org.apache.lucene.analysis.th
Class ThaiWordFilter

java.lang.Object
  extended by org.apache.lucene.util.AttributeSource
      extended by org.apache.lucene.analysis.TokenStream
          extended by org.apache.lucene.analysis.TokenFilter
              extended by 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


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