ceph/src/boost/boost/variant/visitor_ptr.hpp

   1 //-----------------------------------------------------------------------------
   2 // boost variant/visitor_ptr.hpp header file
   3 // See http://www.boost.org for updates, documentation, and revision history.
   4 //-----------------------------------------------------------------------------
   5 //
   6 // Copyright (c) 2002-2003
   7 // Eric Friedman
   8 //
   9 // Distributed under the Boost Software License, Version 1.0. (See
  10 // accompanying file LICENSE_1_0.txt or copy at
  11 // http://www.boost.org/LICENSE_1_0.txt)
  12
  13 #ifndef BOOST_VARIANT_VISITOR_PTR_HPP
  14 #define BOOST_VARIANT_VISITOR_PTR_HPP
  15
  16 #include <boost/variant/bad_visit.hpp>
  17 #include <boost/variant/static_visitor.hpp>
  18
  19 #include <boost/mpl/eval_if.hpp>
  20 #include <boost/mpl/identity.hpp>
  21 #include <boost/throw_exception.hpp>
  22 #include <boost/type_traits/add_reference.hpp>
  23 #include <boost/type_traits/is_reference.hpp>
  24 #include <boost/type_traits/is_void.hpp>
  25
  26 namespace boost {
  27
  28 //////////////////////////////////////////////////////////////////////////
  29 // function template visitor_ptr
  30 //
  31 // Adapts a function pointer for use as visitor capable of handling
  32 // values of a single type. Throws bad_visit if inappropriately applied.
  33 //
  34 template <typename T, typename R>
  35 class visitor_ptr_t
  36     : public static_visitor<R>
  37 {
  38 private: // representation
  39
  40     typedef R (*visitor_t)(T);
  41
  42     visitor_t visitor_;
  43
  44 public: // typedefs
  45
  46     typedef R result_type;
  47
  48 private: // private typedefs
  49
  50     typedef typename mpl::eval_if<
  51           is_reference<T>
  52         , mpl::identity<T>
  53         , add_reference<const T>
  54         >::type argument_fwd_type;
  55
  56 public: // structors
  57
  58     explicit visitor_ptr_t(visitor_t visitor) BOOST_NOEXCEPT
  59       : visitor_(visitor)
  60     {
  61     }
  62
  63 public: // static visitor interfaces
  64
  65     template <typename U>
  66     result_type operator()(const U&) const
  67     {
  68         boost::throw_exception(bad_visit());
  69     }
  70
  71 #if !defined(BOOST_NO_VOID_RETURNS)
  72
  73 public: // static visitor interfaces, cont.
  74
  75     result_type operator()(argument_fwd_type operand) const
  76     {
  77         return visitor_(operand);
  78     }
  79
  80 #else // defined(BOOST_NO_VOID_RETURNS)
  81
  82 private: // helpers, for static visitor interfaces (below)
  83
  84     result_type execute_impl(argument_fwd_type operand, mpl::false_) const
  85     {
  86         return visitor_(operand);
  87     }
  88
  89         BOOST_VARIANT_AUX_RETURN_VOID_TYPE
  90     execute_impl(argument_fwd_type operand, mpl::true_) const
  91     {
  92         visitor_(operand);
  93         BOOST_VARIANT_AUX_RETURN_VOID;
  94     }
  95
  96 public: // static visitor interfaces, cont.
  97
  98         BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(result_type)
  99     operator()(argument_fwd_type operand) const
 100     {
 101         typedef typename is_void<result_type>::type has_void_result;
 102         return execute_impl(operand, has_void_result());
 103     }
 104
 105 #endif // BOOST_NO_VOID_RETURNS workaround
 106
 107 };
 108
 109 template <typename R, typename T>
 110 inline visitor_ptr_t<T,R> visitor_ptr(R (*visitor)(T))
 111 {
 112     return visitor_ptr_t<T,R>(visitor);
 113 }
 114
 115 } // namespace boost
 116
 117 #endif// BOOST_VISITOR_VISITOR_PTR_HPP