Update to current webrtc library
This is from the upstream library commit id 3326535126e435f1ba647885ce43a8f0f3d317eb, corresponding to Chromium 88.0.4290.1.
This commit is contained in:
176
webrtc/rtc_base/numerics/safe_compare.h
Normal file
176
webrtc/rtc_base/numerics/safe_compare.h
Normal file
@ -0,0 +1,176 @@
|
||||
/*
|
||||
* Copyright 2016 The WebRTC Project Authors. All rights reserved.
|
||||
*
|
||||
* Use of this source code is governed by a BSD-style license
|
||||
* that can be found in the LICENSE file in the root of the source
|
||||
* tree. An additional intellectual property rights grant can be found
|
||||
* in the file PATENTS. All contributing project authors may
|
||||
* be found in the AUTHORS file in the root of the source tree.
|
||||
*/
|
||||
|
||||
// This file defines six constexpr functions:
|
||||
//
|
||||
// rtc::SafeEq // ==
|
||||
// rtc::SafeNe // !=
|
||||
// rtc::SafeLt // <
|
||||
// rtc::SafeLe // <=
|
||||
// rtc::SafeGt // >
|
||||
// rtc::SafeGe // >=
|
||||
//
|
||||
// They each accept two arguments of arbitrary types, and in almost all cases,
|
||||
// they simply call the appropriate comparison operator. However, if both
|
||||
// arguments are integers, they don't compare them using C++'s quirky rules,
|
||||
// but instead adhere to the true mathematical definitions. It is as if the
|
||||
// arguments were first converted to infinite-range signed integers, and then
|
||||
// compared, although of course nothing expensive like that actually takes
|
||||
// place. In practice, for signed/signed and unsigned/unsigned comparisons and
|
||||
// some mixed-signed comparisons with a compile-time constant, the overhead is
|
||||
// zero; in the remaining cases, it is just a few machine instructions (no
|
||||
// branches).
|
||||
|
||||
#ifndef RTC_BASE_NUMERICS_SAFE_COMPARE_H_
|
||||
#define RTC_BASE_NUMERICS_SAFE_COMPARE_H_
|
||||
|
||||
#include <stddef.h>
|
||||
#include <stdint.h>
|
||||
|
||||
#include <type_traits>
|
||||
#include <utility>
|
||||
|
||||
#include "rtc_base/type_traits.h"
|
||||
|
||||
namespace rtc {
|
||||
|
||||
namespace safe_cmp_impl {
|
||||
|
||||
template <size_t N>
|
||||
struct LargerIntImpl : std::false_type {};
|
||||
template <>
|
||||
struct LargerIntImpl<sizeof(int8_t)> : std::true_type {
|
||||
using type = int16_t;
|
||||
};
|
||||
template <>
|
||||
struct LargerIntImpl<sizeof(int16_t)> : std::true_type {
|
||||
using type = int32_t;
|
||||
};
|
||||
template <>
|
||||
struct LargerIntImpl<sizeof(int32_t)> : std::true_type {
|
||||
using type = int64_t;
|
||||
};
|
||||
|
||||
// LargerInt<T1, T2>::value is true iff there's a signed type that's larger
|
||||
// than T1 (and no larger than the larger of T2 and int*, for performance
|
||||
// reasons); and if there is such a type, LargerInt<T1, T2>::type is an alias
|
||||
// for it.
|
||||
template <typename T1, typename T2>
|
||||
struct LargerInt
|
||||
: LargerIntImpl<sizeof(T1) < sizeof(T2) || sizeof(T1) < sizeof(int*)
|
||||
? sizeof(T1)
|
||||
: 0> {};
|
||||
|
||||
template <typename T>
|
||||
constexpr typename std::make_unsigned<T>::type MakeUnsigned(T a) {
|
||||
return static_cast<typename std::make_unsigned<T>::type>(a);
|
||||
}
|
||||
|
||||
// Overload for when both T1 and T2 have the same signedness.
|
||||
template <typename Op,
|
||||
typename T1,
|
||||
typename T2,
|
||||
typename std::enable_if<std::is_signed<T1>::value ==
|
||||
std::is_signed<T2>::value>::type* = nullptr>
|
||||
constexpr bool Cmp(T1 a, T2 b) {
|
||||
return Op::Op(a, b);
|
||||
}
|
||||
|
||||
// Overload for signed - unsigned comparison that can be promoted to a bigger
|
||||
// signed type.
|
||||
template <typename Op,
|
||||
typename T1,
|
||||
typename T2,
|
||||
typename std::enable_if<std::is_signed<T1>::value &&
|
||||
std::is_unsigned<T2>::value &&
|
||||
LargerInt<T2, T1>::value>::type* = nullptr>
|
||||
constexpr bool Cmp(T1 a, T2 b) {
|
||||
return Op::Op(a, static_cast<typename LargerInt<T2, T1>::type>(b));
|
||||
}
|
||||
|
||||
// Overload for unsigned - signed comparison that can be promoted to a bigger
|
||||
// signed type.
|
||||
template <typename Op,
|
||||
typename T1,
|
||||
typename T2,
|
||||
typename std::enable_if<std::is_unsigned<T1>::value &&
|
||||
std::is_signed<T2>::value &&
|
||||
LargerInt<T1, T2>::value>::type* = nullptr>
|
||||
constexpr bool Cmp(T1 a, T2 b) {
|
||||
return Op::Op(static_cast<typename LargerInt<T1, T2>::type>(a), b);
|
||||
}
|
||||
|
||||
// Overload for signed - unsigned comparison that can't be promoted to a bigger
|
||||
// signed type.
|
||||
template <typename Op,
|
||||
typename T1,
|
||||
typename T2,
|
||||
typename std::enable_if<std::is_signed<T1>::value &&
|
||||
std::is_unsigned<T2>::value &&
|
||||
!LargerInt<T2, T1>::value>::type* = nullptr>
|
||||
constexpr bool Cmp(T1 a, T2 b) {
|
||||
return a < 0 ? Op::Op(-1, 0) : Op::Op(safe_cmp_impl::MakeUnsigned(a), b);
|
||||
}
|
||||
|
||||
// Overload for unsigned - signed comparison that can't be promoted to a bigger
|
||||
// signed type.
|
||||
template <typename Op,
|
||||
typename T1,
|
||||
typename T2,
|
||||
typename std::enable_if<std::is_unsigned<T1>::value &&
|
||||
std::is_signed<T2>::value &&
|
||||
!LargerInt<T1, T2>::value>::type* = nullptr>
|
||||
constexpr bool Cmp(T1 a, T2 b) {
|
||||
return b < 0 ? Op::Op(0, -1) : Op::Op(a, safe_cmp_impl::MakeUnsigned(b));
|
||||
}
|
||||
|
||||
#define RTC_SAFECMP_MAKE_OP(name, op) \
|
||||
struct name { \
|
||||
template <typename T1, typename T2> \
|
||||
static constexpr bool Op(T1 a, T2 b) { \
|
||||
return a op b; \
|
||||
} \
|
||||
};
|
||||
RTC_SAFECMP_MAKE_OP(EqOp, ==)
|
||||
RTC_SAFECMP_MAKE_OP(NeOp, !=)
|
||||
RTC_SAFECMP_MAKE_OP(LtOp, <)
|
||||
RTC_SAFECMP_MAKE_OP(LeOp, <=)
|
||||
RTC_SAFECMP_MAKE_OP(GtOp, >)
|
||||
RTC_SAFECMP_MAKE_OP(GeOp, >=)
|
||||
#undef RTC_SAFECMP_MAKE_OP
|
||||
|
||||
} // namespace safe_cmp_impl
|
||||
|
||||
#define RTC_SAFECMP_MAKE_FUN(name) \
|
||||
template <typename T1, typename T2> \
|
||||
constexpr \
|
||||
typename std::enable_if<IsIntlike<T1>::value && IsIntlike<T2>::value, \
|
||||
bool>::type Safe##name(T1 a, T2 b) { \
|
||||
/* Unary plus here turns enums into real integral types. */ \
|
||||
return safe_cmp_impl::Cmp<safe_cmp_impl::name##Op>(+a, +b); \
|
||||
} \
|
||||
template <typename T1, typename T2> \
|
||||
constexpr \
|
||||
typename std::enable_if<!IsIntlike<T1>::value || !IsIntlike<T2>::value, \
|
||||
bool>::type Safe##name(const T1& a, \
|
||||
const T2& b) { \
|
||||
return safe_cmp_impl::name##Op::Op(a, b); \
|
||||
}
|
||||
RTC_SAFECMP_MAKE_FUN(Eq)
|
||||
RTC_SAFECMP_MAKE_FUN(Ne)
|
||||
RTC_SAFECMP_MAKE_FUN(Lt)
|
||||
RTC_SAFECMP_MAKE_FUN(Le)
|
||||
RTC_SAFECMP_MAKE_FUN(Gt)
|
||||
RTC_SAFECMP_MAKE_FUN(Ge)
|
||||
#undef RTC_SAFECMP_MAKE_FUN
|
||||
|
||||
} // namespace rtc
|
||||
|
||||
#endif // RTC_BASE_NUMERICS_SAFE_COMPARE_H_
|
76
webrtc/rtc_base/numerics/safe_conversions.h
Normal file
76
webrtc/rtc_base/numerics/safe_conversions.h
Normal file
@ -0,0 +1,76 @@
|
||||
/*
|
||||
* Copyright 2014 The WebRTC Project Authors. All rights reserved.
|
||||
*
|
||||
* Use of this source code is governed by a BSD-style license
|
||||
* that can be found in the LICENSE file in the root of the source
|
||||
* tree. An additional intellectual property rights grant can be found
|
||||
* in the file PATENTS. All contributing project authors may
|
||||
* be found in the AUTHORS file in the root of the source tree.
|
||||
*/
|
||||
|
||||
// Borrowed from Chromium's src/base/numerics/safe_conversions.h.
|
||||
|
||||
#ifndef RTC_BASE_NUMERICS_SAFE_CONVERSIONS_H_
|
||||
#define RTC_BASE_NUMERICS_SAFE_CONVERSIONS_H_
|
||||
|
||||
#include <limits>
|
||||
|
||||
#include "rtc_base/checks.h"
|
||||
#include "rtc_base/numerics/safe_conversions_impl.h"
|
||||
|
||||
namespace rtc {
|
||||
|
||||
// Convenience function that returns true if the supplied value is in range
|
||||
// for the destination type.
|
||||
template <typename Dst, typename Src>
|
||||
inline constexpr bool IsValueInRangeForNumericType(Src value) {
|
||||
return internal::RangeCheck<Dst>(value) == internal::TYPE_VALID;
|
||||
}
|
||||
|
||||
// checked_cast<> and dchecked_cast<> are analogous to static_cast<> for
|
||||
// numeric types, except that they [D]CHECK that the specified numeric
|
||||
// conversion will not overflow or underflow. NaN source will always trigger
|
||||
// the [D]CHECK.
|
||||
template <typename Dst, typename Src>
|
||||
inline constexpr Dst checked_cast(Src value) {
|
||||
RTC_CHECK(IsValueInRangeForNumericType<Dst>(value));
|
||||
return static_cast<Dst>(value);
|
||||
}
|
||||
template <typename Dst, typename Src>
|
||||
inline constexpr Dst dchecked_cast(Src value) {
|
||||
RTC_DCHECK(IsValueInRangeForNumericType<Dst>(value));
|
||||
return static_cast<Dst>(value);
|
||||
}
|
||||
|
||||
// saturated_cast<> is analogous to static_cast<> for numeric types, except
|
||||
// that the specified numeric conversion will saturate rather than overflow or
|
||||
// underflow. NaN assignment to an integral will trigger a RTC_CHECK condition.
|
||||
template <typename Dst, typename Src>
|
||||
inline constexpr Dst saturated_cast(Src value) {
|
||||
// Optimization for floating point values, which already saturate.
|
||||
if (std::numeric_limits<Dst>::is_iec559)
|
||||
return static_cast<Dst>(value);
|
||||
|
||||
switch (internal::RangeCheck<Dst>(value)) {
|
||||
case internal::TYPE_VALID:
|
||||
return static_cast<Dst>(value);
|
||||
|
||||
case internal::TYPE_UNDERFLOW:
|
||||
return std::numeric_limits<Dst>::min();
|
||||
|
||||
case internal::TYPE_OVERFLOW:
|
||||
return std::numeric_limits<Dst>::max();
|
||||
|
||||
// Should fail only on attempting to assign NaN to a saturated integer.
|
||||
case internal::TYPE_INVALID:
|
||||
FATAL();
|
||||
return std::numeric_limits<Dst>::max();
|
||||
}
|
||||
|
||||
FATAL();
|
||||
return static_cast<Dst>(value);
|
||||
}
|
||||
|
||||
} // namespace rtc
|
||||
|
||||
#endif // RTC_BASE_NUMERICS_SAFE_CONVERSIONS_H_
|
177
webrtc/rtc_base/numerics/safe_conversions_impl.h
Normal file
177
webrtc/rtc_base/numerics/safe_conversions_impl.h
Normal file
@ -0,0 +1,177 @@
|
||||
/*
|
||||
* Copyright 2014 The WebRTC Project Authors. All rights reserved.
|
||||
*
|
||||
* Use of this source code is governed by a BSD-style license
|
||||
* that can be found in the LICENSE file in the root of the source
|
||||
* tree. An additional intellectual property rights grant can be found
|
||||
* in the file PATENTS. All contributing project authors may
|
||||
* be found in the AUTHORS file in the root of the source tree.
|
||||
*/
|
||||
|
||||
// Borrowed from Chromium's src/base/numerics/safe_conversions_impl.h.
|
||||
|
||||
#ifndef RTC_BASE_NUMERICS_SAFE_CONVERSIONS_IMPL_H_
|
||||
#define RTC_BASE_NUMERICS_SAFE_CONVERSIONS_IMPL_H_
|
||||
|
||||
#include <limits>
|
||||
|
||||
namespace rtc {
|
||||
namespace internal {
|
||||
|
||||
enum DstSign { DST_UNSIGNED, DST_SIGNED };
|
||||
|
||||
enum SrcSign { SRC_UNSIGNED, SRC_SIGNED };
|
||||
|
||||
enum DstRange { OVERLAPS_RANGE, CONTAINS_RANGE };
|
||||
|
||||
// Helper templates to statically determine if our destination type can contain
|
||||
// all values represented by the source type.
|
||||
|
||||
template <typename Dst,
|
||||
typename Src,
|
||||
DstSign IsDstSigned =
|
||||
std::numeric_limits<Dst>::is_signed ? DST_SIGNED : DST_UNSIGNED,
|
||||
SrcSign IsSrcSigned =
|
||||
std::numeric_limits<Src>::is_signed ? SRC_SIGNED : SRC_UNSIGNED>
|
||||
struct StaticRangeCheck {};
|
||||
|
||||
template <typename Dst, typename Src>
|
||||
struct StaticRangeCheck<Dst, Src, DST_SIGNED, SRC_SIGNED> {
|
||||
typedef std::numeric_limits<Dst> DstLimits;
|
||||
typedef std::numeric_limits<Src> SrcLimits;
|
||||
// Compare based on max_exponent, which we must compute for integrals.
|
||||
static const size_t kDstMaxExponent =
|
||||
DstLimits::is_iec559 ? DstLimits::max_exponent : (sizeof(Dst) * 8 - 1);
|
||||
static const size_t kSrcMaxExponent =
|
||||
SrcLimits::is_iec559 ? SrcLimits::max_exponent : (sizeof(Src) * 8 - 1);
|
||||
static const DstRange value =
|
||||
kDstMaxExponent >= kSrcMaxExponent ? CONTAINS_RANGE : OVERLAPS_RANGE;
|
||||
};
|
||||
|
||||
template <typename Dst, typename Src>
|
||||
struct StaticRangeCheck<Dst, Src, DST_UNSIGNED, SRC_UNSIGNED> {
|
||||
static const DstRange value =
|
||||
sizeof(Dst) >= sizeof(Src) ? CONTAINS_RANGE : OVERLAPS_RANGE;
|
||||
};
|
||||
|
||||
template <typename Dst, typename Src>
|
||||
struct StaticRangeCheck<Dst, Src, DST_SIGNED, SRC_UNSIGNED> {
|
||||
typedef std::numeric_limits<Dst> DstLimits;
|
||||
typedef std::numeric_limits<Src> SrcLimits;
|
||||
// Compare based on max_exponent, which we must compute for integrals.
|
||||
static const size_t kDstMaxExponent =
|
||||
DstLimits::is_iec559 ? DstLimits::max_exponent : (sizeof(Dst) * 8 - 1);
|
||||
static const size_t kSrcMaxExponent = sizeof(Src) * 8;
|
||||
static const DstRange value =
|
||||
kDstMaxExponent >= kSrcMaxExponent ? CONTAINS_RANGE : OVERLAPS_RANGE;
|
||||
};
|
||||
|
||||
template <typename Dst, typename Src>
|
||||
struct StaticRangeCheck<Dst, Src, DST_UNSIGNED, SRC_SIGNED> {
|
||||
static const DstRange value = OVERLAPS_RANGE;
|
||||
};
|
||||
|
||||
enum RangeCheckResult {
|
||||
TYPE_VALID = 0, // Value can be represented by the destination type.
|
||||
TYPE_UNDERFLOW = 1, // Value would overflow.
|
||||
TYPE_OVERFLOW = 2, // Value would underflow.
|
||||
TYPE_INVALID = 3 // Source value is invalid (i.e. NaN).
|
||||
};
|
||||
|
||||
// This macro creates a RangeCheckResult from an upper and lower bound
|
||||
// check by taking advantage of the fact that only NaN can be out of range in
|
||||
// both directions at once.
|
||||
#define BASE_NUMERIC_RANGE_CHECK_RESULT(is_in_upper_bound, is_in_lower_bound) \
|
||||
RangeCheckResult(((is_in_upper_bound) ? 0 : TYPE_OVERFLOW) | \
|
||||
((is_in_lower_bound) ? 0 : TYPE_UNDERFLOW))
|
||||
|
||||
template <typename Dst,
|
||||
typename Src,
|
||||
DstSign IsDstSigned =
|
||||
std::numeric_limits<Dst>::is_signed ? DST_SIGNED : DST_UNSIGNED,
|
||||
SrcSign IsSrcSigned =
|
||||
std::numeric_limits<Src>::is_signed ? SRC_SIGNED : SRC_UNSIGNED,
|
||||
DstRange IsSrcRangeContained = StaticRangeCheck<Dst, Src>::value>
|
||||
struct RangeCheckImpl {};
|
||||
|
||||
// The following templates are for ranges that must be verified at runtime. We
|
||||
// split it into checks based on signedness to avoid confusing casts and
|
||||
// compiler warnings on signed an unsigned comparisons.
|
||||
|
||||
// Dst range always contains the result: nothing to check.
|
||||
template <typename Dst, typename Src, DstSign IsDstSigned, SrcSign IsSrcSigned>
|
||||
struct RangeCheckImpl<Dst, Src, IsDstSigned, IsSrcSigned, CONTAINS_RANGE> {
|
||||
static constexpr RangeCheckResult Check(Src value) { return TYPE_VALID; }
|
||||
};
|
||||
|
||||
// Signed to signed narrowing.
|
||||
template <typename Dst, typename Src>
|
||||
struct RangeCheckImpl<Dst, Src, DST_SIGNED, SRC_SIGNED, OVERLAPS_RANGE> {
|
||||
static constexpr RangeCheckResult Check(Src value) {
|
||||
typedef std::numeric_limits<Dst> DstLimits;
|
||||
return DstLimits::is_iec559
|
||||
? BASE_NUMERIC_RANGE_CHECK_RESULT(
|
||||
value <= static_cast<Src>(DstLimits::max()),
|
||||
value >= static_cast<Src>(DstLimits::max() * -1))
|
||||
: BASE_NUMERIC_RANGE_CHECK_RESULT(
|
||||
value <= static_cast<Src>(DstLimits::max()),
|
||||
value >= static_cast<Src>(DstLimits::min()));
|
||||
}
|
||||
};
|
||||
|
||||
// Unsigned to unsigned narrowing.
|
||||
template <typename Dst, typename Src>
|
||||
struct RangeCheckImpl<Dst, Src, DST_UNSIGNED, SRC_UNSIGNED, OVERLAPS_RANGE> {
|
||||
static constexpr RangeCheckResult Check(Src value) {
|
||||
typedef std::numeric_limits<Dst> DstLimits;
|
||||
return BASE_NUMERIC_RANGE_CHECK_RESULT(
|
||||
value <= static_cast<Src>(DstLimits::max()), true);
|
||||
}
|
||||
};
|
||||
|
||||
// Unsigned to signed.
|
||||
template <typename Dst, typename Src>
|
||||
struct RangeCheckImpl<Dst, Src, DST_SIGNED, SRC_UNSIGNED, OVERLAPS_RANGE> {
|
||||
static constexpr RangeCheckResult Check(Src value) {
|
||||
typedef std::numeric_limits<Dst> DstLimits;
|
||||
return sizeof(Dst) > sizeof(Src)
|
||||
? TYPE_VALID
|
||||
: BASE_NUMERIC_RANGE_CHECK_RESULT(
|
||||
value <= static_cast<Src>(DstLimits::max()), true);
|
||||
}
|
||||
};
|
||||
|
||||
// Signed to unsigned.
|
||||
template <typename Dst, typename Src>
|
||||
struct RangeCheckImpl<Dst, Src, DST_UNSIGNED, SRC_SIGNED, OVERLAPS_RANGE> {
|
||||
typedef std::numeric_limits<Dst> DstLimits;
|
||||
typedef std::numeric_limits<Src> SrcLimits;
|
||||
// Compare based on max_exponent, which we must compute for integrals.
|
||||
static constexpr size_t DstMaxExponent() { return sizeof(Dst) * 8; }
|
||||
static constexpr size_t SrcMaxExponent() {
|
||||
return SrcLimits::is_iec559 ? SrcLimits::max_exponent
|
||||
: (sizeof(Src) * 8 - 1);
|
||||
}
|
||||
static constexpr RangeCheckResult Check(Src value) {
|
||||
return (DstMaxExponent() >= SrcMaxExponent())
|
||||
? BASE_NUMERIC_RANGE_CHECK_RESULT(true,
|
||||
value >= static_cast<Src>(0))
|
||||
: BASE_NUMERIC_RANGE_CHECK_RESULT(
|
||||
value <= static_cast<Src>(DstLimits::max()),
|
||||
value >= static_cast<Src>(0));
|
||||
}
|
||||
};
|
||||
|
||||
template <typename Dst, typename Src>
|
||||
inline constexpr RangeCheckResult RangeCheck(Src value) {
|
||||
static_assert(std::numeric_limits<Src>::is_specialized,
|
||||
"argument must be numeric");
|
||||
static_assert(std::numeric_limits<Dst>::is_specialized,
|
||||
"result must be numeric");
|
||||
return RangeCheckImpl<Dst, Src>::Check(value);
|
||||
}
|
||||
|
||||
} // namespace internal
|
||||
} // namespace rtc
|
||||
|
||||
#endif // RTC_BASE_NUMERICS_SAFE_CONVERSIONS_IMPL_H_
|
335
webrtc/rtc_base/numerics/safe_minmax.h
Normal file
335
webrtc/rtc_base/numerics/safe_minmax.h
Normal file
@ -0,0 +1,335 @@
|
||||
/*
|
||||
* Copyright 2017 The WebRTC Project Authors. All rights reserved.
|
||||
*
|
||||
* Use of this source code is governed by a BSD-style license
|
||||
* that can be found in the LICENSE file in the root of the source
|
||||
* tree. An additional intellectual property rights grant can be found
|
||||
* in the file PATENTS. All contributing project authors may
|
||||
* be found in the AUTHORS file in the root of the source tree.
|
||||
*/
|
||||
|
||||
// Minimum and maximum
|
||||
// ===================
|
||||
//
|
||||
// rtc::SafeMin(x, y)
|
||||
// rtc::SafeMax(x, y)
|
||||
//
|
||||
// (These are both constexpr.)
|
||||
//
|
||||
// Accept two arguments of either any two integral or any two floating-point
|
||||
// types, and return the smaller and larger value, respectively, with no
|
||||
// truncation or wrap-around. If only one of the input types is statically
|
||||
// guaranteed to be able to represent the result, the return type is that type;
|
||||
// if either one would do, the result type is the smaller type. (One of these
|
||||
// two cases always applies.)
|
||||
//
|
||||
// * The case with one floating-point and one integral type is not allowed,
|
||||
// because the floating-point type will have greater range, but may not
|
||||
// have sufficient precision to represent the integer value exactly.)
|
||||
//
|
||||
// Clamp (a.k.a. constrain to a given interval)
|
||||
// ============================================
|
||||
//
|
||||
// rtc::SafeClamp(x, a, b)
|
||||
//
|
||||
// Accepts three arguments of any mix of integral types or any mix of
|
||||
// floating-point types, and returns the value in the closed interval [a, b]
|
||||
// that is closest to x (that is, if x < a it returns a; if x > b it returns b;
|
||||
// and if a <= x <= b it returns x). As for SafeMin() and SafeMax(), there is
|
||||
// no truncation or wrap-around. The result type
|
||||
//
|
||||
// 1. is statically guaranteed to be able to represent the result;
|
||||
//
|
||||
// 2. is no larger than the largest of the three argument types; and
|
||||
//
|
||||
// 3. has the same signedness as the type of the first argument, if this is
|
||||
// possible without violating the First or Second Law.
|
||||
//
|
||||
// There is always at least one type that meets criteria 1 and 2. If more than
|
||||
// one type meets these criteria equally well, the result type is one of the
|
||||
// types that is smallest. Note that unlike SafeMin() and SafeMax(),
|
||||
// SafeClamp() will sometimes pick a return type that isn't the type of any of
|
||||
// its arguments.
|
||||
//
|
||||
// * In this context, a type A is smaller than a type B if it has a smaller
|
||||
// range; that is, if A::max() - A::min() < B::max() - B::min(). For
|
||||
// example, int8_t < int16_t == uint16_t < int32_t, and all integral types
|
||||
// are smaller than all floating-point types.)
|
||||
//
|
||||
// * As for SafeMin and SafeMax, mixing integer and floating-point arguments
|
||||
// is not allowed, because floating-point types have greater range than
|
||||
// integer types, but do not have sufficient precision to represent the
|
||||
// values of most integer types exactly.
|
||||
//
|
||||
// Requesting a specific return type
|
||||
// =================================
|
||||
//
|
||||
// All three functions allow callers to explicitly specify the return type as a
|
||||
// template parameter, overriding the default return type. E.g.
|
||||
//
|
||||
// rtc::SafeMin<int>(x, y) // returns an int
|
||||
//
|
||||
// If the requested type is statically guaranteed to be able to represent the
|
||||
// result, then everything's fine, and the return type is as requested. But if
|
||||
// the requested type is too small, a static_assert is triggered.
|
||||
|
||||
#ifndef RTC_BASE_NUMERICS_SAFE_MINMAX_H_
|
||||
#define RTC_BASE_NUMERICS_SAFE_MINMAX_H_
|
||||
|
||||
#include <limits>
|
||||
#include <type_traits>
|
||||
|
||||
#include "rtc_base/checks.h"
|
||||
#include "rtc_base/numerics/safe_compare.h"
|
||||
#include "rtc_base/type_traits.h"
|
||||
|
||||
namespace rtc {
|
||||
|
||||
namespace safe_minmax_impl {
|
||||
|
||||
// Make the range of a type available via something other than a constexpr
|
||||
// function, to work around MSVC limitations. See
|
||||
// https://blogs.msdn.microsoft.com/vcblog/2015/12/02/partial-support-for-expression-sfinae-in-vs-2015-update-1/
|
||||
template <typename T>
|
||||
struct Limits {
|
||||
static constexpr T lowest = std::numeric_limits<T>::lowest();
|
||||
static constexpr T max = std::numeric_limits<T>::max();
|
||||
};
|
||||
|
||||
template <typename T, bool is_enum = std::is_enum<T>::value>
|
||||
struct UnderlyingType;
|
||||
|
||||
template <typename T>
|
||||
struct UnderlyingType<T, false> {
|
||||
using type = T;
|
||||
};
|
||||
|
||||
template <typename T>
|
||||
struct UnderlyingType<T, true> {
|
||||
using type = typename std::underlying_type<T>::type;
|
||||
};
|
||||
|
||||
// Given two types T1 and T2, find types that can hold the smallest (in
|
||||
// ::min_t) and the largest (in ::max_t) of the two values.
|
||||
template <typename T1,
|
||||
typename T2,
|
||||
bool int1 = IsIntlike<T1>::value,
|
||||
bool int2 = IsIntlike<T2>::value>
|
||||
struct MType {
|
||||
static_assert(int1 == int2,
|
||||
"You may not mix integral and floating-point arguments");
|
||||
};
|
||||
|
||||
// Specialization for when neither type is integral (and therefore presumably
|
||||
// floating-point).
|
||||
template <typename T1, typename T2>
|
||||
struct MType<T1, T2, false, false> {
|
||||
using min_t = typename std::common_type<T1, T2>::type;
|
||||
static_assert(std::is_same<min_t, T1>::value ||
|
||||
std::is_same<min_t, T2>::value,
|
||||
"");
|
||||
|
||||
using max_t = typename std::common_type<T1, T2>::type;
|
||||
static_assert(std::is_same<max_t, T1>::value ||
|
||||
std::is_same<max_t, T2>::value,
|
||||
"");
|
||||
};
|
||||
|
||||
// Specialization for when both types are integral.
|
||||
template <typename T1, typename T2>
|
||||
struct MType<T1, T2, true, true> {
|
||||
// The type with the lowest minimum value. In case of a tie, the type with
|
||||
// the lowest maximum value. In case that too is a tie, the types have the
|
||||
// same range, and we arbitrarily pick T1.
|
||||
using min_t = typename std::conditional<
|
||||
SafeLt(Limits<T1>::lowest, Limits<T2>::lowest),
|
||||
T1,
|
||||
typename std::conditional<
|
||||
SafeGt(Limits<T1>::lowest, Limits<T2>::lowest),
|
||||
T2,
|
||||
typename std::conditional<SafeLe(Limits<T1>::max, Limits<T2>::max),
|
||||
T1,
|
||||
T2>::type>::type>::type;
|
||||
static_assert(std::is_same<min_t, T1>::value ||
|
||||
std::is_same<min_t, T2>::value,
|
||||
"");
|
||||
|
||||
// The type with the highest maximum value. In case of a tie, the types have
|
||||
// the same range (because in C++, integer types with the same maximum also
|
||||
// have the same minimum).
|
||||
static_assert(SafeNe(Limits<T1>::max, Limits<T2>::max) ||
|
||||
SafeEq(Limits<T1>::lowest, Limits<T2>::lowest),
|
||||
"integer types with the same max should have the same min");
|
||||
using max_t = typename std::
|
||||
conditional<SafeGe(Limits<T1>::max, Limits<T2>::max), T1, T2>::type;
|
||||
static_assert(std::is_same<max_t, T1>::value ||
|
||||
std::is_same<max_t, T2>::value,
|
||||
"");
|
||||
};
|
||||
|
||||
// A dummy type that we pass around at compile time but never actually use.
|
||||
// Declared but not defined.
|
||||
struct DefaultType;
|
||||
|
||||
// ::type is A, except we fall back to B if A is DefaultType. We static_assert
|
||||
// that the chosen type can hold all values that B can hold.
|
||||
template <typename A, typename B>
|
||||
struct TypeOr {
|
||||
using type = typename std::
|
||||
conditional<std::is_same<A, DefaultType>::value, B, A>::type;
|
||||
static_assert(SafeLe(Limits<type>::lowest, Limits<B>::lowest) &&
|
||||
SafeGe(Limits<type>::max, Limits<B>::max),
|
||||
"The specified type isn't large enough");
|
||||
static_assert(IsIntlike<type>::value == IsIntlike<B>::value &&
|
||||
std::is_floating_point<type>::value ==
|
||||
std::is_floating_point<type>::value,
|
||||
"float<->int conversions not allowed");
|
||||
};
|
||||
|
||||
} // namespace safe_minmax_impl
|
||||
|
||||
template <
|
||||
typename R = safe_minmax_impl::DefaultType,
|
||||
typename T1 = safe_minmax_impl::DefaultType,
|
||||
typename T2 = safe_minmax_impl::DefaultType,
|
||||
typename R2 = typename safe_minmax_impl::TypeOr<
|
||||
R,
|
||||
typename safe_minmax_impl::MType<
|
||||
typename safe_minmax_impl::UnderlyingType<T1>::type,
|
||||
typename safe_minmax_impl::UnderlyingType<T2>::type>::min_t>::type>
|
||||
constexpr R2 SafeMin(T1 a, T2 b) {
|
||||
static_assert(IsIntlike<T1>::value || std::is_floating_point<T1>::value,
|
||||
"The first argument must be integral or floating-point");
|
||||
static_assert(IsIntlike<T2>::value || std::is_floating_point<T2>::value,
|
||||
"The second argument must be integral or floating-point");
|
||||
return SafeLt(a, b) ? static_cast<R2>(a) : static_cast<R2>(b);
|
||||
}
|
||||
|
||||
template <
|
||||
typename R = safe_minmax_impl::DefaultType,
|
||||
typename T1 = safe_minmax_impl::DefaultType,
|
||||
typename T2 = safe_minmax_impl::DefaultType,
|
||||
typename R2 = typename safe_minmax_impl::TypeOr<
|
||||
R,
|
||||
typename safe_minmax_impl::MType<
|
||||
typename safe_minmax_impl::UnderlyingType<T1>::type,
|
||||
typename safe_minmax_impl::UnderlyingType<T2>::type>::max_t>::type>
|
||||
constexpr R2 SafeMax(T1 a, T2 b) {
|
||||
static_assert(IsIntlike<T1>::value || std::is_floating_point<T1>::value,
|
||||
"The first argument must be integral or floating-point");
|
||||
static_assert(IsIntlike<T2>::value || std::is_floating_point<T2>::value,
|
||||
"The second argument must be integral or floating-point");
|
||||
return SafeGt(a, b) ? static_cast<R2>(a) : static_cast<R2>(b);
|
||||
}
|
||||
|
||||
namespace safe_minmax_impl {
|
||||
|
||||
// Given three types T, L, and H, let ::type be a suitable return value for
|
||||
// SafeClamp(T, L, H). See the docs at the top of this file for details.
|
||||
template <typename T,
|
||||
typename L,
|
||||
typename H,
|
||||
bool int1 = IsIntlike<T>::value,
|
||||
bool int2 = IsIntlike<L>::value,
|
||||
bool int3 = IsIntlike<H>::value>
|
||||
struct ClampType {
|
||||
static_assert(int1 == int2 && int1 == int3,
|
||||
"You may not mix integral and floating-point arguments");
|
||||
};
|
||||
|
||||
// Specialization for when all three types are floating-point.
|
||||
template <typename T, typename L, typename H>
|
||||
struct ClampType<T, L, H, false, false, false> {
|
||||
using type = typename std::common_type<T, L, H>::type;
|
||||
};
|
||||
|
||||
// Specialization for when all three types are integral.
|
||||
template <typename T, typename L, typename H>
|
||||
struct ClampType<T, L, H, true, true, true> {
|
||||
private:
|
||||
// Range of the return value. The return type must be able to represent this
|
||||
// full range.
|
||||
static constexpr auto r_min =
|
||||
SafeMax(Limits<L>::lowest, SafeMin(Limits<H>::lowest, Limits<T>::lowest));
|
||||
static constexpr auto r_max =
|
||||
SafeMin(Limits<H>::max, SafeMax(Limits<L>::max, Limits<T>::max));
|
||||
|
||||
// Is the given type an acceptable return type? (That is, can it represent
|
||||
// all possible return values, and is it no larger than the largest of the
|
||||
// input types?)
|
||||
template <typename A>
|
||||
struct AcceptableType {
|
||||
private:
|
||||
static constexpr bool not_too_large = sizeof(A) <= sizeof(L) ||
|
||||
sizeof(A) <= sizeof(H) ||
|
||||
sizeof(A) <= sizeof(T);
|
||||
static constexpr bool range_contained =
|
||||
SafeLe(Limits<A>::lowest, r_min) && SafeLe(r_max, Limits<A>::max);
|
||||
|
||||
public:
|
||||
static constexpr bool value = not_too_large && range_contained;
|
||||
};
|
||||
|
||||
using best_signed_type = typename std::conditional<
|
||||
AcceptableType<int8_t>::value,
|
||||
int8_t,
|
||||
typename std::conditional<
|
||||
AcceptableType<int16_t>::value,
|
||||
int16_t,
|
||||
typename std::conditional<AcceptableType<int32_t>::value,
|
||||
int32_t,
|
||||
int64_t>::type>::type>::type;
|
||||
|
||||
using best_unsigned_type = typename std::conditional<
|
||||
AcceptableType<uint8_t>::value,
|
||||
uint8_t,
|
||||
typename std::conditional<
|
||||
AcceptableType<uint16_t>::value,
|
||||
uint16_t,
|
||||
typename std::conditional<AcceptableType<uint32_t>::value,
|
||||
uint32_t,
|
||||
uint64_t>::type>::type>::type;
|
||||
|
||||
public:
|
||||
// Pick the best type, preferring the same signedness as T but falling back
|
||||
// to the other one if necessary.
|
||||
using type = typename std::conditional<
|
||||
std::is_signed<T>::value,
|
||||
typename std::conditional<AcceptableType<best_signed_type>::value,
|
||||
best_signed_type,
|
||||
best_unsigned_type>::type,
|
||||
typename std::conditional<AcceptableType<best_unsigned_type>::value,
|
||||
best_unsigned_type,
|
||||
best_signed_type>::type>::type;
|
||||
static_assert(AcceptableType<type>::value, "");
|
||||
};
|
||||
|
||||
} // namespace safe_minmax_impl
|
||||
|
||||
template <
|
||||
typename R = safe_minmax_impl::DefaultType,
|
||||
typename T = safe_minmax_impl::DefaultType,
|
||||
typename L = safe_minmax_impl::DefaultType,
|
||||
typename H = safe_minmax_impl::DefaultType,
|
||||
typename R2 = typename safe_minmax_impl::TypeOr<
|
||||
R,
|
||||
typename safe_minmax_impl::ClampType<
|
||||
typename safe_minmax_impl::UnderlyingType<T>::type,
|
||||
typename safe_minmax_impl::UnderlyingType<L>::type,
|
||||
typename safe_minmax_impl::UnderlyingType<H>::type>::type>::type>
|
||||
R2 SafeClamp(T x, L min, H max) {
|
||||
static_assert(IsIntlike<H>::value || std::is_floating_point<H>::value,
|
||||
"The first argument must be integral or floating-point");
|
||||
static_assert(IsIntlike<T>::value || std::is_floating_point<T>::value,
|
||||
"The second argument must be integral or floating-point");
|
||||
static_assert(IsIntlike<L>::value || std::is_floating_point<L>::value,
|
||||
"The third argument must be integral or floating-point");
|
||||
RTC_DCHECK_LE(min, max);
|
||||
return SafeLe(x, min)
|
||||
? static_cast<R2>(min)
|
||||
: SafeGe(x, max) ? static_cast<R2>(max) : static_cast<R2>(x);
|
||||
}
|
||||
|
||||
} // namespace rtc
|
||||
|
||||
#endif // RTC_BASE_NUMERICS_SAFE_MINMAX_H_
|
Reference in New Issue
Block a user