xapian-core/common/stdclamp.h

   1 /** @file stdclamp.h
   2  * @brief Defines STD_CLAMP like C++17's std::clamp
   3  */
   4 /* Copyright (C) 2017 Olly Betts
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  19  */
  20
  21 #ifndef XAPIAN_INCLUDED_STDCLAMP_H
  22 #define XAPIAN_INCLUDED_STDCLAMP_H
  23
  24 #include <algorithm>
  25
  26 #if __cplusplus >= 201703L
  27 # define STD_CLAMP std::clamp
  28 #else
  29 template<typename T, typename CMP>
  30 constexpr const T&
  31 STD_CLAMP(const T& value, const T& lower, const T& upper, CMP cmp)
  32 {
  33     return cmp(value, lower) ? lower : (cmp(upper, value) ? upper : value);
  34 }
  35
  36 template<typename T>
  37 constexpr const T&
  38 STD_CLAMP(const T& value, const T& lower, const T& upper)
  39 {
  40     return STD_CLAMP(value, lower, upper, std::less<T>());
  41 }
  42 #endif
  43
  44 #endif // XAPIAN_INCLUDED_STDCLAMP_H