esc.cpp

   1 #include "esc.hpp"
   2
   3 #include <fmt/format.h>
   4
   5 #include <algorithm>
   6 #include <iomanip>
   7
   8 std::string esc(std::string_view str, esc_line_option line_option)
   9 {
  10   auto nesc{std::count_if(begin(str), end(str), [](unsigned char c) {
  11     return (!std::isprint(c)) || (c == '\\');
  12   })};
  13   if (!nesc)
  14     return std::string(str);
  15   if (line_option == esc_line_option::multi)
  16     nesc += std::count(begin(str), end(str), '\n');
  17   std::string ret;
  18   ret.reserve(str.length() + nesc);
  19   for (auto c : str) {
  20     switch (c) {
  21     case '\a': ret += "\\a"; break;
  22     case '\b': ret += "\\b"; break;
  23     case '\f': ret += "\\f"; break;
  24     case '\n':
  25       ret += "\\n";
  26       if (line_option == esc_line_option::multi)
  27         ret += '\n';
  28       break;
  29     case '\r': ret += "\\r"; break;
  30     case '\t': ret += "\\t"; break;
  31     case '\v': ret += "\\v"; break;
  32     case '\\': ret += "\\\\"; break;
  33     default:
  34       if (isprint(static_cast<unsigned char>(c))) {
  35         ret += c;
  36       }
  37       else {
  38         ret += fmt::format("\\x{:02x}", static_cast<unsigned char>(c));
  39       }
  40     }
  41   }
  42   if (line_option == esc_line_option::multi) {
  43     auto length = ret.length();
  44     if (length && ('\n' == ret.at(length - 1))) {
  45       ret.erase(length - 1, 1);
  46     }
  47   }
  48   return ret;
  49 }