Module: Xenum::MergeSort

Defined in:
lib/xenum/merge_sort.rb

Defined Under Namespace

Classes: Candidate

Constant Summary collapse

NULL = 
Object.new

Class Method Summary collapse

Class Method Details

.iter(*enums) ⇒ Object 



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# File 'lib/xenum/merge_sort.rb', line 19

def iter(*enums)
  Enumerator.new do |yielder|
    enums = enums.each_with_object([]) do |e, arr|
      c = Candidate.new(e)
      arr << c if c.value != NULL
    end
    enums.sort!{ |a, b| b <=> a }

    resort = -> do
      i = -1
      x = enums[i]
      loop do
        e = enums[i-1]
        break unless e
        break if (e <=> x) >= 0
        enums[i] = e
        i -= 1
      end
      enums[i] = x
    end

    loop do
      break if enums.empty?
      resort.call
      least = enums[-1]
      yielder << least.value
      least.fetch
      next enums.pop if least.value == NULL
    end
  end
end

.recur(*enums) ⇒ Object 



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# File 'lib/xenum/merge_sort.rb', line 6

def recur(*enums)
  case enums.size
  when 0
    [].to_enum
  when 1
    enums[0]
  else
    enums2 = recur(*enums.pop(enums.size / 2))
    enums1 = recur(*enums)
    _recur(enums1, enums2)
  end
end