traits.h File Reference

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Typedefs
template<typename T >
using	VdfByValueOrConstRef
	Template that evaluates to either T or const T & depending on whether T best be passed as value or const reference.

Variables
template<typename , typename = void>
constexpr bool	Vdf_IsEqualityComparableHelper = false
template<typename T >
constexpr bool	VdfIsEqualityComparable
	Variable template that returns true if equality comparison is a valid operation for type T.
template<typename , bool >
constexpr bool	Vdf_AndTypeIsSmall = false
template<typename T >
constexpr bool	Vdf_AndTypeIsSmall< T, true > = sizeof(T) <= sizeof(void*)

Typedef Documentation

VdfByValueOrConstRef

template<typename T >

using VdfByValueOrConstRef

Initial value:

 typename std::conditional_t<
    std::is_pointer_v<T> ||
    Vdf_AndTypeIsSmall<T, std::is_arithmetic_v<T>> ||
    Vdf_AndTypeIsSmall<T, std::is_enum_v<T>>,
    T, const T &>

Template that evaluates to either T or const T & depending on whether T best be passed as value or const reference.

The heuristic here is as follows:

• T if T is a ptr, arithmetic type, or enum, and also <= size of a ptr
• const T & in all other cases

Note that this heuristic is a best guess given a generic type T, but if the type is known the call site may be able to make a more informed decision on how to pass parameters and return values without the use of this facility.

Definition at line 104 of file traits.h.

Variable Documentation

Vdf_AndTypeIsSmall

template<typename , bool >

bool Vdf_AndTypeIsSmall = false

constexpr

Definition at line 84 of file traits.h.

Vdf_AndTypeIsSmall< T, true >

template<typename T >

bool Vdf_AndTypeIsSmall< T, true > = sizeof(T) <= sizeof(void*)

constexpr

Definition at line 89 of file traits.h.

Vdf_IsEqualityComparableHelper

template<typename , typename = void>

bool Vdf_IsEqualityComparableHelper = false

constexpr

Definition at line 27 of file traits.h.

VdfIsEqualityComparable

template<typename T >

bool VdfIsEqualityComparable

constexpr

Initial value:

=
    Vdf_IsEqualityComparableHelper<T>

Variable template that returns true if equality comparison is a valid operation for type T.

For compound types, specializations must be provided along the lines of the following example:

// ContainerType<T> is equality comparable iff T is equality comparable.
template <typename T>
constexpr bool VdfIsEqualityComparable<ContainerType<T>> =
   VdfIsEqualityComparable<T>;

Definition at line 49 of file traits.h.