This reduces the implementation to our much narrower current use-cases, hardcoded directly where we need it. It also unifies google3 and OSS behavior, which may have deviated over time. PiperOrigin-RevId: 502696374pull/11128/head
Mike Kruskal
2 years ago
committed by
Copybara-Service
parent
5a8abe1c20
commit
021435611f
4 changed files with 39 additions and 175 deletions
@ -1,163 +0,0 @@ |
||||
// Protocol Buffers - Google's data interchange format
|
||||
// Copyright 2008 Google Inc. All rights reserved.
|
||||
// https://developers.google.com/protocol-buffers/
|
||||
//
|
||||
// Redistribution and use in source and binary forms, with or without
|
||||
// modification, are permitted provided that the following conditions are
|
||||
// met:
|
||||
//
|
||||
// * Redistributions of source code must retain the above copyright
|
||||
// notice, this list of conditions and the following disclaimer.
|
||||
// * Redistributions in binary form must reproduce the above
|
||||
// copyright notice, this list of conditions and the following disclaimer
|
||||
// in the documentation and/or other materials provided with the
|
||||
// distribution.
|
||||
// * Neither the name of Google Inc. nor the names of its
|
||||
// contributors may be used to endorse or promote products derived from
|
||||
// this software without specific prior written permission.
|
||||
//
|
||||
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||||
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||||
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
||||
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
||||
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
||||
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
||||
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||||
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
||||
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||||
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
||||
#ifndef GOOGLE_PROTOBUF_STUBS_MATHUTIL_H_ |
||||
#define GOOGLE_PROTOBUF_STUBS_MATHUTIL_H_ |
||||
|
||||
#include <float.h> |
||||
|
||||
#include <cmath> |
||||
#include <limits> |
||||
|
||||
#include "google/protobuf/stubs/common.h" |
||||
#include "google/protobuf/stubs/logging.h" |
||||
|
||||
namespace google { |
||||
namespace protobuf { |
||||
namespace internal { |
||||
|
||||
// Like std::make_unsigned_t except floating point types map to themselves.
|
||||
template <typename T> |
||||
using MakeUnsignedT = |
||||
typename std::conditional<std::is_integral<T>::value, std::make_unsigned<T>, |
||||
std::common_type<T>>::type::type; |
||||
|
||||
// Like std::isnan() except a template function that is defined for all numeric
|
||||
// types.
|
||||
template <typename T, |
||||
typename std::enable_if<std::is_integral<T>::value, int>::type = 0> |
||||
bool IsNan(T /*val*/) { |
||||
return false; |
||||
} |
||||
|
||||
template <typename T, typename std::enable_if<std::is_floating_point<T>::value, |
||||
int>::type = 0> |
||||
bool IsNan(T val) { |
||||
return std::isnan(val); |
||||
} |
||||
|
||||
template<typename T> |
||||
bool AlmostEquals(T a, T b) { |
||||
return a == b; |
||||
} |
||||
template<> |
||||
inline bool AlmostEquals(float a, float b) { |
||||
return fabs(a - b) < 32 * FLT_EPSILON; |
||||
} |
||||
|
||||
template<> |
||||
inline bool AlmostEquals(double a, double b) { |
||||
return fabs(a - b) < 32 * DBL_EPSILON; |
||||
} |
||||
|
||||
} // namespace internal
|
||||
|
||||
class MathUtil { |
||||
public: |
||||
template <typename T> |
||||
static T Sign(T value) { |
||||
if (value == T(0) || internal::IsNan(value)) { |
||||
return value; |
||||
} |
||||
return value > T(0) ? 1 : -1; |
||||
} |
||||
|
||||
template <typename T> |
||||
static bool AlmostEquals(T a, T b) { |
||||
return internal::AlmostEquals(a, b); |
||||
} |
||||
|
||||
// Largest of two values.
|
||||
// Works correctly for special floating point values.
|
||||
// Note: 0.0 and -0.0 are not differentiated by Max (Max(0.0, -0.0) is -0.0),
|
||||
// which should be OK because, although they (can) have different
|
||||
// bit representation, they are observably the same when examined
|
||||
// with arithmetic and (in)equality operators.
|
||||
template <typename T> |
||||
static T Max(const T x, const T y) { |
||||
return internal::IsNan(x) || x > y ? x : y; |
||||
} |
||||
|
||||
// Absolute value of x
|
||||
// Works correctly for unsigned types and
|
||||
// for special floating point values.
|
||||
// Note: 0.0 and -0.0 are not differentiated by Abs (Abs(0.0) is -0.0),
|
||||
// which should be OK: see the comment for Max above.
|
||||
template<typename T> |
||||
static T Abs(const T x) { |
||||
return x > T(0) ? x : -x; |
||||
} |
||||
|
||||
// Absolute value of the difference between two numbers.
|
||||
// Works correctly for signed types and special floating point values.
|
||||
template <typename T> |
||||
static typename internal::MakeUnsignedT<T> AbsDiff(const T x, const T y) { |
||||
// Carries out arithmetic as unsigned to avoid overflow.
|
||||
typedef typename internal::MakeUnsignedT<T> R; |
||||
return x > y ? R(x) - R(y) : R(y) - R(x); |
||||
} |
||||
|
||||
// If two (usually floating point) numbers are within a certain
|
||||
// fraction of their magnitude or within a certain absolute margin of error.
|
||||
// This is the same as the following but faster:
|
||||
// WithinFraction(x, y, fraction) || WithinMargin(x, y, margin)
|
||||
// E.g. WithinFraction(0.0, 1e-10, 1e-5) is false but
|
||||
// WithinFractionOrMargin(0.0, 1e-10, 1e-5, 1e-5) is true.
|
||||
template<typename T> |
||||
static bool WithinFractionOrMargin(const T x, const T y, |
||||
const T fraction, const T margin); |
||||
}; |
||||
|
||||
template<typename T> |
||||
bool MathUtil::WithinFractionOrMargin(const T x, const T y, |
||||
const T fraction, const T margin) { |
||||
// Not just "0 <= fraction" to fool the compiler for unsigned types.
|
||||
GOOGLE_DCHECK((T(0) < fraction || T(0) == fraction) && |
||||
fraction < T(1) && |
||||
margin >= T(0)); |
||||
|
||||
// Template specialization will convert the if() condition to a constant,
|
||||
// which will cause the compiler to generate code for either the "if" part
|
||||
// or the "then" part. In this way we avoid a compiler warning
|
||||
// about a potential integer overflow in crosstool v12 (gcc 4.3.1).
|
||||
if (std::numeric_limits<T>::is_integer) { |
||||
return x == y; |
||||
} else { |
||||
if (!std::isfinite(x) || !std::isfinite(y)) { |
||||
return false; |
||||
} |
||||
T relative_margin = static_cast<T>(fraction * Max(Abs(x), Abs(y))); |
||||
return AbsDiff(x, y) <= Max(margin, relative_margin); |
||||
} |
||||
} |
||||
|
||||
} // namespace protobuf
|
||||
} // namespace google
|
||||
|
||||
#endif // GOOGLE_PROTOBUF_STUBS_MATHUTIL_H_
|
||||
Loading…
Reference in new issue