org.apache.lucene.facet.index.streaming
Class CategoryAttributesStream
java.lang.Object
org.apache.lucene.util.AttributeSource
org.apache.lucene.analysis.TokenStream
org.apache.lucene.facet.index.streaming.CategoryAttributesStream
- All Implemented Interfaces:
- Closeable
public class CategoryAttributesStream
- extends TokenStream
An attribute stream built from an Iterable
of
CategoryAttribute
. This stream should then be passed through several
filters (see CategoryParentsStream
, CategoryListTokenizer
and
CategoryTokenizer
) 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.
Method Summary |
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.util.AttributeSource |
addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, restoreState, toString |
categoryAttribute
protected CategoryAttribute categoryAttribute
CategoryAttributesStream
public CategoryAttributesStream(Iterable<CategoryAttribute> iterable)
- Constructor
- Parameters:
iterable
- Iterable
of CategoryAttribute
, from which
categories are taken.
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 appropriate AttributeImpl
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)
and AttributeSource.getAttribute(Class)
,
references to all AttributeImpl
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 class TokenStream
- Returns:
- false for end of stream; true otherwise
- Throws:
IOException
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 a
TokenStream
are intended to be consumed more than once, it is
necessary to implement TokenStream.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 after TokenStream.reset()
).
- Overrides:
reset
in class TokenStream
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