| 1 | // Boost.TypeErasure library |
|---|
| 2 | // |
|---|
| 3 | // Copyright 2011 Steven Watanabe |
|---|
| 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 | // $Id$ |
|---|
| 10 | |
|---|
| 11 | #ifndef BOOST_TYPE_ERASURE_PLACEHOLDER_OF_HPP_INCLUDED |
|---|
| 12 | #define BOOST_TYPE_ERASURE_PLACEHOLDER_OF_HPP_INCLUDED |
|---|
| 13 | |
|---|
| 14 | namespace boost { |
|---|
| 15 | namespace type_erasure { |
|---|
| 16 | |
|---|
| 17 | #ifndef BOOST_TYPE_ERASURE_DOXYGEN |
|---|
| 18 | |
|---|
| 19 | template<class Concept, class T> |
|---|
| 20 | class any; |
|---|
| 21 | |
|---|
| 22 | template<class Concept, class T> |
|---|
| 23 | class param; |
|---|
| 24 | |
|---|
| 25 | #endif |
|---|
| 26 | |
|---|
| 27 | /** |
|---|
| 28 | * A metafunction returning the (const/reference qualified) placeholder |
|---|
| 29 | * corresponding to an @ref any. It will also work for all bases |
|---|
| 30 | * of @ref any, so it can be applied to the @c Base |
|---|
| 31 | * parameter of @ref concept_interface. |
|---|
| 32 | */ |
|---|
| 33 | template<class T> |
|---|
| 34 | struct placeholder_of |
|---|
| 35 | { |
|---|
| 36 | #ifdef BOOST_TYPE_ERASURE_DOXYGEN |
|---|
| 37 | typedef detail::unspecified type; |
|---|
| 38 | #else |
|---|
| 39 | typedef typename ::boost::type_erasure::placeholder_of< |
|---|
| 40 | typename T::_boost_type_erasure_derived_type |
|---|
| 41 | >::type type; |
|---|
| 42 | #endif |
|---|
| 43 | }; |
|---|
| 44 | |
|---|
| 45 | /** INTERNAL ONLY */ |
|---|
| 46 | template<class Concept, class T> |
|---|
| 47 | struct placeholder_of< ::boost::type_erasure::any<Concept, T> > |
|---|
| 48 | { |
|---|
| 49 | typedef T type; |
|---|
| 50 | }; |
|---|
| 51 | |
|---|
| 52 | /** INTERNAL ONLY */ |
|---|
| 53 | template<class Concept, class T> |
|---|
| 54 | struct placeholder_of< ::boost::type_erasure::param<Concept, T> > |
|---|
| 55 | { |
|---|
| 56 | typedef T type; |
|---|
| 57 | }; |
|---|
| 58 | |
|---|
| 59 | #ifndef BOOST_NO_CXX11_TEMPLATE_ALIASES |
|---|
| 60 | |
|---|
| 61 | template<class T> |
|---|
| 62 | using placeholder_of_t = typename ::boost::type_erasure::placeholder_of<T>::type; |
|---|
| 63 | |
|---|
| 64 | #endif |
|---|
| 65 | |
|---|
| 66 | } |
|---|
| 67 | } |
|---|
| 68 | |
|---|
| 69 | #endif |
|---|
| 70 | |
|---|
