Squashed 'third_party/GSL/' content from commit 0cebbd7
Change-Id: Iffb2e32f2f45297ac6d3e82168cd9df4ac5acc2f
git-subtree-dir: third_party/GSL
git-subtree-split: 0cebbd77bfc21acbf1cc05983ad626539eeeb8e0
diff --git a/include/gsl/pointers b/include/gsl/pointers
new file mode 100644
index 0000000..69499d6
--- /dev/null
+++ b/include/gsl/pointers
@@ -0,0 +1,193 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+// 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
+
+#if defined(_MSC_VER) && _MSC_VER < 1910
+#pragma push_macro("constexpr")
+#define constexpr /*constexpr*/
+
+#endif // defined(_MSC_VER) && _MSC_VER < 1910
+
+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_assignable<T&, std::nullptr_t>::value, "T cannot be assigned nullptr.");
+
+ template <typename U, typename = std::enable_if_t<std::is_convertible<U, T>::value>>
+ constexpr explicit 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 explicit not_null(T u) : ptr_(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(not_null&& other) = default;
+ not_null(const not_null& other) = default;
+ not_null& operator=(const not_null& other) = default;
+
+ constexpr T get() const
+ {
+ Ensures(ptr_ != nullptr);
+ return ptr_;
+ }
+
+ constexpr operator T() const { return get(); }
+ constexpr T 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>
+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) -> 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) -> 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) -> 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) -> 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) -> 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) -> 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); }
+};
+
+} // namespace std
+
+#if defined(_MSC_VER) && _MSC_VER < 1910
+#undef constexpr
+#pragma pop_macro("constexpr")
+
+#endif // defined(_MSC_VER) && _MSC_VER < 1910
+
+#endif // GSL_POINTERS_H