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:

java.io.Closeable, java.lang.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

Modifier and Type	Field and Description
static int	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
CharTokenizer() Creates a new CharTokenizer instance
CharTokenizer(AttributeFactory factory) Creates a new CharTokenizer instance
CharTokenizer(AttributeFactory factory, int maxTokenLen) Creates a new CharTokenizer instance

Method Summary

Modifier and Type	Method and Description
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).
static CharTokenizer	fromSeparatorCharPredicate(AttributeFactory factory, java.util.function.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, java.util.function.IntPredicate separatorCharPredicate, java.util.function.IntUnaryOperator normalizer) Deprecated. Normalization should be done in a subsequent TokenFilter
static CharTokenizer	fromSeparatorCharPredicate(java.util.function.IntPredicate separatorCharPredicate) Creates a new instance of CharTokenizer using a custom predicate, supplied as method reference or lambda expression.
static CharTokenizer	fromSeparatorCharPredicate(java.util.function.IntPredicate separatorCharPredicate, java.util.function.IntUnaryOperator normalizer) Deprecated. Normalization should be done in a subsequent TokenFilter
static CharTokenizer	fromTokenCharPredicate(AttributeFactory factory, java.util.function.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, java.util.function.IntPredicate tokenCharPredicate, java.util.function.IntUnaryOperator normalizer) Deprecated. Normalization should be done in a subsequent TokenFilter
static CharTokenizer	fromTokenCharPredicate(java.util.function.IntPredicate tokenCharPredicate) Creates a new instance of CharTokenizer using a custom predicate, supplied as method reference or lambda expression.
static CharTokenizer	fromTokenCharPredicate(java.util.function.IntPredicate tokenCharPredicate, java.util.function.IntUnaryOperator normalizer) Deprecated. Normalization should be done in a subsequent TokenFilter
boolean	incrementToken() Consumers (i.e., IndexWriter) use this method to advance the stream to the next token.
protected abstract boolean	isTokenChar(int c) Returns true iff a codepoint should be included in a token.
protected int	normalize(int c) Deprecated. Normalization should be done in a subsequent TokenFilter
void	reset() This method is called by a consumer before it begins consumption using TokenStream.incrementToken().

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

Field Detail

DEFAULT_MAX_WORD_LEN

public static final int DEFAULT_MAX_WORD_LEN

See Also:

Constant Field Values

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

CharTokenizer

public CharTokenizer(AttributeFactory factory,
                     int maxTokenLen)

Creates a new CharTokenizer instance

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:

java.lang.IllegalArgumentException - if maxTokenLen is invalid.

Method Detail

fromTokenCharPredicate

public static CharTokenizer fromTokenCharPredicate(java.util.function.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,
                                                   java.util.function.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

@Deprecated
public static CharTokenizer fromTokenCharPredicate(java.util.function.IntPredicate tokenCharPredicate,
                                                               java.util.function.IntUnaryOperator normalizer)

Deprecated. Normalization should be done in a subsequent TokenFilter

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

@Deprecated
public static CharTokenizer fromTokenCharPredicate(AttributeFactory factory,
                                                               java.util.function.IntPredicate tokenCharPredicate,
                                                               java.util.function.IntUnaryOperator normalizer)

Deprecated. Normalization should be done in a subsequent TokenFilter

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(java.util.function.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,
                                                       java.util.function.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

@Deprecated
public static CharTokenizer fromSeparatorCharPredicate(java.util.function.IntPredicate separatorCharPredicate,
                                                                   java.util.function.IntUnaryOperator normalizer)

Deprecated. Normalization should be done in a subsequent TokenFilter

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

@Deprecated
public static CharTokenizer fromSeparatorCharPredicate(AttributeFactory factory,
                                                                   java.util.function.IntPredicate separatorCharPredicate,
                                                                   java.util.function.IntUnaryOperator normalizer)

Deprecated. Normalization should be done in a subsequent TokenFilter

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

@Deprecated
protected int normalize(int c)

Deprecated. Normalization should be done in a subsequent TokenFilter

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 java.io.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:

java.io.IOException

end

public final void end()
               throws java.io.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:

java.io.IOException - If an I/O error occurs

reset

public void reset()
           throws java.io.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:

java.io.IOException