org.apache.lucene.analysis.th
Class ThaiWordFilter

java.lang.Object
  org.apache.lucene.util.AttributeSource
      org.apache.lucene.analysis.TokenStream
          org.apache.lucene.analysis.TokenFilter
              org.apache.lucene.analysis.th.ThaiWordFilter

All Implemented Interfaces:

Closeable

public final class ThaiWordFilter
extends TokenFilter

TokenFilter that use BreakIterator to break each Token that is Thai into separate Token(s) for each Thai word.

Please note: Since matchVersion 3.1 on, this filter no longer lowercases non-thai text. ThaiAnalyzer will insert a LowerCaseFilter before this filter so the behaviour of the Analyzer does not change. With version 3.1, the filter handles position increments correctly.

WARNING: this filter may not be supported by all JREs. It is known to work with Sun/Oracle and Harmony JREs. If your application needs to be fully portable, consider using ICUTokenizer instead, which uses an ICU Thai BreakIterator that will always be available.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource

AttributeSource.AttributeFactory, AttributeSource.State

Field Summary

static boolean

DBBI_AVAILABLE True if the JRE supports a working dictionary-based breakiterator for Thai.

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

input

Constructor Summary

ThaiWordFilter(TokenStream input)
Deprecated. Use the ctor with matchVersion instead!

ThaiWordFilter(Version matchVersion, TokenStream input)
Creates a new ThaiWordFilter with the specified match version.

Method Summary

boolean	incrementToken() Consumers (i.e., IndexWriter) use this method to advance the stream to the next token.
void	reset() Reset the filter as well as the input TokenStream.

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

close, end

Methods inherited from class org.apache.lucene.util.AttributeSource

addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, restoreState, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

DBBI_AVAILABLE

public static final boolean DBBI_AVAILABLE

True if the JRE supports a working dictionary-based breakiterator for Thai. If this is false, this filter will not work at all!

Constructor Detail

ThaiWordFilter

@Deprecated
public ThaiWordFilter(TokenStream input)

Deprecated. Use the ctor with matchVersion instead!

Creates a new ThaiWordFilter that also lowercases non-thai text.

ThaiWordFilter

public ThaiWordFilter(Version matchVersion,
                      TokenStream input)

Creates a new ThaiWordFilter with the specified match version.

Method Detail

incrementToken

public boolean incrementToken()
                       throws IOException

Description copied from class: TokenStream

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 AttributeImpls 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(Class) and AttributeSource.getAttribute(Class), references to all AttributeImpls 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 TokenStream.incrementToken().

Specified by:

incrementToken in class TokenStream

Returns:

false for end of stream; true otherwise

Throws:

IOException

reset

public void reset()
           throws IOException

Description copied from class: TokenFilter

Reset the filter as well as the input TokenStream.

Overrides:

reset in class TokenFilter

Throws:

IOException