed by token position. As long as there aren't massive jumps in positions, this is fine. And it assumes there aren't large numbers of tokens at the same position, since it adds them to a linked-list per position in O(N^2) complexity. When there aren't positions in the term vector, it divides the startOffset by 8 to use as a temporary substitute. In that case, tokens with the same startOffset will occupy the same final position; otherwise tokens become adjacent.

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource

AttributeSource.State

Field Summary

Fields

Modifier and Type	Field and Description
static AttributeFactory	ATTRIBUTE_FACTORY

Fields inherited from class org.apache.lucene.analysis.TokenStream

DEFAULT_TOKEN_ATTRIBUTE_FACTORY

Constructor Summary

Constructors

Constructor and Description
TokenStreamFromTermVector(Terms vector, int maxStartOffset) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
Terms	getTermVectorTerms()
boolean	incrementToken()
void	reset()

Methods inherited from class org.apache.lucene.analysis.TokenStream

close, end

Methods inherited from class org.apache.lucene.util.AttributeSource

addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, removeAllAttributes, restoreState, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

ATTRIBUTE_FACTORY

public static final AttributeFactory ATTRIBUTE_FACTORY

Constructor Detail

TokenStreamFromTermVector

public TokenStreamFromTermVector(Terms vector,
                         int maxStartOffset)
                          throws IOException

Constructor. The uninversion doesn't happen here; it's delayed till the first call to incrementToken.

Parameters:

vector - Terms that contains the data for creating the TokenStream. Must have positions and/or offsets.

maxStartOffset - if a token's start offset exceeds this then the token is not added. -1 disables the limit.

Throws:

IOException

Method Detail

getTermVectorTerms

public Terms getTermVectorTerms()

reset

public void reset()
           throws IOException

Overrides:

reset in class TokenStream

Throws:

IOException

incrementToken

public boolean incrementToken()
                       throws IOException

Specified by:

incrementToken in class TokenStream

Throws:

IOException