math_extras.h | Explore in Territory

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#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_WTF_MATH_EXTRAS_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_WTF_MATH_EXTRAS_H_

#include <cmath>
#include <cstddef>
#include <limits>

#include "base/check_op.h"
#include "build/build_config.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"

#if defined(COMPILER_MSVC)
// Make math.h behave like other platforms.
#define _USE_MATH_DEFINES
// Even if math.h was already included, including math.h again with
// _USE_MATH_DEFINES adds the extra defines.
#include <math.h>
#include <stdint.h>
#endif

#if BUILDFLAG(IS_OPENBSD)
#include <machine/ieee.h>
#include <sys/types.h>
#endif

constexpr double kPiDouble = …;
constexpr float kPiFloat = …;

constexpr double kPiOverTwoDouble = …;
constexpr float kPiOverTwoFloat = …;

constexpr double kPiOverFourDouble = …;
constexpr float kPiOverFourFloat = …;

constexpr double kTwoPiDouble = …;
constexpr float kTwoPiFloat = …;

constexpr double Deg2rad(double d) { … }
constexpr double Rad2deg(double r) { … }
constexpr double Deg2grad(double d) { … }
constexpr double Grad2deg(double g) { … }
constexpr double Turn2deg(double t) { … }
constexpr double Deg2turn(double d) { … }
constexpr double Rad2grad(double r) { … }
constexpr double Grad2rad(double g) { … }
constexpr double Turn2grad(double t) { … }
constexpr double Grad2turn(double g) { … }
constexpr double Rad2turn(double r) { … }
constexpr double Turn2rad(double t) { … }

constexpr float Deg2rad(float d) { … }
constexpr float Rad2deg(float r) { … }
constexpr float Deg2grad(float d) { … }
constexpr float Grad2deg(float g) { … }
constexpr float Turn2deg(float t) { … }
constexpr float Deg2turn(float d) { … }
constexpr float Rad2grad(float r) { … }
constexpr float Grad2rad(float g) { … }
constexpr float Turn2grad(float t) { … }
constexpr float Grad2turn(float g) { … }

constexpr double RoundHalfTowardsPositiveInfinity(double value) { … }

constexpr float RoundHalfTowardsPositiveInfinity(float value) { … }

// ClampTo() is implemented by templated helper classes (to allow for partial
// template specialization) as well as several helper functions.

// This helper function can be called when we know that:
// (1) The type signednesses match so the compiler will not produce signed vs.
//     unsigned warnings
// (2) The default type promotions/conversions are sufficient to handle things
//     correctly
template <typename LimitType, typename ValueType>
inline constexpr LimitType ClampToDirectComparison(ValueType value,
                                                   LimitType min,
                                                   LimitType max) { … }

// For any floating-point limits, or integral limits smaller than int64_t, we
// can cast the limits to double without losing precision; then the only cases
// where |value| can't be represented accurately as a double are the ones where
// it's outside the limit range anyway.  So doing all comparisons as doubles
// will give correct results.
//
// In some cases, we can get better performance by using
// ClampToDirectComparison().  We use a templated class to switch between these
// two cases (instead of simply using a conditional within one function) in
// order to only compile the ClampToDirectComparison() code for cases where it
// will actually be used; this prevents the compiler from emitting warnings
// about unsafe code (even though we wouldn't actually be executing that code).
template <bool can_use_direct_comparison,
          typename LimitType,
          typename ValueType>
class ClampToNonLongLongHelper;

ClampToNonLongLongHelper<true, LimitType, ValueType>;

ClampToNonLongLongHelper<false, LimitType, ValueType>;

// The unspecialized version of this templated class handles clamping to
// anything other than [u]int64_t limits.  It simply uses the class above
// to toggle between the "fast" and "safe" clamp implementations.
template <typename LimitType, typename ValueType>
class ClampToHelper { … };

// Clamping to [u]int64_t limits requires more care.  These may not be
// accurately representable as doubles, so instead we cast |value| to the
// limit type. But that cast is undefined if |value| is floating point and
// outside the representable range of the limit type, so we also have to check
// for that case explicitly.
ClampToHelper<int64_t, ValueType>;

// This specialization handles the case where the above partial specialization
// would be potentially incorrect.
template <>
class ClampToHelper<int64_t, uint64_t> { … };

// This is similar to the partial specialization that clamps to int64_t, but
// because the lower-bound check is done for integer value types as well, we
// don't need a <uint64_t, int64_t> full specialization.
ClampToHelper<uint64_t, ValueType>;

template <typename T>
constexpr T DefaultMaximumForClamp() { … }
template <typename T>
constexpr T DefaultMinimumForClamp() { … }

// And, finally, the actual function for people to call.
template <typename LimitType, typename ValueType>
constexpr LimitType ClampTo(
    ValueType value,
    LimitType min = DefaultMinimumForClamp<LimitType>(),
    LimitType max = DefaultMaximumForClamp<LimitType>()) { … }

template <typename LimitType, typename ValueType>
constexpr LimitType ClampToWithNaNTo0(
    ValueType value,
    LimitType min = DefaultMinimumForClamp<LimitType>(),
    LimitType max = DefaultMaximumForClamp<LimitType>()) { … }

constexpr bool IsWithinIntRange(float x) { … }

static constexpr size_t GreatestCommonDivisor(size_t a, size_t b) { … }

constexpr size_t LowestCommonMultiple(size_t a, size_t b) { … }

#endif  // THIRD_PARTY_BLINK_RENDERER_PLATFORM_WTF_MATH_EXTRAS_H_
chromium/third_party/blink/renderer/platform/wtf/math_extras.h
