parses multiple radices using C++11 and some boost

parse_radix.hpp

template<typename T>
T parse_radix(const std::string& str, i32 radix)
{
    assert("provided radix is not between the supported range of 2 and 36" && radix >= 2 && radix <= 36);

    T result = 0;

    auto get_radix_map = [](i32 radix) -> std::map<char, T>
    {
        typedef std::pair<char, T> pair_t;
        std::map<char, T> result;
        if(radix <= 10)
        {
            for(int i = 0; i < radix; i++)
                result.insert(pair_t('0' + i, i));
        }
        else if(radix <= 36)
        {
            for(int i = 0; i < 10; i++)
                result.insert(pair_t('0' + i, i));
            for(int i = 0; i < (radix - 10); i++)
                result.insert(pair_t('a' + i, i + 10));
        }
        return result;
    };

    auto radix_map = get_radix_map(radix);
    for(const char& c : str)
    {
        result *= radix;
        result += radix_map[c];
    }

    return result;
}

template<typename T>
T parse_explicit_radix(const std::string& str)
{
    T result = 0;
    i32 radix = 0;
    std::string parse;

    if(boost::starts_with(str, "0b"))
    {
        radix = 2;
        parse = str.substr(2);
    }
    else if(boost::starts_with(str, "0x"))
    {
        radix = 16;
        parse = str.substr(2);
    }
    else if(boost::starts_with(str, "0"))
    {
        radix = 8;
        parse = str.substr(1);
    }
    else
    {
        radix = 10;
        parse = str;
    }

    return parse_radix<T>(str, radix);
}