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## 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

    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.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
`AttributeSource.AttributeFactory, AttributeSource.State`

Field Summary

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

Constructor Summary
`ICUFoldingFilter(TokenStream input)` Create a new ICUFoldingFilter on the specified input

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`

Methods inherited from class org.apache.lucene.util.AttributeSource
`addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, restoreState, toString`

Methods inherited from class java.lang.Object
`clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

Constructor Detail

### ICUFoldingFilter

    public ICUFoldingFilter(TokenStream input)

  Create a new ICUFoldingFilter on the specified input

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