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Merge pull request #262 from chfast/narrow

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narrow: check for changed sign
This commit is contained in:
Neil MacIntosh 2016-02-19 17:19:51 -08:00
commit ad0905c08b
2 changed files with 66 additions and 37 deletions
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58
include/gsl_util.h
View File

@ -1,17 +1,17 @@
///////////////////////////////////////////////////////////////////////////////
//
// 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.
//
///////////////////////////////////////////////////////////////////////////////
//
// 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.
//
///////////////////////////////////////////////////////////////////////////////
#pragma once
@ -22,23 +22,25 @@
#include "gsl_assert.h" // Ensures/Expects
#include <array>
#include <utility>
#include <type_traits>
#include <exception>
#ifdef _MSC_VER
// No MSVC does constexpr fully yet
#pragma push_macro("constexpr")
#define constexpr
#define constexpr
// MSVC 2013 workarounds
#if _MSC_VER <= 1800
// noexcept is not understood
// noexcept is not understood
#pragma push_macro("noexcept")
#define noexcept
#define noexcept
// turn off some misguided warnings
#pragma warning(push)
#pragma warning(disable: 4351) // warns about newly introduced aggregate initializer behavior
#pragma warning(disable: 4127) // conditional expression is constant
#endif // _MSC_VER <= 1800
@ -63,7 +65,7 @@ public:
final_act(final_act&& other) noexcept
: f_(std::move(other.f_)), invoke_(other.invoke_)
{ other.invoke_ = false; }
final_act(const final_act&) = delete;
final_act& operator=(const final_act&) = delete;
@ -90,15 +92,29 @@ inline constexpr T narrow_cast(U u) noexcept
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>
inline T narrow(U u)
{ T t = narrow_cast<T>(u); if (static_cast<U>(t) != u) throw narrowing_error(); return t; }
{
T t = narrow_cast<T>(u);
if (static_cast<U>(t) != u)
throw narrowing_error();
if (!details::is_same_signedness<T, U>::value && ((t < T{}) != (u < U{})))
throw narrowing_error();
return t;
}
//
// at() - Bounds-checked way of accessing static arrays, std::array, std::vector
//
template <class T, size_t N>
template <class T, size_t N>
constexpr T& at(T(&arr)[N], size_t index)
{ Expects(index < N); return arr[index]; }
@ -122,7 +138,7 @@ constexpr typename Cont::value_type& at(Cont& cont, size_t index)
#undef noexcept
#pragma pop_macro("noexcept")
#pragma warning(pop)
#endif // _MSC_VER <= 1800

45
tests/utils_tests.cpp
View File

@ -1,20 +1,20 @@
///////////////////////////////////////////////////////////////////////////////
//
// 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.
//
///////////////////////////////////////////////////////////////////////////////
//
// 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.
//
///////////////////////////////////////////////////////////////////////////////
#include <UnitTest++/UnitTest++.h>
#include <UnitTest++/UnitTest++.h>
#include <gsl.h>
#include <functional>
@ -95,8 +95,21 @@ SUITE(utils_tests)
char c = narrow<char>(n);
CHECK(c == 120);
n = 300;
n = 300;
CHECK_THROW(narrow<char>(n), narrowing_error);
const auto int32_max = std::numeric_limits<int32_t>::max();
const auto int32_min = std::numeric_limits<int32_t>::min();
CHECK(narrow<uint32_t>(int32_t(0)) == 0);
CHECK(narrow<uint32_t>(int32_t(1)) == 1);
CHECK(narrow<uint32_t>(int32_max) == int32_max);
CHECK_THROW(narrow<uint32_t>(int32_t(-1)), narrowing_error);
CHECK_THROW(narrow<uint32_t>(int32_min), narrowing_error);
n = -42;
CHECK_THROW(narrow<unsigned>(n), narrowing_error);
}
}