Class PrefixAwareTokenFilter

Joins two token streams and leaves the last token of the first stream available to be used when updating the token values in the second stream based on that token.

The default implementation adds last prefix token end offset to the suffix token start and end offsets.

NOTE: This filter might not behave correctly if used with custom Lucene.Net.Util.IAttributes, i.e. Lucene.Net.Util.IAttributes other than the ones located in Lucene.Net.Analysis.TokenAttributes.

Inheritance

object

AttributeSource

TokenStream

PrefixAwareTokenFilter

Implements

IDisposable

Inherited Members

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.MemberwiseClone()

object.ReferenceEquals(object, object)

Namespace: Lucene.Net.Analysis.Miscellaneous

Assembly: Lucene.Net.Analysis.Common.dll

Syntax

public class PrefixAwareTokenFilter : TokenStream, IDisposable

Constructors

PrefixAwareTokenFilter(TokenStream, TokenStream)

Joins two token streams and leaves the last token of the first stream available to be used when updating the token values in the second stream based on that token.

The default implementation adds last prefix token end offset to the suffix token start and end offsets.

NOTE: This filter might not behave correctly if used with custom Lucene.Net.Util.IAttributes, i.e. Lucene.Net.Util.IAttributes other than the ones located in Lucene.Net.Analysis.TokenAttributes.

Declaration

public PrefixAwareTokenFilter(TokenStream prefix, TokenStream suffix)

Parameters

Type	Name	Description
TokenStream	prefix
TokenStream	suffix

Properties

Prefix

Joins two token streams and leaves the last token of the first stream available to be used when updating the token values in the second stream based on that token.

The default implementation adds last prefix token end offset to the suffix token start and end offsets.

NOTE: This filter might not behave correctly if used with custom Lucene.Net.Util.IAttributes, i.e. Lucene.Net.Util.IAttributes other than the ones located in Lucene.Net.Analysis.TokenAttributes.

Declaration

public virtual TokenStream Prefix { get; set; }

Property Value

Type	Description
TokenStream

Suffix

Joins two token streams and leaves the last token of the first stream available to be used when updating the token values in the second stream based on that token.

The default implementation adds last prefix token end offset to the suffix token start and end offsets.

NOTE: This filter might not behave correctly if used with custom Lucene.Net.Util.IAttributes, i.e. Lucene.Net.Util.IAttributes other than the ones located in Lucene.Net.Analysis.TokenAttributes.

Declaration

public virtual TokenStream Suffix { get; set; }

Property Value

Type	Description
TokenStream

Methods

Dispose(bool)

Releases resources associated with this stream.

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

Declaration

protected override void Dispose(bool disposing)

Parameters

Type	Name	Description
bool	disposing

Overrides

TokenStream.Dispose(bool)

End()

This method is called by the consumer after the last token has been consumed, after Lucene.Net.Analysis.TokenStream.IncrementToken() returned false (using the new Lucene.Net.Analysis.TokenStream API). Streams implementing the old API should upgrade to use this feature.

This method can be used to perform any end-of-stream operations, such as setting the final offset of a stream. The final offset of a stream might differ from the offset of the last token eg in case one or more whitespaces followed after the last token, but a WhitespaceTokenizer was used.

Additionally any skipped positions (such as those removed by a stopfilter) can be applied to the position increment, or any adjustment of other attributes where the end-of-stream value may be important.

If you override this method, always call base.End();.

Declaration

public override void End()

Overrides

Lucene.Net.Analysis.TokenStream.End()

Exceptions

Type	Condition
IOException	If an I/O error occurs

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()

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.TokenStream.Reset()

UpdateSuffixToken(Token, Token)

The default implementation adds last prefix token end offset to the suffix token start and end offsets.

Declaration

public virtual Token UpdateSuffixToken(Token suffixToken, Token lastPrefixToken)

Parameters

Type	Name	Description
Token	suffixToken	a token from the suffix stream
Token	lastPrefixToken	the last token from the prefix stream

Returns

Type	Description
Token	consumer token

Implements

IDisposable