org.apache.lucene.analysis

Class AnalyzerWrapper

java.lang.Object

org.apache.lucene.analysis.Analyzer

org.apache.lucene.analysis.AnalyzerWrapper

All Implemented Interfaces:

Closeable, AutoCloseable

Direct Known Subclasses:

DelegatingAnalyzerWrapper

public abstract class AnalyzerWrapper
extends Analyzer

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, Analyzer.TokenStreamComponents) allows the TokenStreamComponents of the wrapped Analyzer to then be wrapped (such as adding a new TokenFilter to form new TokenStreamComponents.

wrapReader(String, Reader) allows the Reader of the wrapped Analyzer to then be wrapped (such as adding a new CharFilter.

Important: If you do not want to wrap the TokenStream using wrapComponents(String, Analyzer.TokenStreamComponents) or the Reader using wrapReader(String, Reader) and just delegate to other analyzers (like by field name), use DelegatingAnalyzerWrapper as superclass!

See Also:

DelegatingAnalyzerWrapper

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.analysis.Analyzer

Analyzer.ReuseStrategy, Analyzer.TokenStreamComponents

Field Summary

Fields inherited from class org.apache.lucene.analysis.Analyzer

GLOBAL_REUSE_STRATEGY, PER_FIELD_REUSE_STRATEGY

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AnalyzerWrapper(Analyzer.ReuseStrategy reuseStrategy) Creates a new AnalyzerWrapper with the given reuse strategy.

Method Summary

Modifier and Type	Method and Description
protected Analyzer.TokenStreamComponents	createComponents(String fieldName) Creates a new Analyzer.TokenStreamComponents instance for this analyzer.
int	getOffsetGap(String fieldName) Just like Analyzer.getPositionIncrementGap(java.lang.String), except for Token offsets instead.
int	getPositionIncrementGap(String fieldName) Invoked before indexing a IndexableField instance if terms have already been added to that field.
protected abstract Analyzer	getWrappedAnalyzer(String fieldName) Retrieves the wrapped Analyzer appropriate for analyzing the field with the given name
Reader	initReader(String fieldName, Reader reader) Override this if you want to add a CharFilter chain.
protected Analyzer.TokenStreamComponents	wrapComponents(String fieldName, Analyzer.TokenStreamComponents components) Wraps / alters the given TokenStreamComponents, taken from the wrapped Analyzer, to form new components.
protected Reader	wrapReader(String fieldName, Reader reader) Wraps / alters the given Reader.

Methods inherited from class org.apache.lucene.analysis.Analyzer

close, getReuseStrategy, getVersion, setVersion, tokenStream, tokenStream

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AnalyzerWrapper

protected AnalyzerWrapper(Analyzer.ReuseStrategy 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: super(delegate.getReuseStrategy());.

If you choose different analyzers per field, use Analyzer.PER_FIELD_REUSE_STRATEGY.

See Also:

Analyzer.getReuseStrategy()

Method Detail

getWrappedAnalyzer

protected abstract Analyzer getWrappedAnalyzer(String fieldName)

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

Parameters:

fieldName - Name of the field which is to be analyzed

Returns:

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

wrapComponents

protected Analyzer.TokenStreamComponents wrapComponents(String fieldName,
                                                        Analyzer.TokenStreamComponents components)

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.

Parameters:

fieldName - Name of the field which is to be analyzed

components - TokenStreamComponents taken from the wrapped Analyzer

Returns:

Wrapped / altered TokenStreamComponents.

wrapReader

protected Reader wrapReader(String fieldName,
                            Reader reader)

Wraps / alters the given Reader. Through this method AnalyzerWrappers can implement initReader(String, Reader). By default, the given reader is returned.

Parameters:

fieldName - name of the field which is to be analyzed

reader - the reader to wrap

Returns:

the wrapped reader

createComponents

protected final Analyzer.TokenStreamComponents createComponents(String fieldName)

Description copied from class: Analyzer

Creates a new Analyzer.TokenStreamComponents instance for this analyzer.

Specified by:

createComponents in class Analyzer

Parameters:

fieldName - the name of the fields content passed to the Analyzer.TokenStreamComponents sink as a reader

Returns:

the Analyzer.TokenStreamComponents for this analyzer.

getPositionIncrementGap

public int getPositionIncrementGap(String fieldName)

Description copied from class: Analyzer

Invoked before indexing a IndexableField instance if terms have already been added to that field. This allows custom analyzers to place an automatic position increment gap between IndexbleField 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 IndexableField instances, are in successive positions, allowing exact PhraseQuery matches, for instance, across IndexableField instance boundaries.

Overrides:

getPositionIncrementGap in class Analyzer

Parameters:

fieldName - IndexableField name being indexed.

Returns:

position increment gap, added to the next token emitted from Analyzer.tokenStream(String,Reader). This value must be >= 0.

getOffsetGap

public int getOffsetGap(String fieldName)

Description copied from class: Analyzer

Just like Analyzer.getPositionIncrementGap(java.lang.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.

Overrides:

getOffsetGap in class Analyzer

Parameters:

fieldName - the field just indexed

Returns:

offset gap, added to the next token emitted from Analyzer.tokenStream(String,Reader). This value must be >= 0.

initReader

public final Reader initReader(String fieldName,
                               Reader reader)

Description copied from class: Analyzer

Override this if you want to add a CharFilter chain.

The default implementation returns reader unchanged.

Overrides:

initReader in class Analyzer

Parameters:

fieldName - IndexableField name being indexed

reader - original Reader

Returns:

reader, optionally decorated with CharFilter(s)