YugabyteDB (2.13.0.0-b42, bfc6a6643e7399ac8a0e81d06a3ee6d6571b33ab)

Coverage Report

Created: 2022-03-09 17:30

/Users/deen/code/yugabyte-db/src/yb/gutil/mathlimits.h
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// Copyright 2005 Google Inc.
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//
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// Licensed to the Apache Software Foundation (ASF) under one
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// or more contributor license agreements.  See the NOTICE file
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// distributed with this work for additional information
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// regarding copyright ownership.  The ASF licenses this file
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// to you under the Apache License, Version 2.0 (the
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// "License"); you may not use this file except in compliance
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// with the License.  You may obtain a copy of the License at
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//
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//   http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing,
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// software distributed under the License is distributed on an
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// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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// KIND, either express or implied.  See the License for the
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// specific language governing permissions and limitations
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// under the License.
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//
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// The following only applies to changes made to this file as part of YugaByte development.
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//
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// Portions Copyright (c) YugaByte, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
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// in compliance with the License.  You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software distributed under the License
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// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
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// or implied.  See the License for the specific language governing permissions and limitations
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// under the License.
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//
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// ---
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//
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//
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// Useful integer and floating point limits and type traits.
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//
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// This partially replaces/duplictes numeric_limits<> from <limits>.
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// We get a Google-style class that we have a greater control over
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// and thus can add new features to it or fix whatever happens to be broken in
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// numeric_limits for the compilers we use.
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//
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#ifndef YB_GUTIL_MATHLIMITS_H
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#define YB_GUTIL_MATHLIMITS_H
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#include <cfloat>
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#include <cmath>
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// ========================================================================= //
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// Useful integer and floating point limits and type traits.
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// This is just for the documentation;
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// real members are defined in our specializations below.
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template<typename T> struct MathLimits {
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  // Type name.
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  typedef T Type;
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  // Unsigned version of the Type with the same byte size.
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  // Same as Type for floating point and unsigned types.
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  typedef T UnsignedType;
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  // If the type supports negative values.
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  static const bool kIsSigned;
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  // If the type supports only integer values.
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  static const bool kIsInteger;
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  // Magnitude-wise smallest representable positive value.
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  static const Type kPosMin;
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  // Magnitude-wise largest representable positive value.
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  static const Type kPosMax;
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  // Smallest representable value.
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  static const Type kMin;
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  // Largest representable value.
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  static const Type kMax;
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  // Magnitude-wise smallest representable negative value.
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  // Present only if kIsSigned.
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  static const Type kNegMin;
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  // Magnitude-wise largest representable negative value.
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  // Present only if kIsSigned.
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  static const Type kNegMax;
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  // Smallest integer x such that 10^x is representable.
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  static const int kMin10Exp;
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  // Largest integer x such that 10^x is representable.
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  static const int kMax10Exp;
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  // Smallest positive value such that Type(1) + kEpsilon != Type(1)
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  static const Type kEpsilon;
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  // Typical rounding error that is enough to cover
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  // a few simple floating-point operations.
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  // Slightly larger than kEpsilon to account for a few rounding errors.
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  // Is zero if kIsInteger.
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  static const Type kStdError;
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  // Number of decimal digits of mantissa precision.
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  // Present only if !kIsInteger.
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  static const int kPrecisionDigits;
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  // Not a number, i.e. result of 0/0.
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  // Present only if !kIsInteger.
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  static const Type kNaN;
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  // Positive infinity, i.e. result of 1/0.
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  // Present only if !kIsInteger.
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  static const Type kPosInf;
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  // Negative infinity, i.e. result of -1/0.
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  // Present only if !kIsInteger.
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  static const Type kNegInf;
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  // NOTE: Special floating point values behave
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  // in a special (but mathematically-logical) way
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  // in terms of (in)equalty comparison and mathematical operations
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  // -- see out unittest for examples.
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  // Special floating point value testers.
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  // Present in integer types for convenience.
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  static bool IsFinite(const Type x);
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  static bool IsNaN(const Type x);
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  static bool IsInf(const Type x);
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  static bool IsPosInf(const Type x);
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  static bool IsNegInf(const Type x);
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};
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// ========================================================================= //
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// All #define-s below are simply to refactor the declarations of
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// MathLimits template specializations.
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// They are all #undef-ined below.
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// The hoop-jumping in *_INT_(MAX|MIN) below is so that the compiler does not
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// get an overflow while computing the constants.
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#define SIGNED_INT_MAX(Type) \
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  (((Type(1) << (sizeof(Type)*8 - 2)) - 1) + (Type(1) << (sizeof(Type)*8 - 2)))
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#define SIGNED_INT_MIN(Type) \
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  (-(Type(1) << (sizeof(Type)*8 - 2)) - (Type(1) << (sizeof(Type)*8 - 2)))
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#define UNSIGNED_INT_MAX(Type) \
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  (((Type(1) << (sizeof(Type)*8 - 1)) - 1) + (Type(1) << (sizeof(Type)*8 - 1)))
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// Compile-time selected log10-related constants for integer types.
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#define SIGNED_MAX_10_EXP(Type) \
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  (sizeof(Type) == 1 ? 2 : ( \
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    sizeof(Type) == 2 ? 4 : ( \
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      sizeof(Type) == 4 ? 9 : ( \
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        sizeof(Type) == 8 ? 18 : -1))))
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#define UNSIGNED_MAX_10_EXP(Type) \
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  (sizeof(Type) == 1 ? 2 : ( \
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    sizeof(Type) == 2 ? 4 : ( \
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      sizeof(Type) == 4 ? 9 : ( \
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        sizeof(Type) == 8 ? 19 : -1))))
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#define DECL_INT_LIMIT_FUNCS \
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  static bool IsFinite(const Type x) { return true; } \
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  static bool IsNaN(const Type x) { return false; } \
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  static bool IsInf(const Type x) { return false; } \
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  static bool IsPosInf(const Type x) { return false; } \
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  static bool IsNegInf(const Type x) { return false; }
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#define DECL_SIGNED_INT_LIMITS(IntType, UnsignedIntType) \
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template<> \
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struct MathLimits<IntType> { \
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  typedef IntType Type; \
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  typedef UnsignedIntType UnsignedType; \
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  static const bool kIsSigned = true; \
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  static const bool kIsInteger = true; \
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  static const Type kPosMin = 1; \
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  static const Type kPosMax = SIGNED_INT_MAX(Type); \
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  static const Type kMin = SIGNED_INT_MIN(Type); \
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  static const Type kMax = kPosMax; \
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  static const Type kNegMin = -1; \
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  static const Type kNegMax = kMin; \
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  static const int kMin10Exp = 0; \
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  static const int kMax10Exp = SIGNED_MAX_10_EXP(Type); \
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  static const Type kEpsilon = 1; \
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  static const Type kStdError = 0; \
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  DECL_INT_LIMIT_FUNCS \
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};
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#define DECL_UNSIGNED_INT_LIMITS(IntType) \
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template<> \
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struct MathLimits<IntType> { \
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  typedef IntType Type; \
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  typedef IntType UnsignedType; \
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  static const bool kIsSigned = false; \
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  static const bool kIsInteger = true; \
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  static const Type kPosMin = 1; \
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  static const Type kPosMax = UNSIGNED_INT_MAX(Type); \
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  static const Type kMin = 0; \
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  static const Type kMax = kPosMax; \
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  static const int kMin10Exp = 0; \
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  static const int kMax10Exp = UNSIGNED_MAX_10_EXP(Type); \
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  static const Type kEpsilon = 1; \
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  static const Type kStdError = 0; \
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  DECL_INT_LIMIT_FUNCS \
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};
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DECL_SIGNED_INT_LIMITS(signed char, unsigned char)
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DECL_SIGNED_INT_LIMITS(signed short int, unsigned short int) // NOLINT
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DECL_SIGNED_INT_LIMITS(signed int, unsigned int)
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DECL_SIGNED_INT_LIMITS(signed long int, unsigned long int) // NOLINT
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DECL_SIGNED_INT_LIMITS(signed long long int, unsigned long long int) // NOLINT
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DECL_UNSIGNED_INT_LIMITS(unsigned char)
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DECL_UNSIGNED_INT_LIMITS(unsigned short int) // NOLINT
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DECL_UNSIGNED_INT_LIMITS(unsigned int)
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DECL_UNSIGNED_INT_LIMITS(unsigned long int) // NOLINT
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DECL_UNSIGNED_INT_LIMITS(unsigned long long int) // NOLINT
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#undef DECL_SIGNED_INT_LIMITS
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#undef DECL_UNSIGNED_INT_LIMITS
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#undef SIGNED_INT_MAX
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#undef SIGNED_INT_MIN
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#undef UNSIGNED_INT_MAX
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#undef SIGNED_MAX_10_EXP
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#undef UNSIGNED_MAX_10_EXP
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#undef DECL_INT_LIMIT_FUNCS
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// ========================================================================= //
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#ifdef WIN32  // Lacks built-in isnan() and isinf()
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#define DECL_FP_LIMIT_FUNCS \
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  static bool IsFinite(const Type x) { return _finite(x); } \
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  static bool IsNaN(const Type x) { return _isnan(x); } \
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  static bool IsInf(const Type x) { return (_fpclass(x) & (_FPCLASS_NINF | _FPCLASS_PINF)) != 0; } \
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  static bool IsPosInf(const Type x) { return _fpclass(x) == _FPCLASS_PINF; } \
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  static bool IsNegInf(const Type x) { return _fpclass(x) == _FPCLASS_NINF; }
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#else
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#define DECL_FP_LIMIT_FUNCS \
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  static bool IsFinite(const Type x) { return !std::isinf(x)  &&  !std::isnan(x); } \
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  static bool IsNaN(const Type x) { return std::isnan(x); } \
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  static bool IsInf(const Type x) { return std::isinf(x); } \
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  static bool IsPosInf(const Type x) { return std::isinf(x)  &&  x > 0; } \
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  static bool IsNegInf(const Type x) { return std::isinf(x)  &&  x < 0; }
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#endif
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// We can't put floating-point constant values in the header here because
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// such constants are not considered to be primitive-type constants by gcc.
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// CAVEAT: Hence, they are going to be initialized only during
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// the global objects construction time.
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#define DECL_FP_LIMITS(FP_Type, PREFIX) \
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template<> \
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struct MathLimits<FP_Type> { \
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  typedef FP_Type Type; \
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  typedef FP_Type UnsignedType; \
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  static const bool kIsSigned = true; \
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  static const bool kIsInteger = false; \
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  static const Type kPosMin; \
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  static const Type kPosMax; \
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  static const Type kMin; \
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  static const Type kMax; \
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  static const Type kNegMin; \
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  static const Type kNegMax; \
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  static const int kMin10Exp = PREFIX##_MIN_10_EXP; \
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  static const int kMax10Exp = PREFIX##_MAX_10_EXP; \
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  static const Type kEpsilon; \
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  static const Type kStdError; \
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  static const int kPrecisionDigits = PREFIX##_DIG; \
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  static const Type kNaN; \
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  static const Type kPosInf; \
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  static const Type kNegInf; \
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  DECL_FP_LIMIT_FUNCS \
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};
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DECL_FP_LIMITS(float, FLT)
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DECL_FP_LIMITS(double, DBL)
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DECL_FP_LIMITS(long double, LDBL)
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#undef DECL_FP_LIMITS
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#undef DECL_FP_LIMIT_FUNCS
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// ========================================================================= //
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#endif  // YB_GUTIL_MATHLIMITS_H