Class GraphTokenFilter
- 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.analysis.TokenFilter
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- org.apache.lucene.analysis.GraphTokenFilter
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- All Implemented Interfaces:
Closeable,AutoCloseable,Unwrappable<TokenStream>
public abstract class GraphTokenFilter extends TokenFilter
An abstract TokenFilter that exposes its input stream as a graphCall
incrementBaseToken()to move the root of the graph to the next position in the TokenStream,incrementGraphToken()to move along the current graph, andincrementGraph()to reset to the next graph based at the current root.For example, given the stream 'a b/c:2 d e`, then with the base token at 'a', incrementGraphToken() will produce the stream 'a b d e', and then after calling incrementGraph() will produce the stream 'a c e'.
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Nested Class Summary
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Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.State
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Field Summary
Fields Modifier and Type Field Description static intMAX_GRAPH_STACK_SIZEThe maximum permitted number of routes through a graphstatic intMAX_TOKEN_CACHE_SIZEThe maximum permitted read-ahead in the token stream-
Fields inherited from class org.apache.lucene.analysis.TokenFilter
input
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Fields inherited from class org.apache.lucene.analysis.TokenStream
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
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Constructor Summary
Constructors Constructor Description GraphTokenFilter(TokenStream input)Create a new GraphTokenFilter
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description voidend()This method is called by the consumer after the last token has been consumed, afterTokenStream.incrementToken()returnedfalse(using the newTokenStreamAPI).intgetTrailingPositions()Return the number of trailing positions at the end of the graphprotected booleanincrementBaseToken()Move the root of the graph to the next token in the wrapped TokenStreamprotected booleanincrementGraph()Reset to the root token again, and move down the next route through the graphprotected booleanincrementGraphToken()Move to the next token in the current route through the graphvoidreset()This method is called by a consumer before it begins consumption usingTokenStream.incrementToken().-
Methods inherited from class org.apache.lucene.analysis.TokenFilter
close, unwrap
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Methods inherited from class org.apache.lucene.analysis.TokenStream
incrementToken
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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 Detail
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MAX_GRAPH_STACK_SIZE
public static final int MAX_GRAPH_STACK_SIZE
The maximum permitted number of routes through a graph- See Also:
- Constant Field Values
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MAX_TOKEN_CACHE_SIZE
public static final int MAX_TOKEN_CACHE_SIZE
The maximum permitted read-ahead in the token stream- See Also:
- Constant Field Values
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Constructor Detail
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GraphTokenFilter
public GraphTokenFilter(TokenStream input)
Create a new GraphTokenFilter
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Method Detail
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incrementBaseToken
protected final boolean incrementBaseToken() throws IOExceptionMove the root of the graph to the next token in the wrapped TokenStream- Returns:
falseif the underlying stream is exhausted- Throws:
IOException
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incrementGraphToken
protected final boolean incrementGraphToken() throws IOExceptionMove to the next token in the current route through the graph- Returns:
falseif there are not more tokens in the current graph- Throws:
IOException
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incrementGraph
protected final boolean incrementGraph() throws IOExceptionReset to the root token again, and move down the next route through the graph- Returns:
- false if there are no more routes through the graph
- Throws:
IOException
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getTrailingPositions
public int getTrailingPositions()
Return the number of trailing positions at the end of the graphNB this should only be called after
incrementGraphToken()has returnedfalse
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end
public void end() throws IOExceptionDescription copied from class:TokenFilterThis method is called by the consumer after the last token has been consumed, afterTokenStream.incrementToken()returnedfalse(using the newTokenStreamAPI). 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().NOTE: The default implementation chains the call to the input TokenStream, so be sure to call
super.end()first when overriding this method.- Overrides:
endin classTokenFilter- Throws:
IOException- If an I/O error occurs
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reset
public void reset() throws IOExceptionDescription copied from class:TokenFilterThis 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.,Tokenizerwill throwIllegalStateExceptionon further usage).NOTE: The default implementation chains the call to the input TokenStream, so be sure to call
super.reset()when overriding this method.- Overrides:
resetin classTokenFilter- Throws:
IOException
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