/*
 * to_int.hpp -- safely convert string to integers
 *
 * Copyright (c) 2017-2018 David Demelier <markand@malikania.fr>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef TO_INT_HPP
#define TO_INT_HPP

/**
 * \file to_int.hpp
 * \brief Safely convert string to integers.
 */

#include <boost/optional.hpp>

#include <cstdlib>
#include <limits>
#include <string>
#include <type_traits>

/**
 * Convert the given string into a signed integer.
 *
 * \param str the string to convert
 * \param min the minimum value allowed
 * \param max the maximum value allowed
 * \return the value or boost::none if not convertible
 */
template <typename T = int>
boost::optional<T> to_int(const std::string& str,
                          T min = std::numeric_limits<T>::min(),
                          T max = std::numeric_limits<T>::max()) noexcept
{
    static_assert(std::is_signed<T>::value, "must be signed");

    char* end;
    auto v = std::strtoll(str.c_str(), &end, 10);

    if (*end != '\0' || v < min || v > max)
        return boost::none;

    return static_cast<T>(v);
}

/**
 * Convert the given string into a unsigned integer.
 *
 * \note invalid numbers are valid as well
 * \param str the string to convert
 * \param min the minimum value allowed
 * \param max the maximum value allowed
 * \return the value or boost::none if not convertible
 */
template <typename T = unsigned>
boost::optional<T> to_uint(const std::string& str,
                           T min = std::numeric_limits<T>::min(),
                           T max = std::numeric_limits<T>::max()) noexcept
{
    static_assert(std::is_unsigned<T>::value, "must be unsigned");

    char* end;
    auto v = std::strtoull(str.c_str(), &end, 10);

    if (*end != '\0' || v < min || v > max)
        return boost::none;

    return static_cast<T>(v);
}

#endif // !TO_INT_HPP