parser.ex

defmodule Parser do
	@dict HashDict.new([{"foo", "bar"}, {"baz", "buzz"}])

	defrecord :state, [in_match: false, escaping: false, key: ""]
	def translate(string) do
		translate(string, :state[])
	end

	defp translate("", _), do: ""
	defp translate(<<"\\", rest:: binary>>, state) do
		<<"\\", translate(rest, state.escaping(true))::binary>>
	end
	defp translate(<<char::[binary, size(1)], rest::binary>>, state = :state[escaping: true]) do
		<<char::binary, translate(rest, state.escaping(false))::binary>>
	end
	defp translate(<<"$", rest::binary>>, state = :state[in_match: true]) do
		case @dict[state.key] do
			nil -> raise SyntaxError
			word -> <<word::binary, translate(rest, state.in_match(false))::binary>>
		end
	end
	defp translate(<<"$", rest::binary>>, state = :state[in_match: false]) do
		translate(rest, state.in_match(true).key(""))
	end
	defp translate(<<char::[binary, size(1)], rest::binary>>, state = :state[in_match: true]) do
		translate(rest, state.key("#{state.key}#{char}"))
	end
	defp translate(<<char::[binary, size(1)], rest::binary>>, state) do
		<<char::binary, translate(rest, state)::binary>>
	end
end