Class PatternCaptureGroupTokenFilter

CaptureGroup uses .NET regexes to emit multiple tokens - one for each capture group in one or more patterns.

For example, a pattern like:

"(https?://([a-zA-Z\-_0-9.]+))"

when matched against the string "http://www.foo.com/index" would return the tokens "https://www.foo.com" and "www.foo.com".

If none of the patterns match, or if preserveOriginal is true, the original token will be preserved.

Each pattern is matched as often as it can be, so the pattern "(...)", when matched against "abcdefghi" would produce ["abc","def","ghi"]

A camelCaseFilter could be written as:

"([A-Z]{2,})",                                 
       "(?<![A-Z])([A-Z][a-z]+)",                     
       "(?:^|\\b|(?<=[0-9_])|(?<=[A-Z]{2}))([a-z]+)", 
       "([0-9]+)"

plus if preserveOriginal is true, it would also return camelCaseFilter

Inheritance

object

AttributeSource

TokenStream

TokenFilter

PatternCaptureGroupTokenFilter

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.Pattern

Assembly: Lucene.Net.Analysis.Common.dll

Syntax

public sealed class PatternCaptureGroupTokenFilter : TokenFilter, IDisposable

Constructors

PatternCaptureGroupTokenFilter(TokenStream, bool, params Regex[])

Creates a new PatternCaptureGroupTokenFilter

Declaration

public PatternCaptureGroupTokenFilter(TokenStream input, bool preserveOriginal, params Regex[] patterns)

Parameters

Type	Name	Description
TokenStream	input	the input Lucene.Net.Analysis.TokenStream
bool	preserveOriginal	set to true to return the original token even if one of the patterns matches
Regex[]	patterns	an array of Lucene.Net.Analysis.Pattern objects to match against each token

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