394 lines
14 KiB
C
394 lines
14 KiB
C
|
// Copyright 2017 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_NUMERICS_CHECKED_MATH_H_
|
||
|
|
#define BASE_NUMERICS_CHECKED_MATH_H_
|
||
|
|
|
||
|
|
#include <stddef.h>
|
||
|
|
|
||
|
|
#include <limits>
|
||
|
|
#include <type_traits>
|
||
|
|
|
||
|
|
#include "base/numerics/checked_math_impl.h"
|
||
|
|
|
||
|
|
namespace base {
|
||
|
|
namespace internal {
|
||
|
|
|
||
|
|
template <typename T>
|
||
|
|
class CheckedNumeric {
|
||
|
|
static_assert(std::is_arithmetic<T>::value,
|
||
|
|
"CheckedNumeric<T>: T must be a numeric type.");
|
||
|
|
|
||
|
|
public:
|
||
|
|
using type = T;
|
||
|
|
|
||
|
|
constexpr CheckedNumeric() = default;
|
||
|
|
|
||
|
|
// Copy constructor.
|
||
|
|
template <typename Src>
|
||
|
|
constexpr CheckedNumeric(const CheckedNumeric<Src>& rhs)
|
||
|
|
: state_(rhs.state_.value(), rhs.IsValid()) {}
|
||
|
|
|
||
|
|
template <typename Src>
|
||
|
|
friend class CheckedNumeric;
|
||
|
|
|
||
|
|
// This is not an explicit constructor because we implicitly upgrade regular
|
||
|
|
// numerics to CheckedNumerics to make them easier to use.
|
||
|
|
template <typename Src>
|
||
|
|
constexpr CheckedNumeric(Src value) // NOLINT(runtime/explicit)
|
||
|
|
: state_(value) {
|
||
|
|
static_assert(std::is_arithmetic<Src>::value, "Argument must be numeric.");
|
||
|
|
}
|
||
|
|
|
||
|
|
// This is not an explicit constructor because we want a seamless conversion
|
||
|
|
// from StrictNumeric types.
|
||
|
|
template <typename Src>
|
||
|
|
constexpr CheckedNumeric(
|
||
|
|
StrictNumeric<Src> value) // NOLINT(runtime/explicit)
|
||
|
|
: state_(static_cast<Src>(value)) {}
|
||
|
|
|
||
|
|
// IsValid() - The public API to test if a CheckedNumeric is currently valid.
|
||
|
|
// A range checked destination type can be supplied using the Dst template
|
||
|
|
// parameter.
|
||
|
|
template <typename Dst = T>
|
||
|
|
constexpr bool IsValid() const {
|
||
|
|
return state_.is_valid() &&
|
||
|
|
IsValueInRangeForNumericType<Dst>(state_.value());
|
||
|
|
}
|
||
|
|
|
||
|
|
// AssignIfValid(Dst) - Assigns the underlying value if it is currently valid
|
||
|
|
// and is within the range supported by the destination type. Returns true if
|
||
|
|
// successful and false otherwise.
|
||
|
|
template <typename Dst>
|
||
|
|
#if defined(__clang__) || defined(__GNUC__)
|
||
|
|
__attribute__((warn_unused_result))
|
||
|
|
#elif defined(_MSC_VER)
|
||
|
|
_Check_return_
|
||
|
|
#endif
|
||
|
|
constexpr bool
|
||
|
|
AssignIfValid(Dst* result) const {
|
||
|
|
return BASE_NUMERICS_LIKELY(IsValid<Dst>())
|
||
|
|
? ((*result = static_cast<Dst>(state_.value())), true)
|
||
|
|
: false;
|
||
|
|
}
|
||
|
|
|
||
|
|
// ValueOrDie() - The primary accessor for the underlying value. If the
|
||
|
|
// current state is not valid it will CHECK and crash.
|
||
|
|
// A range checked destination type can be supplied using the Dst template
|
||
|
|
// parameter, which will trigger a CHECK if the value is not in bounds for
|
||
|
|
// the destination.
|
||
|
|
// The CHECK behavior can be overridden by supplying a handler as a
|
||
|
|
// template parameter, for test code, etc. However, the handler cannot access
|
||
|
|
// the underlying value, and it is not available through other means.
|
||
|
|
template <typename Dst = T, class CheckHandler = CheckOnFailure>
|
||
|
|
constexpr StrictNumeric<Dst> ValueOrDie() const {
|
||
|
|
return BASE_NUMERICS_LIKELY(IsValid<Dst>())
|
||
|
|
? static_cast<Dst>(state_.value())
|
||
|
|
: CheckHandler::template HandleFailure<Dst>();
|
||
|
|
}
|
||
|
|
|
||
|
|
// 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.
|
||
|
|
// A range checked destination type can be supplied using the Dst template
|
||
|
|
// parameter. WARNING: This function may fail to compile or CHECK at runtime
|
||
|
|
// if the supplied default_value is not within range of the destination type.
|
||
|
|
template <typename Dst = T, typename Src>
|
||
|
|
constexpr StrictNumeric<Dst> ValueOrDefault(const Src default_value) const {
|
||
|
|
return BASE_NUMERICS_LIKELY(IsValid<Dst>())
|
||
|
|
? static_cast<Dst>(state_.value())
|
||
|
|
: checked_cast<Dst>(default_value);
|
||
|
|
}
|
||
|
|
|
||
|
|
// Returns a checked numeric of the specified type, cast from the current
|
||
|
|
// CheckedNumeric. If the current state is invalid or the destination cannot
|
||
|
|
// represent the result then the returned CheckedNumeric will be invalid.
|
||
|
|
template <typename Dst>
|
||
|
|
constexpr CheckedNumeric<typename UnderlyingType<Dst>::type> Cast() const {
|
||
|
|
return *this;
|
||
|
|
}
|
||
|
|
|
||
|
|
// This friend method is available solely for providing more detailed logging
|
||
|
|
// in the the tests. Do not implement it in production code, because the
|
||
|
|
// underlying values may change at any time.
|
||
|
|
template <typename U>
|
||
|
|
friend U GetNumericValueForTest(const CheckedNumeric<U>& src);
|
||
|
|
|
||
|
|
// Prototypes for the supported arithmetic operator overloads.
|
||
|
|
template <typename Src>
|
||
|
|
constexpr CheckedNumeric& operator+=(const Src rhs);
|
||
|
|
template <typename Src>
|
||
|
|
constexpr CheckedNumeric& operator-=(const Src rhs);
|
||
|
|
template <typename Src>
|
||
|
|
constexpr CheckedNumeric& operator*=(const Src rhs);
|
||
|
|
template <typename Src>
|
||
|
|
constexpr CheckedNumeric& operator/=(const Src rhs);
|
||
|
|
template <typename Src>
|
||
|
|
constexpr CheckedNumeric& operator%=(const Src rhs);
|
||
|
|
template <typename Src>
|
||
|
|
constexpr CheckedNumeric& operator<<=(const Src rhs);
|
||
|
|
template <typename Src>
|
||
|
|
constexpr CheckedNumeric& operator>>=(const Src rhs);
|
||
|
|
template <typename Src>
|
||
|
|
constexpr CheckedNumeric& operator&=(const Src rhs);
|
||
|
|
template <typename Src>
|
||
|
|
constexpr CheckedNumeric& operator|=(const Src rhs);
|
||
|
|
template <typename Src>
|
||
|
|
constexpr CheckedNumeric& operator^=(const Src rhs);
|
||
|
|
|
||
|
|
constexpr CheckedNumeric operator-() const {
|
||
|
|
// The negation of two's complement int min is int min, so we simply
|
||
|
|
// check for that in the constexpr case.
|
||
|
|
// We use an optimized code path for a known run-time variable.
|
||
|
|
return MustTreatAsConstexpr(state_.value()) || !std::is_signed<T>::value ||
|
||
|
|
std::is_floating_point<T>::value
|
||
|
|
? CheckedNumeric<T>(
|
||
|
|
NegateWrapper(state_.value()),
|
||
|
|
IsValid() && (!std::is_signed<T>::value ||
|
||
|
|
std::is_floating_point<T>::value ||
|
||
|
|
NegateWrapper(state_.value()) !=
|
||
|
|
std::numeric_limits<T>::lowest()))
|
||
|
|
: FastRuntimeNegate();
|
||
|
|
}
|
||
|
|
|
||
|
|
constexpr CheckedNumeric operator~() const {
|
||
|
|
return CheckedNumeric<decltype(InvertWrapper(T()))>(
|
||
|
|
InvertWrapper(state_.value()), IsValid());
|
||
|
|
}
|
||
|
|
|
||
|
|
constexpr CheckedNumeric Abs() const {
|
||
|
|
return !IsValueNegative(state_.value()) ? *this : -*this;
|
||
|
|
}
|
||
|
|
|
||
|
|
template <typename U>
|
||
|
|
constexpr CheckedNumeric<typename MathWrapper<CheckedMaxOp, T, U>::type> Max(
|
||
|
|
const U rhs) const {
|
||
|
|
using R = typename UnderlyingType<U>::type;
|
||
|
|
using result_type = typename MathWrapper<CheckedMaxOp, T, U>::type;
|
||
|
|
// TODO(jschuh): This can be converted to the MathOp version and remain
|
||
|
|
// constexpr once we have C++14 support.
|
||
|
|
return CheckedNumeric<result_type>(
|
||
|
|
static_cast<result_type>(
|
||
|
|
IsGreater<T, R>::Test(state_.value(), Wrapper<U>::value(rhs))
|
||
|
|
? state_.value()
|
||
|
|
: Wrapper<U>::value(rhs)),
|
||
|
|
state_.is_valid() && Wrapper<U>::is_valid(rhs));
|
||
|
|
}
|
||
|
|
|
||
|
|
template <typename U>
|
||
|
|
constexpr CheckedNumeric<typename MathWrapper<CheckedMinOp, T, U>::type> Min(
|
||
|
|
const U rhs) const {
|
||
|
|
using R = typename UnderlyingType<U>::type;
|
||
|
|
using result_type = typename MathWrapper<CheckedMinOp, T, U>::type;
|
||
|
|
// TODO(jschuh): This can be converted to the MathOp version and remain
|
||
|
|
// constexpr once we have C++14 support.
|
||
|
|
return CheckedNumeric<result_type>(
|
||
|
|
static_cast<result_type>(
|
||
|
|
IsLess<T, R>::Test(state_.value(), Wrapper<U>::value(rhs))
|
||
|
|
? state_.value()
|
||
|
|
: Wrapper<U>::value(rhs)),
|
||
|
|
state_.is_valid() && Wrapper<U>::is_valid(rhs));
|
||
|
|
}
|
||
|
|
|
||
|
|
// This function is available only for integral types. It returns an unsigned
|
||
|
|
// integer of the same width as the source type, containing the absolute value
|
||
|
|
// of the source, and properly handling signed min.
|
||
|
|
constexpr CheckedNumeric<typename UnsignedOrFloatForSize<T>::type>
|
||
|
|
UnsignedAbs() const {
|
||
|
|
return CheckedNumeric<typename UnsignedOrFloatForSize<T>::type>(
|
||
|
|
SafeUnsignedAbs(state_.value()), state_.is_valid());
|
||
|
|
}
|
||
|
|
|
||
|
|
constexpr CheckedNumeric& operator++() {
|
||
|
|
*this += 1;
|
||
|
|
return *this;
|
||
|
|
}
|
||
|
|
|
||
|
|
constexpr CheckedNumeric operator++(int) {
|
||
|
|
CheckedNumeric value = *this;
|
||
|
|
*this += 1;
|
||
|
|
return value;
|
||
|
|
}
|
||
|
|
|
||
|
|
constexpr CheckedNumeric& operator--() {
|
||
|
|
*this -= 1;
|
||
|
|
return *this;
|
||
|
|
}
|
||
|
|
|
||
|
|
constexpr CheckedNumeric operator--(int) {
|
||
|
|
CheckedNumeric value = *this;
|
||
|
|
*this -= 1;
|
||
|
|
return value;
|
||
|
|
}
|
||
|
|
|
||
|
|
// These perform the actual math operations on the CheckedNumerics.
|
||
|
|
// Binary arithmetic operations.
|
||
|
|
template <template <typename, typename, typename> class M,
|
||
|
|
typename L,
|
||
|
|
typename R>
|
||
|
|
static constexpr CheckedNumeric MathOp(const L lhs, const R rhs) {
|
||
|
|
using Math = typename MathWrapper<M, L, R>::math;
|
||
|
|
T result = 0;
|
||
|
|
bool is_valid =
|
||
|
|
Wrapper<L>::is_valid(lhs) && Wrapper<R>::is_valid(rhs) &&
|
||
|
|
Math::Do(Wrapper<L>::value(lhs), Wrapper<R>::value(rhs), &result);
|
||
|
|
return CheckedNumeric<T>(result, is_valid);
|
||
|
|
}
|
||
|
|
|
||
|
|
// Assignment arithmetic operations.
|
||
|
|
template <template <typename, typename, typename> class M, typename R>
|
||
|
|
constexpr CheckedNumeric& MathOp(const R rhs) {
|
||
|
|
using Math = typename MathWrapper<M, T, R>::math;
|
||
|
|
T result = 0; // Using T as the destination saves a range check.
|
||
|
|
bool is_valid = state_.is_valid() && Wrapper<R>::is_valid(rhs) &&
|
||
|
|
Math::Do(state_.value(), Wrapper<R>::value(rhs), &result);
|
||
|
|
*this = CheckedNumeric<T>(result, is_valid);
|
||
|
|
return *this;
|
||
|
|
}
|
||
|
|
|
||
|
|
private:
|
||
|
|
CheckedNumericState<T> state_;
|
||
|
|
|
||
|
|
CheckedNumeric FastRuntimeNegate() const {
|
||
|
|
T result;
|
||
|
|
bool success = CheckedSubOp<T, T>::Do(T(0), state_.value(), &result);
|
||
|
|
return CheckedNumeric<T>(result, IsValid() && success);
|
||
|
|
}
|
||
|
|
|
||
|
|
template <typename Src>
|
||
|
|
constexpr CheckedNumeric(Src value, bool is_valid)
|
||
|
|
: state_(value, is_valid) {}
|
||
|
|
|
||
|
|
// These wrappers allow us to handle state the same way for both
|
||
|
|
// CheckedNumeric and POD arithmetic types.
|
||
|
|
template <typename Src>
|
||
|
|
struct Wrapper {
|
||
|
|
static constexpr bool is_valid(Src) { return true; }
|
||
|
|
static constexpr Src value(Src value) { return value; }
|
||
|
|
};
|
||
|
|
|
||
|
|
template <typename Src>
|
||
|
|
struct Wrapper<CheckedNumeric<Src>> {
|
||
|
|
static constexpr bool is_valid(const CheckedNumeric<Src> v) {
|
||
|
|
return v.IsValid();
|
||
|
|
}
|
||
|
|
static constexpr Src value(const CheckedNumeric<Src> v) {
|
||
|
|
return v.state_.value();
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
template <typename Src>
|
||
|
|
struct Wrapper<StrictNumeric<Src>> {
|
||
|
|
static constexpr bool is_valid(const StrictNumeric<Src>) { return true; }
|
||
|
|
static constexpr Src value(const StrictNumeric<Src> v) {
|
||
|
|
return static_cast<Src>(v);
|
||
|
|
}
|
||
|
|
};
|
||
|
|
};
|
||
|
|
|
||
|
|
// Convenience functions to avoid the ugly template disambiguator syntax.
|
||
|
|
template <typename Dst, typename Src>
|
||
|
|
constexpr bool IsValidForType(const CheckedNumeric<Src> value) {
|
||
|
|
return value.template IsValid<Dst>();
|
||
|
|
}
|
||
|
|
|
||
|
|
template <typename Dst, typename Src>
|
||
|
|
constexpr StrictNumeric<Dst> ValueOrDieForType(
|
||
|
|
const CheckedNumeric<Src> value) {
|
||
|
|
return value.template ValueOrDie<Dst>();
|
||
|
|
}
|
||
|
|
|
||
|
|
template <typename Dst, typename Src, typename Default>
|
||
|
|
constexpr StrictNumeric<Dst> ValueOrDefaultForType(
|
||
|
|
const CheckedNumeric<Src> value,
|
||
|
|
const Default default_value) {
|
||
|
|
return value.template ValueOrDefault<Dst>(default_value);
|
||
|
|
}
|
||
|
|
|
||
|
|
// Convience wrapper to return a new CheckedNumeric from the provided arithmetic
|
||
|
|
// or CheckedNumericType.
|
||
|
|
template <typename T>
|
||
|
|
constexpr CheckedNumeric<typename UnderlyingType<T>::type> MakeCheckedNum(
|
||
|
|
const T value) {
|
||
|
|
return value;
|
||
|
|
}
|
||
|
|
|
||
|
|
// These implement the variadic wrapper for the math operations.
|
||
|
|
template <template <typename, typename, typename> class M,
|
||
|
|
typename L,
|
||
|
|
typename R>
|
||
|
|
constexpr CheckedNumeric<typename MathWrapper<M, L, R>::type> CheckMathOp(
|
||
|
|
const L lhs,
|
||
|
|
const R rhs) {
|
||
|
|
using Math = typename MathWrapper<M, L, R>::math;
|
||
|
|
return CheckedNumeric<typename Math::result_type>::template MathOp<M>(lhs,
|
||
|
|
rhs);
|
||
|
|
}
|
||
|
|
|
||
|
|
// General purpose wrapper template for arithmetic operations.
|
||
|
|
template <template <typename, typename, typename> class M,
|
||
|
|
typename L,
|
||
|
|
typename R,
|
||
|
|
typename... Args>
|
||
|
|
constexpr CheckedNumeric<typename ResultType<M, L, R, Args...>::type>
|
||
|
|
CheckMathOp(const L lhs, const R rhs, const Args... args) {
|
||
|
|
return CheckMathOp<M>(CheckMathOp<M>(lhs, rhs), args...);
|
||
|
|
}
|
||
|
|
|
||
|
|
BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Add, +, +=)
|
||
|
|
BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Sub, -, -=)
|
||
|
|
BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Mul, *, *=)
|
||
|
|
BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Div, /, /=)
|
||
|
|
BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Mod, %, %=)
|
||
|
|
BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Lsh, <<, <<=)
|
||
|
|
BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Rsh, >>, >>=)
|
||
|
|
BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, And, &, &=)
|
||
|
|
BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Or, |, |=)
|
||
|
|
BASE_NUMERIC_ARITHMETIC_OPERATORS(Checked, Check, Xor, ^, ^=)
|
||
|
|
BASE_NUMERIC_ARITHMETIC_VARIADIC(Checked, Check, Max)
|
||
|
|
BASE_NUMERIC_ARITHMETIC_VARIADIC(Checked, Check, Min)
|
||
|
|
|
||
|
|
// These are some extra StrictNumeric operators to support simple pointer
|
||
|
|
// arithmetic with our result types. Since wrapping on a pointer is always
|
||
|
|
// bad, we trigger the CHECK condition here.
|
||
|
|
template <typename L, typename R>
|
||
|
|
L* operator+(L* lhs, const StrictNumeric<R> rhs) {
|
||
|
|
uintptr_t result = CheckAdd(reinterpret_cast<uintptr_t>(lhs),
|
||
|
|
CheckMul(sizeof(L), static_cast<R>(rhs)))
|
||
|
|
.template ValueOrDie<uintptr_t>();
|
||
|
|
return reinterpret_cast<L*>(result);
|
||
|
|
}
|
||
|
|
|
||
|
|
template <typename L, typename R>
|
||
|
|
L* operator-(L* lhs, const StrictNumeric<R> rhs) {
|
||
|
|
uintptr_t result = CheckSub(reinterpret_cast<uintptr_t>(lhs),
|
||
|
|
CheckMul(sizeof(L), static_cast<R>(rhs)))
|
||
|
|
.template ValueOrDie<uintptr_t>();
|
||
|
|
return reinterpret_cast<L*>(result);
|
||
|
|
}
|
||
|
|
|
||
|
|
} // namespace internal
|
||
|
|
|
||
|
|
using internal::CheckedNumeric;
|
||
|
|
using internal::IsValidForType;
|
||
|
|
using internal::ValueOrDieForType;
|
||
|
|
using internal::ValueOrDefaultForType;
|
||
|
|
using internal::MakeCheckedNum;
|
||
|
|
using internal::CheckMax;
|
||
|
|
using internal::CheckMin;
|
||
|
|
using internal::CheckAdd;
|
||
|
|
using internal::CheckSub;
|
||
|
|
using internal::CheckMul;
|
||
|
|
using internal::CheckDiv;
|
||
|
|
using internal::CheckMod;
|
||
|
|
using internal::CheckLsh;
|
||
|
|
using internal::CheckRsh;
|
||
|
|
using internal::CheckAnd;
|
||
|
|
using internal::CheckOr;
|
||
|
|
using internal::CheckXor;
|
||
|
|
|
||
|
|
} // namespace base
|
||
|
|
|
||
|
|
#endif // BASE_NUMERICS_CHECKED_MATH_H_
|