swap.hpp 2.0 KB

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  1. // Copyright (C) 2007, 2008 Steven Watanabe, Joseph Gauterin, Niels Dekker
  2. //
  3. // Distributed under the Boost Software License, Version 1.0. (See
  4. // accompanying file LICENSE_1_0.txt or copy at
  5. // http://www.boost.org/LICENSE_1_0.txt)
  6. // For more information, see http://www.boost.org
  7. #ifndef BOOST_CORE_SWAP_HPP
  8. #define BOOST_CORE_SWAP_HPP
  9. // Note: the implementation of this utility contains various workarounds:
  10. // - swap_impl is put outside the boost namespace, to avoid infinite
  11. // recursion (causing stack overflow) when swapping objects of a primitive
  12. // type.
  13. // - swap_impl has a using-directive, rather than a using-declaration,
  14. // because some compilers (including MSVC 7.1, Borland 5.9.3, and
  15. // Intel 8.1) don't do argument-dependent lookup when it has a
  16. // using-declaration instead.
  17. // - boost::swap has two template arguments, instead of one, to
  18. // avoid ambiguity when swapping objects of a Boost type that does
  19. // not have its own boost::swap overload.
  20. #include <boost/core/enable_if.hpp>
  21. #include <boost/config.hpp>
  22. #include <utility> //for std::swap (C++11)
  23. #include <algorithm> //for std::swap (C++98)
  24. #include <cstddef> //for std::size_t
  25. namespace boost_swap_impl
  26. {
  27. // we can't use type_traits here
  28. template<class T> struct is_const { enum _vt { value = 0 }; };
  29. template<class T> struct is_const<T const> { enum _vt { value = 1 }; };
  30. template<class T>
  31. BOOST_GPU_ENABLED
  32. void swap_impl(T& left, T& right)
  33. {
  34. using namespace std;//use std::swap if argument dependent lookup fails
  35. swap(left,right);
  36. }
  37. template<class T, std::size_t N>
  38. BOOST_GPU_ENABLED
  39. void swap_impl(T (& left)[N], T (& right)[N])
  40. {
  41. for (std::size_t i = 0; i < N; ++i)
  42. {
  43. ::boost_swap_impl::swap_impl(left[i], right[i]);
  44. }
  45. }
  46. }
  47. namespace boost
  48. {
  49. template<class T1, class T2>
  50. BOOST_GPU_ENABLED
  51. typename enable_if_c< !boost_swap_impl::is_const<T1>::value && !boost_swap_impl::is_const<T2>::value >::type
  52. swap(T1& left, T2& right)
  53. {
  54. ::boost_swap_impl::swap_impl(left, right);
  55. }
  56. }
  57. #endif