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.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource

AttributeSource.AttributeFactory, AttributeSource.State

Field Summary

protected CategoryAttribute

categoryAttribute

Constructor Summary

CategoryAttributesStream(Iterable<CategoryAttribute> iterable)
Constructor

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.analysis.TokenStream

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

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

categoryAttribute

protected CategoryAttribute categoryAttribute

Constructor Detail

CategoryAttributesStream

public CategoryAttributesStream(Iterable<CategoryAttribute> iterable)

Constructor

Parameters:

iterable - Iterable of CategoryAttribute, from which categories are taken.

Method Detail

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 AttributeImpls 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 AttributeImpls 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