rewrite argument parsing

src/argparse.hpp

@@ -0,0 +1,110 @@
+/* argparse.hpp - Copyright (C) 2024 a dinosaur (zlib, see COPYING.txt) */
+
+#ifndef ARGPARSE_HPP
+#define ARGPARSE_HPP
+
+#include <initializer_list>
+#include <functional>
+#include <string>
+#include <ostream>
+#include <span>
+#include <ranges>
+#include <string_view>
+#include <vector>
+
+namespace ArgParse
+{
+	struct Option
+	{
+		char flag;
+		const char* argumentName;
+		bool required;
+		const char* helpString;
+	};
+
+	enum class ParseCtrl
+	{
+		CONTINUE,
+		QUIT_EARLY,
+		QUIT_ERR_UNKNOWN,
+		QUIT_ERR_UNEXPECTED,
+		QUIT_ERR_EXPECTARG,
+		QUIT_ERR_INVALID,
+		QUIT_ERR_RANGE
+	};
+
+	enum class ParseErr
+	{
+		OK,
+		OPT_UNKNOWN,
+		UNEXPECTED,
+		ARG_EXPECTED,
+		ARG_INVALID,
+		ARG_RANGE
+	};
+
+	using HandleOption = std::function<ParseCtrl(int, const std::string_view)>;
+
+	class ParserState
+	{
+		bool expectArg = false;
+		int flagChar;
+		HandleOption handler;
+		const std::initializer_list<Option>& options;
+
+	public:
+		ParserState(HandleOption handler, const std::initializer_list<Option>& options) noexcept
+			: handler(handler), options(options) {}
+		[[nodiscard]] bool ExpectingArg() const { return expectArg; }
+		[[nodiscard]] ParseCtrl Next(const std::string_view token);
+	};
+
+	class ArgParser
+	{
+		const std::string name;
+		std::initializer_list<Option> options;
+		HandleOption handler;
+
+	public:
+		explicit ArgParser(const std::string_view argv0, std::initializer_list<Option> options, HandleOption&& handler) noexcept;
+
+		[[nodiscard]] const std::string_view GetName() const { return name; }
+
+		void ShowShortUsage(std::ostream& out) const;
+		void ShowHelpUsage(std::ostream& out) const;
+
+		template <typename V>
+		ParseErr Parse(V args)
+		{
+			ParserState state(handler, options);
+			for (auto arg : args)
+			{
+				switch (state.Next(arg))
+				{
+				case ParseCtrl::CONTINUE:            continue;
+				case ParseCtrl::QUIT_EARLY:          return ParseErr::OK;
+				case ParseCtrl::QUIT_ERR_UNKNOWN:    return ParseErr::OPT_UNKNOWN;
+				case ParseCtrl::QUIT_ERR_UNEXPECTED: return ParseErr::UNEXPECTED;
+				case ParseCtrl::QUIT_ERR_EXPECTARG:  return ParseErr::ARG_EXPECTED;
+				case ParseCtrl::QUIT_ERR_INVALID:    return ParseErr::ARG_INVALID;
+				case ParseCtrl::QUIT_ERR_RANGE:      return ParseErr::ARG_RANGE;
+				}
+			}
+			return state.ExpectingArg() ? ParseErr::ARG_EXPECTED : ParseErr::OK;
+		}
+
+		inline ParseErr Parse(std::initializer_list<std::string_view> args)
+		{
+			return Parse<std::initializer_list<std::string_view>>(args);
+		}
+
+		inline ParseErr Parse(std::span<char*> args)
+		{
+			return Parse(args | std::views::transform([](char const* v){ return std::string_view(v); }));
+		}
+	};
+}
+
+extern bool ReadParamFile(std::vector<std::string>& tokens, std::istream& file);
+
+#endif//ARGPARSE_HPP