Lucene.Net  3.0.3
Lucene.Net is a port of the Lucene search engine library, written in C# and targeted at .NET runtime users.
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Lucene.Net.Analysis.CachingTokenFilter Class Reference

This class can be used if the token attributes of a TokenStream are intended to be consumed more than once. It caches all token attribute states locally in a List. More...

Inherits Lucene.Net.Analysis.TokenFilter.

Public Member Functions

 CachingTokenFilter (TokenStream input)
 
override bool IncrementToken ()
 Consumers (i.e., IndexWriter) use this method to advance the stream to the next token. Implementing classes must implement this method and update the appropriate Util.Attributes with the attributes of the next token.
 
override void End ()
 This method is called by the consumer after the last token has been consumed, after IncrementToken returned false (using the new 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.
 
override void Reset ()
 Resets this stream to the beginning. This is an optional operation, so subclasses may or may not implement this method. Reset() is not needed for the standard indexing process. However, if the tokens of a TokenStream are intended to be consumed more than once, it is necessary to implement Reset(). Note that if your TokenStream caches tokens and feeds them back again after a reset, it is imperative that you clone the tokens when you store them away (on the first pass) as well as when you return them (on future passes after Reset()).
 
- Public Member Functions inherited from Lucene.Net.Analysis.TokenFilter
override void End ()
 Performs end-of-stream operations, if any, and calls then end() on the input TokenStream.NOTE: Be sure to call super.end() first when overriding this method.
 
override void Reset ()
 Reset the filter as well as the input TokenStream.
 
- Public Member Functions inherited from Lucene.Net.Analysis.TokenStream
void Close ()
 Releases resources associated with this stream.
 
void Dispose ()
 
- Public Member Functions inherited from Lucene.Net.Util.AttributeSource
 AttributeSource ()
 An AttributeSource using the default attribute factory AttributeSource.AttributeFactory.DEFAULT_ATTRIBUTE_FACTORY.
 
 AttributeSource (AttributeSource input)
 An AttributeSource that uses the same attributes as the supplied one.
 
 AttributeSource (AttributeFactory factory)
 An AttributeSource using the supplied AttributeFactory for creating new IAttribute instances.
 
virtual IEnumerable< Type > GetAttributeTypesIterator ()
 Returns a new iterator that iterates the attribute classes in the same order they were added in. Signature for Java 1.5: public Iterator<Class<? extends Attribute>> getAttributeClassesIterator()
 
virtual IEnumerable< AttributeGetAttributeImplsIterator ()
 Returns a new iterator that iterates all unique Attribute implementations. This iterator may contain less entries that GetAttributeTypesIterator, if one instance implements more than one Attribute interface. Signature for Java 1.5: public Iterator<AttributeImpl> getAttributeImplsIterator()
 
virtual void AddAttributeImpl (Attribute att)
 Expert: Adds a custom AttributeImpl instance with one or more Attribute interfaces.
 
virtual T AddAttribute< T > ()
 The caller must pass in a Class<? extends Attribute> value. This method first checks if an instance of that class is already in this AttributeSource and returns it. Otherwise a new instance is created, added to this AttributeSource and returned.
 
virtual bool HasAttribute< T > ()
 The caller must pass in a Class<? extends Attribute> value. Returns true, iff this AttributeSource contains the passed-in Attribute.
 
virtual T GetAttribute< T > ()
 The caller must pass in a Class<? extends Attribute> value. Returns the instance of the passed in Attribute contained in this AttributeSource
 
virtual void ClearAttributes ()
 Resets all Attributes in this AttributeSource by calling Attribute.Clear() on each Attribute implementation.
 
virtual State CaptureState ()
 Captures the state of all Attributes. The return value can be passed to RestoreState to restore the state of this or another AttributeSource.
 
virtual void RestoreState (State state)
 Restores this state by copying the values of all attribute implementations that this state contains into the attributes implementations of the targetStream. The targetStream must contain a corresponding instance for each argument contained in this state (e.g. it is not possible to restore the state of an AttributeSource containing a TermAttribute into a AttributeSource using a Token instance as implementation).
 
override int GetHashCode ()
 
override bool Equals (System.Object obj)
 
override System.String ToString ()
 
virtual AttributeSource CloneAttributes ()
 Performs a clone of all Attribute instances returned in a new AttributeSource instance. This method can be used to e.g. create another TokenStream with exactly the same attributes (using AttributeSource(AttributeSource))
 

Additional Inherited Members

- Protected Member Functions inherited from Lucene.Net.Analysis.TokenFilter
override void Dispose (bool disposing)
 
- Properties inherited from Lucene.Net.Util.AttributeSource
virtual AttributeFactory Factory [get]
 Returns the used AttributeFactory.
 
virtual bool HasAttributes [get]
 Returns true, iff this AttributeSource has any attributes
 

Detailed Description

This class can be used if the token attributes of a TokenStream are intended to be consumed more than once. It caches all token attribute states locally in a List.

CachingTokenFilter implements the optional method TokenStream.Reset(), which repositions the stream to the first Token.

Definition at line 29 of file CachingTokenFilter.cs.

Constructor & Destructor Documentation

Lucene.Net.Analysis.CachingTokenFilter.CachingTokenFilter ( TokenStream  input)

Definition at line 35 of file CachingTokenFilter.cs.

Member Function Documentation

override void Lucene.Net.Analysis.CachingTokenFilter.End ( )
virtual

This method is called by the consumer after the last token has been consumed, after IncrementToken returned false (using the new 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.

<throws> IOException </throws>

Reimplemented from Lucene.Net.Analysis.TokenStream.

Definition at line 59 of file CachingTokenFilter.cs.

override bool Lucene.Net.Analysis.CachingTokenFilter.IncrementToken ( )
virtual

Consumers (i.e., IndexWriter) use this method to advance the stream to the next token. Implementing classes must implement this method and update the appropriate Util.Attributes 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 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 AttributeSource.AddAttribute{T}() and AttributeSource.GetAttribute{T}(), references to all Util.Attributes 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 IncrementToken().

Returns
false for end of stream; true otherwise

Implements Lucene.Net.Analysis.TokenStream.

Definition at line 39 of file CachingTokenFilter.cs.

override void Lucene.Net.Analysis.CachingTokenFilter.Reset ( )
virtual

Resets this stream to the beginning. This is an optional operation, so subclasses may or may not implement this method. Reset() is not needed for the standard indexing process. However, if the tokens of a TokenStream are intended to be consumed more than once, it is necessary to implement Reset(). Note that if your TokenStream caches tokens and feeds them back again after a reset, it is imperative that you clone the tokens when you store them away (on the first pass) as well as when you return them (on future passes after Reset()).

Reimplemented from Lucene.Net.Analysis.TokenStream.

Definition at line 67 of file CachingTokenFilter.cs.


The documentation for this class was generated from the following file: