ceph/src/boost/boost/poly_collection/detail/any_iterator.hpp

   1 /* Copyright 2016 Joaquin M Lopez Munoz.
   2  * Distributed under the Boost Software License, Version 1.0.
   3  * (See accompanying file LICENSE_1_0.txt or copy at
   4  * http://www.boost.org/LICENSE_1_0.txt)
   5  *
   6  * See http://www.boost.org/libs/poly_collection for library home page.
   7  */
   8
   9 #ifndef BOOST_POLY_COLLECTION_DETAIL_ANY_ITERATOR_HPP
  10 #define BOOST_POLY_COLLECTION_DETAIL_ANY_ITERATOR_HPP
  11
  12 #if defined(_MSC_VER)
  13 #pragma once
  14 #endif
  15
  16 #include <boost/iterator/iterator_adaptor.hpp>
  17 #include <boost/type_erasure/any_cast.hpp>
  18 #include <type_traits>
  19 #include <utility>
  20
  21 namespace boost{
  22
  23 namespace poly_collection{
  24
  25 namespace detail{
  26
  27 /* type_erasure::any<Concept>* adaptor convertible to pointer to wrapped
  28  * entity.
  29  */
  30
  31 template<typename Any>
  32 class any_iterator:public boost::iterator_adaptor<any_iterator<Any>,Any*>
  33 {
  34 public:
  35   any_iterator()=default;
  36   explicit any_iterator(Any* p)noexcept:any_iterator::iterator_adaptor_{p}{}
  37   any_iterator(const any_iterator&)=default;
  38   any_iterator& operator=(const any_iterator&)=default;
  39
  40   template<
  41     typename NonConstAny,
  42     typename std::enable_if<
  43       std::is_same<Any,const NonConstAny>::value>::type* =nullptr
  44   >
  45   any_iterator(const any_iterator<NonConstAny>& x)noexcept:
  46     any_iterator::iterator_adaptor_{x.base()}{}
  47
  48   template<
  49     typename NonConstAny,
  50     typename std::enable_if<
  51       std::is_same<Any,const NonConstAny>::value>::type* =nullptr
  52   >
  53   any_iterator& operator=(const any_iterator<NonConstAny>& x)noexcept
  54   {
  55     this->base_reference()=x.base();
  56     return *this;
  57   }
  58
  59   /* interoperability with Any* */
  60
  61   any_iterator& operator=(Any* p)noexcept
  62     {this->base_reference()=p;return *this;}
  63   operator Any*()const noexcept{return this->base();}
  64
  65   /* interoperability with Concrete* */
  66
  67   template<
  68     typename Concrete,
  69     typename std::enable_if<
  70       /* can't compile-time check concept compliance */
  71       !std::is_const<Any>::value||std::is_const<Concrete>::value
  72     >::type* =nullptr
  73   >
  74   explicit operator Concrete*()const noexcept
  75   {
  76     return const_cast<Concrete*>(
  77       static_cast<typename std::remove_const<Concrete>::type*>(
  78         type_erasure::any_cast<void*>(this->base())));
  79   }
  80
  81 private:
  82   template<typename>
  83   friend class any_iterator;
  84 };
  85
  86 } /* namespace poly_collection::detail */
  87
  88 } /* namespace poly_collection */
  89
  90 } /* namespace boost */
  91
  92 #endif