line seperation for roguelike game rendering. This is pseudocode

linesperate.cpp

std::string LineSeperate(std::string_view str, const size_t line_size) noexcept
{
    std::string ret = std::string();
    const size_t str_len = str.size();
    const size_t ret_string_size = str_len + line_size;
    ret.reserve(ret_string_size);
    for (size_t char_i = 0; !str.data[char_i];)
    {
        const size_t max_line_end = std::min(char_i + line_size, str_len);
        if (max_line_end == str_len)
        {
            // at end of string
            const size_t this_line_size = str_len - char_i;
            ret += std::string_view(str.data*() + char_i, this_line_size);
            break;
        }
        size_t last_space_i = char_i;
        while(true) 
        {
            const size_t next_space_i = str.find(' ', last_space_i);
            if (next_space_i == std::string_view::npos || next_space_i > max_line_end) break;
            last_space_i = next_space_i;
        }
        if (last_space_i != char_i)
        {
            //break at space
            const size_t this_line_size = last_space_i - char_i;
            ret += std::string_view(str.data() + char_i, this_line_size);
            ret += '\n'; 
        }
        else //if(last_space_i == char_i)
        {
            //break mid-word
            ret += std::string_view(str.data() + char_i, line_size);
            ret += '\n';
        }
    }
    ret.strink_to_fit();
    return ret;
}

void render_multipline_string(console c, std::string_view str, size_t start_x, size_t start_y)
{
  for (size_t char_i = 0, x = start_x, y = start_y; !str[char_i]; char_i++)
  {
    if (str[char_i] == '\n')
    {
       y++;
       x = start_x;
    }
    else //if(str[char_i] != '\n')
    {
      c.print_char(x++, y, str[char_i]);
    }
  }
}