Class StemmerOverrideFilter
- All Implemented Interfaces:
Closeable
,AutoCloseable
,Unwrappable<TokenStream>
KeywordAttribute
aware stemmer with custom
dictionary-based stemming.-
Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic class
This builder builds anFST
for theStemmerOverrideFilter
static final class
A read-only 4-byte FST backed map that allows fast case-insensitive key value lookups forStemmerOverrideFilter
Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.State
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate final FST.BytesReader
private final KeywordAttribute
private char[]
private final StemmerOverrideFilter.StemmerOverrideMap
private final CharTermAttribute
Fields inherited from class org.apache.lucene.analysis.TokenFilter
input
Fields inherited from class org.apache.lucene.analysis.TokenStream
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
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Constructor Summary
ConstructorsConstructorDescriptionStemmerOverrideFilter
(TokenStream input, StemmerOverrideFilter.StemmerOverrideMap stemmerOverrideMap) Create a new StemmerOverrideFilter, performing dictionary-based stemming with the provideddictionary
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Method Summary
Modifier and TypeMethodDescriptionboolean
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
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 Details
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stemmerOverrideMap
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termAtt
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keywordAtt
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fstReader
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scratchArc
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spare
private char[] spare
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Constructor Details
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StemmerOverrideFilter
public StemmerOverrideFilter(TokenStream input, StemmerOverrideFilter.StemmerOverrideMap stemmerOverrideMap) Create a new StemmerOverrideFilter, performing dictionary-based stemming with the provideddictionary
.Any dictionary-stemmed terms will be marked with
KeywordAttribute
so that they will not be stemmed with stemmers down the chain.
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Method Details
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incrementToken
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:
IOException
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