forked from pz4kybsvg/Conception
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
86 lines
2.6 KiB
86 lines
2.6 KiB
#pragma once
|
|
|
|
#include <memory>
|
|
#include <type_traits>
|
|
|
|
namespace drake {
|
|
|
|
/** @cond */
|
|
|
|
namespace is_cloneable_internal {
|
|
|
|
// Default case; assumes that a class is *not* cloneable.
|
|
template <typename T, class>
|
|
struct is_cloneable_helper : std::false_type {};
|
|
|
|
// Special sauce for SFINAE. Only compiles if it can finds the method
|
|
// `unique_ptr<T> T::Clone() const`. If this exists, the is_cloneable implicitly
|
|
// prefers this overload over the default overload.
|
|
template <typename T>
|
|
struct is_cloneable_helper<
|
|
T,
|
|
typename std::enable_if_t<std::is_same_v<
|
|
decltype(std::declval<const T>().Clone().release()),
|
|
typename std::remove_const_t<T>*>>>
|
|
: std::true_type {};
|
|
|
|
} // namespace is_cloneable_internal
|
|
|
|
/** @endcond */
|
|
|
|
/**
|
|
@anchor is_cloneable_doc
|
|
Provides method for determining at run time if a class is "cloneable".
|
|
|
|
__Usage__
|
|
|
|
This gets used like `type_traits` functions (e.g., `is_copy_constructible`,
|
|
`is_same`, etc.) To determine if a class is cloneable simply invoke:
|
|
|
|
@code
|
|
bool value = drake::is_cloneable<Foo>::value;
|
|
@endcode
|
|
|
|
If `Foo` is cloneable, it will evaluate to true. It can also be used in
|
|
compile-time tests (e.g., SFINAE and `static_assert`s):
|
|
|
|
@code
|
|
static_assert(is_cloneable<Foo>::value, "This method requires its classes to "
|
|
"be cloneable.");
|
|
@endcode
|
|
|
|
__Definition of "cloneability"__
|
|
|
|
To be cloneable, the class `Foo` must have a _public_ method of the form:
|
|
@code
|
|
unique_ptr<Foo> Foo::Clone() const;
|
|
@endcode
|
|
Note that "friend" access for the %is_cloneable-using class is not sufficient.
|
|
The `Foo::Clone()` method must actually be public.
|
|
|
|
<!-- Developer note: if you change or extend the definition of an acceptable
|
|
clone method here, be sure to consider whether
|
|
copyable_unique_ptr::can_clone() should be changed as well. -->
|
|
|
|
The pointer contained in the returned `unique_ptr` must point to a
|
|
heap-allocated deep copy of the _concrete_ object. This test can confirm the
|
|
proper signature, but cannot confirm the heap-allocated deep copy. A Clone()
|
|
method that doesn't return such a copy of the _concrete_ object should be
|
|
considered a malformed function.
|
|
|
|
@warning It is important to note, that a `Clone()` method that returns a
|
|
`unique_ptr` to a _super_ class is _not_ sufficient to be cloneable. In other
|
|
words the presence of:
|
|
@code
|
|
unique_ptr<Base> Derived::Clone() const;
|
|
@endcode
|
|
will not make the `Derived` class cloneable.
|
|
|
|
@tparam T The class to test for cloneability.
|
|
*/
|
|
template <typename T>
|
|
using is_cloneable =
|
|
is_cloneable_internal::is_cloneable_helper<T, void>;
|
|
|
|
} // namespace drake
|