Class: Factbase::IndexedAnd

Inherits:
Object
  • Object
show all
Defined in:
lib/factbase/indexed/indexed_and.rb

Overview

Indexed term ‘and’.

Instance Method Summary collapse

Constructor Details

#initialize(term, idx) ⇒ IndexedAnd

Returns a new instance of IndexedAnd.



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# File 'lib/factbase/indexed/indexed_and.rb', line 8

def initialize(term, idx)
  @term = term
  @idx = idx
end

Instance Method Details

#predict(maps, fb, params) ⇒ Object 



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# File 'lib/factbase/indexed/indexed_and.rb', line 13

def predict(maps, fb, params)
  return nil if @idx.nil?
  key = [maps.object_id, @term.operands.first, @term.op]
  r = nil
  if @term.operands.all? { |o| o.op == :eq } && @term.operands.size > 1 \
    && @term.operands.all? { |o| o.operands.first.is_a?(Symbol) && _scalar?(o.operands[1]) }
    props = @term.operands.map { |o| o.operands.first }.sort
    key = [maps.object_id, props, :multi_and_eq]
    if @idx[key].nil?
      @idx[key] = {}
      maps.to_a.each do |m|
        _all_tuples(m, props).each do |t|
          @idx[key][t] = [] if @idx[key][t].nil?
          @idx[key][t].append(m)
        end
      end
    end
    tuples = Enumerator.product(
      *@term.operands.sort_by { |o| o.operands.first }.map do |o|
        if o.operands[1].is_a?(Symbol)
          params[o.operands[1].to_s] || []
        else
          [o.operands[1]]
        end
      end
    )
    j = tuples.map { |t| @idx[key][t] || [] }.reduce(&:|)
    r = (maps & []) | j
  else
    @term.operands.each do |o|
      n = o.predict(maps, fb, params)
      break if n.nil?
      if r.nil?
        r = n
      elsif n.size < r.size * 8 # to skip some obvious matchings
        r &= n.to_a
      end
      break if r.size < maps.size / 32 # it's already small enough
      break if r.size < 128 # it's obviously already small enough
    end
  end
  r
end