string_template_utils.h

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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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#ifndef INCLUDE_STRING_TEMPLATE_UTILS_H_
#define INCLUDE_STRING_TEMPLATE_UTILS_H_

#include <cstring>
#include <string>

static inline size_t length_of_string(const std::string &s) { return s.size(); }

static inline size_t length_of_string(const char *s) { return strlen(s); }

template <typename S>
size_t sum_sizeof_strings(S s) {
  return length_of_string(s);
}

template <typename H, typename... T>
size_t sum_sizeof_strings(H head, T... tail) {
  return length_of_string(head) + sum_sizeof_strings(tail...);
}

template <typename S>
void concatenate_acc(std::string *acc, S s) {
  *acc += s;
}

template <typename H, typename... T>
void concatenate_acc(std::string *acc, H head, T... tail) {
  *acc += head;
  concatenate_acc(acc, tail...);
}

/**
  Concatenate a list of std::string or '\0'-terminated strings

  @note throws std::bad_alloc

  @param s      List of std::string or '\0'-terminated strings

  @returns concatenated string
*/
template <typename... S>
std::string concatenate(S... s) {
  std::string acc;
  acc.reserve(sum_sizeof_strings(s...));
  concatenate_acc(&acc, s...);
  return acc;
}

#endif  // INCLUDE_STRING_TEMPLATE_UTILS_H_