myflat.rb

#!/usr/bin/env ruby
# https://gist.github.com/hoanga/4955d1da5479dbff12c3eb33b9d26107

# Returns a flattened version of all elements in the array.  Same as Array.flatten
def my_flatten(arr)
  result = []

  arr.each do |elem|
    if elem.kind_of?(Array)
      result.concat(my_flatten(elem))
    else
      result << elem
    end
  end
  return result
end


if __FILE__ == $0
  def run_test(input, output)
    puts "=========================="
    puts "Input: #{input}"
    puts "Expected: #{output}"
    puts "Got: #{my_flatten(input)}"
    puts "Passed? #{my_flatten(input) == output}"
    puts ""
  end

  # Test 1
  test_input_array1 = [[1, 2], [3], 4, 5, [7, [8]]]
  test_output_array1 = [1,2,3,4,5,7,8]

  # Test 2
  test_input_array2 = [1, "bb", [[[3]]], [4], :foo, [7, [8]]]
  test_output_array2 = [1,"bb",3,4,:foo,7,8]

  run_test(test_input_array1, test_output_array1)
  run_test(test_input_array2, test_output_array2)
end