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/gsl_util b/include/gsl/gsl_util
new file mode 100644
index 0000000..25f8502
--- /dev/null
+++ b/include/gsl/gsl_util
@@ -0,0 +1,158 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+// 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_UTIL_H
+#define GSL_UTIL_H
+
+#include <gsl/gsl_assert> // for Expects
+
+#include <array>
+#include <cstddef> // for ptrdiff_t, size_t
+#include <exception> // for exception
+#include <initializer_list> // for initializer_list
+#include <type_traits> // for is_signed, integral_constant
+#include <utility> // for forward
+
+#if defined(_MSC_VER)
+
+#pragma warning(push)
+#pragma warning(disable : 4127) // conditional expression is constant
+
+#if _MSC_VER < 1910
+#pragma push_macro("constexpr")
+#define constexpr /*constexpr*/
+#endif // _MSC_VER < 1910
+#endif // _MSC_VER
+
+namespace gsl
+{
+//
+// GSL.util: utilities
+//
+
+// index type for all container indexes/subscripts/sizes
+using index = std::ptrdiff_t;
+
+// final_action allows you to ensure something gets run at the end of a scope
+template <class F>
+class final_action
+{
+public:
+ explicit final_action(F f) noexcept : f_(std::move(f)) {}
+
+ final_action(final_action&& other) noexcept : f_(std::move(other.f_)), invoke_(other.invoke_)
+ {
+ other.invoke_ = false;
+ }
+
+ final_action(const final_action&) = delete;
+ final_action& operator=(const final_action&) = delete;
+ final_action& operator=(final_action&&) = delete;
+
+ ~final_action() noexcept
+ {
+ if (invoke_) f_();
+ }
+
+private:
+ F f_;
+ bool invoke_ {true};
+};
+
+// finally() - convenience function to generate a final_action
+template <class F>
+
+final_action<F> finally(const F& f) noexcept
+{
+ return final_action<F>(f);
+}
+
+template <class F>
+final_action<F> finally(F&& f) noexcept
+{
+ return final_action<F>(std::forward<F>(f));
+}
+
+// narrow_cast(): a searchable way to do narrowing casts of values
+template <class T, class U>
+constexpr T narrow_cast(U&& u) noexcept
+{
+ return static_cast<T>(std::forward<U>(u));
+}
+
+struct narrowing_error : public std::exception
+{
+};
+
+namespace details
+{
+ template <class T, class U>
+ struct is_same_signedness
+ : public std::integral_constant<bool, std::is_signed<T>::value == std::is_signed<U>::value>
+ {
+ };
+}
+
+// narrow() : a checked version of narrow_cast() that throws if the cast changed the value
+template <class T, class U>
+T narrow(U u)
+{
+ T t = narrow_cast<T>(u);
+ if (static_cast<U>(t) != u) gsl::details::throw_exception(narrowing_error());
+ if (!details::is_same_signedness<T, U>::value && ((t < T{}) != (u < U{})))
+ gsl::details::throw_exception(narrowing_error());
+ return t;
+}
+
+//
+// at() - Bounds-checked way of accessing builtin arrays, std::array, std::vector
+//
+template <class T, std::size_t N>
+constexpr T& at(T (&arr)[N], const index i)
+{
+ Expects(i >= 0 && i < narrow_cast<index>(N));
+ return arr[static_cast<std::size_t>(i)];
+}
+
+template <class Cont>
+constexpr auto at(Cont& cont, const index i) -> decltype(cont[cont.size()])
+{
+ Expects(i >= 0 && i < narrow_cast<index>(cont.size()));
+ using size_type = decltype(cont.size());
+ return cont[static_cast<size_type>(i)];
+}
+
+template <class T>
+constexpr T at(const std::initializer_list<T> cont, const index i)
+{
+ Expects(i >= 0 && i < narrow_cast<index>(cont.size()));
+ return *(cont.begin() + i);
+}
+
+} // namespace gsl
+
+#if defined(_MSC_VER)
+#if _MSC_VER < 1910
+#undef constexpr
+#pragma pop_macro("constexpr")
+
+#endif // _MSC_VER < 1910
+
+#pragma warning(pop)
+
+#endif // _MSC_VER
+
+#endif // GSL_UTIL_H