Class: Ferret::Search::BooleanQuery::BooleanWeight

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(query, searcher) ⇒ BooleanWeight

Returns a new instance of BooleanWeight.



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# File 'lib/ferret/search/boolean_query.rb', line 106

def initialize(query, searcher)
  @query = query
  @weights = []
 
  @similarity = query.similarity(searcher)
  query.clauses.each do |clause|
    @weights << clause.query.create_weight(searcher)
  end
end

Instance Attribute Details

#query ⇒ Object (readonly)

Returns the value of attribute query.



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# File 'lib/ferret/search/boolean_query.rb', line 104

def query
  @query
end

#similarity ⇒ Object

Returns the value of attribute similarity.



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# File 'lib/ferret/search/boolean_query.rb', line 102

def similarity
  @similarity
end

#weights ⇒ Object

Returns the value of attribute weights.



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# File 'lib/ferret/search/boolean_query.rb', line 103

def weights
  @weights
end

Instance Method Details

#explain(reader, doc) ⇒ Object 



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# File 'lib/ferret/search/boolean_query.rb', line 163

def explain(reader, doc)
 
  sum_expl = Explanation.new()
  sum_expl.description = "sum of:"
  coord = 0
  max_coord = 0
  sum = 0.0

  @weights.each_with_index do |weight, i|
    clause = @query.clauses[i]
    explanation = weight.explain(reader, doc)
    max_coord += 1 if not clause.prohibited?
    if explanation.value > 0 
      if not clause.prohibited?
        sum_expl << explanation
        sum += explanation.value
        coord += 1
      else 
        return Explanation.new(0.0, "match prohibited")
      end
    elsif clause.required?
      return Explanation.new(0.0, "match required")
    end
  end
  sum_expl.value = sum

  if (coord == 1)                          # only one clause matched
    sum_expl = sum_expl.details[0]         # eliminate wrapper
  end

  coord_factor = @similarity.coord(coord, max_coord)
  if (coord_factor == 1.0)                # coord is no-op
    return sum_expl                       # eliminate wrapper
  else 
    result = Explanation.new()
    result.description = "product of:"
    result << sum_expl
    result << Explanation.new(coord_factor, "coord(#{coord}/#{max_coord})")
    result.value = sum * coord_factor
    return result
  end
end

#normalize(norm) ⇒ Object 



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# File 'lib/ferret/search/boolean_query.rb', line 135

def normalize(norm) 
  norm *= @query.boost()
  @weights.each_with_index do |weight, i|
    clause = @query.clauses[i]
    if not clause.prohibited?
      weight.normalize(norm)
    end
  end
end

#scorer(reader) ⇒ Object

returns

An alternative Scorer that uses and provides skip_to(),

and scores documents in document number order.



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# File 'lib/ferret/search/boolean_query.rb', line 147

def scorer(reader)
  result = BooleanScorer.new(@similarity)

  @weights.each_with_index do |weight, i|
    clause = @query.clauses[i]
    sub_scorer = weight.scorer(reader)
    if (sub_scorer != nil)
      result.add_scorer(sub_scorer, clause.occur)
    elsif (clause.required?())
      return nil
    end
  end

  return result
end

#sum_of_squared_weights ⇒ Object 



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# File 'lib/ferret/search/boolean_query.rb', line 120

def sum_of_squared_weights()
  sum = 0
  @weights.each_with_index do |weight, i|
    clause = @query.clauses[i]
    if not clause.prohibited?
      sum += weight.sum_of_squared_weights()         # sum sub weights
    end
  end

  sum *= @query.boost() * @query.boost()             # boost each sub-weight

  return sum 
end

#value ⇒ Object 



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# File 'lib/ferret/search/boolean_query.rb', line 116

def value()
  return @query.boost()
end