Class CJKBigramFilter

Forms bigrams of CJK terms that are generated from StandardTokenizer or ICUTokenizer.

CJK types are set by these tokenizers, but you can also use CJKBigramFilter(TokenStream, CJKScript) to explicitly control which of the CJK scripts are turned into bigrams.

By default, when a CJK character has no adjacent characters to form a bigram, it is output in unigram form. If you want to always output both unigrams and bigrams, set the

outputUnigrams

flag in CJKBigramFilter(TokenStream, CJKScript, bool). This can be used for a combined unigram+bigram approach.

In all cases, all non-CJK input is passed thru unmodified.

Inheritance

object

AttributeSource

TokenStream

TokenFilter

CJKBigramFilter

Implements

IDisposable

Inherited Members

TokenFilter.End()

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.Cjk

Assembly: Lucene.Net.Analysis.Common.dll

Syntax

public sealed class CJKBigramFilter : TokenFilter, IDisposable

Constructors

CJKBigramFilter(TokenStream)

Calls CJKBigramFilter(@in, CJKScript.HAN | CJKScript.HIRAGANA | CJKScript.KATAKANA | CJKScript.HANGUL)

Declaration

public CJKBigramFilter(TokenStream @in)

Parameters

Type	Name	Description
TokenStream	in	Input Lucene.Net.Analysis.TokenStream

CJKBigramFilter(TokenStream, CJKScript)

Calls CJKBigramFilter(in, flags, false)

Declaration

public CJKBigramFilter(TokenStream @in, CJKScript flags)

Parameters

Type	Name	Description
TokenStream	in	Input Lucene.Net.Analysis.TokenStream
CJKScript	flags	OR'ed set from HAN, HIRAGANA, KATAKANA, HANGUL

CJKBigramFilter(TokenStream, CJKScript, bool)

Create a new CJKBigramFilter, specifying which writing systems should be bigrammed, and whether or not unigrams should also be output.

Declaration

public CJKBigramFilter(TokenStream @in, CJKScript flags, bool outputUnigrams)

Parameters

Type	Name	Description
TokenStream	in	Input Lucene.Net.Analysis.TokenStream
CJKScript	flags	OR'ed set from HAN, HIRAGANA, KATAKANA, HANGUL
bool	outputUnigrams	true if unigrams for the selected writing systems should also be output. when this is false, this is only done when there are no adjacent characters to form a bigram.

Fields

DOUBLE_TYPE

when we emit a bigram, its then marked as this type

Declaration

public const string DOUBLE_TYPE = "<DOUBLE>"

Field Value

Type	Description
string

SINGLE_TYPE

when we emit a unigram, its then marked as this type

Declaration

public const string SINGLE_TYPE = "<SINGLE>"

Field Value

Type	Description
string

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()

Reset()

This method is called by a consumer before it begins consumption using Lucene.Net.Analysis.TokenStream.IncrementToken().

Resets this stream to a clean state. Stateful implementations must implement this method so that they can be reused, just as if they had been created fresh.

If you override this method, always call base.Reset(), otherwise some internal state will not be correctly reset (e.g., Lucene.Net.Analysis.Tokenizer will throw InvalidOperationException on further usage).

Declaration

public override void Reset()

Overrides

Lucene.Net.Analysis.TokenFilter.Reset()

Remarks

NOTE: The default implementation chains the call to the input Lucene.Net.Analysis.TokenStream, so be sure to call base.Reset() when overriding this method.

Implements

IDisposable