Package org.apache.lucene.analysis.miscellaneous

Class LimitTokenOffsetFilter

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

org.apache.lucene.analysis.miscellaneous.LimitTokenOffsetFilter

All Implemented Interfaces:

Closeable, AutoCloseable

public final class LimitTokenOffsetFilter
extends TokenFilter

Lets all tokens pass through until it sees one with a start offset <= a configured limit, which won't pass and ends the stream. This can be useful to limit highlighting, for example.

By default, this filter ignores any tokens in the wrapped TokenStream once the limit has been exceeded, which can result in reset() being called prior to incrementToken() returning false. For most TokenStream implementations this should be acceptable, and faster then consuming the full stream. If you are wrapping a TokenStream which requires that the full stream of tokens be exhausted in order to function properly, use the LimitTokenOffsetFilter(TokenStream, int, boolean) option.

Nested Class Summary

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

AttributeSource.State

Field Summary

Fields

Modifier and Type	Field	Description
private final boolean	consumeAllTokens
private int	maxStartOffset
private final OffsetAttribute	offsetAttrib

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

input

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

DEFAULT_TOKEN_ATTRIBUTE_FACTORY

Constructor Summary

Constructors

Constructor	Description
LimitTokenOffsetFilter(TokenStream input, int maxStartOffset)	Lets all tokens pass through until it sees one with a start offset <= maxStartOffset which won't pass and ends the stream.
LimitTokenOffsetFilter(TokenStream input, int maxStartOffset, boolean consumeAllTokens)

Method Summary

Modifier and Type	Method	Description
boolean	incrementToken()	Consumers (i.e., IndexWriter) use this method to advance the stream to the next token.

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

close, end, reset

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 Details

offsetAttrib

private final OffsetAttribute offsetAttrib

maxStartOffset

private int maxStartOffset

consumeAllTokens

private final boolean consumeAllTokens

Constructor Details

LimitTokenOffsetFilter

public LimitTokenOffsetFilter(TokenStream input,
 int maxStartOffset)

Lets all tokens pass through until it sees one with a start offset <= maxStartOffset which won't pass and ends the stream. It won't consume any tokens afterwards.

Parameters:

maxStartOffset - the maximum start offset allowed

LimitTokenOffsetFilter

public LimitTokenOffsetFilter(TokenStream input,
 int maxStartOffset,
 boolean consumeAllTokens)

Method Details

incrementToken

public boolean incrementToken()
                       throws 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:

IOException