ini.cpp

#ifndef INI_H_INCLUDED
#define INI_H_INCLUDED

#include <ios>
#include <string>
#include <fstream>
#include <stdexcept>
#include <algorithm>
#include <string_view>

#include "ini.h"


// A VERY rudimentary ini lexer.

ini_lexer::ini_lexer(const char* Filename)
	:File(Filename, std::ios::binary), Line(), LineNum(0), Filename(Filename) {
	if (!File) {
		throw std::runtime_error(std::string("Unable to open configuration file: ") + Filename);
	}
}

ini_token ini_lexer::Next() {
	ini_token r = {};

	while (std::getline(File, Line)) {
		LineNum += 1;

		auto Begin = TrimLeft(Line.begin(), Line.end());
		auto End = TrimRight(Begin, std::find(Begin, Line.end(), ';'));

		if (Begin == End) {
			continue;
		}

		if (Begin[0] == '[') {
			if (End[-1] != ']') {
				Error("Invalid section name. Starts with '[' but does not end with ']'.");
			}

			r.Type = ini_token_type::Section;

			++Begin;
			--End;
		}
		else {
			auto Middle = std::find(Begin, End, '=');
			if (Middle == End) {
				Error("Expected '=' followed by a value but found nothing.");
			}

			r.Type = ini_token_type::KeyValue;

			r.Value = StringView(TrimLeft(Middle + 1, End), End);

			if (r.Value.empty()) {
				Error("Empty value string.");
			}

			End = TrimRight(Begin, Middle);
		}

		std::for_each(Begin, End, [](auto& c) {
			c = ('A' <= c && c <= 'z') ? c | 32 : c;
			});

		r.Key = StringView(Begin, End);

		if (r.Key.empty()) {
			Error("Empty key string.");
		}

		break;
	}

	return r;
}

std::string ini_lexer::Name() const {
	return Filename + (":" + std::to_string(LineNum));
}

void ini_lexer::Error(const char* Message) const {
    throw std::runtime_error(Name() + ": " + Message);
}


#endif // INI_H_INCLUDED