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:

java.io.Closeable, java.lang.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.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	TokenStreamFromTermVector.TokenLL

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

AttributeSource.State

Field Summary

Fields

Modifier and Type	Field and Description
private TokenStreamFromTermVector.TokenLL	firstToken
private TokenStreamFromTermVector.TokenLL	incrementToken
private boolean	initialized
private int	maxStartOffset
private OffsetAttribute	offsetAttribute
private PayloadAttribute	payloadAttribute
private BytesRefArray	payloadsBytesRefArray
private PositionIncrementAttribute	positionIncrementAttribute
private BytesRefBuilder	spareBytesRefBuilder
private CharTermAttribute	termAttribute
private CharsRefBuilder	termCharsBuilder
private Terms	vector

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

Modifier and Type	Method and Description
Terms	getTermVectorTerms()
boolean	incrementToken() Consumers (i.e., IndexWriter) use this method to advance the stream to the next token.
private void	init()
private TokenStreamFromTermVector.TokenLL[]	initTokensArray()
void	reset() This method is called by a consumer before it begins consumption using TokenStream.incrementToken().

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, endAttributes, 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

vector

private final Terms vector

termAttribute

private final CharTermAttribute termAttribute

positionIncrementAttribute

private final PositionIncrementAttribute positionIncrementAttribute

maxStartOffset

private final int maxStartOffset

offsetAttribute

private OffsetAttribute offsetAttribute

payloadAttribute

private PayloadAttribute payloadAttribute

termCharsBuilder

private CharsRefBuilder termCharsBuilder

payloadsBytesRefArray

private BytesRefArray payloadsBytesRefArray

spareBytesRefBuilder

private BytesRefBuilder spareBytesRefBuilder

firstToken

private TokenStreamFromTermVector.TokenLL firstToken

incrementToken

private TokenStreamFromTermVector.TokenLL incrementToken

initialized

private boolean initialized

Constructor Detail

TokenStreamFromTermVector

public TokenStreamFromTermVector(Terms vector,
                                 int maxStartOffset)
                          throws java.io.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:

java.io.IOException

Method Detail

getTermVectorTerms

public Terms getTermVectorTerms()

reset

public void reset()
           throws java.io.IOException

Description copied from class: TokenStream

This method is called by a consumer before it begins consumption using TokenStream.incrementToken().

Resets this stream to a clean state. Stateful implementations must implement this method so that they can be reused, just as if they had been created fresh.

If you override this method, always call super.reset(), otherwise some internal state will not be correctly reset (e.g., Tokenizer will throw IllegalStateException on further usage).

Overrides:

reset in class TokenStream

Throws:

java.io.IOException

init

private void init()
           throws java.io.IOException

Throws:

java.io.IOException

initTokensArray

private TokenStreamFromTermVector.TokenLL[] initTokensArray()
                                                     throws java.io.IOException

Throws:

java.io.IOException

incrementToken

public boolean incrementToken()
                       throws java.io.IOException

Description copied from class: TokenStream

Consumers (i.e., IndexWriter) use this method to advance the stream to the next token. Implementing classes must implement this method and update the appropriate AttributeImpls with the attributes of the next token.

The producer must make no assumptions about the attributes after the method has been returned: the caller may arbitrarily change it. If the producer needs to preserve the state for subsequent calls, it can use AttributeSource.captureState() to create a copy of the current attribute state.

This method is called for every token of a document, so an efficient implementation is crucial for good performance. To avoid calls to AttributeSource.addAttribute(Class) and AttributeSource.getAttribute(Class), references to all AttributeImpls that this stream uses should be retrieved during instantiation.

To ensure that filters and consumers know which attributes are available, the attributes must be added during instantiation. Filters and consumers are not required to check for availability of attributes in TokenStream.incrementToken().

Specified by:

incrementToken in class TokenStream

Returns:

false for end of stream; true otherwise

Throws:

java.io.IOException