Class ConcatenatingTokenStream
- All Implemented Interfaces:
Closeable
,AutoCloseable
Offsets from the second and subsequent sources are incremented to behave as if all the inputs were from a single source.
All of the input TokenStreams must have the same attribute implementations
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Nested Class Summary
Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.State
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate int
private int
private final OffsetAttribute
private int
private final PositionIncrementAttribute
private final PositionIncrementAttribute[]
private final OffsetAttribute[]
private final TokenStream[]
Fields inherited from class org.apache.lucene.analysis.TokenStream
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
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Constructor Summary
ConstructorsConstructorDescriptionConcatenatingTokenStream
(TokenStream... sources) Create a new ConcatenatingTokenStream from a set of inputs -
Method Summary
Modifier and TypeMethodDescriptionvoid
close()
Releases resources associated with this stream.private static AttributeSource
combineSources
(TokenStream... sources) void
end()
This method is called by the consumer after the last token has been consumed, afterTokenStream.incrementToken()
returnedfalse
(using the newTokenStream
API).boolean
Consumers (i.e.,IndexWriter
) use this method to advance the stream to the next token.void
reset()
This method is called by a consumer before it begins consumption usingTokenStream.incrementToken()
.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
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Field Details
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sources
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sourceOffsets
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sourceIncrements
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offsetAtt
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posIncAtt
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currentSource
private int currentSource -
offsetIncrement
private int offsetIncrement -
initialPositionIncrement
private int initialPositionIncrement
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Constructor Details
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ConcatenatingTokenStream
Create a new ConcatenatingTokenStream from a set of inputs- Parameters:
sources
- an array of TokenStream inputs to concatenate
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Method Details
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combineSources
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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
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end
Description copied from class:TokenStream
This method is called by the consumer after the last token has been consumed, afterTokenStream.incrementToken()
returnedfalse
(using the newTokenStream
API). Streams implementing the old API should upgrade to use this feature.This method can be used to perform any end-of-stream operations, such as setting the final offset of a stream. The final offset of a stream might differ from the offset of the last token eg in case one or more whitespaces followed after the last token, but a WhitespaceTokenizer was used.
Additionally any skipped positions (such as those removed by a stopfilter) can be applied to the position increment, or any adjustment of other attributes where the end-of-stream value may be important.
If you override this method, always call
super.end()
.- Overrides:
end
in classTokenStream
- Throws:
IOException
- If an I/O error occurs
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reset
Description copied from class:TokenStream
This method is called by a consumer before it begins consumption usingTokenStream.incrementToken()
.Resets this stream to a clean state. Stateful implementations must implement this method so that they can be reused, just as if they had been created fresh.
If you override this method, always call
super.reset()
, otherwise some internal state will not be correctly reset (e.g.,Tokenizer
will throwIllegalStateException
on further usage).- Overrides:
reset
in classTokenStream
- Throws:
IOException
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close
Description copied from class:TokenStream
Releases resources associated with this stream.If you override this method, always call
super.close()
, otherwise some internal state will not be correctly reset (e.g.,Tokenizer
will throwIllegalStateException
on reuse).- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Overrides:
close
in classTokenStream
- Throws:
IOException
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