Package org.apache.lucene.analysis.commongrams

Class CommonGramsQueryFilter

java.lang.Object
org.apache.lucene.util.AttributeSource
org.apache.lucene.analysis.TokenStream
org.apache.lucene.analysis.TokenFilter
org.apache.lucene.analysis.commongrams.CommonGramsQueryFilter
All Implemented Interfaces:
Closeable, AutoCloseable
public final class CommonGramsQueryFilter extends TokenFilter
Wrap a CommonGramsFilter optimizing phrase queries by only returning single words when they are not a member of a bigram. Example:
  • query input to CommonGramsFilter: "the rain in spain falls mainly"
  • output of CommomGramsFilter/input to CommonGramsQueryFilter: |"the, "the-rain"|"rain" "rain-in"|"in, "in-spain"|"spain"|"falls"|"mainly"
  • output of CommonGramsQueryFilter:"the-rain", "rain-in" ,"in-spain", "falls", "mainly"

  • Constructor Details

    • CommonGramsQueryFilter

      public CommonGramsQueryFilter(CommonGramsFilter input)
      Constructs a new CommonGramsQueryFilter based on the provided CommomGramsFilter
      Parameters:
      input - CommonGramsFilter the QueryFilter will use

  • Method Details

    • reset

      public void reset() throws IOException
      This method is called by a consumer before it begins consumption using TokenStream.incrementToken().

      Resets this stream to a clean state. Stateful implementations must implement this method so that they can be reused, just as if they had been created fresh.

      If you override this method, always call super.reset(), otherwise some internal state will not be correctly reset (e.g., Tokenizer will throw IllegalStateException on further usage).

      NOTE: The default implementation chains the call to the input TokenStream, so be sure to call super.reset() when overriding this method.

      Overrides:
      reset in class TokenFilter
      Throws:
      IOException

    • incrementToken

      public boolean incrementToken() throws IOException
      Output bigrams whenever possible to optimize queries. Only output unigrams when they are not a member of a bigram. Example:
      • input: "the rain in spain falls mainly"
      • output:"the-rain", "rain-in" ,"in-spain", "falls", "mainly"
      Specified by:
      incrementToken in class TokenStream
      Returns:
      false for end of stream; true otherwise
      Throws:
      IOException

    • isGramType

      public boolean isGramType()
      Convenience method to check if the current type is a gram type
      Returns:
      true if the current type is a gram type, false otherwise