elem.hpp 2.1 KB

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  1. # /* Copyright (C) 2001
  2. # * Housemarque Oy
  3. # * http://www.housemarque.com
  4. # *
  5. # * Distributed under the Boost Software License, Version 1.0. (See
  6. # * accompanying file LICENSE_1_0.txt or copy at
  7. # * http://www.boost.org/LICENSE_1_0.txt)
  8. # */
  9. #
  10. # /* Revised by Paul Mensonides (2002-2011) */
  11. # /* Revised by Edward Diener (2011,2014,2020) */
  12. #
  13. # /* See http://www.boost.org for most recent version. */
  14. #
  15. # ifndef BOOST_PREPROCESSOR_TUPLE_ELEM_HPP
  16. # define BOOST_PREPROCESSOR_TUPLE_ELEM_HPP
  17. #
  18. # include <boost/preprocessor/cat.hpp>
  19. # include <boost/preprocessor/config/config.hpp>
  20. # include <boost/preprocessor/facilities/expand.hpp>
  21. # include <boost/preprocessor/facilities/overload.hpp>
  22. # include <boost/preprocessor/tuple/rem.hpp>
  23. # include <boost/preprocessor/variadic/elem.hpp>
  24. # include <boost/preprocessor/tuple/detail/is_single_return.hpp>
  25. #
  26. # if BOOST_PP_VARIADICS_MSVC
  27. # define BOOST_PP_TUPLE_ELEM(...) BOOST_PP_TUPLE_ELEM_I(BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_ELEM_O_, __VA_ARGS__), (__VA_ARGS__))
  28. # define BOOST_PP_TUPLE_ELEM_I(m, args) BOOST_PP_TUPLE_ELEM_II(m, args)
  29. # define BOOST_PP_TUPLE_ELEM_II(m, args) BOOST_PP_CAT(m ## args,)
  30. /*
  31. Use BOOST_PP_REM_CAT if it is a single element tuple ( which might be empty )
  32. else use BOOST_PP_REM. This fixes a VC++ problem with an empty tuple and BOOST_PP_TUPLE_ELEM
  33. functionality. See tuple_elem_bug_test.cxx.
  34. */
  35. # define BOOST_PP_TUPLE_ELEM_O_2(n, tuple) \
  36. BOOST_PP_VARIADIC_ELEM(n, BOOST_PP_EXPAND(BOOST_PP_TUPLE_IS_SINGLE_RETURN(BOOST_PP_REM_CAT,BOOST_PP_REM,tuple) tuple)) \
  37. /**/
  38. # else
  39. # define BOOST_PP_TUPLE_ELEM(...) BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_ELEM_O_, __VA_ARGS__)(__VA_ARGS__)
  40. # define BOOST_PP_TUPLE_ELEM_O_2(n, tuple) BOOST_PP_VARIADIC_ELEM(n, BOOST_PP_REM tuple)
  41. # endif
  42. # define BOOST_PP_TUPLE_ELEM_O_3(size, n, tuple) BOOST_PP_TUPLE_ELEM_O_2(n, tuple)
  43. #
  44. # /* directly used elsewhere in Boost... */
  45. #
  46. # define BOOST_PP_TUPLE_ELEM_1_0(a) a
  47. #
  48. # define BOOST_PP_TUPLE_ELEM_2_0(a, b) a
  49. # define BOOST_PP_TUPLE_ELEM_2_1(a, b) b
  50. #
  51. # define BOOST_PP_TUPLE_ELEM_3_0(a, b, c) a
  52. # define BOOST_PP_TUPLE_ELEM_3_1(a, b, c) b
  53. # define BOOST_PP_TUPLE_ELEM_3_2(a, b, c) c
  54. #
  55. # endif