xapian-core/common/alignment_cast.h

   1 /** @file alignment_cast.h
   2  * @brief Cast a pointer we know is suitably aligned
   3  */
   4 /* Copyright (C) 2016 Olly Betts
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to
   8  * deal in the Software without restriction, including without limitation the
   9  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
  10  * sell copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  19  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  21  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  22  * IN THE SOFTWARE.
  23  */
  24
  25 #ifndef XAPIAN_ALIGNMENT_CAST_H
  26 #define XAPIAN_ALIGNMENT_CAST_H
  27
  28 #include <type_traits>
  29
  30 /** Cast a pointer we know is suitably aligned.
  31  *
  32  *  Has the same effect as reinterpret_cast<T> but avoids warnings about
  33  *  alignment issues.
  34  *
  35  *  Version for const pointers.
  36  */
  37 template<typename T, typename U>
  38 typename std::enable_if<std::is_const<typename std::remove_pointer<U>::type>::value, T>::type
  39 alignment_cast(U ptr)
  40 {
  41     return static_cast<T>(static_cast<const void*>(ptr));
  42 }
  43
  44 /** Cast a pointer we know is suitably aligned.
  45  *
  46  *  Has the same effect as reinterpret_cast<T> but avoids warnings about
  47  *  alignment issues.
  48  *
  49  *  Version for non-const pointers.
  50  */
  51 template<typename T, typename U>
  52 typename std::enable_if<!std::is_const<typename std::remove_pointer<U>::type>::value, T>::type
  53 alignment_cast(U ptr)
  54 {
  55     return static_cast<T>(static_cast<void*>(ptr));
  56 }
  57
  58 #endif /* XAPIAN_ALIGNMENT_CAST_H */