rewrite argument parsing

src/argparse.cpp

@@ -0,0 +1,180 @@
+/* argparse.cpp - Copyright (C) 2024 a dinosaur (zlib, see COPYING.txt) */
+
+#include "argparse.hpp"
+#include <iomanip>
+#include <filesystem>
+#include <optional>
+
+
+ArgParse::ArgParser::ArgParser(
+	const std::string_view argv0,
+	std::initializer_list<Option> options,
+	HandleOption&& handler
+) noexcept :
+	name(std::filesystem::path(argv0).filename().string()),
+	options(options),
+	handler(std::forward<HandleOption>(handler)) {}
+
+
+void ArgParse::ArgParser::ShowShortUsage(std::ostream& out) const
+{
+	out << "Usage: " << name;
+	for (const auto& it : options)
+	{
+		if (it.argumentName)
+		{
+			// Option with argument
+			it.required
+				? out << " <-" << it.flag << ' ' << it.argumentName << '>'
+				: out << " [-" << it.flag << ' ' << it.argumentName << ']';
+		}
+		else
+		{
+			// Argument-less flag
+			it.required
+				? out << " <-" << it.flag << '>'
+				: out << " [-" << it.flag << ']';
+		}
+	}
+	out << std::endl;
+}
+
+void ArgParse::ArgParser::ShowHelpUsage(std::ostream& out) const
+{
+	// Base usage
+	out << "Usage: " << name << " [-";
+	for (const auto& it : options)
+		if (!it.required)
+			out << it.flag;
+	out << "] <-";
+	for (const auto& it : options)
+		if (it.required)
+			out << it.flag;
+	out << ">" << std::endl;
+
+	// Determine the alignment width from the longest argument
+	auto paramLength = [](const Option& p) -> int { return p.argumentName
+		? static_cast<int>(std::strlen(p.argumentName) + 3)
+		: 1; };
+	auto longestParam = std::max(options, [=](auto a, auto b) -> bool { return paramLength(a) < paramLength(b); });
+	auto alignWidth = paramLength(longestParam) + 3;
+
+	// print argument descriptions
+	for (const auto& it : options)
+	{
+		auto decorateArgument = [=] { return " <" + std::string(it.argumentName) + "> "; };
+		out << "  -" << it.flag
+			<< std::left << std::setw(alignWidth) << std::setfill('-') << (it.argumentName ? decorateArgument() : " ")
+			<< " " << it.helpString << std::endl;
+	}
+	out << std::flush;
+}
+
+
+ArgParse::ParseCtrl ArgParse::ParserState::Next(const std::string_view token)
+{
+	auto getFlag = [](const std::string_view s) { return s[0] == '-' && s[1] ? std::optional<int>(s[1]) : std::nullopt; };
+	auto getOption = [&](int flag) -> std::optional<std::reference_wrapper<const Option>>
+	{
+		for (auto& opt : options)
+			if (opt.flag == flag)
+				return std::optional(std::cref(opt));
+		return {};
+	};
+
+	if (expectArg)
+	{
+		expectArg = false;
+		return handler(flagChar, token);
+	}
+	else
+	{
+		auto flag = getFlag(token);
+		if (flag.has_value())
+		{
+			flagChar = flag.value();
+			const auto opt = getOption(flagChar);
+			if (opt.has_value())
+			{
+				bool expect = opt.value().get().argumentName != nullptr;
+				if (token.length() <= 2)
+				{
+					expectArg = expect;
+					if (!expectArg)
+						return handler(flagChar, "");
+				}
+				else
+				{
+					return handler(flagChar, expect ? token.substr(2) : "");
+				}
+			}
+		}
+		else if (!token.empty())
+		{
+			return ParseCtrl::QUIT_ERR_UNEXPECTED;
+		}
+	}
+
+	return ParseCtrl::CONTINUE;
+}
+
+
+bool ReadParamFile(std::vector<std::string>& tokens, std::istream& file)
+{
+	bool inQuote = false;
+	std::string quoteStr;
+	const auto store = [&](const std::string_view token, bool quote)
+	{
+		if (quote)
+			quoteStr = token;
+		else
+			tokens.emplace_back(token);
+	};
+
+	while (!file.eof())
+	{
+		if (!inQuote)
+		{
+			std::string token;
+			file >> token;
+			if (!token.empty())
+			{
+				std::string::size_type beg = 0, end;
+				while ((end = token.find_first_of('"', beg)) != std::string::npos)
+				{
+					auto size = end - beg;
+					if (size > 0)
+						store(token.substr(beg, size), !inQuote);
+					inQuote = !inQuote;
+					beg = end + 1;
+				}
+				if (beg > 0)
+				{
+					auto size = token.length() - beg;
+					if (size > 0)
+						token = token.substr(beg);
+					else
+						token.clear();
+				}
+				if (!token.empty())
+					store(token, inQuote);
+			}
+		}
+		else
+		{
+			const int c = file.get();
+			if (c == '"')
+			{
+				tokens.emplace_back(quoteStr);
+				quoteStr.clear();
+				inQuote = false;
+			}
+			else
+			{
+				quoteStr.push_back(c);
+			}
+		}
+	}
+
+	return !inQuote;
+}