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Merge safe-duration-cast.h into chrono.h

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This commit is contained in:
Victor Zverovich 2019-11-20 07:51:14 -08:00
parent 093e554211
commit 092d2dc7b2
3 changed files with 281 additions and 300 deletions
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3
CMakeLists.txt
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@ -150,8 +150,7 @@ endfunction()
# Define the fmt library, its includes and the needed defines.
add_headers(FMT_HEADERS chrono.h color.h compile.h core.h format.h format-inl.h
locale.h ostream.h posix.h printf.h ranges.h
safe-duration-cast.h)
locale.h ostream.h posix.h printf.h ranges.h)
set(FMT_SOURCES src/format.cc src/posix.cc)
add_library(fmt ${FMT_SOURCES} ${FMT_HEADERS} README.rst ChangeLog.rst)

285
include/fmt/chrono.h
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@ -16,16 +16,291 @@
#include <locale>
#include <sstream>
// enable safe chrono durations, unless explicitly disabled
FMT_BEGIN_NAMESPACE
// Enable safe chrono durations, unless explicitly disabled.
#ifndef FMT_SAFE_DURATION_CAST
# define FMT_SAFE_DURATION_CAST 1
#endif
#if FMT_SAFE_DURATION_CAST
# include "safe-duration-cast.h"
#endif
FMT_BEGIN_NAMESPACE
// For conversion between std::chrono::durations without undefined
// behaviour or erroneous results.
// This is a stripped down version of duration_cast, for inclusion in fmt.
// See https://github.com/pauldreik/safe_duration_cast
//
// Copyright Paul Dreik 2019
namespace safe_duration_cast {
template <typename To, typename From,
FMT_ENABLE_IF(!std::is_same<From, To>::value &&
std::numeric_limits<From>::is_signed ==
std::numeric_limits<To>::is_signed)>
FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
ec = 0;
using F = std::numeric_limits<From>;
using T = std::numeric_limits<To>;
static_assert(F::is_integer, "From must be integral");
static_assert(T::is_integer, "To must be integral");
// A and B are both signed, or both unsigned.
if (F::digits <= T::digits) {
// From fits in To without any problem.
} else {
// From does not always fit in To, resort to a dynamic check.
if (from < T::min() || from > T::max()) {
// outside range.
ec = 1;
return {};
}
}
return static_cast<To>(from);
}
/**
* converts From to To, without loss. If the dynamic value of from
* can't be converted to To without loss, ec is set.
*/
template <typename To, typename From,
FMT_ENABLE_IF(!std::is_same<From, To>::value &&
std::numeric_limits<From>::is_signed !=
std::numeric_limits<To>::is_signed)>
FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
ec = 0;
using F = std::numeric_limits<From>;
using T = std::numeric_limits<To>;
static_assert(F::is_integer, "From must be integral");
static_assert(T::is_integer, "To must be integral");
if (F::is_signed && !T::is_signed) {
// From may be negative, not allowed!
if (fmt::internal::is_negative(from)) {
ec = 1;
return {};
}
// From is positive. Can it always fit in To?
if (F::digits <= T::digits) {
// yes, From always fits in To.
} else {
// from may not fit in To, we have to do a dynamic check
if (from > static_cast<From>(T::max())) {
ec = 1;
return {};
}
}
}
if (!F::is_signed && T::is_signed) {
// can from be held in To?
if (F::digits < T::digits) {
// yes, From always fits in To.
} else {
// from may not fit in To, we have to do a dynamic check
if (from > static_cast<From>(T::max())) {
// outside range.
ec = 1;
return {};
}
}
}
// reaching here means all is ok for lossless conversion.
return static_cast<To>(from);
} // function
template <typename To, typename From,
FMT_ENABLE_IF(std::is_same<From, To>::value)>
FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
ec = 0;
return from;
} // function
// clang-format off
/**
* converts From to To if possible, otherwise ec is set.
*
* input | output
* ---------------------------------|---------------
* NaN | NaN
* Inf | Inf
* normal, fits in output | converted (possibly lossy)
* normal, does not fit in output | ec is set
* subnormal | best effort
* -Inf | -Inf
*/
// clang-format on
template <typename To, typename From,
FMT_ENABLE_IF(!std::is_same<From, To>::value)>
FMT_CONSTEXPR To safe_float_conversion(const From from, int& ec) {
ec = 0;
using T = std::numeric_limits<To>;
static_assert(std::is_floating_point<From>::value, "From must be floating");
static_assert(std::is_floating_point<To>::value, "To must be floating");
// catch the only happy case
if (std::isfinite(from)) {
if (from >= T::lowest() && from <= T::max()) {
return static_cast<To>(from);
}
// not within range.
ec = 1;
return {};
}
// nan and inf will be preserved
return static_cast<To>(from);
} // function
template <typename To, typename From,
FMT_ENABLE_IF(std::is_same<From, To>::value)>
FMT_CONSTEXPR To safe_float_conversion(const From from, int& ec) {
ec = 0;
static_assert(std::is_floating_point<From>::value, "From must be floating");
return from;
}
/**
* safe duration cast between integral durations
*/
template <typename To, typename FromRep, typename FromPeriod,
FMT_ENABLE_IF(std::is_integral<FromRep>::value),
FMT_ENABLE_IF(std::is_integral<typename To::rep>::value)>
To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
int& ec) {
using From = std::chrono::duration<FromRep, FromPeriod>;
ec = 0;
// the basic idea is that we need to convert from count() in the from type
// to count() in the To type, by multiplying it with this:
struct Factor
: std::ratio_divide<typename From::period, typename To::period> {};
static_assert(Factor::num > 0, "num must be positive");
static_assert(Factor::den > 0, "den must be positive");
// the conversion is like this: multiply from.count() with Factor::num
// /Factor::den and convert it to To::rep, all this without
// overflow/underflow. let's start by finding a suitable type that can hold
// both To, From and Factor::num
using IntermediateRep =
typename std::common_type<typename From::rep, typename To::rep,
decltype(Factor::num)>::type;
// safe conversion to IntermediateRep
IntermediateRep count =
lossless_integral_conversion<IntermediateRep>(from.count(), ec);
if (ec) {
return {};
}
// multiply with Factor::num without overflow or underflow
if (Factor::num != 1) {
const auto max1 = internal::max_value<IntermediateRep>() / Factor::num;
if (count > max1) {
ec = 1;
return {};
}
const auto min1 = std::numeric_limits<IntermediateRep>::min() / Factor::num;
if (count < min1) {
ec = 1;
return {};
}
count *= Factor::num;
}
// this can't go wrong, right? den>0 is checked earlier.
if (Factor::den != 1) {
count /= Factor::den;
}
// convert to the to type, safely
using ToRep = typename To::rep;
const ToRep tocount = lossless_integral_conversion<ToRep>(count, ec);
if (ec) {
return {};
}
return To{tocount};
}
/**
* safe duration_cast between floating point durations
*/
template <typename To, typename FromRep, typename FromPeriod,
FMT_ENABLE_IF(std::is_floating_point<FromRep>::value),
FMT_ENABLE_IF(std::is_floating_point<typename To::rep>::value)>
To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
int& ec) {
using From = std::chrono::duration<FromRep, FromPeriod>;
ec = 0;
if (std::isnan(from.count())) {
// nan in, gives nan out. easy.
return To{std::numeric_limits<typename To::rep>::quiet_NaN()};
}
// maybe we should also check if from is denormal, and decide what to do about
// it.
// +-inf should be preserved.
if (std::isinf(from.count())) {
return To{from.count()};
}
// the basic idea is that we need to convert from count() in the from type
// to count() in the To type, by multiplying it with this:
struct Factor
: std::ratio_divide<typename From::period, typename To::period> {};
static_assert(Factor::num > 0, "num must be positive");
static_assert(Factor::den > 0, "den must be positive");
// the conversion is like this: multiply from.count() with Factor::num
// /Factor::den and convert it to To::rep, all this without
// overflow/underflow. let's start by finding a suitable type that can hold
// both To, From and Factor::num
using IntermediateRep =
typename std::common_type<typename From::rep, typename To::rep,
decltype(Factor::num)>::type;
// force conversion of From::rep -> IntermediateRep to be safe,
// even if it will never happen be narrowing in this context.
IntermediateRep count =
safe_float_conversion<IntermediateRep>(from.count(), ec);
if (ec) {
return {};
}
// multiply with Factor::num without overflow or underflow
if (Factor::num != 1) {
constexpr auto max1 = internal::max_value<IntermediateRep>() /
static_cast<IntermediateRep>(Factor::num);
if (count > max1) {
ec = 1;
return {};
}
constexpr auto min1 = std::numeric_limits<IntermediateRep>::lowest() /
static_cast<IntermediateRep>(Factor::num);
if (count < min1) {
ec = 1;
return {};
}
count *= static_cast<IntermediateRep>(Factor::num);
}
// this can't go wrong, right? den>0 is checked earlier.
if (Factor::den != 1) {
using common_t = typename std::common_type<IntermediateRep, intmax_t>::type;
count /= static_cast<common_t>(Factor::den);
}
// convert to the to type, safely
using ToRep = typename To::rep;
const ToRep tocount = safe_float_conversion<ToRep>(count, ec);
if (ec) {
return {};
}
return To{tocount};
}
} // namespace safe_duration_cast
#endif
// Prevents expansion of a preceding token as a function-style macro.
// Usage: f FMT_NOMACRO()

293
include/fmt/safe-duration-cast.h
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@ -1,293 +0,0 @@
/*
* For conversion between std::chrono::durations without undefined
* behaviour or erroneous results.
* This is a stripped down version of duration_cast, for inclusion in fmt.
* See https://github.com/pauldreik/safe_duration_cast
*
* Copyright Paul Dreik 2019
*
* This file is licensed under the fmt license, see format.h
*/
#include <chrono>
#include <cmath>
#include <limits>
#include <type_traits>
#include "format.h"
FMT_BEGIN_NAMESPACE
namespace safe_duration_cast {
template <typename To, typename From,
FMT_ENABLE_IF(!std::is_same<From, To>::value &&
std::numeric_limits<From>::is_signed ==
std::numeric_limits<To>::is_signed)>
FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
ec = 0;
using F = std::numeric_limits<From>;
using T = std::numeric_limits<To>;
static_assert(F::is_integer, "From must be integral");
static_assert(T::is_integer, "To must be integral");
// A and B are both signed, or both unsigned.
if (F::digits <= T::digits) {
// From fits in To without any problem.
} else {
// From does not always fit in To, resort to a dynamic check.
if (from < T::min() || from > T::max()) {
// outside range.
ec = 1;
return {};
}
}
return static_cast<To>(from);
}
/**
* converts From to To, without loss. If the dynamic value of from
* can't be converted to To without loss, ec is set.
*/
template <typename To, typename From,
FMT_ENABLE_IF(!std::is_same<From, To>::value &&
std::numeric_limits<From>::is_signed !=
std::numeric_limits<To>::is_signed)>
FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
ec = 0;
using F = std::numeric_limits<From>;
using T = std::numeric_limits<To>;
static_assert(F::is_integer, "From must be integral");
static_assert(T::is_integer, "To must be integral");
if (F::is_signed && !T::is_signed) {
// From may be negative, not allowed!
if (fmt::internal::is_negative(from)) {
ec = 1;
return {};
}
// From is positive. Can it always fit in To?
if (F::digits <= T::digits) {
// yes, From always fits in To.
} else {
// from may not fit in To, we have to do a dynamic check
if (from > static_cast<From>(T::max())) {
ec = 1;
return {};
}
}
}
if (!F::is_signed && T::is_signed) {
// can from be held in To?
if (F::digits < T::digits) {
// yes, From always fits in To.
} else {
// from may not fit in To, we have to do a dynamic check
if (from > static_cast<From>(T::max())) {
// outside range.
ec = 1;
return {};
}
}
}
// reaching here means all is ok for lossless conversion.
return static_cast<To>(from);
} // function
template <typename To, typename From,
FMT_ENABLE_IF(std::is_same<From, To>::value)>
FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
ec = 0;
return from;
} // function
// clang-format off
/**
* converts From to To if possible, otherwise ec is set.
*
* input | output
* ---------------------------------|---------------
* NaN | NaN
* Inf | Inf
* normal, fits in output | converted (possibly lossy)
* normal, does not fit in output | ec is set
* subnormal | best effort
* -Inf | -Inf
*/
// clang-format on
template <typename To, typename From,
FMT_ENABLE_IF(!std::is_same<From, To>::value)>
FMT_CONSTEXPR To safe_float_conversion(const From from, int& ec) {
ec = 0;
using T = std::numeric_limits<To>;
static_assert(std::is_floating_point<From>::value, "From must be floating");
static_assert(std::is_floating_point<To>::value, "To must be floating");
// catch the only happy case
if (std::isfinite(from)) {
if (from >= T::lowest() && from <= T::max()) {
return static_cast<To>(from);
}
// not within range.
ec = 1;
return {};
}
// nan and inf will be preserved
return static_cast<To>(from);
} // function
template <typename To, typename From,
FMT_ENABLE_IF(std::is_same<From, To>::value)>
FMT_CONSTEXPR To safe_float_conversion(const From from, int& ec) {
ec = 0;
static_assert(std::is_floating_point<From>::value, "From must be floating");
return from;
}
/**
* safe duration cast between integral durations
*/
template <typename To, typename FromRep, typename FromPeriod,
FMT_ENABLE_IF(std::is_integral<FromRep>::value),
FMT_ENABLE_IF(std::is_integral<typename To::rep>::value)>
To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
int& ec) {
using From = std::chrono::duration<FromRep, FromPeriod>;
ec = 0;
// the basic idea is that we need to convert from count() in the from type
// to count() in the To type, by multiplying it with this:
struct Factor
: std::ratio_divide<typename From::period, typename To::period> {};
static_assert(Factor::num > 0, "num must be positive");
static_assert(Factor::den > 0, "den must be positive");
// the conversion is like this: multiply from.count() with Factor::num
// /Factor::den and convert it to To::rep, all this without
// overflow/underflow. let's start by finding a suitable type that can hold
// both To, From and Factor::num
using IntermediateRep =
typename std::common_type<typename From::rep, typename To::rep,
decltype(Factor::num)>::type;
// safe conversion to IntermediateRep
IntermediateRep count =
lossless_integral_conversion<IntermediateRep>(from.count(), ec);
if (ec) {
return {};
}
// multiply with Factor::num without overflow or underflow
if (Factor::num != 1) {
const auto max1 = internal::max_value<IntermediateRep>() / Factor::num;
if (count > max1) {
ec = 1;
return {};
}
const auto min1 = std::numeric_limits<IntermediateRep>::min() / Factor::num;
if (count < min1) {
ec = 1;
return {};
}
count *= Factor::num;
}
// this can't go wrong, right? den>0 is checked earlier.
if (Factor::den != 1) {
count /= Factor::den;
}
// convert to the to type, safely
using ToRep = typename To::rep;
const ToRep tocount = lossless_integral_conversion<ToRep>(count, ec);
if (ec) {
return {};
}
return To{tocount};
}
/**
* safe duration_cast between floating point durations
*/
template <typename To, typename FromRep, typename FromPeriod,
FMT_ENABLE_IF(std::is_floating_point<FromRep>::value),
FMT_ENABLE_IF(std::is_floating_point<typename To::rep>::value)>
To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
int& ec) {
using From = std::chrono::duration<FromRep, FromPeriod>;
ec = 0;
if (std::isnan(from.count())) {
// nan in, gives nan out. easy.
return To{std::numeric_limits<typename To::rep>::quiet_NaN()};
}
// maybe we should also check if from is denormal, and decide what to do about
// it.
// +-inf should be preserved.
if (std::isinf(from.count())) {
return To{from.count()};
}
// the basic idea is that we need to convert from count() in the from type
// to count() in the To type, by multiplying it with this:
struct Factor
: std::ratio_divide<typename From::period, typename To::period> {};
static_assert(Factor::num > 0, "num must be positive");
static_assert(Factor::den > 0, "den must be positive");
// the conversion is like this: multiply from.count() with Factor::num
// /Factor::den and convert it to To::rep, all this without
// overflow/underflow. let's start by finding a suitable type that can hold
// both To, From and Factor::num
using IntermediateRep =
typename std::common_type<typename From::rep, typename To::rep,
decltype(Factor::num)>::type;
// force conversion of From::rep -> IntermediateRep to be safe,
// even if it will never happen be narrowing in this context.
IntermediateRep count =
safe_float_conversion<IntermediateRep>(from.count(), ec);
if (ec) {
return {};
}
// multiply with Factor::num without overflow or underflow
if (Factor::num != 1) {
constexpr auto max1 = internal::max_value<IntermediateRep>() /
static_cast<IntermediateRep>(Factor::num);
if (count > max1) {
ec = 1;
return {};
}
constexpr auto min1 = std::numeric_limits<IntermediateRep>::lowest() /
static_cast<IntermediateRep>(Factor::num);
if (count < min1) {
ec = 1;
return {};
}
count *= static_cast<IntermediateRep>(Factor::num);
}
// this can't go wrong, right? den>0 is checked earlier.
if (Factor::den != 1) {
using common_t = typename std::common_type<IntermediateRep, intmax_t>::type;
count /= static_cast<common_t>(Factor::den);
}
// convert to the to type, safely
using ToRep = typename To::rep;
const ToRep tocount = safe_float_conversion<ToRep>(count, ec);
if (ec) {
return {};
}
return To{tocount};
}
} // namespace safe_duration_cast
FMT_END_NAMESPACE