error_handler.hpp

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//
// Struct error_handler
//
// Copyright (c) 2015, Christof Metzger-Kraus, Helmholtz-Zentrum Berlin
// All rights reserved
//
// This file is part of OPAL.
//
// OPAL is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// You should have received a copy of the GNU General Public License
// along with OPAL. If not, see <https://www.gnu.org/licenses/>.
//
#ifndef ERROR_HANDLER_HPP_
#define ERROR_HANDLER_HPP_
 
#include <iostream>
#include <string>
#include <vector>
 
namespace SDDS {
    //  The error handler
    template <typename Iterator>
    struct error_handler {
        template <typename, typename, typename>
        struct result {
            typedef void type;
        };
 
        error_handler(Iterator first, Iterator last) : first(first), last(last) {}
 
        template <typename Message, typename What>
        void operator()(Message const& message, What const& what, Iterator err_pos) const {
            int line;
            Iterator line_start = get_pos(err_pos, line);
            if (err_pos != last) {
                std::cout << message << what << " line " << line << ':' << std::endl;
                std::cout << get_line(line_start) << std::endl;
                for (; line_start != err_pos; ++line_start)
                    std::cout << ' ';
                std::cout << '^' << std::endl;
            } else {
                std::cout << "Unexpected end of file. ";
                std::cout << message << what << " line " << line << std::endl;
            }
        }
 
        Iterator get_pos(Iterator err_pos, int& line) const {
            line                = 1;
            Iterator i          = first;
            Iterator line_start = first;
            while (i != err_pos) {
                bool eol = false;
                if (i != err_pos && *i == '\r')  // CR
                {
                    eol        = true;
                    line_start = ++i;
                }
                if (i != err_pos && *i == '\n')  // LF
                {
                    eol        = true;
                    line_start = ++i;
                }
                if (eol)
                    ++line;
                else
                    ++i;
            }
            return line_start;
        }
 
        std::string get_line(Iterator err_pos) const {
            Iterator i = err_pos;
            // position i to the next EOL
            while (i != last && (*i != '\r' && *i != '\n'))
                ++i;
            return std::string(err_pos, i);
        }
 
        Iterator first;
        Iterator last;
        std::vector<Iterator> iters;
    };
}  // namespace SDDS
 
#endif