加所有权之前

2026-08-28 12:14:15 +08:00
parent 81d3d50966
commit 0bc281b6b9
86 changed files with 12167 additions and 427 deletions
@@ -0,0 +1,100 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+// 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_NARROW_H
+#define GSL_NARROW_H
+#include "./assert"  // for GSL_SUPPRESS
+#include "./util"    // for narrow_cast
+#include <exception> // for std::exception
+namespace gsl
+{
+namespace details
+{
+    template <class T, class U>
+    constexpr bool static_cast_is_defined(U u, /*is_floating_point_to_integral=*/std::true_type)
+    {
+        if (std::is_same<typename std::remove_cv<T>::type, bool>::value) { return true; }
+
+        U upper_bound{1};
+        for (int i = 0; i < std::numeric_limits<T>::digits; i++)
+        {
+            upper_bound *= std::numeric_limits<T>::radix;
+        }
+
+        if (u >= U{}) { return u < upper_bound; }
+        if (!std::is_signed<T>::value) { return u > U{-1}; }
+
+        return u + upper_bound > U{-1};
+    }
+
+    template <class T, class U>
+    constexpr bool static_cast_is_defined(U, /*is_floating_point_to_integral=*/std::false_type)
+    {
+        return true;
+    }
+} // namespace details
+
+struct narrowing_error : public std::exception
+{
+    const char* what() const noexcept override { return "narrowing_error"; }
+};
+
+// narrow() : a checked version of narrow_cast() that throws if the cast changed the value
+template <class T, class U, typename std::enable_if<std::is_arithmetic<T>::value>::type* = nullptr>
+GSL_SUPPRESS(type.1) constexpr T narrow(U u)
+{
+    constexpr const bool is_different_signedness =
+        (std::is_signed<T>::value != std::is_signed<U>::value);
+
+    using is_floating_point_to_integral =
+        std::integral_constant<bool,
+                               std::is_integral<T>::value && std::is_floating_point<U>::value>;
+    if (!details::static_cast_is_defined<T, U>(u, is_floating_point_to_integral{}))
+    {
+        throw narrowing_error{};
+    }
+
+    GSL_SUPPRESS(es.103) // don't overflow
+    GSL_SUPPRESS(es.104) // don't underflow
+    const T t = narrow_cast<T>(u);
+
+#if defined(__clang__) || defined(__GNUC__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wfloat-equal"
+#endif
+    // Note: NaN will always throw, since NaN != NaN
+    if (static_cast<U>(t) != u || (is_different_signedness && ((t < T{}) != (u < U{}))))
+    {
+        throw narrowing_error{};
+    }
+#if defined(__clang__) || defined(__GNUC__)
+#pragma GCC diagnostic pop
+#endif
+
+    return t;
+}
+
+template <class T, class U, typename std::enable_if<!std::is_arithmetic<T>::value>::type* = nullptr>
+GSL_SUPPRESS(type.1) constexpr T narrow(U u)
+{
+    const T t = narrow_cast<T>(u);
+
+    if (static_cast<U>(t) != u) { throw narrowing_error{}; }
+
+    return t;
+}
+} // namespace gsl
+#endif // GSL_NARROW_H