org.apache.lucene.analysis.core

Class LetterTokenizer

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.Tokenizer

org.apache.lucene.analysis.util.CharTokenizer

org.apache.lucene.analysis.core.LetterTokenizer

All Implemented Interfaces:

Closeable, AutoCloseable

public class LetterTokenizer
extends CharTokenizer

A LetterTokenizer is a tokenizer that divides text at non-letters. That's to say, it defines tokens as maximal strings of adjacent letters, as defined by java.lang.Character.isLetter() predicate.

Note: this does a decent job for most European languages, but does a terrible job for some Asian languages, where words are not separated by spaces.

Nested Class Summary

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

AttributeSource.State

Field Summary

Fields inherited from class org.apache.lucene.analysis.util.CharTokenizer

DEFAULT_MAX_WORD_LEN

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
LetterTokenizer() Construct a new LetterTokenizer.
LetterTokenizer(AttributeFactory factory) Construct a new LetterTokenizer using a given AttributeFactory.
LetterTokenizer(AttributeFactory factory, int maxTokenLen) Construct a new LetterTokenizer using a given AttributeFactory.

Method Summary

Modifier and Type	Method and Description
protected boolean	isTokenChar(int c) Collects only characters which satisfy Character.isLetter(int).

Methods inherited from class org.apache.lucene.analysis.util.CharTokenizer

end, fromSeparatorCharPredicate, fromSeparatorCharPredicate, fromTokenCharPredicate, fromTokenCharPredicate, incrementToken, reset

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

close, 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

Constructor Detail

LetterTokenizer

public LetterTokenizer()

Construct a new LetterTokenizer.

LetterTokenizer

public LetterTokenizer(AttributeFactory factory)

Construct a new LetterTokenizer using a given AttributeFactory.

Parameters:

factory - the attribute factory to use for this Tokenizer

LetterTokenizer

public LetterTokenizer(AttributeFactory factory,
                       int maxTokenLen)

Construct a new LetterTokenizer using a given AttributeFactory.

Parameters:

factory - the attribute factory to use for this Tokenizer

maxTokenLen - maximum token length the tokenizer will emit. Must be greater than 0 and less than MAX_TOKEN_LENGTH_LIMIT (1024*1024)

Throws:

IllegalArgumentException - if maxTokenLen is invalid.

Method Detail

isTokenChar

protected boolean isTokenChar(int c)

Collects only characters which satisfy Character.isLetter(int).

Specified by:

isTokenChar in class CharTokenizer