std::string trim functions

// trim from start (in place)
static inline void ltrim(std::string &s) {
   s.erase(s.begin(), std::find_if(s.begin(), s.end(), [](int ch) {
      return !std::isspace(ch);
   }));
}

// trim from end (in place)
static inline void rtrim(std::string &s) {
   s.erase(std::find_if(s.rbegin(), s.rend(), [](int ch) {
      return !std::isspace(ch);
   }).base(), s.end());
}

// trim from both ends (in place)
static inline void trim(std::string &s) {
   ltrim(s);
   rtrim(s);
}

// trim from start (copying)
static inline std::string ltrim_copy(std::string s) {
   ltrim(s);
   return s;
}

// trim from end (copying)
static inline std::string rtrim_copy(std::string s) {
   rtrim(s);
   return s;
}