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Mark checked_cast, dchecked_cast, and saturated_cast as constexpr

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to allow use them in other constexpr functions.
c++14 extends what can be in constexpr function making this change possible.

Bug: None
Change-Id: I6ae55b0b9b936021b57aa83ea5dd77d73be511a3
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/159026
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29743}
This commit is contained in:
Danil Chapovalov 2019-11-07 13:40:43 +01:00 committed by Commit Bot
parent fd80438111
commit 2bc811ea07
2 changed files with 19 additions and 17 deletions
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8
rtc_base/numerics/safe_conversions.h
View file

@ -23,7 +23,7 @@ namespace rtc {
// Convenience function that returns true if the supplied value is in range // Convenience function that returns true if the supplied value is in range
// for the destination type. // for the destination type.
template <typename Dst, typename Src> template <typename Dst, typename Src>
inline bool IsValueInRangeForNumericType(Src value) { inline constexpr bool IsValueInRangeForNumericType(Src value) {
return internal::RangeCheck<Dst>(value) == internal::TYPE_VALID; return internal::RangeCheck<Dst>(value) == internal::TYPE_VALID;
} }
@ -32,12 +32,12 @@ inline bool IsValueInRangeForNumericType(Src value) {
// conversion will not overflow or underflow. NaN source will always trigger // conversion will not overflow or underflow. NaN source will always trigger
// the [D]CHECK. // the [D]CHECK.
template <typename Dst, typename Src> template <typename Dst, typename Src>
inline Dst checked_cast(Src value) { inline constexpr Dst checked_cast(Src value) {
RTC_CHECK(IsValueInRangeForNumericType<Dst>(value)); RTC_CHECK(IsValueInRangeForNumericType<Dst>(value));
return static_cast<Dst>(value); return static_cast<Dst>(value);
} }
template <typename Dst, typename Src> template <typename Dst, typename Src>
inline Dst dchecked_cast(Src value) { inline constexpr Dst dchecked_cast(Src value) {
RTC_DCHECK(IsValueInRangeForNumericType<Dst>(value)); RTC_DCHECK(IsValueInRangeForNumericType<Dst>(value));
return static_cast<Dst>(value); return static_cast<Dst>(value);
} }
@ -46,7 +46,7 @@ inline Dst dchecked_cast(Src value) {
// that the specified numeric conversion will saturate rather than overflow or // that the specified numeric conversion will saturate rather than overflow or
// underflow. NaN assignment to an integral will trigger a RTC_CHECK condition. // underflow. NaN assignment to an integral will trigger a RTC_CHECK condition.
template <typename Dst, typename Src> template <typename Dst, typename Src>
inline Dst saturated_cast(Src value) { inline constexpr Dst saturated_cast(Src value) {
// Optimization for floating point values, which already saturate. // Optimization for floating point values, which already saturate.
if (std::numeric_limits<Dst>::is_iec559) if (std::numeric_limits<Dst>::is_iec559)
return static_cast<Dst>(value); return static_cast<Dst>(value);

28
rtc_base/numerics/safe_conversions_impl.h
View file

@ -101,13 +101,13 @@ struct RangeCheckImpl {};
// Dst range always contains the result: nothing to check. // Dst range always contains the result: nothing to check.
template <typename Dst, typename Src, DstSign IsDstSigned, SrcSign IsSrcSigned> template <typename Dst, typename Src, DstSign IsDstSigned, SrcSign IsSrcSigned>
struct RangeCheckImpl<Dst, Src, IsDstSigned, IsSrcSigned, CONTAINS_RANGE> { struct RangeCheckImpl<Dst, Src, IsDstSigned, IsSrcSigned, CONTAINS_RANGE> {
static RangeCheckResult Check(Src value) { return TYPE_VALID; } static constexpr RangeCheckResult Check(Src value) { return TYPE_VALID; }
}; };
// Signed to signed narrowing. // Signed to signed narrowing.
template <typename Dst, typename Src> template <typename Dst, typename Src>
struct RangeCheckImpl<Dst, Src, DST_SIGNED, SRC_SIGNED, OVERLAPS_RANGE> { struct RangeCheckImpl<Dst, Src, DST_SIGNED, SRC_SIGNED, OVERLAPS_RANGE> {
static RangeCheckResult Check(Src value) { static constexpr RangeCheckResult Check(Src value) {
typedef std::numeric_limits<Dst> DstLimits; typedef std::numeric_limits<Dst> DstLimits;
return DstLimits::is_iec559 return DstLimits::is_iec559
? BASE_NUMERIC_RANGE_CHECK_RESULT( ? BASE_NUMERIC_RANGE_CHECK_RESULT(
@ -122,7 +122,7 @@ struct RangeCheckImpl<Dst, Src, DST_SIGNED, SRC_SIGNED, OVERLAPS_RANGE> {
// Unsigned to unsigned narrowing. // Unsigned to unsigned narrowing.
template <typename Dst, typename Src> template <typename Dst, typename Src>
struct RangeCheckImpl<Dst, Src, DST_UNSIGNED, SRC_UNSIGNED, OVERLAPS_RANGE> { struct RangeCheckImpl<Dst, Src, DST_UNSIGNED, SRC_UNSIGNED, OVERLAPS_RANGE> {
static RangeCheckResult Check(Src value) { static constexpr RangeCheckResult Check(Src value) {
typedef std::numeric_limits<Dst> DstLimits; typedef std::numeric_limits<Dst> DstLimits;
return BASE_NUMERIC_RANGE_CHECK_RESULT( return BASE_NUMERIC_RANGE_CHECK_RESULT(
value <= static_cast<Src>(DstLimits::max()), true); value <= static_cast<Src>(DstLimits::max()), true);
@ -132,7 +132,7 @@ struct RangeCheckImpl<Dst, Src, DST_UNSIGNED, SRC_UNSIGNED, OVERLAPS_RANGE> {
// Unsigned to signed. // Unsigned to signed.
template <typename Dst, typename Src> template <typename Dst, typename Src>
struct RangeCheckImpl<Dst, Src, DST_SIGNED, SRC_UNSIGNED, OVERLAPS_RANGE> { struct RangeCheckImpl<Dst, Src, DST_SIGNED, SRC_UNSIGNED, OVERLAPS_RANGE> {
static RangeCheckResult Check(Src value) { static constexpr RangeCheckResult Check(Src value) {
typedef std::numeric_limits<Dst> DstLimits; typedef std::numeric_limits<Dst> DstLimits;
return sizeof(Dst) > sizeof(Src) return sizeof(Dst) > sizeof(Src)
? TYPE_VALID ? TYPE_VALID
@ -144,14 +144,16 @@ struct RangeCheckImpl<Dst, Src, DST_SIGNED, SRC_UNSIGNED, OVERLAPS_RANGE> {
// Signed to unsigned. // Signed to unsigned.
template <typename Dst, typename Src> template <typename Dst, typename Src>
struct RangeCheckImpl<Dst, Src, DST_UNSIGNED, SRC_SIGNED, OVERLAPS_RANGE> { struct RangeCheckImpl<Dst, Src, DST_UNSIGNED, SRC_SIGNED, OVERLAPS_RANGE> {
static RangeCheckResult Check(Src value) { typedef std::numeric_limits<Dst> DstLimits;
typedef std::numeric_limits<Dst> DstLimits; typedef std::numeric_limits<Src> SrcLimits;
typedef std::numeric_limits<Src> SrcLimits; // Compare based on max_exponent, which we must compute for integrals.
// Compare based on max_exponent, which we must compute for integrals. static constexpr size_t DstMaxExponent() { return sizeof(Dst) * 8; }
static const size_t kDstMaxExponent = sizeof(Dst) * 8; static constexpr size_t SrcMaxExponent() {
static const size_t kSrcMaxExponent = return SrcLimits::is_iec559 ? SrcLimits::max_exponent
SrcLimits::is_iec559 ? SrcLimits::max_exponent : (sizeof(Src) * 8 - 1); : (sizeof(Src) * 8 - 1);
return (kDstMaxExponent >= kSrcMaxExponent) }
static constexpr RangeCheckResult Check(Src value) {
return (DstMaxExponent() >= SrcMaxExponent())
? BASE_NUMERIC_RANGE_CHECK_RESULT(true, ? BASE_NUMERIC_RANGE_CHECK_RESULT(true,
value >= static_cast<Src>(0)) value >= static_cast<Src>(0))
: BASE_NUMERIC_RANGE_CHECK_RESULT( : BASE_NUMERIC_RANGE_CHECK_RESULT(
@ -161,7 +163,7 @@ struct RangeCheckImpl<Dst, Src, DST_UNSIGNED, SRC_SIGNED, OVERLAPS_RANGE> {
}; };
template <typename Dst, typename Src> template <typename Dst, typename Src>
inline RangeCheckResult RangeCheck(Src value) { inline constexpr RangeCheckResult RangeCheck(Src value) {
static_assert(std::numeric_limits<Src>::is_specialized, static_assert(std::numeric_limits<Src>::is_specialized,
"argument must be numeric"); "argument must be numeric");
static_assert(std::numeric_limits<Dst>::is_specialized, static_assert(std::numeric_limits<Dst>::is_specialized,