flattenator.rb

# == Flattenator
#
# Author: Wilbert Ribeiro
#
# Ruby is an object-oriented language, that can support other paradigms like 
# functional style of programming.
#
# Flattenator class provides an improved way to flatten ruby arrays with any
# dimension, using functional style to increase performance.
#
# A minimal implementation could be:
#
#   => Flattenator.flatten!([1,2,3,[4,5,[6,7,[8]]],9,10])
#   => [1,2,3,4,5,6,7,8,9,10]

require 'rubygems'
require 'rspec'

class Flattenator
  class << self
    def flatten!(array)
      return nil unless array.is_a?(Array)
      array.reduce([]){|a,b| b.is_a?(Array) ? a.concat(flatten!(b)) : a << b }
    end
  end
end

describe Flattenator do
  let(:array) { [1,2,3,[4,5,[6,7,[8]]],9,10] }

  it 'should flatten array' do
    expect(Flattenator.flatten!(array)).to eq([1,2,3,4,5,6,7,8,9,10])
  end

  it 'should return nil if array is nil' do
    expect(Flattenator.flatten!(nil)).to eq(nil)
  end

  it 'should return nil if param is not array' do
    expect(Flattenator.flatten!(1)).to eq(nil)
  end

  it 'should return empty array' do
    expect(Flattenator.flatten!([])).to eq([])
  end
end