feat: Introduce a modular argument convention system for GNU and Windows styles, add .clang-format, and update CMake configuration to C++17.

src/headers/conventions/base_convention.hpp

@@ -0,0 +1,35 @@
+#pragma once
+#include <string>
+#include <utility>
+
+#ifndef BASE_CONVENTION_HPP
+#define BASE_CONVENTION_HPP
+
+namespace argument_parser::conventions {
+	enum class argument_type { SHORT, LONG, POSITIONAL, INTERCHANGABLE, ERROR };
+
+	using parsed_argument = std::pair<argument_type, std::string>;
+
+	class base_convention {
+	public:
+		virtual std::string extract_value(std::string const &) const = 0;
+		virtual parsed_argument get_argument(std::string const &) const = 0;
+		virtual bool requires_next_token() const = 0;
+		virtual std::string name() const = 0;
+		virtual std::string short_prec() const = 0;
+		virtual std::string long_prec() const = 0;
+
+	protected:
+		base_convention() = default;
+		~base_convention() = default;
+	};
+	using convention = base_convention;
+} // namespace argument_parser::conventions
+
+namespace argument_parser::conventions::helpers {
+	static std::string to_lower(std::string s);
+
+	static std::string to_upper(std::string s);
+} // namespace argument_parser::conventions::helpers
+
+#endif