Class PorterStemFilter
- All Implemented Interfaces:
Closeable
,AutoCloseable
,Unwrappable<TokenStream>
To use this filter with other analyzers, you'll want to write an Analyzer class that sets up
the TokenStream chain as you want it. To use this with LowerCaseTokenizer, for example, you'd
write an analyzer like this:
class MyAnalyzer extends Analyzer { @Override protected TokenStreamComponents createComponents(String fieldName) { Tokenizer source = new LowerCaseTokenizer(version, reader); return new TokenStreamComponents(source, new PorterStemFilter(source)); } }
Note: This filter is aware of the KeywordAttribute
. To prevent certain terms from
being passed to the stemmer KeywordAttribute.isKeyword()
should be set to true
in a previous TokenStream
.
Note: For including the original term as well as the stemmed version, see KeywordRepeatFilterFactory
-
Nested Class Summary
Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.State
-
Field Summary
FieldsModifier and TypeFieldDescriptionprivate final KeywordAttribute
private final PorterStemmer
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
-
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionfinal boolean
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
-
Field Details
-
stemmer
-
termAtt
-
keywordAttr
-
-
Constructor Details
-
PorterStemFilter
-
-
Method Details
-
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
-