Class ContextSuggestField.PrefixTokenFilter
- 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.search.suggest.document.ContextSuggestField.PrefixTokenFilter
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
,Unwrappable<TokenStream>
- Enclosing class:
- ContextSuggestField
private static final class ContextSuggestField.PrefixTokenFilter extends TokenFilter
TheContextSuggestField.PrefixTokenFilter
wraps aTokenStream
and adds a set prefixes ahead. The position attribute will not be incremented for the prefixes.
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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 java.util.Iterator<java.lang.CharSequence>
currentPrefix
private PositionIncrementAttribute
posAttr
private java.lang.Iterable<java.lang.CharSequence>
prefixes
private char
separator
private CharTermAttribute
termAttr
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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 PrefixTokenFilter(TokenStream input, char separator, java.lang.Iterable<java.lang.CharSequence> prefixes)
Create a newContextSuggestField.PrefixTokenFilter
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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.void
reset()
This method is called by a consumer before it begins consumption usingTokenStream.incrementToken()
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Methods inherited from class org.apache.lucene.analysis.TokenFilter
close, end, 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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separator
private final char separator
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termAttr
private final CharTermAttribute termAttr
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posAttr
private final PositionIncrementAttribute posAttr
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prefixes
private final java.lang.Iterable<java.lang.CharSequence> prefixes
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currentPrefix
private java.util.Iterator<java.lang.CharSequence> currentPrefix
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Constructor Detail
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PrefixTokenFilter
public PrefixTokenFilter(TokenStream input, char separator, java.lang.Iterable<java.lang.CharSequence> prefixes)
Create a newContextSuggestField.PrefixTokenFilter
- Parameters:
input
-TokenStream
to wrapseparator
- Character used separate prefixes from other tokensprefixes
-Iterable
ofCharSequence
which keeps all prefixes
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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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reset
public void reset() throws java.io.IOException
Description copied from class:TokenFilter
This method is called by a consumer before it begins consumption usingTokenStream.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 throwIllegalStateException
on further usage).NOTE: The default implementation chains the call to the input TokenStream, so be sure to call
super.reset()
when overriding this method.- Overrides:
reset
in classTokenFilter
- Throws:
java.io.IOException
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