Class FilteringTokenFilter
- java.lang.Object
-
- org.apache.lucene.util.AttributeSource
-
- org.apache.lucene.analysis.TokenStream
-
- org.apache.lucene.analysis.TokenFilter
-
- org.apache.lucene.analysis.FilteringTokenFilter
-
- All Implemented Interfaces:
Closeable
,AutoCloseable
- Direct Known Subclasses:
JapanesePartOfSpeechStopFilter
,LengthFilter
,StopFilter
,TypeTokenFilter
public abstract class FilteringTokenFilter extends TokenFilter
Abstract base class for TokenFilters that may remove tokens. You have to implementaccept()
and return a boolean if the current token should be preserved.incrementToken()
uses this method to decide if a token should be passed to the caller.
-
-
Nested Class Summary
-
Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.AttributeFactory, AttributeSource.State
-
-
Field Summary
-
Fields inherited from class org.apache.lucene.analysis.TokenFilter
input
-
-
Constructor Summary
Constructors Constructor Description FilteringTokenFilter(boolean enablePositionIncrements, TokenStream input)
-
Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description protected abstract boolean
accept()
Override this method and return if the current input token should be returned byincrementToken()
.boolean
getEnablePositionIncrements()
boolean
incrementToken()
Consumers (i.e.,IndexWriter
) use this method to advance the stream to the next token.void
reset()
Reset the filter as well as the input TokenStream.void
setEnablePositionIncrements(boolean enable)
Iftrue
, this TokenFilter will preserve positions of the incoming tokens (ie, accumulate and set position increments of the removed tokens).-
Methods inherited from class org.apache.lucene.analysis.TokenFilter
close, end
-
Methods inherited from class org.apache.lucene.util.AttributeSource
addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, restoreState, toString
-
-
-
-
Constructor Detail
-
FilteringTokenFilter
public FilteringTokenFilter(boolean enablePositionIncrements, TokenStream input)
-
-
Method Detail
-
accept
protected abstract boolean accept() throws IOException
Override this method and return if the current input token should be returned byincrementToken()
.- Throws:
IOException
-
incrementToken
public final 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 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
-
reset
public void reset() throws IOException
Description copied from class:TokenFilter
Reset the filter as well as the input TokenStream.- Overrides:
reset
in classTokenFilter
- Throws:
IOException
-
getEnablePositionIncrements
public boolean getEnablePositionIncrements()
- See Also:
setEnablePositionIncrements(boolean)
-
setEnablePositionIncrements
public void setEnablePositionIncrements(boolean enable)
Iftrue
, this TokenFilter will preserve positions of the incoming tokens (ie, accumulate and set position increments of the removed tokens). Generally,true
is best as it does not lose information (positions of the original tokens) during indexing.When set, when a token is stopped (omitted), the position increment of the following token is incremented.
NOTE: be sure to also set
QueryParser.setEnablePositionIncrements(boolean)
if you use QueryParser to create queries.
-
-