Class CategoryAttributesStream
- 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.facet.index.streaming.CategoryAttributesStream
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- All Implemented Interfaces:
Closeable
,AutoCloseable
public class CategoryAttributesStream extends TokenStream
An attribute stream built from anIterable
ofCategoryAttribute
. This stream should then be passed through several filters (seeCategoryParentsStream
,CategoryListTokenizer
andCategoryTokenizer
) until a token stream is produced that can be indexed by Lucene.A CategoryAttributesStream object can be reused for producing more than one stream. To do that, the user should cause the underlying Iterable
object to return a new set of categories, and then call reset()
to allow this stream to be used again.- WARNING: This API is experimental and might change in incompatible ways in the next release.
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Nested Class Summary
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Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.AttributeFactory, AttributeSource.State
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Field Summary
Fields Modifier and Type Field Description protected CategoryAttribute
categoryAttribute
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Constructor Summary
Constructors Constructor Description CategoryAttributesStream(Iterable<CategoryAttribute> iterable)
Constructor
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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()
Resets this stream to the beginning.-
Methods inherited from class org.apache.lucene.analysis.TokenStream
close, end
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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
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Field Detail
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categoryAttribute
protected CategoryAttribute categoryAttribute
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Constructor Detail
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CategoryAttributesStream
public CategoryAttributesStream(Iterable<CategoryAttribute> iterable)
Constructor- Parameters:
iterable
-Iterable
ofCategoryAttribute
, from which categories are taken.
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Method Detail
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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
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reset
public void reset()
Description copied from class:TokenStream
Resets this stream to the beginning. This is an optional operation, so subclasses may or may not implement this method.TokenStream.reset()
is not needed for the standard indexing process. However, if the tokens of aTokenStream
are intended to be consumed more than once, it is necessary to implementTokenStream.reset()
. Note that if your TokenStream caches tokens and feeds them back again after a reset, it is imperative that you clone the tokens when you store them away (on the first pass) as well as when you return them (on future passes afterTokenStream.reset()
).- Overrides:
reset
in classTokenStream
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