al/eax_exception.cpp

   1 #include "config.h"
   2
   3 #include "eax_exception.h"
   4
   5 #include <cassert>
   6
   7 #include <string>
   8
   9
  10 EaxException::EaxException(
  11     const char* context,
  12     const char* message)
  13     :
  14     std::runtime_error{make_message(context, message)}
  15 {
  16 }
  17
  18 std::string EaxException::make_message(
  19     const char* context,
  20     const char* message)
  21 {
  22     const auto context_size = (context ? std::string::traits_type::length(context) : 0);
  23     const auto has_contex = (context_size > 0);
  24
  25     const auto message_size = (message ? std::string::traits_type::length(message) : 0);
  26     const auto has_message = (message_size > 0);
  27
  28     if (!has_contex && !has_message)
  29     {
  30         return std::string{};
  31     }
  32
  33     static constexpr char left_prefix[] = "[";
  34     const auto left_prefix_size = std::string::traits_type::length(left_prefix);
  35
  36     static constexpr char right_prefix[] = "] ";
  37     const auto right_prefix_size = std::string::traits_type::length(right_prefix);
  38
  39     const auto what_size =
  40         (
  41             has_contex ?
  42             left_prefix_size + context_size + right_prefix_size :
  43             0) +
  44         message_size +
  45         1;
  46
  47     auto what = std::string{};
  48     what.reserve(what_size);
  49
  50     if (has_contex)
  51     {
  52         what.append(left_prefix, left_prefix_size);
  53         what.append(context, context_size);
  54         what.append(right_prefix, right_prefix_size);
  55     }
  56
  57     if (has_message)
  58     {
  59         what.append(message, message_size);
  60     }
  61
  62     return what;
  63 }