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Diffstat (limited to 'src/google/protobuf/stubs/mathlimits.h')
-rw-r--r-- | src/google/protobuf/stubs/mathlimits.h | 279 |
1 files changed, 279 insertions, 0 deletions
diff --git a/src/google/protobuf/stubs/mathlimits.h b/src/google/protobuf/stubs/mathlimits.h new file mode 100644 index 00000000..d9846940 --- /dev/null +++ b/src/google/protobuf/stubs/mathlimits.h @@ -0,0 +1,279 @@ +// 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. + +// All Rights Reserved. +// +// Author: Maxim Lifantsev +// +// Useful integer and floating point limits and type traits. +// +// This partially replaces/duplictes numeric_limits<> from <limits>. +// We get a Google-style class that we have a greater control over +// and thus can add new features to it or fix whatever happens to be broken in +// numeric_limits for the compilers we use. +// + +#ifndef UTIL_MATH_MATHLIMITS_H__ +#define UTIL_MATH_MATHLIMITS_H__ + +// <math.h> lacks a lot of prototypes. However, this file needs <math.h> to +// access old-fashioned isinf et al. Even worse more: this file must not +// include <cmath> because that breaks the definition of isinf with gcc 4.9. +// +// TODO(mec): after C++11 everywhere, use <cmath> and std::isinf in this file. +#include <math.h> +#include <string.h> + +#include <cfloat> + +#include <google/protobuf/stubs/common.h> + +// ========================================================================= // + +// Useful integer and floating point limits and type traits. +// This is just for the documentation; +// real members are defined in our specializations below. +namespace google { +namespace protobuf { +template<typename T> struct MathLimits { + // Type name. + typedef T Type; + // Unsigned version of the Type with the same byte size. + // Same as Type for floating point and unsigned types. + typedef T UnsignedType; + // If the type supports negative values. + static const bool kIsSigned; + // If the type supports only integer values. + static const bool kIsInteger; + // Magnitude-wise smallest representable positive value. + static const Type kPosMin; + // Magnitude-wise largest representable positive value. + static const Type kPosMax; + // Smallest representable value. + static const Type kMin; + // Largest representable value. + static const Type kMax; + // Magnitude-wise smallest representable negative value. + // Present only if kIsSigned. + static const Type kNegMin; + // Magnitude-wise largest representable negative value. + // Present only if kIsSigned. + static const Type kNegMax; + // Smallest integer x such that 10^x is representable. + static const int kMin10Exp; + // Largest integer x such that 10^x is representable. + static const int kMax10Exp; + // Smallest positive value such that Type(1) + kEpsilon != Type(1) + static const Type kEpsilon; + // Typical rounding error that is enough to cover + // a few simple floating-point operations. + // Slightly larger than kEpsilon to account for a few rounding errors. + // Is zero if kIsInteger. + static const Type kStdError; + // Number of decimal digits of mantissa precision. + // Present only if !kIsInteger. + static const int kPrecisionDigits; + // Not a number, i.e. result of 0/0. + // Present only if !kIsInteger. + static const Type kNaN; + // Positive infinity, i.e. result of 1/0. + // Present only if !kIsInteger. + static const Type kPosInf; + // Negative infinity, i.e. result of -1/0. + // Present only if !kIsInteger. + static const Type kNegInf; + + // NOTE: Special floating point values behave + // in a special (but mathematically-logical) way + // in terms of (in)equalty comparison and mathematical operations + // -- see out unittest for examples. + + // Special floating point value testers. + // Present in integer types for convenience. + static bool IsFinite(const Type x); + static bool IsNaN(const Type x); + static bool IsInf(const Type x); + static bool IsPosInf(const Type x); + static bool IsNegInf(const Type x); +}; + +// ========================================================================= // + +// All #define-s below are simply to refactor the declarations of +// MathLimits template specializations. +// They are all #undef-ined below. + +// The hoop-jumping in *_INT_(MAX|MIN) below is so that the compiler does not +// get an overflow while computing the constants. + +#define SIGNED_INT_MAX(Type) \ + (((Type(1) << (sizeof(Type)*8 - 2)) - 1) + (Type(1) << (sizeof(Type)*8 - 2))) + +#define SIGNED_INT_MIN(Type) \ + (-(Type(1) << (sizeof(Type)*8 - 2)) - (Type(1) << (sizeof(Type)*8 - 2))) + +#define UNSIGNED_INT_MAX(Type) \ + (((Type(1) << (sizeof(Type)*8 - 1)) - 1) + (Type(1) << (sizeof(Type)*8 - 1))) + +// Compile-time selected log10-related constants for integer types. +#define SIGNED_MAX_10_EXP(Type) \ + (sizeof(Type) == 1 ? 2 : ( \ + sizeof(Type) == 2 ? 4 : ( \ + sizeof(Type) == 4 ? 9 : ( \ + sizeof(Type) == 8 ? 18 : -1)))) + +#define UNSIGNED_MAX_10_EXP(Type) \ + (sizeof(Type) == 1 ? 2 : ( \ + sizeof(Type) == 2 ? 4 : ( \ + sizeof(Type) == 4 ? 9 : ( \ + sizeof(Type) == 8 ? 19 : -1)))) + +#define DECL_INT_LIMIT_FUNCS \ + static bool IsFinite(const Type /*x*/) { return true; } \ + static bool IsNaN(const Type /*x*/) { return false; } \ + static bool IsInf(const Type /*x*/) { return false; } \ + static bool IsPosInf(const Type /*x*/) { return false; } \ + static bool IsNegInf(const Type /*x*/) { return false; } + +#define DECL_SIGNED_INT_LIMITS(IntType, UnsignedIntType) \ +template<> \ +struct LIBPROTOBUF_EXPORT MathLimits<IntType> { \ + typedef IntType Type; \ + typedef UnsignedIntType UnsignedType; \ + static const bool kIsSigned = true; \ + static const bool kIsInteger = true; \ + static const Type kPosMin = 1; \ + static const Type kPosMax = SIGNED_INT_MAX(Type); \ + static const Type kMin = SIGNED_INT_MIN(Type); \ + static const Type kMax = kPosMax; \ + static const Type kNegMin = -1; \ + static const Type kNegMax = kMin; \ + static const int kMin10Exp = 0; \ + static const int kMax10Exp = SIGNED_MAX_10_EXP(Type); \ + static const Type kEpsilon = 1; \ + static const Type kStdError = 0; \ + DECL_INT_LIMIT_FUNCS \ +}; + +#define DECL_UNSIGNED_INT_LIMITS(IntType) \ +template<> \ +struct LIBPROTOBUF_EXPORT MathLimits<IntType> { \ + typedef IntType Type; \ + typedef IntType UnsignedType; \ + static const bool kIsSigned = false; \ + static const bool kIsInteger = true; \ + static const Type kPosMin = 1; \ + static const Type kPosMax = UNSIGNED_INT_MAX(Type); \ + static const Type kMin = 0; \ + static const Type kMax = kPosMax; \ + static const int kMin10Exp = 0; \ + static const int kMax10Exp = UNSIGNED_MAX_10_EXP(Type); \ + static const Type kEpsilon = 1; \ + static const Type kStdError = 0; \ + DECL_INT_LIMIT_FUNCS \ +}; + +DECL_SIGNED_INT_LIMITS(signed char, unsigned char) +DECL_SIGNED_INT_LIMITS(signed short int, unsigned short int) +DECL_SIGNED_INT_LIMITS(signed int, unsigned int) +DECL_SIGNED_INT_LIMITS(signed long int, unsigned long int) +DECL_SIGNED_INT_LIMITS(signed long long int, unsigned long long int) +DECL_UNSIGNED_INT_LIMITS(unsigned char) +DECL_UNSIGNED_INT_LIMITS(unsigned short int) +DECL_UNSIGNED_INT_LIMITS(unsigned int) +DECL_UNSIGNED_INT_LIMITS(unsigned long int) +DECL_UNSIGNED_INT_LIMITS(unsigned long long int) + +#undef DECL_SIGNED_INT_LIMITS +#undef DECL_UNSIGNED_INT_LIMITS +#undef SIGNED_INT_MAX +#undef SIGNED_INT_MIN +#undef UNSIGNED_INT_MAX +#undef SIGNED_MAX_10_EXP +#undef UNSIGNED_MAX_10_EXP +#undef DECL_INT_LIMIT_FUNCS + +// ========================================================================= // +#ifdef WIN32 // Lacks built-in isnan() and isinf() +#define DECL_FP_LIMIT_FUNCS \ + static bool IsFinite(const Type x) { return _finite(x); } \ + static bool IsNaN(const Type x) { return _isnan(x); } \ + static bool IsInf(const Type x) { return (_fpclass(x) & (_FPCLASS_NINF | _FPCLASS_PINF)) != 0; } \ + static bool IsPosInf(const Type x) { return _fpclass(x) == _FPCLASS_PINF; } \ + static bool IsNegInf(const Type x) { return _fpclass(x) == _FPCLASS_NINF; } +#else +#define DECL_FP_LIMIT_FUNCS \ + static bool IsFinite(const Type x) { return !isinf(x) && !isnan(x); } \ + static bool IsNaN(const Type x) { return isnan(x); } \ + static bool IsInf(const Type x) { return isinf(x); } \ + static bool IsPosInf(const Type x) { return isinf(x) && x > 0; } \ + static bool IsNegInf(const Type x) { return isinf(x) && x < 0; } +#endif + +// We can't put floating-point constant values in the header here because +// such constants are not considered to be primitive-type constants by gcc. +// CAVEAT: Hence, they are going to be initialized only during +// the global objects construction time. +#define DECL_FP_LIMITS(FP_Type, PREFIX) \ +template<> \ +struct LIBPROTOBUF_EXPORT MathLimits<FP_Type> { \ + typedef FP_Type Type; \ + typedef FP_Type UnsignedType; \ + static const bool kIsSigned = true; \ + static const bool kIsInteger = false; \ + static const Type kPosMin; \ + static const Type kPosMax; \ + static const Type kMin; \ + static const Type kMax; \ + static const Type kNegMin; \ + static const Type kNegMax; \ + static const int kMin10Exp = PREFIX##_MIN_10_EXP; \ + static const int kMax10Exp = PREFIX##_MAX_10_EXP; \ + static const Type kEpsilon; \ + static const Type kStdError; \ + static const int kPrecisionDigits = PREFIX##_DIG; \ + static const Type kNaN; \ + static const Type kPosInf; \ + static const Type kNegInf; \ + DECL_FP_LIMIT_FUNCS \ +}; + +DECL_FP_LIMITS(float, FLT) +DECL_FP_LIMITS(double, DBL) +DECL_FP_LIMITS(long double, LDBL) + +#undef DECL_FP_LIMITS +#undef DECL_FP_LIMIT_FUNCS + +// ========================================================================= // +} // namespace protobuf +} // namespace google + +#endif // UTIL_MATH_MATHLIMITS_H__ |