org.apache.lucene.analysis.ngram

Class EdgeNGramTokenizer

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.Tokenizer

org.apache.lucene.analysis.ngram.EdgeNGramTokenizer

All Implemented Interfaces:

Closeable

public final class EdgeNGramTokenizer
extends Tokenizer

Tokenizes the input from an edge into n-grams of given size(s).

This Tokenizer create n-grams from the beginning edge or ending edge of a input token. MaxGram can't be larger than 1024 because of limitation.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	EdgeNGramTokenizer.Side Specifies which side of the input the n-gram should be generated from

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

AttributeSource.AttributeFactory, AttributeSource.State

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_MAX_GRAM_SIZE
static int	DEFAULT_MIN_GRAM_SIZE
static EdgeNGramTokenizer.Side	DEFAULT_SIDE

Fields inherited from class org.apache.lucene.analysis.Tokenizer

input

Constructor Summary

Constructors

Constructor and Description
EdgeNGramTokenizer(AttributeSource.AttributeFactory factory, Reader input, EdgeNGramTokenizer.Side side, int minGram, int maxGram) Creates EdgeNGramTokenizer that can generate n-grams in the sizes of the given range
EdgeNGramTokenizer(AttributeSource.AttributeFactory factory, Reader input, String sideLabel, int minGram, int maxGram) Creates EdgeNGramTokenizer that can generate n-grams in the sizes of the given range
EdgeNGramTokenizer(AttributeSource source, Reader input, EdgeNGramTokenizer.Side side, int minGram, int maxGram) Creates EdgeNGramTokenizer that can generate n-grams in the sizes of the given range
EdgeNGramTokenizer(AttributeSource source, Reader input, String sideLabel, int minGram, int maxGram) Creates EdgeNGramTokenizer that can generate n-grams in the sizes of the given range
EdgeNGramTokenizer(Reader input, EdgeNGramTokenizer.Side side, int minGram, int maxGram) Creates EdgeNGramTokenizer that can generate n-grams in the sizes of the given range
EdgeNGramTokenizer(Reader input, String sideLabel, int minGram, int maxGram) Creates EdgeNGramTokenizer that can generate n-grams in the sizes of the given range

Method Summary

Methods

Modifier and Type	Method and Description
void	end() This method is called by the consumer after the last token has been consumed, after TokenStream.incrementToken() returned false (using the new TokenStream API).
boolean	incrementToken() Returns the next token in the stream, or null at EOS.
void	reset() Resets this stream to the beginning.

Methods inherited from class org.apache.lucene.analysis.Tokenizer

close, correctOffset, reset

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

DEFAULT_SIDE

public static final EdgeNGramTokenizer.Side DEFAULT_SIDE

DEFAULT_MAX_GRAM_SIZE

public static final int DEFAULT_MAX_GRAM_SIZE

See Also:

Constant Field Values

DEFAULT_MIN_GRAM_SIZE

public static final int DEFAULT_MIN_GRAM_SIZE

See Also:

Constant Field Values

Constructor Detail

EdgeNGramTokenizer

public EdgeNGramTokenizer(Reader input,
                  EdgeNGramTokenizer.Side side,
                  int minGram,
                  int maxGram)

Creates EdgeNGramTokenizer that can generate n-grams in the sizes of the given range

Parameters:

input - Reader holding the input to be tokenized

side - the EdgeNGramTokenizer.Side from which to chop off an n-gram

minGram - the smallest n-gram to generate

maxGram - the largest n-gram to generate

EdgeNGramTokenizer

public EdgeNGramTokenizer(AttributeSource source,
                  Reader input,
                  EdgeNGramTokenizer.Side side,
                  int minGram,
                  int maxGram)

Creates EdgeNGramTokenizer that can generate n-grams in the sizes of the given range

Parameters:

source - AttributeSource to use

input - Reader holding the input to be tokenized

side - the EdgeNGramTokenizer.Side from which to chop off an n-gram

minGram - the smallest n-gram to generate

maxGram - the largest n-gram to generate

EdgeNGramTokenizer

public EdgeNGramTokenizer(AttributeSource.AttributeFactory factory,
                  Reader input,
                  EdgeNGramTokenizer.Side side,
                  int minGram,
                  int maxGram)

Creates EdgeNGramTokenizer that can generate n-grams in the sizes of the given range

Parameters:

factory - AttributeSource.AttributeFactory to use

input - Reader holding the input to be tokenized

side - the EdgeNGramTokenizer.Side from which to chop off an n-gram

minGram - the smallest n-gram to generate

maxGram - the largest n-gram to generate

EdgeNGramTokenizer

public EdgeNGramTokenizer(Reader input,
                  String sideLabel,
                  int minGram,
                  int maxGram)

Creates EdgeNGramTokenizer that can generate n-grams in the sizes of the given range

Parameters:

input - Reader holding the input to be tokenized

sideLabel - the name of the EdgeNGramTokenizer.Side from which to chop off an n-gram

minGram - the smallest n-gram to generate

maxGram - the largest n-gram to generate

EdgeNGramTokenizer

public EdgeNGramTokenizer(AttributeSource source,
                  Reader input,
                  String sideLabel,
                  int minGram,
                  int maxGram)

Creates EdgeNGramTokenizer that can generate n-grams in the sizes of the given range

Parameters:

source - AttributeSource to use

input - Reader holding the input to be tokenized

sideLabel - the name of the EdgeNGramTokenizer.Side from which to chop off an n-gram

minGram - the smallest n-gram to generate

maxGram - the largest n-gram to generate

EdgeNGramTokenizer

public EdgeNGramTokenizer(AttributeSource.AttributeFactory factory,
                  Reader input,
                  String sideLabel,
                  int minGram,
                  int maxGram)

Creates EdgeNGramTokenizer that can generate n-grams in the sizes of the given range

Parameters:

factory - AttributeSource.AttributeFactory to use

input - Reader holding the input to be tokenized

sideLabel - the name of the EdgeNGramTokenizer.Side from which to chop off an n-gram

minGram - the smallest n-gram to generate

maxGram - the largest n-gram to generate

Method Detail

incrementToken

public boolean incrementToken()
                       throws IOException

Returns the next token in the stream, or null at EOS.

Specified by:

incrementToken in class TokenStream

Returns:

false for end of stream; true otherwise

Throws:

IOException

end

public void end()

Description copied from class: TokenStream

This method is called by the consumer after the last token has been consumed, after TokenStream.incrementToken() returned false (using the new TokenStream 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.

Overrides:

end in class TokenStream

reset

public void reset()
           throws IOException

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

Throws:

IOException