Regex key -> value hash: https://glot.io/snippets/em9zobxd1f

gistfile1.rb

class MyHash
  def initialize
    @keys = []
    @values = []
  end

  def [] index
    @keys.each_with_index do |v, i|
      if index =~ v
        return @values[i]
      end
    end
    
    nil
  end
  
  def []=(key, value)
    @keys << key
    @values << value
  end
end

somehash = MyHash.new

somehash[/someregex/i] = 2

puts somehash["somestring"].inspect # nil
puts somehash["somEregexlalalala"].inspect # somevalue