org.apache.lucene.analysis.util

Class CharTokenizer

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.Tokenizer

org.apache.lucene.analysis.util.CharTokenizer

All Implemented Interfaces:

Closeable, AutoCloseable

Direct Known Subclasses:

LetterTokenizer, UnicodeWhitespaceTokenizer, WhitespaceTokenizer

public abstract class CharTokenizer
extends Tokenizer

An abstract base class for simple, character-oriented tokenizers.

The base class also provides factories to create instances of CharTokenizer using Java 8 lambdas or method references. It is possible to create an instance which behaves exactly like LetterTokenizer:

 Tokenizer tok = CharTokenizer.fromTokenCharPredicate(Character::isLetter);
 

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.Tokenizer

input

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

DEFAULT_TOKEN_ATTRIBUTE_FACTORY

Constructor Summary

Constructors

Constructor and Description
CharTokenizer() Creates a new CharTokenizer instance
CharTokenizer(AttributeFactory factory) Creates a new CharTokenizer instance

Method Summary

Modifier and Type	Method and Description
void	end()
static CharTokenizer	fromSeparatorCharPredicate(AttributeFactory factory, IntPredicate separatorCharPredicate) Creates a new instance of CharTokenizer with the supplied attribute factory using a custom predicate, supplied as method reference or lambda expression.
static CharTokenizer	fromSeparatorCharPredicate(AttributeFactory factory, IntPredicate separatorCharPredicate, IntUnaryOperator normalizer) Creates a new instance of CharTokenizer with the supplied attribute factory using a custom predicate.
static CharTokenizer	fromSeparatorCharPredicate(IntPredicate separatorCharPredicate) Creates a new instance of CharTokenizer using a custom predicate, supplied as method reference or lambda expression.
static CharTokenizer	fromSeparatorCharPredicate(IntPredicate separatorCharPredicate, IntUnaryOperator normalizer) Creates a new instance of CharTokenizer using a custom predicate, supplied as method reference or lambda expression.
static CharTokenizer	fromTokenCharPredicate(AttributeFactory factory, IntPredicate tokenCharPredicate) Creates a new instance of CharTokenizer with the supplied attribute factory using a custom predicate, supplied as method reference or lambda expression.
static CharTokenizer	fromTokenCharPredicate(AttributeFactory factory, IntPredicate tokenCharPredicate, IntUnaryOperator normalizer) Creates a new instance of CharTokenizer with the supplied attribute factory using a custom predicate, supplied as method reference or lambda expression.
static CharTokenizer	fromTokenCharPredicate(IntPredicate tokenCharPredicate) Creates a new instance of CharTokenizer using a custom predicate, supplied as method reference or lambda expression.
static CharTokenizer	fromTokenCharPredicate(IntPredicate tokenCharPredicate, IntUnaryOperator normalizer) Creates a new instance of CharTokenizer using a custom predicate, supplied as method reference or lambda expression.
boolean	incrementToken()
protected abstract boolean	isTokenChar(int c) Returns true iff a codepoint should be included in a token.
protected int	normalize(int c) Called on each token character to normalize it before it is added to the token.
void	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

CharTokenizer

public CharTokenizer()

Creates a new CharTokenizer instance

CharTokenizer

public CharTokenizer(AttributeFactory factory)

Creates a new CharTokenizer instance

Parameters:

factory - the attribute factory to use for this Tokenizer

Method Detail

fromTokenCharPredicate

public static CharTokenizer fromTokenCharPredicate(IntPredicate tokenCharPredicate)

Creates a new instance of CharTokenizer using a custom predicate, supplied as method reference or lambda expression. The predicate should return true for all valid token characters.

This factory is intended to be used with lambdas or method references. E.g., an elegant way to create an instance which behaves exactly as LetterTokenizer is:

 Tokenizer tok = CharTokenizer.fromTokenCharPredicate(Character::isLetter);
 

fromTokenCharPredicate

public static CharTokenizer fromTokenCharPredicate(AttributeFactory factory,
                                                   IntPredicate tokenCharPredicate)

Creates a new instance of CharTokenizer with the supplied attribute factory using a custom predicate, supplied as method reference or lambda expression. The predicate should return true for all valid token characters.

This factory is intended to be used with lambdas or method references. E.g., an elegant way to create an instance which behaves exactly as LetterTokenizer is:

 Tokenizer tok = CharTokenizer.fromTokenCharPredicate(factory, Character::isLetter);
 

fromTokenCharPredicate

public static CharTokenizer fromTokenCharPredicate(IntPredicate tokenCharPredicate,
                                                   IntUnaryOperator normalizer)

Creates a new instance of CharTokenizer using a custom predicate, supplied as method reference or lambda expression. The predicate should return true for all valid token characters. This factory also takes a function to normalize chars, e.g., lowercasing them, supplied as method reference or lambda expression.

This factory is intended to be used with lambdas or method references. E.g., an elegant way to create an instance which behaves exactly as LowerCaseTokenizer is:

 Tokenizer tok = CharTokenizer.fromTokenCharPredicate(Character::isLetter, Character::toLowerCase);
 

fromTokenCharPredicate

public static CharTokenizer fromTokenCharPredicate(AttributeFactory factory,
                                                   IntPredicate tokenCharPredicate,
                                                   IntUnaryOperator normalizer)

Creates a new instance of CharTokenizer with the supplied attribute factory using a custom predicate, supplied as method reference or lambda expression. The predicate should return true for all valid token characters. This factory also takes a function to normalize chars, e.g., lowercasing them, supplied as method reference or lambda expression.

This factory is intended to be used with lambdas or method references. E.g., an elegant way to create an instance which behaves exactly as LowerCaseTokenizer is:

 Tokenizer tok = CharTokenizer.fromTokenCharPredicate(factory, Character::isLetter, Character::toLowerCase);
 

fromSeparatorCharPredicate

public static CharTokenizer fromSeparatorCharPredicate(IntPredicate separatorCharPredicate)

Creates a new instance of CharTokenizer using a custom predicate, supplied as method reference or lambda expression. The predicate should return true for all valid token separator characters. This method is provided for convenience to easily use predicates that are negated (they match the separator characters, not the token characters).

This factory is intended to be used with lambdas or method references. E.g., an elegant way to create an instance which behaves exactly as WhitespaceTokenizer is:

 Tokenizer tok = CharTokenizer.fromSeparatorCharPredicate(Character::isWhitespace);
 

fromSeparatorCharPredicate

public static CharTokenizer fromSeparatorCharPredicate(AttributeFactory factory,
                                                       IntPredicate separatorCharPredicate)

Creates a new instance of CharTokenizer with the supplied attribute factory using a custom predicate, supplied as method reference or lambda expression. The predicate should return true for all valid token separator characters.

This factory is intended to be used with lambdas or method references. E.g., an elegant way to create an instance which behaves exactly as WhitespaceTokenizer is:

 Tokenizer tok = CharTokenizer.fromSeparatorCharPredicate(factory, Character::isWhitespace);
 

fromSeparatorCharPredicate

public static CharTokenizer fromSeparatorCharPredicate(IntPredicate separatorCharPredicate,
                                                       IntUnaryOperator normalizer)

Creates a new instance of CharTokenizer using a custom predicate, supplied as method reference or lambda expression. The predicate should return true for all valid token separator characters. This factory also takes a function to normalize chars, e.g., lowercasing them, supplied as method reference or lambda expression.

This factory is intended to be used with lambdas or method references. E.g., an elegant way to create an instance which behaves exactly as the combination WhitespaceTokenizer and LowerCaseFilter is:

 Tokenizer tok = CharTokenizer.fromSeparatorCharPredicate(Character::isWhitespace, Character::toLowerCase);
 

fromSeparatorCharPredicate

public static CharTokenizer fromSeparatorCharPredicate(AttributeFactory factory,
                                                       IntPredicate separatorCharPredicate,
                                                       IntUnaryOperator normalizer)

Creates a new instance of CharTokenizer with the supplied attribute factory using a custom predicate. The predicate should return true for all valid token separator characters. This factory also takes a function to normalize chars, e.g., lowercasing them, supplied as method reference or lambda expression.

This factory is intended to be used with lambdas or method references. E.g., an elegant way to create an instance which behaves exactly as WhitespaceTokenizer and LowerCaseFilter is:

 Tokenizer tok = CharTokenizer.fromSeparatorCharPredicate(factory, Character::isWhitespace, Character::toLowerCase);
 

isTokenChar

protected abstract boolean isTokenChar(int c)

Returns true iff a codepoint should be included in a token. This tokenizer generates as tokens adjacent sequences of codepoints which satisfy this predicate. Codepoints for which this is false are used to define token boundaries and are not included in tokens.

normalize

protected int normalize(int c)

Called on each token character to normalize it before it is added to the token. The default implementation does nothing. Subclasses may use this to, e.g., lowercase tokens.

incrementToken

public final boolean incrementToken()
                             throws IOException

Specified by:

incrementToken in class TokenStream

Throws:

IOException

end

public final void end()
               throws IOException

Overrides:

end in class TokenStream

Throws:

IOException

reset

public void reset()
           throws IOException

Overrides:

reset in class Tokenizer

Throws:

IOException