From 8beadace371835200e46ec5877fdf8727d7bb84c Mon Sep 17 00:00:00 2001 From: vitaut Date: Sat, 21 Nov 2015 07:20:18 -0800 Subject: [PATCH] Improve detection of isinf, isnan and getsign --- format.h | 123 ++++++++++++++++++++------------------- test/format-impl-test.cc | 2 +- 2 files changed, 65 insertions(+), 60 deletions(-) diff --git a/format.h b/format.h index 4d51f0c9..b7c23a4c 100644 --- a/format.h +++ b/format.h @@ -215,18 +215,73 @@ inline uint32_t clzll(uint64_t x) { # define FMT_ASSERT(condition, message) assert((condition) && message) #endif -// Dummy implementations of signbit and _ecvt_s called if corresponding system -// functions are not available. These functions are in the namespace fmt_system -// rather than fmt::internal to make sure they don't hide the potential -// overloads in the std namespace. -namespace fmt_system { +namespace fmt { +namespace internal { struct DummyInt { int data[2]; operator int() const { return 0; } }; +typedef std::numeric_limits FPUtil; + +// Dummy implementations of system functions such as signbit and ecvt called +// if the latter are not available. inline DummyInt signbit(...) { return DummyInt(); } inline DummyInt _ecvt_s(...) { return DummyInt(); } +inline DummyInt isinf(...) { return DummyInt(); } +inline DummyInt _finite(...) { return DummyInt(); } +inline DummyInt isnan(...) { return DummyInt(); } +inline DummyInt _isnan(...) { return DummyInt(); } } +} // namespace fmt + +namespace std { +// Standard permits specialization of std::numeric_limits. This specialization +// is used to resolve ambiguity between isinf and std::isinf in glibc: +// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48891 +// and the same for isnan and signbit. +template <> +class numeric_limits : + public std::numeric_limits { + public: + // Portable version of isinf. + template + static bool isinfinity(T x) { + using namespace fmt::internal; + // The resolution "priority" is: + // isinf macro > std::isinf > ::isinf > fmt::internal::isinf + if (sizeof(isinf(x)) == sizeof(bool) || sizeof(isinf(x)) == sizeof(int)) + return isinf(x); + return !_finite(x); + } + + // Portable version of isnan. + template + static bool isnotanumber(T x) { + using namespace fmt::internal; + if (sizeof(isnan(x)) == sizeof(bool) || sizeof(isnan(x)) == sizeof(int)) + return isnan(x); + return _isnan(x); + } + + // Portable version of signbit. + static bool isnegative(double x) { + using namespace fmt::internal; + if (sizeof(signbit(x)) == sizeof(int)) + return signbit(x); + if (x < 0) return true; + if (!isnotanumber(x)) return false; + int dec = 0, sign = 0; + if (sizeof(_ecvt_s(0, 0, x, 0, 0, 0)) == sizeof(int)) { + char buffer[2]; // The buffer size must be >= 2 or _ecvt_s will fail. + _ecvt_s(buffer, sizeof(buffer), x, 0, &dec, &sign); + return sign; + } + char *result = ecvt(x, 0, &dec, &sign); + (void)result; // Suppress a warning about unused return value of ecvt. + return sign; + } +}; +} // namespace std namespace fmt { @@ -592,56 +647,6 @@ class FixedBuffer : public fmt::Buffer { void grow(std::size_t size); }; -// Portable version of signbit. -inline int getsign(double x) { - // When compiled in C++11 mode signbit is no longer a macro but a - // function defined in namespace std and the macro is undefined. - using namespace std; - using namespace fmt_system; - if (sizeof(signbit(x)) == sizeof(int)) - return signbit(x); - if (x < 0) return 1; - if (x == x) return 0; - int dec = 0, sign = 0; - if (sizeof(_ecvt_s(0, 0, x, 0, 0, 0)) == sizeof(int)) { - char buffer[2]; // The buffer size must be >= 2 or _ecvt_s will fail. - _ecvt_s(buffer, sizeof(buffer), x, 0, &dec, &sign); - return sign; - } - char *result = ecvt(x, 0, &dec, &sign); - (void)result; // Suppress warning about unused return value of ecvt. - return sign; -} - -#if !defined(_MSC_VER) && !defined(__BORLANDC__) -// Portable version of isinf. -# ifdef isinf -inline int isinfinity(double x) { return isinf(x); } -inline int isinfinity(long double x) { return isinf(x); } -# else -inline int isinfinity(double x) { return std::isinf(x); } -inline int isinfinity(long double x) { return std::isinf(x); } -# endif - -// Portable version of isnan. -# ifdef isnan -inline int isnotanumber(double x) { return isnan(x); } -inline int isnotanumber(long double x) { return isnan(x); } -# else -inline int isnotanumber(double x) { return std::isnan(x); } -inline int isnotanumber(long double x) { return std::isnan(x); } -# endif -#else -inline int isinfinity(double x) { return !_finite(x); } -inline int isinfinity(long double x) { - return !_finite(static_cast(x)); -} -inline int isnotanumber(double x) { return _isnan(x); } -inline int isnotanumber(long double x) { - return _isnan(static_cast(x)); -} -#endif - template class BasicCharTraits { public: @@ -2411,16 +2416,16 @@ void BasicWriter::write_double( } char sign = 0; - // Use getsign instead of value < 0 because the latter is always + // Use isnegative instead of value < 0 because the latter is always // false for NaN. - if (internal::getsign(static_cast(value))) { + if (internal::FPUtil::isnegative(static_cast(value))) { sign = '-'; value = -value; } else if (spec.flag(SIGN_FLAG)) { sign = spec.flag(PLUS_FLAG) ? '+' : ' '; } - if (internal::isnotanumber(value)) { + if (internal::FPUtil::isnotanumber(value)) { // Format NaN ourselves because sprintf's output is not consistent // across platforms. std::size_t nan_size = 4; @@ -2435,7 +2440,7 @@ void BasicWriter::write_double( return; } - if (internal::isinfinity(value)) { + if (internal::FPUtil::isinfinity(value)) { // Format infinity ourselves because sprintf's output is not consistent // across platforms. std::size_t inf_size = 4; diff --git a/test/format-impl-test.cc b/test/format-impl-test.cc index dbf1f580..9948a848 100644 --- a/test/format-impl-test.cc +++ b/test/format-impl-test.cc @@ -49,7 +49,7 @@ TEST(FormatTest, ArgConverter) { TEST(FormatTest, FormatNegativeNaN) { double nan = std::numeric_limits::quiet_NaN(); - if (fmt::internal::getsign(-nan)) + if (fmt::internal::FPUtil::isnegative(-nan)) EXPECT_EQ("-nan", fmt::format("{}", -nan)); else fmt::print("Warning: compiler doesn't handle negative NaN correctly");