org.apache.lucene.analysis.standard

Class StandardTokenizer

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.Tokenizer

org.apache.lucene.analysis.standard.StandardTokenizer

All Implemented Interfaces:

Closeable, AutoCloseable

public final class StandardTokenizer
extends Tokenizer

A grammar-based tokenizer constructed with JFlex.

This class implements the Word Break rules from the Unicode Text Segmentation algorithm, as specified in Unicode Standard Annex #29.

Many applications have specific tokenizer needs. If this tokenizer does not suit your application, please consider copying this source code directory to your project and maintaining your own grammar-based tokenizer.

Nested Class Summary

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

AttributeSource.State

Field Summary

Fields

Modifier and Type	Field and Description
static int	ALPHANUM Alpha/numeric token type
static int	EMOJI Emoji token type.
static int	HANGUL Hangul token type
static int	HIRAGANA Hiragana token type
static int	IDEOGRAPHIC Ideographic token type
static int	KATAKANA Katakana token type
static int	MAX_TOKEN_LENGTH_LIMIT Absolute maximum sized token
static int	NUM Numeric token type
static int	SOUTHEAST_ASIAN Southeast Asian token type
static String[]	TOKEN_TYPES String token types that correspond to token type int constants

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

input

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

DEFAULT_TOKEN_ATTRIBUTE_FACTORY

Constructor Summary

Constructors

Constructor and Description
StandardTokenizer() Creates a new instance of the StandardTokenizer.
StandardTokenizer(AttributeFactory factory) Creates a new StandardTokenizer with a given AttributeFactory

Method Summary

Modifier and Type	Method and Description
void	close() Releases resources associated with this stream.
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).
int	getMaxTokenLength() Returns the current maximum token length
boolean	incrementToken() 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 using TokenStream.incrementToken().
void	setMaxTokenLength(int length) Set the max allowed token length.

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

correctOffset, setReader

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

Methods inherited from class java.lang.Object

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

Field Detail

ALPHANUM

public static final int ALPHANUM

Alpha/numeric token type

See Also:

Constant Field Values

NUM

public static final int NUM

Numeric token type

See Also:

Constant Field Values

SOUTHEAST_ASIAN

public static final int SOUTHEAST_ASIAN

Southeast Asian token type

See Also:

Constant Field Values

IDEOGRAPHIC

public static final int IDEOGRAPHIC

Ideographic token type

See Also:

Constant Field Values

HIRAGANA

public static final int HIRAGANA

Hiragana token type

See Also:

Constant Field Values

KATAKANA

public static final int KATAKANA

Katakana token type

See Also:

Constant Field Values

HANGUL

public static final int HANGUL

Hangul token type

See Also:

Constant Field Values

EMOJI

public static final int EMOJI

Emoji token type.

See Also:

Constant Field Values

TOKEN_TYPES

public static final String[] TOKEN_TYPES

String token types that correspond to token type int constants

MAX_TOKEN_LENGTH_LIMIT

public static final int MAX_TOKEN_LENGTH_LIMIT

Absolute maximum sized token

See Also:

Constant Field Values

Constructor Detail

StandardTokenizer

public StandardTokenizer()

Creates a new instance of the StandardTokenizer. Attaches the input to the newly created JFlex scanner. See http://issues.apache.org/jira/browse/LUCENE-1068

StandardTokenizer

public StandardTokenizer(AttributeFactory factory)

Creates a new StandardTokenizer with a given AttributeFactory

Method Detail

setMaxTokenLength

public void setMaxTokenLength(int length)

Set the max allowed token length. Tokens larger than this will be chopped up at this token length and emitted as multiple tokens. If you need to skip such large tokens, you could increase this max length, and then use LengthFilter to remove long tokens. The default is StandardAnalyzer.DEFAULT_MAX_TOKEN_LENGTH.

Throws:

IllegalArgumentException - if the given length is outside of the range [1, 1048576].

getMaxTokenLength

public int getMaxTokenLength()

Returns the current maximum token length

See Also:

setMaxTokenLength(int)

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

end

public final void end()
               throws IOException

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.

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 class TokenStream

Throws:

IOException - If an I/O error occurs

close

public void close()
           throws IOException

Description copied from class: Tokenizer

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 throw IllegalStateException on reuse).

NOTE: The default implementation closes the input Reader, so be sure to call super.close() when overriding this method.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class Tokenizer

Throws:

IOException

reset

public void reset()
           throws IOException

Description copied from class: TokenStream

This method is called by a consumer before it begins consumption using TokenStream.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 throw IllegalStateException on further usage).

Overrides:

reset in class Tokenizer

Throws:

IOException