NoteParser.cpp

#include <string>
#include <fstream>
#include <vector>
#include <utility>
#include <cctype>
#include <iterator>

struct parse_result
{
	std::vector<std::string> text;
	std::vector<std::string> tokens;
};

template <typename BidirIt>
std::pair<BidirIt, BidirIt> trim(BidirIt first, BidirIt last)
{
	while (first != last && std::isspace(*first))
	{
		++first;
	}

	--last;

	while (last != first && std::isspace(*last))
	{
		--last;
	}

	return{ first, last };
}



parse_result parse(const std::string& file_name)
{
	std::ifstream file(file_name);

	if (!file.is_open())
	{
		throw std::runtime_error("couldn't open file");
	}

	std::vector<std::string> text;
	std::vector<std::string> tokens;

	std::string buffer;
	char current_delim = '<';
	char next_delim = '>';
	while (std::getline(file, buffer, current_delim))
	{
		//everything UNTIL token opening
		if (current_delim == '<')
		{
			if (buffer.size() > 0 && !(buffer.size() == 1 && buffer.front() == '\n'))
			{
				auto range = trim(buffer.begin(), buffer.end());
				std::string::size_type first = std::distance(buffer.begin(), range.first);
				std::string::size_type last = std::distance(buffer.begin(), range.second);
				text.push_back(buffer.substr(first, last));
			}
		}
		else
		{
			tokens.push_back(buffer);
		}

		std::swap(current_delim, next_delim);
	}

	return { text, tokens };
}

#include <iostream>

std::ostream& operator<<(std::ostream& os, const parse_result&  res)
{
	for (decltype(res.text.size()) i = 0; i < res.text.size(); ++i)
	{
		//every text has pre and post tokens, so 2x
		os << '<' << res.tokens[i * 2] << '>' << '\n';
		os << res.text[i] << '\n';
		os << '<' << res.tokens[i * 2 + 1] << '>' << '\n';
	}

	return os;
}

int main()
{
	auto result = parse("myfile.txt");
	std::cout << result;

	std::cin.get();
}