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Add pointer_traits with to_address
This commit is contained in:
Glen Fernandes
256
include/boost/core/pointer_traits.hpp
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256
include/boost/core/pointer_traits.hpp
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/*
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Copyright 2017 Glen Joseph Fernandes
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(glenjofe@gmail.com)
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Distributed under the Boost Software License, Version 1.0.
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(http://www.boost.org/LICENSE_1_0.txt)
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*/
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#ifndef BOOST_CORE_POINTER_TRAITS_HPP
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#define BOOST_CORE_POINTER_TRAITS_HPP
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#include <boost/config.hpp>
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#include <boost/detail/workaround.hpp>
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#if !defined(BOOST_NO_CXX11_ALLOCATOR) && \
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!BOOST_WORKAROUND(BOOST_MSVC, < 1910)
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#include <memory>
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#else
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#include <boost/core/addressof.hpp>
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#endif
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namespace boost {
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template<class T>
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struct pointer_traits;
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namespace detail {
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template<class U>
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static typename pointer_traits<U>::element_type*
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ptr_traits_address(U v) BOOST_NOEXCEPT
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{
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return pointer_traits<U>::to_address(v);
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}
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} /* detail */
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#if !defined(BOOST_NO_CXX11_ALLOCATOR) && \
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!BOOST_WORKAROUND(BOOST_MSVC, < 1910)
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template<class T>
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struct pointer_traits
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: std::pointer_traits<T> {
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template<class U>
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struct rebind_to {
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typedef typename std::pointer_traits<T>::template rebind<U> type;
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};
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static typename std::pointer_traits<T>::element_type*
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to_address(T v) BOOST_NOEXCEPT {
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return detail::ptr_traits_address(v.operator->());
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}
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};
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template<class T>
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struct pointer_traits<T*>
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: std::pointer_traits<T*> {
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template<class U>
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struct rebind_to {
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typedef U* type;
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};
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static T* to_address(T* v) BOOST_NOEXCEPT {
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return v;
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}
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};
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#else
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namespace detail {
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struct ptr_traits_none { char first; char second; };
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template<class T>
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struct ptr_traits_has_element {
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private:
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template<class U>
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static ptr_traits_none call(...);
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template<class U>
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static char call(typename U::element_type* = 0);
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public:
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BOOST_STATIC_CONSTEXPR bool value = sizeof(call<T>(0)) == 1;
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};
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template<class T>
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struct ptr_traits_first;
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#if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
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template<template<class, class...> class T, class U, class... Args>
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struct ptr_traits_first<T<U, Args...> > {
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typedef U type;
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};
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#else
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template<template<class> class T, class U>
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struct ptr_traits_first<T<U> > {
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typedef U type;
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};
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template<template<class, class> class T, class U1, class U2>
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struct ptr_traits_first<T<U1, U2> > {
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typedef U1 type;
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};
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template<template<class, class, class> class T, class U1, class U2, class U3>
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struct ptr_traits_first<T<U1, U2, U3> > {
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typedef U1 type;
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};
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#endif
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template<class T, bool = ptr_traits_has_element<T>::value>
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struct ptr_traits_element;
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template<class T>
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struct ptr_traits_element<T, true> {
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typedef typename T::element_type type;
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};
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template<class T>
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struct ptr_traits_element<T, false> {
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typedef typename ptr_traits_first<T>::type type;
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};
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template<class T>
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struct ptr_traits_has_difference {
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private:
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template<class U>
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static ptr_traits_none call(...);
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template<class U>
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static char call(typename U::difference_type* = 0);
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public:
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BOOST_STATIC_CONSTEXPR bool value = sizeof(call<T>(0)) == 1;
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};
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template<class T, bool = ptr_traits_has_difference<T>::value>
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struct ptr_traits_difference;
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template<class T>
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struct ptr_traits_difference<T, true> {
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typedef typename T::difference_type type;
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};
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template<class T>
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struct ptr_traits_difference<T, false> {
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typedef std::ptrdiff_t type;
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};
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template<class T>
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struct ptr_traits_has_rebind {
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private:
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template<class U>
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static ptr_traits_none call(...);
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template<class U>
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static char call(typename U::template rebind<U>* = 0);
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public:
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BOOST_STATIC_CONSTEXPR bool value = sizeof(call<T>(0)) == 1;
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};
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template<class T, class V>
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struct ptr_traits_rebind_to;
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#if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
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template<template<class, class...> class T, class U, class... Args, class V>
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struct ptr_traits_rebind_to<T<U, Args...>, V> {
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typedef T<V, Args...> type;
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};
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#else
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template<template<class> class T, class U, class V>
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struct ptr_traits_rebind_to<T<U>, V> {
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typedef T<V> type;
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};
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template<template<class, class> class T, class U1, class U2, class V>
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struct ptr_traits_rebind_to<T<U1, U2>, V> {
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typedef T<V, U2> type;
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};
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template<template<class, class, class> class T,
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class U1, class U2, class U3, class V>
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struct ptr_traits_rebind_to<T<U1, U2, U3>, V> {
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typedef T<V, U2, U3> type;
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};
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#endif
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#if !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES)
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template<class T, class U, bool = ptr_traits_has_rebind<T>::value>
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struct ptr_traits_rebind;
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template<class T, class U>
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struct ptr_traits_rebind<T, U, true> {
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typedef typename T::template rebind<U> type;
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};
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template<class T, class U>
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struct ptr_traits_rebind<T, U, false> {
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typedef typename ptr_traits_rebind_to<T, U>::type type;
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};
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#else
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template<class T, class U>
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struct ptr_traits_rebind {
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typedef typename ptr_traits_rebind_to<T, U>::type type;
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};
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#endif
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template<class T>
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struct ptr_traits_value {
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typedef T type;
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};
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template<>
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struct ptr_traits_value<void> {
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typedef struct { } type;
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};
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} /* detail */
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template<class T>
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struct pointer_traits {
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typedef T pointer;
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typedef typename detail::ptr_traits_element<T>::type element_type;
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typedef typename detail::ptr_traits_difference<T>::type difference_type;
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template<class U>
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struct rebind_to {
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typedef typename detail::ptr_traits_rebind<T, U>::type type;
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};
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#if !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES)
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template<class U>
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using rebind = typename detail::ptr_traits_rebind<T, U>::type;
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#endif
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static pointer
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pointer_to(typename detail::ptr_traits_value<element_type>::type& v) {
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return pointer::pointer_to(v);
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}
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static element_type* to_address(pointer v) BOOST_NOEXCEPT {
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return detail::ptr_traits_address(v.operator->());
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}
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};
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template<class T>
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struct pointer_traits<T*> {
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typedef T* pointer;
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typedef T element_type;
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typedef std::ptrdiff_t difference_type;
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template<class U>
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struct rebind_to {
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typedef U* type;
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};
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#if !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES)
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template<class U>
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using rebind = U*;
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#endif
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static T*
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pointer_to(typename detail::ptr_traits_value<T>::type& v) BOOST_NOEXCEPT {
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return addressof(v);
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}
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static T* to_address(T* v) BOOST_NOEXCEPT {
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return v;
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}
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};
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#endif
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} /* boost */
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#endif
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