Class DelimitedTermFrequencyTokenFilter
- 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.DelimitedTermFrequencyTokenFilter
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
public final class DelimitedTermFrequencyTokenFilter extends TokenFilter
Characters before the delimiter are the "token", the textual integer after is the term frequency. To use thisTokenFilter
the field must be indexed withIndexOptions.DOCS_AND_FREQS
but no positions or offsets.For example, if the delimiter is '|', then for the string "foo|5", "foo" is the token and "5" is a term frequency. If there is no delimiter, the TokenFilter does not modify the term frequency.
Note make sure your Tokenizer doesn't split on the delimiter, or this won't work
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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 static char
DEFAULT_DELIMITER
private char
delimiter
private CharTermAttribute
termAtt
private TermFrequencyAttribute
tfAtt
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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 DelimitedTermFrequencyTokenFilter(TokenStream input)
DelimitedTermFrequencyTokenFilter(TokenStream input, char delimiter)
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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
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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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DEFAULT_DELIMITER
public static final char DEFAULT_DELIMITER
- See Also:
- Constant Field Values
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delimiter
private final char delimiter
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termAtt
private final CharTermAttribute termAtt
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tfAtt
private final TermFrequencyAttribute tfAtt
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Constructor Detail
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DelimitedTermFrequencyTokenFilter
public DelimitedTermFrequencyTokenFilter(TokenStream input)
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DelimitedTermFrequencyTokenFilter
public DelimitedTermFrequencyTokenFilter(TokenStream input, char delimiter)
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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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