Class LowerCaseFilter

Normalizes token text to lower case.

You must specify the required Lucene.Net.Util.LuceneVersion compatibility when creating LowerCaseFilter:

  • As of 3.1, supplementary characters are properly lowercased.
Inheritance
object
AttributeSource
TokenStream
TokenFilter
LowerCaseFilter
Implements
Inherited Members
TokenFilter.End()
TokenFilter.Reset()
TokenStream.Dispose()
AttributeSource.GetAttributeFactory()
AttributeSource.GetAttributeClassesEnumerator()
AttributeSource.GetAttributeImplsEnumerator()
AttributeSource.AddAttributeImpl(Attribute)
AttributeSource.AddAttribute<T>()
AttributeSource.HasAttributes
AttributeSource.HasAttribute<T>()
AttributeSource.GetAttribute<T>()
AttributeSource.ClearAttributes()
AttributeSource.CaptureState()
AttributeSource.RestoreState(AttributeSource.State)
AttributeSource.GetHashCode()
AttributeSource.ReflectWith(IAttributeReflector)
AttributeSource.CloneAttributes()
AttributeSource.CopyTo(AttributeSource)
AttributeSource.ToString()
Namespace: Lucene.Net.Analysis.Core
Assembly: Lucene.Net.Analysis.Common.dll
Syntax
public sealed class LowerCaseFilter : TokenFilter, IDisposable

Constructors

LowerCaseFilter(LuceneVersion, TokenStream)

Create a new LowerCaseFilter, that normalizes token text to lower case.

Declaration
public LowerCaseFilter(LuceneVersion matchVersion, TokenStream @in)
Parameters
Type Name Description
LuceneVersion matchVersion

See Lucene.Net.Util.LuceneVersion
TokenStream in

Lucene.Net.Analysis.TokenStream to filter

Methods

IncrementToken()

Consumers (i.e., Lucene.Net.Index.IndexWriter) use this method to advance the stream to the next token. Implementing classes must implement this method and update the appropriate Lucene.Net.Util.IAttributes with the attributes of the next token.

The producer must make no assumptions about the attributes after the method has been returned: the caller may arbitrarily change it. If the producer needs to preserve the state for subsequent calls, it can use Lucene.Net.Util.AttributeSource.CaptureState() to create a copy of the current attribute state.

this method is called for every token of a document, so an efficient implementation is crucial for good performance. To avoid calls to Lucene.Net.Util.AttributeSource.AddAttribute<T>() and Lucene.Net.Util.AttributeSource.GetAttribute<T>(), references to all Lucene.Net.Util.IAttributes that this stream uses should be retrieved during instantiation.

To ensure that filters and consumers know which attributes are available, the attributes must be added during instantiation. Filters and consumers are not required to check for availability of attributes in Lucene.Net.Analysis.TokenStream.IncrementToken().
Declaration
public override sealed bool IncrementToken()
Returns
Type Description
bool

false for end of stream; true otherwise
Overrides
Lucene.Net.Analysis.TokenStream.IncrementToken()

Implements