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vectorwrapper
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Allow extra casting if users explicitly whitelist them. 

They'll have to make VectorTypeInfo<V> inherit from
is_castable_to<U> for every U they want the V to be
castable to. Note that if they also want U to be castable
to V (so the other way around) they'll have to explicitly
whitelist that conversion too in VectorTypeInfo<U>.
This commit is contained in:
King_DuckZ 2017-07-27 23:42:21 +01:00
parent b7616a4fcf
commit 421e5e2433
2 changed files with 52 additions and 4 deletions
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27
include/vectorwrapper/vectorwrapper.hpp
View File

@ -134,6 +134,22 @@ namespace vwr {
enum { value = true };
};
template <typename V> struct get_wrapped_ifn {
typedef V type;
};
template <typename T> struct get_wrapped_ifn<Vec<T>> {
typedef T type;
};
template <typename V1, typename V2>
struct directly_convertible {
enum {
value =
not HasGetAtMethod<VectorWrapperInfo<typename get_wrapped_ifn<V1>::type>>::value and
not HasGetAtMethod<VectorWrapperInfo<typename get_wrapped_ifn<V2>::type>>::value
};
};
template <typename V>
class VecBase {
friend Vec<V>& assign_same_type<V> ( Vec<V>& parLeft, const Vec<V>& parRight );
@ -160,9 +176,14 @@ namespace vwr {
const vector_type& data ( void ) const { return m_wrapped; }
template <typename V2>
const typename std::enable_if<is_vec<V2>::value, V2>::type& cast ( void ) const;
const typename std::enable_if<is_vec<V2>::value and directly_convertible<V, V2>::value, V2>::type& cast ( void ) const;
template <typename V2>
typename std::enable_if<is_vec<V2>::value, V2>::type& cast ( void );
typename std::enable_if<is_vec<V2>::value and directly_convertible<V, V2>::value, V2>::type& cast ( void );
template <typename V2>
const typename std::enable_if<is_vec<V2>::value and not directly_convertible<V, V2>::value, V2>::type& cast ( void ) const;
template <typename V2>
typename std::enable_if<is_vec<V2>::value and not directly_convertible<V, V2>::value, V2>::type& cast ( void );
template <typename V2> VecBase& operator+= ( const VecBase<V2>& parOther );
template <typename V2> VecBase& operator-= ( const VecBase<V2>& parOther );
@ -330,6 +351,8 @@ namespace vwr {
Vec<typename std::common_type<V1, V2>::type> binary_op ( const Vec<V1>& parLeft, const Vec<V2>& parRight, Op parOp, const Vec<typename std::common_type<V1, V2>::type>& parLastVal, bt::number_seq<size_type, I...> );
} //namespace implem
template <typename V> struct is_castable_to { };
template <typename V, size_type S>
class Vec : public implem::VecBase<V> {
public:

29
include/vectorwrapper/vectorwrapper.inl
View File

@ -83,7 +83,7 @@ namespace vwr {
template <typename V>
template <typename V2>
const typename std::enable_if<is_vec<V2>::value, V2>::type& VecBase<V>::cast() const {
auto VecBase<V>::cast() const -> const typename std::enable_if<is_vec<V2>::value and directly_convertible<V, V2>::value, V2>::type& {
static_assert(sizeof(V2) <= sizeof(VecBase<V>) - min_offset<V>::value, "V2 must fit in V starting from the first coordinate");
static_assert(std::is_standard_layout<V2>::value, "V2 must be a standard layout type");
static_assert(min_offset<typename is_vec<V2>::vector_type>::value == 0, "V2 must not have any properties before the first coordinate");
@ -103,7 +103,32 @@ namespace vwr {
template <typename V>
template <typename V2>
typename std::enable_if<is_vec<V2>::value, V2>::type& VecBase<V>::cast() {
auto VecBase<V>::cast() -> typename std::enable_if<is_vec<V2>::value and directly_convertible<V, V2>::value, V2>::type& {
return const_cast<V2&>(const_cast<const VecBase<V>*>(this)->cast<V2>());
}
template <typename V>
template <typename V2>
auto VecBase<V>::cast() const -> const typename std::enable_if<is_vec<V2>::value and not directly_convertible<V, V2>::value, V2>::type& {
static_assert(std::is_standard_layout<V2>::value, "V2 must be a standard layout type");
typedef typename is_vec<V2>::vector_type v2_type;
static_assert(std::is_base_of<is_castable_to<typename VectorWrapperInfo<v2_type>::vector_type>, VectorWrapperInfo<V>>::value, "Casting for this type has to be explicitly enabled");
//Assert that V2 won't stomp on part of V's data, unless the user
//has explicitly said he doesn't care.
static_assert((sizeof(typename VectorWrapperInfo<typename is_vec<V2>::vector_type>::scalar_type) * VectorWrapperInfo<typename is_vec<V2>::vector_type>::dimensions == sizeof(V2)) or
IsCastIgnoreTrailingPropertiesSet<typename is_vec<V2>::vector_type>::value,
"V2 must not have any properties past the last coordinate");
static_assert(alignof(typename VectorWrapperInfo<V>::scalar_type) == alignof(V2), "Casting to V2 would give you a misaligned variable");
return *reinterpret_cast<const V2*>(
reinterpret_cast<const char*>(&(*this)[0])
);
}
template <typename V>
template <typename V2>
auto VecBase<V>::cast() -> typename std::enable_if<is_vec<V2>::value and not directly_convertible<V, V2>::value, V2>::type& {
return const_cast<V2&>(const_cast<const VecBase<V>*>(this)->cast<V2>());
}