Class: Ferret::Search::SortComparator

Inherits:
Object
  • Object
show all
Defined in:
lib/ferret/search/sort_comparator.rb

Overview

Abstract base class for sorting hits returned by a Query.

This class should only be used if the other SortField types (SCORE, DOC, STRING, INT, FLOAT) do not provide an adequate sorting. It maintains an internal cache of values which could be quite large. The cache is an array of Comparable, one for each document in the index. There is a distinct Comparable for each unique term in the field - if some documents have the same term in the field, the cache array will have entries which reference the same Comparable.

Author

Tim Jones

Instance Method Summary collapse

Instance Method Details

#get_comparable(term_text) ⇒ Object

Returns an object which, when sorted according to natural order, will order the Term values in the correct order. For example, if the Terms contained integer values, this method would return term_text.to_i. Note that this might not always be the most efficient implementation - for this particular example, a better implementation might be to make a ScoreDocLookupComparator that uses an internal lookup table of int.

term_text

The textual value of the term.

returns

An object representing term_text that sorts according to the natural order of term_text.

See ScoreDocComparator

Raises:

  • (NotImplementedError) 


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# File 'lib/ferret/search/sort_comparator.rb', line 56

def get_comparable(term_text)
  raise NotImplementedError
end

#new_comparator(reader, field_name) ⇒ Object

Creates a comparator for the field in the given index.

reader

Index to create comparator for.

field_name

Field to create comparator for.

returns

Comparator of ScoreDoc objects.



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# File 'lib/ferret/search/sort_comparator.rb', line 20

def new_comparator(reader, field_name)
  cached_values = FieldCache::DEFAULT.custom(reader, field, self)
  
  score_doc_comparator =  ScoreDocComparator.new() 

  class <<score_doc_comparator
    attr_writer :cache_values
    def compare(i, j) 
      return @cached_values[i.doc] <=> @cached_values[j.doc]
    end

    def sort_value(i) 
      return @cached_values[i.doc]
    end

    def sort_type()
      return SortField::SortType::CUSTOM
    end
  end
  score_doc_comparator.cached_values = cached_values
  return score_doc_comparator
end