Class LimitTokenOffsetFilter
- java.lang.Object
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- org.apache.lucene.util.AttributeSource
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- org.apache.lucene.analysis.TokenStream
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- org.apache.lucene.analysis.TokenFilter
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- org.apache.lucene.analysis.miscellaneous.LimitTokenOffsetFilter
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
,Unwrappable<TokenStream>
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 inreset()
being called prior toincrementToken()
returningfalse
. For mostTokenStream
implementations this should be acceptable, and faster then consuming the full stream. If you are wrapping aTokenStream
which requires that the full stream of tokens be exhausted in order to function properly, use theLimitTokenOffsetFilter(TokenStream, int, boolean)
option.
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Nested Class Summary
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Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.State
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Field Summary
Fields Modifier and Type Field Description private boolean
consumeAllTokens
private int
maxStartOffset
private OffsetAttribute
offsetAttrib
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Fields inherited from class org.apache.lucene.analysis.TokenFilter
input
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Fields inherited from class org.apache.lucene.analysis.TokenStream
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
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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)
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Method Summary
All Methods Instance Methods Concrete Methods 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, unwrap
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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
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Field Detail
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offsetAttrib
private final OffsetAttribute offsetAttrib
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maxStartOffset
private int maxStartOffset
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consumeAllTokens
private final boolean consumeAllTokens
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Constructor Detail
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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
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LimitTokenOffsetFilter
public LimitTokenOffsetFilter(TokenStream input, int maxStartOffset, boolean consumeAllTokens)
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Method Detail
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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 appropriateAttributeImpl
s 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)
andAttributeSource.getAttribute(Class)
, references to allAttributeImpl
s 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 classTokenStream
- Returns:
- false for end of stream; true otherwise
- Throws:
java.io.IOException
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