Class AnalyzerWrapper

Extension to Analyzer suitable for Analyzers which wrap other Analyzers.

GetWrappedAnalyzer(string) allows the Analyzer to wrap multiple Analyzers which are selected on a per field basis.

WrapComponents(string, TokenStreamComponents) allows the TokenStreamComponents of the wrapped Analyzer to then be wrapped (such as adding a new TokenFilter to form new TokenStreamComponents).
Inheritance
object
Analyzer
AnalyzerWrapper
Implements
Inherited Members
Namespace: Lucene.Net.Analysis
Assembly: Lucene.Net.dll
Syntax
public abstract class AnalyzerWrapper : Analyzer, IDisposable

Constructors

AnalyzerWrapper()

Creates a new AnalyzerWrapper. Since the ReuseStrategy of the wrapped Analyzers are unknown, PER_FIELD_REUSE_STRATEGY is assumed.

Declaration
[Obsolete("Use AnalyzerWrapper(Analyzer.ReuseStrategy) and specify a valid Analyzer.ReuseStrategy, probably retrieved from the wrapped analyzer using Analyzer.Strategy.")]
protected AnalyzerWrapper()

AnalyzerWrapper(ReuseStrategy)

Creates a new AnalyzerWrapper with the given reuse strategy.

If you want to wrap a single delegate Analyzer you can probably reuse its strategy when instantiating this subclass: base(innerAnalyzer.Strategy).

If you choose different analyzers per field, use PER_FIELD_REUSE_STRATEGY.
Declaration
protected AnalyzerWrapper(ReuseStrategy reuseStrategy)
Parameters
Type Name Description
ReuseStrategy reuseStrategy
See Also

Methods

CreateComponents(string, TextReader)

Creates a new TokenStreamComponents instance for this analyzer.

Declaration
protected override sealed TokenStreamComponents CreateComponents(string fieldName, TextReader aReader)
Parameters
Type Name Description
string fieldName

the name of the fields content passed to the TokenStreamComponents sink as a reader
TextReader aReader
Returns
Type Description
TokenStreamComponents

the TokenStreamComponents for this analyzer.
Overrides

GetOffsetGap(string)

Just like GetPositionIncrementGap(string), except for Token offsets instead. By default this returns 1. this method is only called if the field produced at least one token for indexing.

Declaration
public override int GetOffsetGap(string fieldName)
Parameters
Type Name Description
string fieldName

the field just indexed
Returns
Type Description
int

offset gap, added to the next token emitted from GetTokenStream(string, TextReader). this value must be >= 0.
Overrides

GetPositionIncrementGap(string)

Invoked before indexing a IIndexableField instance if terms have already been added to that field. This allows custom analyzers to place an automatic position increment gap between IIndexableField instances using the same field name. The default value position increment gap is 0. With a 0 position increment gap and the typical default token position increment of 1, all terms in a field, including across IIndexableField instances, are in successive positions, allowing exact PhraseQuery matches, for instance, across IIndexableField instance boundaries.

Declaration
public override int GetPositionIncrementGap(string fieldName)
Parameters
Type Name Description
string fieldName

IIndexableField name being indexed.
Returns
Type Description
int

position increment gap, added to the next token emitted from GetTokenStream(string, TextReader). this value must be >= 0.
Overrides

GetWrappedAnalyzer(string)

Retrieves the wrapped Analyzer appropriate for analyzing the field with the given name

Declaration
protected abstract Analyzer GetWrappedAnalyzer(string fieldName)
Parameters
Type Name Description
string fieldName

Name of the field which is to be analyzed
Returns
Type Description
Analyzer

Analyzer for the field with the given name. Assumed to be non-null

InitReader(string, TextReader)

Override this if you want to add a CharFilter chain.

The default implementation returns reader unchanged.
Declaration
protected override TextReader InitReader(string fieldName, TextReader reader)
Parameters
Type Name Description
string fieldName

IIndexableField name being indexed
TextReader reader

original TextReader
Returns
Type Description
TextReader

reader, optionally decorated with CharFilter(s)
Overrides

WrapComponents(string, TokenStreamComponents)

Wraps / alters the given TokenStreamComponents, taken from the wrapped Analyzer, to form new components. It is through this method that new TokenFilters can be added by AnalyzerWrappers. By default, the given components are returned.

Declaration
protected virtual TokenStreamComponents WrapComponents(string fieldName, TokenStreamComponents components)
Parameters
Type Name Description
string fieldName

Name of the field which is to be analyzed
TokenStreamComponents components

TokenStreamComponents taken from the wrapped Analyzer
Returns
Type Description
TokenStreamComponents

Wrapped / altered TokenStreamComponents.

WrapReader(string, TextReader)

Wraps / alters the given TextReader. Through this method AnalyzerWrappers can implement InitReader(string, TextReader). By default, the given reader is returned.

Declaration
protected virtual TextReader WrapReader(string fieldName, TextReader reader)
Parameters
Type Name Description
string fieldName

name of the field which is to be analyzed
TextReader reader

the reader to wrap
Returns
Type Description
TextReader

the wrapped reader

Implements