Make VALID_DIRECTIONS to Set

[kamipo]

require "benchmark/ips"
require "set"

array = [:asc, :desc, :ASC, :DESC, "asc", "desc", "ASC", "DESC"]
set   = array.to_set
item  = "DESC"

Benchmark.ips do |x|
  x.report "array" do
    array.include?(item)
  end
  x.report "set" do
    set.include?(item)
  end
end

% ruby array_vs_set.rb
Warming up --------------------------------------
               array   188.441k i/100ms
                 set   229.531k i/100ms
Calculating -------------------------------------
               array      3.508M (± 9.0%) i/s -     17.525M in   5.043058s
                 set      5.134M (± 7.6%) i/s -     25.707M in   5.038921s

[pixeltrix]

In the scheme of things I don't think this will make much difference but thanks anyway! 👍