Benchmark flatten alternatives

flatten_alternatives

# methods defined on main:Object
def iron(array)
  a = []
  array.each do |element|
    if element.is_a? Array
      a.push(*iron(element))
    else
      a.append(element)
    end
  end
  a
end

def implode(array)
  array.each_with_object([]) do |element, flat|
    flat.push(*(element.is_a?(Array) ? implode(element) : element))
  end
end

def stomp(array)
  array.inject([]) { |a, element| a + Array(element.is_a?(Array) ? element.stomp : element) }
end

# In class methods

class Array
  def implode
    each_with_object([]) do |element, flat|
      flat.push(*(element.is_a?(Array) ? element.implode : element))
    end
  end

  def iron
    a = []
    each do |element|
      if element.is_a? Array
        a.push(*element.iron)
      else
        a.append(element)
      end
    end
    a
  end

  def stomp
    inject([]) { |a, element| a + Array(element.is_a?(Array) ? element.stomp : element) }
  end
end

# Benchmark comparing all the above with Array#flatten

def run_bm(n=50_000, a=[[9, 8, 7, 4], 1, 6, 4, [9, 4, 2]])
  Benchmark.bm do |bm|
    bm.report('Array#implode')       { n.times { a.implode } }
    bm.report('main:Object#implode') { n.times { implode(a) } }
    bm.report('Array#iron')          { n.times { a.iron } }
    bm.report('main:Object#iron')    { n.times { iron(a) } }
    bm.report('Array#stomp')         { n.times { a.stomp } }
    bm.report('main:Object#stomp')   { n.times { stomp(a) } }
    bm.report('Array#flatten')       { n.times { a.flatten } }
  end
end

# Benchmark Results
                        user       system     total    real
Array#implode           0.360000   0.000000   0.360000 (  0.368209)
main:Object#implode     0.290000   0.000000   0.290000 (  0.287446)
Array#iron              0.150000   0.000000   0.150000 (  0.149134)
main:Object#iron        0.140000   0.000000   0.140000 (  0.144023)
Array#stomp             0.430000   0.000000   0.430000 (  0.425000)
main:Object#stomp       0.410000   0.000000   0.410000 (  0.408995)
Array#flatten           0.110000   0.000000   0.110000 (  0.108783)