Class ReversedWildcardFilterFactory

  • public class ReversedWildcardFilterFactory
    extends org.apache.lucene.analysis.util.TokenFilterFactory
    Factory for ReversedWildcardFilter-s. When this factory is added to an analysis chain, it will be used both for filtering the tokens during indexing, and to determine the query processing of this field during search.

    This class supports the following init arguments:

    • withOriginal - if true, then produce both original and reversed tokens at the same positions. If false, then produce only reversed tokens.
    • maxPosAsterisk - maximum position (1-based) of the asterisk wildcard ('*') that triggers the reversal of query term. Asterisk that occurs at positions higher than this value will not cause the reversal of query term. Defaults to 2, meaning that asterisks on positions 1 and 2 will cause a reversal.
    • maxPosQuestion - maximum position (1-based) of the question mark wildcard ('?') that triggers the reversal of query term. Defaults to 1. Set this to 0, and maxPosAsterisk to 1 to reverse only pure suffix queries (i.e. ones with a single leading asterisk).
    • maxFractionAsterisk - additional parameter that triggers the reversal if asterisk ('*') position is less than this fraction of the query token length. Defaults to 0.0f (disabled).
    • minTrailing - minimum number of trailing characters in query token after the last wildcard character. For good performance this should be set to a value larger than 1. Defaults to 2.
    Note 1: This filter always reverses input tokens during indexing. Note 2: Query tokens without wildcard characters will never be reversed.
     <fieldType name="text_rvswc" class="solr.TextField" positionIncrementGap="100">
       <analyzer type="index">
         <tokenizer class="solr.WhitespaceTokenizerFactory"/>
         <filter class="solr.ReversedWildcardFilterFactory" withOriginal="true"
                 maxPosAsterisk="2" maxPosQuestion="1" minTrailing="2" maxFractionAsterisk="0"/>
       <analyzer type="query">
         <tokenizer class="solr.WhitespaceTokenizerFactory"/>
    • Field Summary

      • Fields inherited from class org.apache.lucene.analysis.util.AbstractAnalysisFactory

        LUCENE_MATCH_VERSION_PARAM, luceneMatchVersion
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      org.apache.lucene.analysis.TokenStream create​(org.apache.lucene.analysis.TokenStream input)  
      char getMarkerChar()  
      boolean shouldReverse​(String token)
      This method encapsulates the logic that determines whether a query token should be reversed in order to use the reversed terms in the index.
      • Methods inherited from class org.apache.lucene.analysis.util.TokenFilterFactory

        availableTokenFilters, forName, lookupClass, reloadTokenFilters
      • Methods inherited from class org.apache.lucene.analysis.util.AbstractAnalysisFactory

        get, get, get, get, get, getBoolean, getChar, getClassArg, getFloat, getInt, getLines, getLuceneMatchVersion, getOriginalArgs, getPattern, getSet, getSnowballWordSet, getWordSet, isExplicitLuceneMatchVersion, require, require, require, requireBoolean, requireChar, requireFloat, requireInt, setExplicitLuceneMatchVersion, splitAt, splitFileNames
    • Constructor Detail

      • ReversedWildcardFilterFactory

        public ReversedWildcardFilterFactory​(Map<String,​String> args)
        Creates a new ReversedWildcardFilterFactory
    • Method Detail

      • create

        public org.apache.lucene.analysis.TokenStream create​(org.apache.lucene.analysis.TokenStream input)
        Specified by:
        create in class org.apache.lucene.analysis.util.TokenFilterFactory
      • shouldReverse

        public boolean shouldReverse​(String token)
        This method encapsulates the logic that determines whether a query token should be reversed in order to use the reversed terms in the index.
        token - input token.
        true if input token should be reversed, false otherwise.
      • getMarkerChar

        public char getMarkerChar()