Class ICUTransformFilter

A Lucene.Net.Analysis.TokenFilter that transforms text with ICU.

Inheritance

object

AttributeSource

TokenStream

TokenFilter

ICUTransformFilter

Implements

IDisposable

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.Equals(object)

AttributeSource.ReflectAsString(bool)

AttributeSource.ReflectWith(IAttributeReflector)

AttributeSource.CloneAttributes()

AttributeSource.CopyTo(AttributeSource)

AttributeSource.ToString()

object.Equals(object, object)

object.GetType()

object.ReferenceEquals(object, object)

Namespace: Lucene.Net.Analysis.Icu

Assembly: Lucene.Net.ICU.dll

Syntax

public sealed class ICUTransformFilter : TokenFilter, IDisposable

Remarks

ICU provides text-transformation functionality via its Transliteration API. Although script conversion is its most common use, a Transliterator can actually perform a more general class of tasks. In fact, Transliterator defines a very general API which specifies only that a segment of the input text is replaced by new text. The particulars of this conversion are determined entirely by subclasses of Transliterator.

Some useful transformations for search are built-in:

• Conversion from Traditional to Simplified Chinese characters
• Conversion from Hiragana to Katakana
• Conversion from Fullwidth to Halfwidth forms.
• Script conversions, for example Serbian Cyrillic to Latin

Example usage:

stream = new ICUTransformFilter(stream, Transliterator.GetInstance("Traditional-Simplified"));

For more details, see the ICU User Guide.

Constructors

ICUTransformFilter(TokenStream, Transliterator)

Create a new ICUTransformFilter that transforms text on the given stream.

Declaration

public ICUTransformFilter(TokenStream input, Transliterator transform)

Parameters

Type	Name	Description
TokenStream	input	Lucene.Net.Analysis.TokenStream to filter.
Transliterator	transform	Transliterator to transform the text.

Remarks

ICU provides text-transformation functionality via its Transliteration API. Although script conversion is its most common use, a Transliterator can actually perform a more general class of tasks. In fact, Transliterator defines a very general API which specifies only that a segment of the input text is replaced by new text. The particulars of this conversion are determined entirely by subclasses of Transliterator.

Some useful transformations for search are built-in:

• Conversion from Traditional to Simplified Chinese characters
• Conversion from Hiragana to Katakana
• Conversion from Fullwidth to Halfwidth forms.
• Script conversions, for example Serbian Cyrillic to Latin

Example usage:

stream = new ICUTransformFilter(stream, Transliterator.GetInstance("Traditional-Simplified"));

For more details, see the ICU User Guide.

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 bool IncrementToken()

Returns

Type	Description
bool	false for end of stream; true otherwise

Overrides

Lucene.Net.Analysis.TokenStream.IncrementToken()

Remarks

ICU provides text-transformation functionality via its Transliteration API. Although script conversion is its most common use, a Transliterator can actually perform a more general class of tasks. In fact, Transliterator defines a very general API which specifies only that a segment of the input text is replaced by new text. The particulars of this conversion are determined entirely by subclasses of Transliterator.

Some useful transformations for search are built-in:

• Conversion from Traditional to Simplified Chinese characters
• Conversion from Hiragana to Katakana
• Conversion from Fullwidth to Halfwidth forms.
• Script conversions, for example Serbian Cyrillic to Latin

Example usage:

stream = new ICUTransformFilter(stream, Transliterator.GetInstance("Traditional-Simplified"));

For more details, see the ICU User Guide.

Implements

IDisposable