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

public final class StandardTokenizer
extends Tokenizer

A grammar-based tokenizer constructed with JFlex

This should be a good tokenizer for most European-language documents:

• Splits words at punctuation characters, removing punctuation. However, a dot that's not followed by whitespace is considered part of a token.
• Splits words at hyphens, unless there's a number in the token, in which case the whole token is interpreted as a product number and is not split.
• Recognizes email addresses and internet hostnames as one token.

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.

You must specify the required Version compatibility when creating StandardAnalyzer:

• As of 2.4, Tokens incorrectly identified as acronyms are corrected (see LUCENE-1608

Nested Class Summary

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

AttributeSource.AttributeFactory, AttributeSource.State

Field Summary

static int	ACRONYM
static int	ACRONYM_DEP Deprecated. this solves a bug where HOSTs that end with '.' are identified as ACRONYMs.
static int	ALPHANUM
static int	APOSTROPHE
static int	CJ
static int	COMPANY
static int	EMAIL
static int	HOST
static int	NUM
static String[]	TOKEN_TYPES String token types that correspond to token type int constants

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

input

Constructor Summary

StandardTokenizer(Version matchVersion, AttributeSource.AttributeFactory factory, Reader input)
Creates a new StandardTokenizer with a given AttributeSource.AttributeFactory

StandardTokenizer(Version matchVersion, AttributeSource source, Reader input)
Creates a new StandardTokenizer with a given AttributeSource.

StandardTokenizer(Version matchVersion, Reader input)
Creates a new instance of the StandardTokenizer.

Method Summary

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()
boolean	incrementToken() Consumers (i.e., IndexWriter) use this method to advance the stream to the next token.
boolean	isReplaceInvalidAcronym() Deprecated. Remove in 3.X and make true the only valid value
void	reset() Resets this stream to the beginning.
void	reset(Reader reader) Expert: Reset the tokenizer to a new reader.
void	setMaxTokenLength(int length) Set the max allowed token length.
void	setReplaceInvalidAcronym(boolean replaceInvalidAcronym) Deprecated. Remove in 3.X and make true the only valid value See https://issues.apache.org/jira/browse/LUCENE-1068

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

close, correctOffset

Methods inherited from class org.apache.lucene.util.AttributeSource

addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, 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

See Also:

Constant Field Values

APOSTROPHE

public static final int APOSTROPHE

See Also:

Constant Field Values

ACRONYM

public static final int ACRONYM

See Also:

Constant Field Values

COMPANY

public static final int COMPANY

See Also:

Constant Field Values

EMAIL

public static final int EMAIL

See Also:

Constant Field Values

HOST

public static final int HOST

See Also:

Constant Field Values

NUM

public static final int NUM

See Also:

Constant Field Values

CJ

public static final int CJ

See Also:

Constant Field Values

ACRONYM_DEP

public static final int ACRONYM_DEP

Deprecated. this solves a bug where HOSTs that end with '.' are identified as ACRONYMs.

See Also:

Constant Field Values

TOKEN_TYPES

public static final String[] TOKEN_TYPES

String token types that correspond to token type int constants

Constructor Detail

StandardTokenizer

public StandardTokenizer(Version matchVersion,
                         Reader input)

Creates a new instance of the StandardTokenizer. Attaches the input to the newly created JFlex scanner.

Parameters:

input - The input reader See http://issues.apache.org/jira/browse/LUCENE-1068

StandardTokenizer

public StandardTokenizer(Version matchVersion,
                         AttributeSource source,
                         Reader input)

Creates a new StandardTokenizer with a given AttributeSource.

StandardTokenizer

public StandardTokenizer(Version matchVersion,
                         AttributeSource.AttributeFactory factory,
                         Reader input)

Creates a new StandardTokenizer with a given AttributeSource.AttributeFactory

Method Detail

setMaxTokenLength

public void setMaxTokenLength(int length)

Set the max allowed token length. Any token longer than this is skipped.

getMaxTokenLength

public int getMaxTokenLength()

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()

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

reset

public void reset(Reader reader)
           throws IOException

Description copied from class: Tokenizer

Expert: Reset the tokenizer to a new reader. Typically, an analyzer (in its reusableTokenStream method) will use this to re-use a previously created tokenizer.

Overrides:

reset in class Tokenizer

Throws:

IOException

isReplaceInvalidAcronym

public boolean isReplaceInvalidAcronym()

Deprecated. Remove in 3.X and make true the only valid value

Prior to https://issues.apache.org/jira/browse/LUCENE-1068, StandardTokenizer mischaracterized as acronyms tokens like www.abc.com when they should have been labeled as hosts instead.

Returns:

true if StandardTokenizer now returns these tokens as Hosts, otherwise false

setReplaceInvalidAcronym

public void setReplaceInvalidAcronym(boolean replaceInvalidAcronym)

Deprecated. Remove in 3.X and make true the only valid value See https://issues.apache.org/jira/browse/LUCENE-1068

Parameters:

replaceInvalidAcronym - Set to true to replace mischaracterized acronyms as HOST.