module Dentaku::TokenMatchers

def self.matcher(symbol)
  @matchers ||= [
    :datetime, :numeric, :string, :addsub, :subtract, :muldiv, :pow, :mod,
    :comparator, :comp_gt, :comp_lt, :open, :close, :comma,
    :non_close_plus, :non_group, :non_group_star, :arguments,
    :logical, :combinator, :if, :round, :roundup, :rounddown, :not,
    :anchored_minus, :math_neg_pow, :math_neg_mul
  ].each_with_object({}) do |name, matchers|
    matchers[name] = TokenMatcher.send(name)
  end
  @matchers.fetch(symbol) do
    raise "Unknown token symbol #{ symbol }"
  end
end