# Uses of Interface
org.apache.lucene.util.Unwrappable

Packages that use Unwrappable
Package
Description
org.apache.lucene.analysis
Text analysis.
org.apache.lucene.index
Code to maintain and access indices.
org.apache.lucene.search
Code to search indices.

- ## Uses of Unwrappable in org.apache.lucene.analysis

  Classes in org.apache.lucene.analysis that implement Unwrappable
  Modifier and Type
  Class
  Description
  `final class`
  `CachingTokenFilter`
  This class can be used if the token attributes of a TokenStream are intended to be consumed more than once.
  `class`
  `FilteringTokenFilter`
  Abstract base class for TokenFilters that may remove tokens.
  `class`
  `GraphTokenFilter`
  An abstract TokenFilter that exposes its input stream as a graph
  `class`
  `LowerCaseFilter`
  Normalizes token text to lower case.
  `class`
  `StopFilter`
  Removes stop words from a token stream.
  `class`
  `TokenFilter`
  A TokenFilter is a TokenStream whose input is another TokenStream.

- ## Uses of Unwrappable in org.apache.lucene.index

  Classes in org.apache.lucene.index that implement Unwrappable
  Modifier and Type
  Class
  Description
  `static class`
  `FilterLeafReader.FilterPostingsEnum`
  Base class for filtering `PostingsEnum` implementations.
  `class`
  `FilterMergePolicy`
  A wrapper for `MergePolicy` instances.
  `class`
  `OneMergeWrappingMergePolicy`
  A wrapping merge policy that wraps the `MergePolicy.OneMerge` objects returned by the wrapped merge policy.
  `final class`
  `SoftDeletesRetentionMergePolicy`
  This `MergePolicy` allows to carry over soft deleted documents across merges.
  `class`
  `UpgradeIndexMergePolicy`
  This `MergePolicy` is used for upgrading all existing segments of an index when calling `IndexWriter.forceMerge(int)`.

- ## Uses of Unwrappable in org.apache.lucene.search

  Classes in org.apache.lucene.search that implement Unwrappable
  Modifier and Type
  Class
  Description
  `class`
  `FilterScorer`
  A `FilterScorer` contains another `Scorer`, which it uses as its basic source of data, possibly transforming the data along the way or providing additional functionality.