fmt.h

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/*
* (C) 2023 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
 
#ifndef BOTAN_UTIL_FMT_H_
#define BOTAN_UTIL_FMT_H_
 
#include <botan/types.h>
#include <locale>
#include <sstream>
#include <string>
#include <string_view>
 
namespace Botan {
 
namespace fmt_detail {
 
inline void do_fmt(std::ostringstream& oss, std::string_view format) {
   oss << format;
}
 
template <typename T, typename... Ts>
void do_fmt(std::ostringstream& oss, std::string_view format, const T& val, const Ts&... rest) {
   size_t i = 0;
 
   while(i < format.size()) {
      if(format[i] == '{' && (format.size() > (i + 1)) && format.at(i + 1) == '}') {
         oss << val;
         return do_fmt(oss, format.substr(i + 2), rest...);
      } else {
         oss << format[i];
      }
 
      i += 1;
   }
}
 
}  // namespace fmt_detail
 
/**
* Simple formatter utility.
*
* Should be replaced with std::format once that's available on all our
* supported compilers.
*
* '{}' markers in the format string are replaced by the arguments.
* Unlike std::format, there is no support for escaping or for any kind
* of conversion flags.
*/
template <typename... T>
std::string fmt(std::string_view format, const T&... args) {
   std::ostringstream oss;
   oss.imbue(std::locale::classic());
   fmt_detail::do_fmt(oss, format, args...);
   return oss.str();
}
 
}  // namespace Botan
 
#endif