org.apache.lucene.analysis.standard
Class StandardTokenizer

java.lang.Object
  org.apache.lucene.analysis.TokenStream
      org.apache.lucene.analysis.Tokenizer
          org.apache.lucene.analysis.standard.StandardTokenizer

public 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.

Field Summary

static int	ACRONYM
static int	ACRONYM_DEP Deprecated. this solves a bug where HOSTs that end with '.' are identified as ACRONYMs. It is deprecated and will be removed in the next release.
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
static String[]	tokenImage Deprecated. Please use TOKEN_TYPES instead

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

input

Constructor Summary

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

StandardTokenizer(Reader input, boolean replaceInvalidAcronym)
Creates a new instance of the StandardTokenizer.

Method Summary

int	getMaxTokenLength()
boolean	isReplaceInvalidAcronym() Deprecated. Remove in 3.X and make true the only valid value
Token	next(Token reusableToken) Returns the next token in the stream, or null at EOS.
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

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

next

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, 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. It is deprecated and will be removed in the next release.

See Also:

Constant Field Values

TOKEN_TYPES

public static final String[] TOKEN_TYPES

String token types that correspond to token type int constants

tokenImage

public static final String[] tokenImage

Deprecated. Please use TOKEN_TYPES instead

Constructor Detail

StandardTokenizer

public StandardTokenizer(Reader input)

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

StandardTokenizer

public StandardTokenizer(Reader input,
                         boolean replaceInvalidAcronym)

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

Parameters:

input - The input reader

replaceInvalidAcronym - Set to true to replace mischaracterized acronyms with HOST. See http://issues.apache.org/jira/browse/LUCENE-1068

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)

next

public Token next(Token reusableToken)
           throws IOException

Description copied from class: TokenStream

Returns the next token in the stream, or null at EOS. When possible, the input Token should be used as the returned Token (this gives fastest tokenization performance), but this is not required and a new Token may be returned. Callers may re-use a single Token instance for successive calls to this method.

This implicitly defines a "contract" between consumers (callers of this method) and producers (implementations of this method that are the source for tokens):

• A consumer must fully consume the previously returned Token before calling this method again.
• A producer must call Token.clear() before setting the fields in it & returning it

Also, the producer must make no assumptions about a Token after it has been returned: the caller may arbitrarily change it. If the producer needs to hold onto the token for subsequent calls, it must clone() it before storing it. Note that a TokenFilter is considered a consumer.

Overrides:

next in class TokenStream

Parameters:

reusableToken - a Token that may or may not be used to return; this parameter should never be null (the callee is not required to check for null before using it, but it is a good idea to assert that it is not null.)

Returns:

next token in the stream or null if end-of-stream was hit

Throws:

IOException

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. 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 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 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.