--- /dev/null
+///////////////////////////////////////////////////////////////////////////////
+//
+// Copyright (c) 2015 Microsoft Corporation. All rights reserved.
+//
+// This code is licensed under the MIT License (MIT).
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef GSL_POINTERS_H
+#define GSL_POINTERS_H
+
+#include <gsl/gsl_assert> // for Ensures, Expects
+
+#include <algorithm> // for forward
+#include <iosfwd> // for ptrdiff_t, nullptr_t, ostream, size_t
+#include <memory> // for shared_ptr, unique_ptr
+#include <system_error> // for hash
+#include <type_traits> // for enable_if_t, is_convertible, is_assignable
+
+namespace gsl
+{
+
+//
+// GSL.owner: ownership pointers
+//
+using std::unique_ptr;
+using std::shared_ptr;
+
+//
+// owner
+//
+// owner<T> is designed as a bridge for code that must deal directly with owning pointers for some reason
+//
+// T must be a pointer type
+// - disallow construction from any type other than pointer type
+//
+template <class T, class = std::enable_if_t<std::is_pointer<T>::value>>
+using owner = T;
+
+//
+// not_null
+//
+// Restricts a pointer or smart pointer to only hold non-null values.
+//
+// Has zero size overhead over T.
+//
+// If T is a pointer (i.e. T == U*) then
+// - allow construction from U*
+// - disallow construction from nullptr_t
+// - disallow default construction
+// - ensure construction from null U* fails
+// - allow implicit conversion to U*
+//
+template <class T>
+class not_null
+{
+public:
+ static_assert(std::is_convertible<decltype(std::declval<T>() != nullptr), bool>::value, "T cannot be compared to nullptr.");
+
+ template <typename U, typename = std::enable_if_t<std::is_convertible<U, T>::value>>
+ constexpr not_null(U&& u) : ptr_(std::forward<U>(u))
+ {
+ Expects(ptr_ != nullptr);
+ }
+
+ template <typename = std::enable_if_t<!std::is_same<std::nullptr_t, T>::value>>
+ constexpr not_null(T u) : ptr_(std::move(u))
+ {
+ Expects(ptr_ != nullptr);
+ }
+
+ template <typename U, typename = std::enable_if_t<std::is_convertible<U, T>::value>>
+ constexpr not_null(const not_null<U>& other) : not_null(other.get())
+ {
+ }
+
+ not_null(const not_null& other) = default;
+ not_null& operator=(const not_null& other) = default;
+ constexpr std::conditional_t<std::is_copy_constructible<T>::value, T, const T&> get() const
+ {
+ Ensures(ptr_ != nullptr);
+ return ptr_;
+ }
+
+ constexpr operator T() const { return get(); }
+ constexpr decltype(auto) operator->() const { return get(); }
+ constexpr decltype(auto) operator*() const { return *get(); }
+
+ // prevents compilation when someone attempts to assign a null pointer constant
+ not_null(std::nullptr_t) = delete;
+ not_null& operator=(std::nullptr_t) = delete;
+
+ // unwanted operators...pointers only point to single objects!
+ not_null& operator++() = delete;
+ not_null& operator--() = delete;
+ not_null operator++(int) = delete;
+ not_null operator--(int) = delete;
+ not_null& operator+=(std::ptrdiff_t) = delete;
+ not_null& operator-=(std::ptrdiff_t) = delete;
+ void operator[](std::ptrdiff_t) const = delete;
+
+private:
+ T ptr_;
+};
+
+template <class T>
+auto make_not_null(T&& t) noexcept {
+ return not_null<std::remove_cv_t<std::remove_reference_t<T>>>{std::forward<T>(t)};
+}
+
+template <class T>
+std::ostream& operator<<(std::ostream& os, const not_null<T>& val)
+{
+ os << val.get();
+ return os;
+}
+
+template <class T, class U>
+auto operator==(const not_null<T>& lhs, const not_null<U>& rhs) noexcept(noexcept(lhs.get() == rhs.get())) -> decltype(lhs.get() == rhs.get())
+{
+ return lhs.get() == rhs.get();
+}
+
+template <class T, class U>
+auto operator!=(const not_null<T>& lhs, const not_null<U>& rhs) noexcept(noexcept(lhs.get() != rhs.get())) -> decltype(lhs.get() != rhs.get())
+{
+ return lhs.get() != rhs.get();
+}
+
+template <class T, class U>
+auto operator<(const not_null<T>& lhs, const not_null<U>& rhs) noexcept(noexcept(lhs.get() < rhs.get())) -> decltype(lhs.get() < rhs.get())
+{
+ return lhs.get() < rhs.get();
+}
+
+template <class T, class U>
+auto operator<=(const not_null<T>& lhs, const not_null<U>& rhs) noexcept(noexcept(lhs.get() <= rhs.get())) -> decltype(lhs.get() <= rhs.get())
+{
+ return lhs.get() <= rhs.get();
+}
+
+template <class T, class U>
+auto operator>(const not_null<T>& lhs, const not_null<U>& rhs) noexcept(noexcept(lhs.get() > rhs.get())) -> decltype(lhs.get() > rhs.get())
+{
+ return lhs.get() > rhs.get();
+}
+
+template <class T, class U>
+auto operator>=(const not_null<T>& lhs, const not_null<U>& rhs) noexcept(noexcept(lhs.get() >= rhs.get())) -> decltype(lhs.get() >= rhs.get())
+{
+ return lhs.get() >= rhs.get();
+}
+
+// more unwanted operators
+template <class T, class U>
+std::ptrdiff_t operator-(const not_null<T>&, const not_null<U>&) = delete;
+template <class T>
+not_null<T> operator-(const not_null<T>&, std::ptrdiff_t) = delete;
+template <class T>
+not_null<T> operator+(const not_null<T>&, std::ptrdiff_t) = delete;
+template <class T>
+not_null<T> operator+(std::ptrdiff_t, const not_null<T>&) = delete;
+
+} // namespace gsl
+
+namespace std
+{
+template <class T>
+struct hash<gsl::not_null<T>>
+{
+ std::size_t operator()(const gsl::not_null<T>& value) const { return hash<T>{}(value.get()); }
+};
+
+} // namespace std
+
+namespace gsl
+{
+
+//
+// strict_not_null
+//
+// Restricts a pointer or smart pointer to only hold non-null values,
+//
+// - provides a strict (i.e. explicit constructor from T) wrapper of not_null
+// - to be used for new code that wishes the design to be cleaner and make not_null
+// checks intentional, or in old code that would like to make the transition.
+//
+// To make the transition from not_null, incrementally replace not_null
+// by strict_not_null and fix compilation errors
+//
+// Expect to
+// - remove all unneeded conversions from raw pointer to not_null and back
+// - make API clear by specifying not_null in parameters where needed
+// - remove unnecessary asserts
+//
+template <class T>
+class strict_not_null: public not_null<T>
+{
+public:
+
+ template <typename U, typename = std::enable_if_t<std::is_convertible<U, T>::value>>
+ constexpr explicit strict_not_null(U&& u) :
+ not_null<T>(std::forward<U>(u))
+ {}
+
+ template <typename = std::enable_if_t<!std::is_same<std::nullptr_t, T>::value>>
+ constexpr explicit strict_not_null(T u) :
+ not_null<T>(u)
+ {}
+
+ template <typename U, typename = std::enable_if_t<std::is_convertible<U, T>::value>>
+ constexpr strict_not_null(const not_null<U>& other) :
+ not_null<T>(other)
+ {}
+
+ template <typename U, typename = std::enable_if_t<std::is_convertible<U, T>::value>>
+ constexpr strict_not_null(const strict_not_null<U>& other) :
+ not_null<T>(other)
+ {}
+
+ strict_not_null(strict_not_null&& other) = default;
+ strict_not_null(const strict_not_null& other) = default;
+ strict_not_null& operator=(const strict_not_null& other) = default;
+ strict_not_null& operator=(const not_null<T>& other)
+ {
+ not_null<T>::operator=(other);
+ return *this;
+ }
+
+ // prevents compilation when someone attempts to assign a null pointer constant
+ strict_not_null(std::nullptr_t) = delete;
+ strict_not_null& operator=(std::nullptr_t) = delete;
+
+ // unwanted operators...pointers only point to single objects!
+ strict_not_null& operator++() = delete;
+ strict_not_null& operator--() = delete;
+ strict_not_null operator++(int) = delete;
+ strict_not_null operator--(int) = delete;
+ strict_not_null& operator+=(std::ptrdiff_t) = delete;
+ strict_not_null& operator-=(std::ptrdiff_t) = delete;
+ void operator[](std::ptrdiff_t) const = delete;
+};
+
+// more unwanted operators
+template <class T, class U>
+std::ptrdiff_t operator-(const strict_not_null<T>&, const strict_not_null<U>&) = delete;
+template <class T>
+strict_not_null<T> operator-(const strict_not_null<T>&, std::ptrdiff_t) = delete;
+template <class T>
+strict_not_null<T> operator+(const strict_not_null<T>&, std::ptrdiff_t) = delete;
+template <class T>
+strict_not_null<T> operator+(std::ptrdiff_t, const strict_not_null<T>&) = delete;
+
+template <class T>
+auto make_strict_not_null(T&& t) noexcept {
+ return strict_not_null<std::remove_cv_t<std::remove_reference_t<T>>>{std::forward<T>(t)};
+}
+
+#if ( defined(__cpp_deduction_guides) && (__cpp_deduction_guides >= 201611L) )
+
+// deduction guides to prevent the ctad-maybe-unsupported warning
+template <class T> not_null(T) -> not_null<T>;
+template <class T> strict_not_null(T) -> strict_not_null<T>;
+
+#endif // ( defined(__cpp_deduction_guides) && (__cpp_deduction_guides >= 201611L) )
+
+} // namespace gsl
+
+namespace std
+{
+template <class T>
+struct hash<gsl::strict_not_null<T>>
+{
+ std::size_t operator()(const gsl::strict_not_null<T>& value) const { return hash<T>{}(value.get()); }
+};
+
+} // namespace std
+
+#endif // GSL_POINTERS_H
projects / ceph.git / blobdiff