Class OpenNLPChunkerFilter

Run OpenNLP chunker. Prerequisite: the OpenNLPTokenizer and OpenNLPPOSFilter must precede this filter. Tags terms in the Lucene.Net.Analysis.TokenAttributes.ITypeAttribute, replacing the POS tags previously put there by OpenNLPPOSFilter.

The Lucene.Net.Analysis.Payloads.TypeAsPayloadTokenFilter can be used to copy the POS tag values to Lucene.Net.Analysis.TokenAttributes.IPayloadAttribute, which will index the value. Alternatively, the Lucene.Net.Analysis.Miscellaneous.TypeAsSynonymFilter creates a cloned token at the same position as each tagged token, and copies the Lucene.Net.Analysis.TokenAttributes.ITypeAttribute value to the Lucene.Net.Analysis.TokenAttributes.ICharTermAttribute, optionally with a customized prefix (so that tags effectively occupy a different namespace from token text).
Inheritance
object
AttributeSource
TokenStream
TokenFilter
OpenNLPChunkerFilter
Implements
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.ReflectWith(IAttributeReflector)
AttributeSource.CloneAttributes()
AttributeSource.CopyTo(AttributeSource)
AttributeSource.ToString()
Namespace: Lucene.Net.Analysis.OpenNlp
Assembly: Lucene.Net.Analysis.OpenNLP.dll
Syntax
public sealed class OpenNLPChunkerFilter : TokenFilter, IDisposable

Constructors

OpenNLPChunkerFilter(TokenStream, NLPChunkerOp)

Run OpenNLP chunker. Prerequisite: the OpenNLPTokenizer and OpenNLPPOSFilter must precede this filter. Tags terms in the Lucene.Net.Analysis.TokenAttributes.ITypeAttribute, replacing the POS tags previously put there by OpenNLPPOSFilter.

The Lucene.Net.Analysis.Payloads.TypeAsPayloadTokenFilter can be used to copy the POS tag values to Lucene.Net.Analysis.TokenAttributes.IPayloadAttribute, which will index the value. Alternatively, the Lucene.Net.Analysis.Miscellaneous.TypeAsSynonymFilter creates a cloned token at the same position as each tagged token, and copies the Lucene.Net.Analysis.TokenAttributes.ITypeAttribute value to the Lucene.Net.Analysis.TokenAttributes.ICharTermAttribute, optionally with a customized prefix (so that tags effectively occupy a different namespace from token text).
Declaration
public OpenNLPChunkerFilter(TokenStream input, NLPChunkerOp chunkerOp)
Parameters
Type Name Description
TokenStream input
NLPChunkerOp chunkerOp

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()

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