Array#override

override.rb

require 'test/unit'


# Array#override
# 
# [0, 0, 0, 0, 0].override(['a', 'b']) 
# => ['a', 'b', 0, 0, 0]
# 
# [0, 0, 0, 0, 0].override(['a', 'b'], 2) 
# => [0, 0, 'a', 'b', 0]
class Array
  def override(array, shift=0)
    _self = self.dup
    _array = array.dup
    _array.reject!.with_index{|_v, i| i >= _self.length }

    _self.each.with_index(shift) do |_v, i|
      break if i - shift >= _array.length
      _self[i] = _array[i - shift]
    end

    _self.slice(0, self.length)
  end
end

class ArrayTest < Test::Unit::TestCase
  def test_override
    ov = ['2018-11-1', '2018-12-1', '2019-1-1']

    assert_equal Array.new(10).fill(0).override(ov), ['2018-11-1', '2018-12-1', '2019-1-1', 0, 0, 0, 0, 0, 0, 0]
    assert_equal Array.new(10).fill(0).override(ov, 2), [0, 0, '2018-11-1', '2018-12-1', '2019-1-1', 0, 0, 0, 0, 0]
    assert_equal Array.new(2).fill(0).override(ov), ['2018-11-1', '2018-12-1']
    assert_equal Array.new(2).fill(0).override(ov, 1), [0, '2018-11-1']
    assert_equal Array.new(2).fill(0).override(ov, 2), [0, 0]
    assert_equal Array.new(10).fill(0).override(ov, -2), ['2019-1-1', 0, 0, 0, 0, 0, 0, 0, '2018-11-1', '2018-12-1']
  end
end