# 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.