50 lines
1.7 KiB
Plaintext
50 lines
1.7 KiB
Plaintext
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///////////////////////////////////////////////////////////////////////////////
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//
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// Copyright (c) 2015 Microsoft Corporation. All rights reserved.
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//
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// This code is licensed under the MIT License (MIT).
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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//
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///////////////////////////////////////////////////////////////////////////////
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#ifndef GSL_NARROW_H
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#define GSL_NARROW_H
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#include <gsl/assert> // for Expects
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#include <gsl/util> // for narrow_cast
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namespace gsl
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{
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struct narrowing_error : public std::exception
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{
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const char* what() const noexcept override { return "narrowing_error"; }
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};
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// narrow() : a checked version of narrow_cast() that throws if the cast changed the value
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template <class T, class U>
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// clang-format off
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GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
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GSL_SUPPRESS(f.6) // NO-FORMAT: attribute // TODO: MSVC /analyze does not recognise noexcept(false)
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// clang-format on
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constexpr T narrow(U u) noexcept(false)
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{
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constexpr const bool is_different_signedness =
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(std::is_signed<T>::value != std::is_signed<U>::value);
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const T t = narrow_cast<T>(u);
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if (static_cast<U>(t) != u || (is_different_signedness && ((t < T{}) != (u < U{}))))
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{
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throw narrowing_error{};
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}
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return t;
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}
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} // namespace gsl
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#endif // GSL_NARROW_H
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