F5/unison
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

core: (fixes #387) Fix MakeCallbackAccessor compilation error

Browse Source 
Use more specific properties of containers to identify containers for specialization
This commit is contained in:
Steven Smith
2021-04-15 13:26:12 -07:00
committed by Tom Henderson
parent acec4714bb
commit bbcea3e502
1 changed files with 58 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

64
src/core/model/attribute-container-accessor-helper.h
View File

@@ -31,15 +31,67 @@
namespace ns3 {
/**
* Compile time check if type T has const iterator.
*/
template<typename T>
struct has_const_iterator
{
private:
typedef char yes;
typedef struct { char array[2]; } no;
template<typename C> static yes test(typename C::const_iterator*);
template<typename C> static no test(...);
public:
static const bool value = sizeof(test<T>(0)) == sizeof(yes);
typedef T type;
};
/**
* Compile time check if type T has begin() and end() methods.
*/
template <typename T>
struct has_begin_end
{
template<typename C> static char (&f(typename std::enable_if<
std::is_same<decltype(static_cast<typename C::const_iterator (C::*)() const>(&C::begin)),
typename C::const_iterator(C::*)() const>::value, void>::type*))[1];
template<typename C> static char (&f(...))[2];
template<typename C> static char (&g(typename std::enable_if<
std::is_same<decltype(static_cast<typename C::const_iterator (C::*)() const>(&C::end)),
typename C::const_iterator(C::*)() const>::value, void>::type*))[1];
template<typename C> static char (&g(...))[2];
static bool const beg_value = sizeof(f<T>(0)) == 1;
static bool const end_value = sizeof(g<T>(0)) == 1;
};
/**
* Compile time check if type T is a container.
*
* Container here means has an iterator and supports begin() and end()
* methods.
*
* Can be used when defining specializations when a type T is an STL
* like container.
*/
template<typename T>
struct is_container : std::integral_constant<bool, has_const_iterator<T>::value && has_begin_end<T>::beg_value && has_begin_end<T>::end_value>
{ };
/**
* \ingroup attributeimpl
*
* DoMakeAccessorHelperOne specialization for member containers
*
* The template parameter list contains an extra parameter that disambiguates
* the templated Ptr type from container types by taking advantage of the fact
* that container types have multiple template arguments and Ptr has only one.
* This disambiguation works but is not sufficiently robust as a long term solution.
* The template parameter list contains an extra parameter that is
* intended to disambiguate an attribute container from any other
* templated attribute, e.g Ptr or Callback. Disambiguation is based
* on begin/end and iterator.
*
* \tparam V \explicit The specific AttributeValue type to use to represent
* the Attribute.
@@ -50,7 +102,7 @@ namespace ns3 {
* \returns The AttributeAccessor.
*/
template <typename V, typename T, template <typename...> class U, typename ...I,
typename = typename std::enable_if< (sizeof...(I) > 1), void>::type >
typename = typename std::enable_if< ( is_container< U<I...> >::value ), void>::type >
inline
Ptr<const AttributeAccessor>
DoMakeAccessorHelperOne (U<I...> T::*memberContainer)
@@ -98,4 +150,4 @@ DoMakeAccessorHelperOne (U<I...> T::*memberContainer)
} // namespace ns3
#endif // ATTRIBUTE_CONTAINER_ACCESSOR_HELPER_H
#endif // ATTRIBUTE_CONTAINER_ACCESSOR_HELPER_H