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Diffstat (limited to 'third_party/numerics/safe_math.h')
| -rw-r--r-- | third_party/numerics/safe_math.h | 271 |
1 files changed, 0 insertions, 271 deletions
diff --git a/third_party/numerics/safe_math.h b/third_party/numerics/safe_math.h deleted file mode 100644 index 4b38ff2b1f..0000000000 --- a/third_party/numerics/safe_math.h +++ /dev/null @@ -1,271 +0,0 @@ -// Copyright 2014 The Chromium Authors. All rights reserved. -// Use of this source code is governed by a BSD-style license that can be -// found in the LICENSE file. - -#ifndef BASE_SAFE_MATH_H_ -#define BASE_SAFE_MATH_H_ - -#include "safe_math_impl.h" - -namespace base { - -namespace internal { - -// CheckedNumeric implements all the logic and operators for detecting integer -// boundary conditions such as overflow, underflow, and invalid conversions. -// The CheckedNumeric type implicitly converts from floating point and integer -// data types, and contains overloads for basic arithmetic operations (i.e.: +, -// -, *, /, %). -// -// The following methods convert from CheckedNumeric to standard numeric values: -// IsValid() - Returns true if the underlying numeric value is valid (i.e. has -// has not wrapped and is not the result of an invalid conversion). -// ValueOrDie() - Returns the underlying value. If the state is not valid this -// call will crash on a CHECK. -// ValueOrDefault() - Returns the current value, or the supplied default if the -// state is not valid. -// ValueFloating() - Returns the underlying floating point value (valid only -// only for floating point CheckedNumeric types). -// -// Bitwise operations are explicitly not supported, because correct -// handling of some cases (e.g. sign manipulation) is ambiguous. Comparison -// operations are explicitly not supported because they could result in a crash -// on a CHECK condition. You should use patterns like the following for these -// operations: -// Bitwise operation: -// CheckedNumeric<int> checked_int = untrusted_input_value; -// int x = checked_int.ValueOrDefault(0) | kFlagValues; -// Comparison: -// CheckedNumeric<size_t> checked_size; -// CheckedNumeric<int> checked_size = untrusted_input_value; -// checked_size = checked_size + HEADER LENGTH; -// if (checked_size.IsValid() && checked_size.ValueOrDie() < buffer_size) -// Do stuff... -template <typename T> -class CheckedNumeric { - public: - typedef T type; - - CheckedNumeric() {} - - // Copy constructor. - template <typename Src> - CheckedNumeric(const CheckedNumeric<Src>& rhs) - : state_(rhs.ValueUnsafe(), rhs.validity()) {} - - template <typename Src> - CheckedNumeric(Src value, RangeConstraint validity) - : state_(value, validity) {} - - // This is not an explicit constructor because we implicitly upgrade regular - // numerics to CheckedNumerics to make them easier to use. - template <typename Src> - CheckedNumeric(Src value) - : state_(value) { - COMPILE_ASSERT(std::numeric_limits<Src>::is_specialized, - argument_must_be_numeric); - } - - // IsValid() is the public API to test if a CheckedNumeric is currently valid. - bool IsValid() const { return validity() == RANGE_VALID; } - - // ValueOrDie() The primary accessor for the underlying value. If the current - // state is not valid it will CHECK and crash. - T ValueOrDie() const { - CHECK(IsValid()); - return state_.value(); - } - - // ValueOrDefault(T default_value) A convenience method that returns the - // current value if the state is valid, and the supplied default_value for - // any other state. - T ValueOrDefault(T default_value) const { - return IsValid() ? state_.value() : default_value; - } - - // ValueFloating() - Since floating point values include their validity state, - // we provide an easy method for extracting them directly, without a risk of - // crashing on a CHECK. - T ValueFloating() const { - COMPILE_ASSERT(std::numeric_limits<T>::is_iec559, argument_must_be_float); - return CheckedNumeric<T>::cast(*this).ValueUnsafe(); - } - - // validity() - DO NOT USE THIS IN EXTERNAL CODE - It is public right now for - // tests and to avoid a big matrix of friend operator overloads. But the - // values it returns are likely to change in the future. - // Returns: current validity state (i.e. valid, overflow, underflow, nan). - // TODO(jschuh): crbug.com/332611 Figure out and implement semantics for - // saturation/wrapping so we can expose this state consistently and implement - // saturated arithmetic. - RangeConstraint validity() const { return state_.validity(); } - - // ValueUnsafe() - DO NOT USE THIS IN EXTERNAL CODE - It is public right now - // for tests and to avoid a big matrix of friend operator overloads. But the - // values it returns are likely to change in the future. - // Returns: the raw numeric value, regardless of the current state. - // TODO(jschuh): crbug.com/332611 Figure out and implement semantics for - // saturation/wrapping so we can expose this state consistently and implement - // saturated arithmetic. - T ValueUnsafe() const { return state_.value(); } - - // Prototypes for the supported arithmetic operator overloads. - template <typename Src> CheckedNumeric& operator+=(Src rhs); - template <typename Src> CheckedNumeric& operator-=(Src rhs); - template <typename Src> CheckedNumeric& operator*=(Src rhs); - template <typename Src> CheckedNumeric& operator/=(Src rhs); - template <typename Src> CheckedNumeric& operator%=(Src rhs); - - CheckedNumeric operator-() const { - RangeConstraint validity; - T value = CheckedNeg(state_.value(), &validity); - // Negation is always valid for floating point. - if (std::numeric_limits<T>::is_iec559) - return CheckedNumeric<T>(value); - - validity = GetRangeConstraint(state_.validity() | validity); - return CheckedNumeric<T>(value, validity); - } - - CheckedNumeric Abs() const { - RangeConstraint validity; - T value = CheckedAbs(state_.value(), &validity); - // Absolute value is always valid for floating point. - if (std::numeric_limits<T>::is_iec559) - return CheckedNumeric<T>(value); - - validity = GetRangeConstraint(state_.validity() | validity); - return CheckedNumeric<T>(value, validity); - } - - CheckedNumeric& operator++() { - *this += 1; - return *this; - } - - CheckedNumeric operator++(int) { - CheckedNumeric value = *this; - *this += 1; - return value; - } - - CheckedNumeric& operator--() { - *this -= 1; - return *this; - } - - CheckedNumeric operator--(int) { - CheckedNumeric value = *this; - *this -= 1; - return value; - } - - // These static methods behave like a convenience cast operator targeting - // the desired CheckedNumeric type. As an optimization, a reference is - // returned when Src is the same type as T. - template <typename Src> - static CheckedNumeric<T> cast( - Src u, - typename enable_if<std::numeric_limits<Src>::is_specialized, int>::type = - 0) { - return u; - } - - template <typename Src> - static CheckedNumeric<T> cast( - const CheckedNumeric<Src>& u, - typename enable_if<!is_same<Src, T>::value, int>::type = 0) { - return u; - } - - static const CheckedNumeric<T>& cast(const CheckedNumeric<T>& u) { return u; } - - private: - CheckedNumericState<T> state_; -}; - -// This is the boilerplate for the standard arithmetic operator overloads. A -// macro isn't the prettiest solution, but it beats rewriting these five times. -// Some details worth noting are: -// * We apply the standard arithmetic promotions. -// * We skip range checks for floating points. -// * We skip range checks for destination integers with sufficient range. -// TODO(jschuh): extract these out into templates. -#define BASE_NUMERIC_ARITHMETIC_OPERATORS(NAME, OP, COMPOUND_OP) \ - /* Binary arithmetic operator for CheckedNumerics of the same type. */ \ - template <typename T> \ - CheckedNumeric<typename ArithmeticPromotion<T>::type> operator OP( \ - const CheckedNumeric<T>& lhs, const CheckedNumeric<T>& rhs) { \ - typedef typename ArithmeticPromotion<T>::type Promotion; \ - /* Floating point always takes the fast path */ \ - if (std::numeric_limits<T>::is_iec559) \ - return CheckedNumeric<T>(lhs.ValueUnsafe() OP rhs.ValueUnsafe()); \ - if (IsIntegerArithmeticSafe<Promotion, T, T>::value) \ - return CheckedNumeric<Promotion>( \ - lhs.ValueUnsafe() OP rhs.ValueUnsafe(), \ - GetRangeConstraint(rhs.validity() | lhs.validity())); \ - RangeConstraint validity = RANGE_VALID; \ - T result = Checked##NAME(static_cast<Promotion>(lhs.ValueUnsafe()), \ - static_cast<Promotion>(rhs.ValueUnsafe()), \ - &validity); \ - return CheckedNumeric<Promotion>( \ - result, \ - GetRangeConstraint(validity | lhs.validity() | rhs.validity())); \ - } \ - /* Assignment arithmetic operator implementation from CheckedNumeric. */ \ - template <typename T> \ - template <typename Src> \ - CheckedNumeric<T>& CheckedNumeric<T>::operator COMPOUND_OP(Src rhs) { \ - *this = CheckedNumeric<T>::cast(*this) OP CheckedNumeric<Src>::cast(rhs); \ - return *this; \ - } \ - /* Binary arithmetic operator for CheckedNumeric of different type. */ \ - template <typename T, typename Src> \ - CheckedNumeric<typename ArithmeticPromotion<T, Src>::type> operator OP( \ - const CheckedNumeric<Src>& lhs, const CheckedNumeric<T>& rhs) { \ - typedef typename ArithmeticPromotion<T, Src>::type Promotion; \ - if (IsIntegerArithmeticSafe<Promotion, T, Src>::value) \ - return CheckedNumeric<Promotion>( \ - lhs.ValueUnsafe() OP rhs.ValueUnsafe(), \ - GetRangeConstraint(rhs.validity() | lhs.validity())); \ - return CheckedNumeric<Promotion>::cast(lhs) \ - OP CheckedNumeric<Promotion>::cast(rhs); \ - } \ - /* Binary arithmetic operator for left CheckedNumeric and right numeric. */ \ - template <typename T, typename Src> \ - CheckedNumeric<typename ArithmeticPromotion<T, Src>::type> operator OP( \ - const CheckedNumeric<T>& lhs, Src rhs) { \ - typedef typename ArithmeticPromotion<T, Src>::type Promotion; \ - if (IsIntegerArithmeticSafe<Promotion, T, Src>::value) \ - return CheckedNumeric<Promotion>(lhs.ValueUnsafe() OP rhs, \ - lhs.validity()); \ - return CheckedNumeric<Promotion>::cast(lhs) \ - OP CheckedNumeric<Promotion>::cast(rhs); \ - } \ - /* Binary arithmetic operator for right numeric and left CheckedNumeric. */ \ - template <typename T, typename Src> \ - CheckedNumeric<typename ArithmeticPromotion<T, Src>::type> operator OP( \ - Src lhs, const CheckedNumeric<T>& rhs) { \ - typedef typename ArithmeticPromotion<T, Src>::type Promotion; \ - if (IsIntegerArithmeticSafe<Promotion, T, Src>::value) \ - return CheckedNumeric<Promotion>(lhs OP rhs.ValueUnsafe(), \ - rhs.validity()); \ - return CheckedNumeric<Promotion>::cast(lhs) \ - OP CheckedNumeric<Promotion>::cast(rhs); \ - } - -BASE_NUMERIC_ARITHMETIC_OPERATORS(Add, +, += ) -BASE_NUMERIC_ARITHMETIC_OPERATORS(Sub, -, -= ) -BASE_NUMERIC_ARITHMETIC_OPERATORS(Mul, *, *= ) -BASE_NUMERIC_ARITHMETIC_OPERATORS(Div, /, /= ) -BASE_NUMERIC_ARITHMETIC_OPERATORS(Mod, %, %= ) - -#undef BASE_NUMERIC_ARITHMETIC_OPERATORS - -} // namespace internal - -using internal::CheckedNumeric; - -} // namespace base - -#endif // BASE_SAFE_MATH_H_ |