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Unified Diff: base/numerics/safe_math.h

Issue 2472933003: Simplify Checked arithmetic functions in base/numerics (Closed)
Patch Set: typo Created 4 years, 1 month ago
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Index: base/numerics/safe_math.h
diff --git a/base/numerics/safe_math.h b/base/numerics/safe_math.h
index d0003b79db0face241564f62de2c9e59586eaba2..0c88a7c2a30d6efb4597007be46056eb1d2fc999 100644
--- a/base/numerics/safe_math.h
+++ b/base/numerics/safe_math.h
@@ -59,11 +59,10 @@ class CheckedNumeric {
// Copy constructor.
template <typename Src>
CheckedNumeric(const CheckedNumeric<Src>& rhs)
- : state_(rhs.ValueUnsafe(), rhs.validity()) {}
+ : state_(rhs.ValueUnsafe(), rhs.IsValid()) {}
template <typename Src>
- CheckedNumeric(Src value, RangeConstraint validity)
- : state_(value, validity) {}
+ CheckedNumeric(Src value, bool is_valid) : state_(value, is_valid) {}
// This is not an explicit constructor because we implicitly upgrade regular
// numerics to CheckedNumerics to make them easier to use.
@@ -82,7 +81,7 @@ class CheckedNumeric {
}
// IsValid() is the public API to test if a CheckedNumeric is currently valid.
- bool IsValid() const { return validity() == RANGE_VALID; }
+ bool IsValid() const { return state_.is_valid(); }
// ValueOrDie() The primary accessor for the underlying value. If the current
// state is not valid it will CHECK and crash.
@@ -106,22 +105,10 @@ class CheckedNumeric {
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.
+ // values it returns are unintuitive and 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.
@@ -132,25 +119,25 @@ class CheckedNumeric {
template <typename Src> CheckedNumeric& operator%=(Src rhs);
CheckedNumeric operator-() const {
- RangeConstraint validity;
- T value = CheckedNeg(state_.value(), &validity);
+ bool is_valid;
+ T value = CheckedNeg(state_.value(), &is_valid);
// 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);
+ is_valid &= state_.is_valid();
+ return CheckedNumeric<T>(value, is_valid);
}
CheckedNumeric Abs() const {
- RangeConstraint validity;
- T value = CheckedAbs(state_.value(), &validity);
+ bool is_valid;
+ T value = CheckedAbs(state_.value(), &is_valid);
// 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);
+ is_valid &= state_.is_valid();
+ return CheckedNumeric<T>(value, is_valid);
}
// This function is available only for integral types. It returns an unsigned
@@ -158,7 +145,7 @@ class CheckedNumeric {
// of the source, and properly handling signed min.
CheckedNumeric<typename UnsignedOrFloatForSize<T>::type> UnsignedAbs() const {
return CheckedNumeric<typename UnsignedOrFloatForSize<T>::type>(
- CheckedUnsignedAbs(state_.value()), state_.validity());
+ CheckedUnsignedAbs(state_.value()), state_.is_valid());
}
CheckedNumeric& operator++() {
@@ -224,72 +211,69 @@ class CheckedNumeric {
// * 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 = static_cast<T>( \
- 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<typename UnderlyingType<Src>::type>::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, \
- typename std::enable_if<std::is_arithmetic<Src>::value>::type* = \
- nullptr> \
- 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 left numeric and right CheckedNumeric. */ \
- template <typename T, typename Src, \
- typename std::enable_if<std::is_arithmetic<Src>::value>::type* = \
- nullptr> \
- 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); \
+#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(), \
+ rhs.IsValid() && lhs.IsValid()); \
+ bool is_valid = true; \
+ T result = static_cast<T>( \
+ Checked##NAME(static_cast<Promotion>(lhs.ValueUnsafe()), \
+ static_cast<Promotion>(rhs.ValueUnsafe()), &is_valid)); \
+ return CheckedNumeric<Promotion>( \
+ result, is_valid && lhs.IsValid() && rhs.IsValid()); \
+ } \
+ /* 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<typename UnderlyingType<Src>::type>::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(), \
+ rhs.IsValid() && lhs.IsValid()); \
+ return CheckedNumeric<Promotion>::cast(lhs) \
+ OP CheckedNumeric<Promotion>::cast(rhs); \
+ } \
+ /* Binary arithmetic operator for left CheckedNumeric and right numeric. */ \
+ template <typename T, typename Src, \
+ typename std::enable_if<std::is_arithmetic<Src>::value>::type* = \
+ nullptr> \
+ 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.IsValid()); \
+ return CheckedNumeric<Promotion>::cast(lhs) \
+ OP CheckedNumeric<Promotion>::cast(rhs); \
+ } \
+ /* Binary arithmetic operator for left numeric and right CheckedNumeric. */ \
+ template <typename T, typename Src, \
+ typename std::enable_if<std::is_arithmetic<Src>::value>::type* = \
+ nullptr> \
+ 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.IsValid()); \
+ return CheckedNumeric<Promotion>::cast(lhs) \
+ OP CheckedNumeric<Promotion>::cast(rhs); \
}
BASE_NUMERIC_ARITHMETIC_OPERATORS(Add, +, += )
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