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

src/source/conventions/implementations/gnu_argument_convention.cpp

@@ -0,0 +1,75 @@
+#include "gnu_argument_convention.hpp"
+#include "base_convention.hpp"
+#include <stdexcept>
+
+bool starts_with(std::string const &s, std::string const &prefix) {
+	return s.rfind(prefix, 0) == 0;
+}
+
+namespace argument_parser::conventions::implementations {
+	parsed_argument gnu_argument_convention::get_argument(std::string const &raw) const {
+		if (starts_with(raw, long_prec()))
+			return {argument_type::LONG, raw.substr(2)};
+		else if (starts_with(raw, short_prec()))
+			return {argument_type::SHORT, raw.substr(1)};
+		else
+			return {argument_type::ERROR, "GNU standard convention does not allow arguments without a preceding dash."};
+	}
+
+	std::string gnu_argument_convention::extract_value(std::string const & /*raw*/) const {
+		throw std::runtime_error("No inline value in standard GNU convention.");
+	}
+
+	bool gnu_argument_convention::requires_next_token() const {
+		return true;
+	}
+
+	std::string gnu_argument_convention::name() const {
+		return "GNU-style long options";
+	}
+
+	std::string gnu_argument_convention::short_prec() const {
+		return "-";
+	}
+
+	std::string gnu_argument_convention::long_prec() const {
+		return "--";
+	}
+} // namespace argument_parser::conventions::implementations
+
+namespace argument_parser::conventions::implementations {
+	parsed_argument gnu_equal_argument_convention::get_argument(std::string const &raw) const {
+		auto pos = raw.find('=');
+		auto arg = pos != std::string::npos ? raw.substr(0, pos) : raw;
+		if (starts_with(arg, long_prec()))
+			return {argument_type::LONG, arg.substr(2)};
+		else if (starts_with(arg, short_prec()))
+			return {argument_type::SHORT, arg.substr(1)};
+		else
+			return {argument_type::ERROR, "GNU standard convention does not allow arguments without a preceding dash."};
+	}
+
+	std::string gnu_equal_argument_convention::extract_value(std::string const &raw) const {
+		auto pos = raw.find('=');
+		if (pos == std::string::npos || pos + 1 >= raw.size())
+			throw std::runtime_error("Expected value after '='.");
+		return raw.substr(pos + 1);
+	}
+
+	bool gnu_equal_argument_convention::requires_next_token() const {
+		return false;
+	}
+
+	std::string gnu_equal_argument_convention::name() const {
+		return "GNU-style long options (equal signed form)";
+	}
+
+	std::string gnu_equal_argument_convention::short_prec() const {
+		return "-";
+	}
+
+	std::string gnu_equal_argument_convention::long_prec() const {
+		return "--";
+	}
+
+} // namespace argument_parser::conventions::implementations