diff options
| -rw-r--r-- | gsl/gsl_util | 39 |
1 files changed, 28 insertions, 11 deletions
diff --git a/gsl/gsl_util b/gsl/gsl_util index f0ac964..a8a41ae 100644 --- a/gsl/gsl_util +++ b/gsl/gsl_util @@ -48,6 +48,18 @@ #endif // _MSC_VER +// AFAIK there's no way to detect in GCC or MSVC. GCC has an __EXCEPTIONS macro, +// but that is only defined if `-fexceptions` is *explicitly* passed on the +// command line; defaulting to exceptions enabled will not set this macro. +// +// Non-Clang users will need to defined GSL_NO_EXCEPTIONS explicitly from the +// command line if they are building with exceptions disabled. +#if defined(__clang__) && !__has_feature(cxx_exceptions) +// If building with -fno-exceptions, we'll fall back to gsl::Ensures in places +// where we would have normally thrown an exception. +#define GSL_NO_EXCEPTIONS +#endif // defined(__has_feature) && !__has_feature(cxx_exceptions) + namespace gsl { // @@ -125,9 +137,14 @@ template <class T, class U> inline T narrow(U u) { T t = narrow_cast<T>(u); +#ifndef GSL_NO_EXCEPTIONS if (static_cast<U>(t) != u) throw narrowing_error(); if (!details::is_same_signedness<T, U>::value && ((t < T{}) != (u < U{}))) throw narrowing_error(); +#else + Ensures(static_cast<U>(t) == u); + Ensures(!(!details::is_same_signedness<T, U>::value && ((t < T{}) != (u < U{})))); +#endif return t; } @@ -135,30 +152,30 @@ inline T narrow(U u) // at() - Bounds-checked way of accessing static arrays, std::array, std::vector // template <class T, size_t N> -constexpr T& at(T (&arr)[N], size_t index) +constexpr T& at(T (&arr)[N], std::ptrdiff_t index) { - Expects(index < N); - return arr[index]; + Expects(index >= 0 && index < narrow_cast<std::ptrdiff_t>(N)); + return arr[static_cast<size_t>(index)]; } template <class T, size_t N> -constexpr T& at(std::array<T, N>& arr, size_t index) +constexpr T& at(std::array<T, N>& arr, std::ptrdiff_t index) { - Expects(index < N); - return arr[index]; + Expects(index >= 0 && index < narrow_cast<std::ptrdiff_t>(N)); + return arr[static_cast<size_t>(index)]; } template <class Cont> -constexpr typename Cont::value_type& at(Cont& cont, size_t index) +constexpr typename Cont::value_type& at(Cont& cont, std::ptrdiff_t index) { - Expects(index < cont.size()); - return cont[index]; + Expects(index >= 0 && index < narrow_cast<std::ptrdiff_t>(cont.size())); + return cont[static_cast<typename Cont::size_type>(index)]; } template <class T> -constexpr const T& at(std::initializer_list<T> cont, size_t index) +constexpr const T& at(std::initializer_list<T> cont, std::ptrdiff_t index) { - Expects(index < cont.size()); + Expects(index >= 0 && index < narrow_cast<std::ptrdiff_t>(cont.size())); return *(cont.begin() + index); } |