Contents

class Array
  # Similar to +reduce+/+inject+, but also returns intermediate values. Has the same interface as +reduce+/+inject+, so an initial value, an oprator or both can be supplied. This method may eventually be moved to the +Enumerable+ module.
  #
  #   a = [*1..4]
  #   a.reductions(:+)
  #   #=> 10
  #   a.reductions(50, :+)
  #   #=> 60
  #   %w(a b c).reductions { |s1, s2| s1+s2 }
  #   #=> ["a", "ab", "abc"]
  def reductions(*args, &block)
    arr = dup

    if args.size == 1
      Symbol === (arg = args.first) ? op = arg : initial = arg
    else
      initial, op, _ = args
    end

    raise ArgumentError, "Need an operator or block" unless op || block

    initial ||= arr.shift

    arr.inject([initial, [initial]]) do |(acc, result), el|
      val = op ? acc.send(op, el) : yield(acc, el)
      [val, result << val]
    end.last
  end
end

Version data entries

3 entries across 3 versions & 1 rubygems

Version	Path
shenanigans-1.0.13	lib/shenanigans/array/reductions.rb
shenanigans-1.0.11	lib/shenanigans/array/reductions.rb
shenanigans-1.0.10	lib/shenanigans/array/reductions.rb