Module: Enumerable

Defined in:
lib/xenum.rb

Instance Method Summary collapse

Instance Method Details

#lazy_flatten(level = nil) ⇒ Object 



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# File 'lib/xenum.rb', line 10

def lazy_flatten(level = nil)
  these = self
  level = -1 if level.nil?

  Enumerator.new do |yielder|
    level.nil?
    these.each do |this|
      if Enumerable === this && level != 0
        this.lazy_flatten(level - 1).each do |sub|
           yielder.yield(sub)
        end
        next
      end

      yielder.yield(this)
    end
  end
end

#lazy_product(*enums) ⇒ Object 



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# File 'lib/xenum.rb', line 29

def lazy_product(*enums)
  if enums.empty?
    return Enumerator.new do |yielder|
      each do |this|
        yielder.yield([this])
      end
    end
  end

  Enumerator.new do |yielder|
    each do |this|
      head = [this]
      enums[0].lazy_product(*enums[1..-1]).each do |tail|
        yielder.yield(head + tail)
      end
    end
  end
end

#merge_sort(that) ⇒ Object 



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# File 'lib/xenum.rb', line 48

def merge_sort(that)
  this = Enumerator === self ? self : self.to_enum
  that = Enumerator === that ? that : that.to_enum

  Enumerator.new do |e|
    a = Xenum::NULL
    b = Xenum::NULL
    remain = nil

    loop do
      if a == Xenum::NULL
        a = begin
              this.next
            rescue StopIteration
              remain = that
              break
            end
      end

      if b == Xenum::NULL
        b = begin
              that.next
            rescue StopIteration
              remain = this
              break
            end
      end

      if (a <=> b) <= 0
        e.yield(a)
        a = Xenum::NULL
      else
        e.yield(b)
        b = Xenum::NULL
      end
    end

    e.yield(a) if a != Xenum::NULL
    e.yield(b) if b != Xenum::NULL

    loop do
      e.yield(remain.next)
    rescue StopIteration
      break
    end
  end
end