## org.apache.lucene.analysis.miscellaneous
Class ScandinavianFoldingFilter

    java.lang.Object
      org.apache.lucene.util.AttributeSource
          org.apache.lucene.analysis.TokenStream
              org.apache.lucene.analysis.TokenFilter
                  org.apache.lucene.analysis.miscellaneous.ScandinavianFoldingFilter

All Implemented Interfaces:
  Closeable

    public final class ScandinavianFoldingFilter

extends TokenFilter

This filter folds Scandinavian characters åÅäæÄÆ->a and öÖøØ->o. It also discriminate against use of double vowels aa, ae, ao, oe and oo, leaving just the first one.

It's is a semantically more destructive solution than `ScandinavianNormalizationFilter` but can in addition help with matching raksmorgas as räksmörgås.

blåbærsyltetøj == blåbärsyltetöj == blaabaarsyltetoej == blabarsyltetoj räksmörgås == ræksmørgås == ræksmörgaos == raeksmoergaas == raksmorgas

Background: Swedish åäö are in fact the same letters as Norwegian and Danish åæø and thus interchangeable when used between these languages. They are however folded differently when people type them on a keyboard lacking these characters.

In that situation almost all Swedish people use a, a, o instead of å, ä, ö.

Norwegians and Danes on the other hand usually type aa, ae and oe instead of å, æ and ø. Some do however use a, a, o, oo, ao and sometimes permutations of everything above.

This filter solves that mismatch problem, but might also cause new.

See Also:
  `ScandinavianNormalizationFilter`

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
`ScandinavianFoldingFilter(TokenStream input)`

Method Summary
`boolean` `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`

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

Constructor Detail

### ScandinavianFoldingFilter

    public ScandinavianFoldingFilter(TokenStream input)

Method Detail

### incrementToken

    public boolean incrementToken()
                           throws IOException

  Specified by:
    `incrementToken` in class `TokenStream`
  Throws:
    `IOException`

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