Package org.apache.lucene.analysis.icu

Class ICUFoldingFilter

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

org.apache.lucene.analysis.icu.ICUNormalizer2Filter

org.apache.lucene.analysis.icu.ICUFoldingFilter

All Implemented Interfaces:

Closeable, AutoCloseable, Unwrappable<TokenStream>

public final class ICUFoldingFilter
extends ICUNormalizer2Filter

A TokenFilter that applies search term folding to Unicode text, applying foldings from UTR#30 Character Foldings.

This filter applies the following foldings from the report to unicode text:

• Accent removal
• Case folding
• Canonical duplicates folding
• Dashes folding
• Diacritic removal (including stroke, hook, descender)
• Greek letterforms folding
• Han Radical folding
• Hebrew Alternates folding
• Jamo folding
• Letterforms folding
• Math symbol folding
• Multigraph Expansions: All
• Native digit folding
• No-break folding
• Overline folding
• Positional forms folding
• Small forms folding
• Space folding
• Spacing Accents folding
• Subscript folding
• Superscript folding
• Suzhou Numeral folding
• Symbol folding
• Underline folding
• Vertical forms folding
• Width folding

Additionally, Default Ignorables are removed, and text is normalized to NFKC. All foldings, case folding, and normalization mappings are applied recursively to ensure a fully folded and normalized result.

A normalizer with additional settings such as a filter that lists characters not to be normalized can be passed in the constructor.

Nested Class Summary

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

AttributeSource.State

Field Summary

Fields

Modifier and Type	Field	Description
static final com.ibm.icu.text.Normalizer2	NORMALIZER	A normalizer for search term folding to Unicode text, applying foldings from UTR#30 Character Foldings.

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

input

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

DEFAULT_TOKEN_ATTRIBUTE_FACTORY

Constructor Summary

Constructors

Constructor	Description
ICUFoldingFilter(TokenStream input)	Create a new ICUFoldingFilter on the specified input
ICUFoldingFilter(TokenStream input, com.ibm.icu.text.Normalizer2 normalizer)	Create a new ICUFoldingFilter on the specified input with the specified normalizer

Method Summary

Methods inherited from class org.apache.lucene.analysis.icu.ICUNormalizer2Filter

incrementToken

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

close, end, reset, unwrap

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 Details

NORMALIZER

public static final com.ibm.icu.text.Normalizer2 NORMALIZER

A normalizer for search term folding to Unicode text, applying foldings from UTR#30 Character Foldings.

Constructor Details

ICUFoldingFilter

public ICUFoldingFilter(TokenStream input)

Create a new ICUFoldingFilter on the specified input

ICUFoldingFilter

public ICUFoldingFilter(TokenStream input,
 com.ibm.icu.text.Normalizer2 normalizer)

Create a new ICUFoldingFilter on the specified input with the specified normalizer