org.apache.lucene.index.memory

Class SynonymTokenFilter

public class SynonymTokenFilter extends TokenFilter

Injects additional tokens for synonyms of token terms fetched from the underlying child stream; the child stream must deliver lowercase tokens for synonyms to be found.

Author: whoschek.AT.lbl.DOT.gov

Field Summary
static StringSYNONYM_TOKEN_TYPE
The Token.type used to indicate a synonym to higher level filters.
Constructor Summary
SynonymTokenFilter(TokenStream input, SynonymMap synonyms, int maxSynonyms)
Creates an instance for the given underlying stream and synonym table.
Method Summary
protected TokencreateToken(String synonym, Token current)
Creates and returns a token for the given synonym of the current input token; Override for custom (stateless or stateful) behaviour, if desired.
Tokennext()
Returns the next token in the stream, or null at EOS.

Field Detail

SYNONYM_TOKEN_TYPE

public static final String SYNONYM_TOKEN_TYPE
The Token.type used to indicate a synonym to higher level filters.

Constructor Detail

SynonymTokenFilter

public SynonymTokenFilter(TokenStream input, SynonymMap synonyms, int maxSynonyms)
Creates an instance for the given underlying stream and synonym table.

Parameters: input the underlying child token stream synonyms the map used to extract synonyms for terms maxSynonyms the maximum number of synonym tokens to return per underlying token word (a value of Integer.MAX_VALUE indicates unlimited)

Method Detail

createToken

protected Token createToken(String synonym, Token current)
Creates and returns a token for the given synonym of the current input token; Override for custom (stateless or stateful) behaviour, if desired.

Parameters: synonym a synonym for the current token's term current the current token from the underlying child stream

Returns: a new token, or null to indicate that the given synonym should be ignored

next

public Token next()
Returns the next token in the stream, or null at EOS.
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