module Steep
  InstanceMethodName = _ = Struct.new(:type_name, :method_name, keyword_init: true) do
    # @implements InstanceMethodName
    def to_s
      "#{type_name}##{method_name}"
    end
  end

  SingletonMethodName = _ = Struct.new(:type_name, :method_name, keyword_init: true) do
    # @implements SingletonMethodName
    def to_s
      "#{type_name}.#{method_name}"
    end
  end

  class ::Object
    def MethodName(string)
      case string
      when /#/
        type_name, method_name = string.split(/#/, 2)
        type_name or raise
        method_name or raise
        InstanceMethodName.new(type_name: TypeName(type_name), method_name: method_name.to_sym)
      when /\./
        type_name, method_name = string.split(/\./, 2)
        type_name or raise
        method_name or raise
        SingletonMethodName.new(type_name: TypeName(type_name), method_name: method_name.to_sym)
      else
        raise "Unexpected method name: #{string}"
      end
    end
  end
end