265 lines
8.9 KiB
C++
265 lines
8.9 KiB
C++
// Copyright 2017 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_NUMERICS_CLAMPED_MATH_H_
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#define BASE_NUMERICS_CLAMPED_MATH_H_
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#include <stddef.h>
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#include <limits>
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#include <type_traits>
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#include "base/numerics/clamped_math_impl.h"
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namespace base {
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namespace internal {
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template <typename T>
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class ClampedNumeric {
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static_assert(std::is_arithmetic<T>::value,
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"ClampedNumeric<T>: T must be a numeric type.");
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public:
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using type = T;
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constexpr ClampedNumeric() : value_(0) {}
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// Copy constructor.
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template <typename Src>
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constexpr ClampedNumeric(const ClampedNumeric<Src>& rhs)
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: value_(saturated_cast<T>(rhs.value_)) {}
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template <typename Src>
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friend class ClampedNumeric;
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// This is not an explicit constructor because we implicitly upgrade regular
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// numerics to ClampedNumerics to make them easier to use.
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template <typename Src>
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constexpr ClampedNumeric(Src value) // NOLINT(runtime/explicit)
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: value_(saturated_cast<T>(value)) {
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static_assert(std::is_arithmetic<Src>::value, "Argument must be numeric.");
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}
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// This is not an explicit constructor because we want a seamless conversion
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// from StrictNumeric types.
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template <typename Src>
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constexpr ClampedNumeric(
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StrictNumeric<Src> value) // NOLINT(runtime/explicit)
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: value_(saturated_cast<T>(static_cast<Src>(value))) {}
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// Returns a ClampedNumeric of the specified type, cast from the current
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// ClampedNumeric, and saturated to the destination type.
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template <typename Dst>
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constexpr ClampedNumeric<typename UnderlyingType<Dst>::type> Cast() const {
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return *this;
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}
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// Prototypes for the supported arithmetic operator overloads.
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template <typename Src>
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constexpr ClampedNumeric& operator+=(const Src rhs);
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template <typename Src>
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constexpr ClampedNumeric& operator-=(const Src rhs);
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template <typename Src>
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constexpr ClampedNumeric& operator*=(const Src rhs);
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template <typename Src>
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constexpr ClampedNumeric& operator/=(const Src rhs);
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template <typename Src>
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constexpr ClampedNumeric& operator%=(const Src rhs);
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template <typename Src>
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constexpr ClampedNumeric& operator<<=(const Src rhs);
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template <typename Src>
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constexpr ClampedNumeric& operator>>=(const Src rhs);
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template <typename Src>
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constexpr ClampedNumeric& operator&=(const Src rhs);
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template <typename Src>
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constexpr ClampedNumeric& operator|=(const Src rhs);
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template <typename Src>
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constexpr ClampedNumeric& operator^=(const Src rhs);
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constexpr ClampedNumeric operator-() const {
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// The negation of two's complement int min is int min, so that's the
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// only overflow case where we will saturate.
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return ClampedNumeric<T>(SaturatedNegWrapper(value_));
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}
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constexpr ClampedNumeric operator~() const {
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return ClampedNumeric<decltype(InvertWrapper(T()))>(InvertWrapper(value_));
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}
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constexpr ClampedNumeric Abs() const {
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// The negation of two's complement int min is int min, so that's the
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// only overflow case where we will saturate.
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return ClampedNumeric<T>(SaturatedAbsWrapper(value_));
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}
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template <typename U>
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constexpr ClampedNumeric<typename MathWrapper<ClampedMaxOp, T, U>::type> Max(
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const U rhs) const {
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using result_type = typename MathWrapper<ClampedMaxOp, T, U>::type;
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return ClampedNumeric<result_type>(
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ClampedMaxOp<T, U>::Do(value_, Wrapper<U>::value(rhs)));
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}
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template <typename U>
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constexpr ClampedNumeric<typename MathWrapper<ClampedMinOp, T, U>::type> Min(
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const U rhs) const {
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using result_type = typename MathWrapper<ClampedMinOp, T, U>::type;
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return ClampedNumeric<result_type>(
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ClampedMinOp<T, U>::Do(value_, Wrapper<U>::value(rhs)));
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}
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// This function is available only for integral types. It returns an unsigned
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// integer of the same width as the source type, containing the absolute value
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// of the source, and properly handling signed min.
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constexpr ClampedNumeric<typename UnsignedOrFloatForSize<T>::type>
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UnsignedAbs() const {
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return ClampedNumeric<typename UnsignedOrFloatForSize<T>::type>(
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SafeUnsignedAbs(value_));
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}
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constexpr ClampedNumeric& operator++() {
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*this += 1;
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return *this;
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}
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constexpr ClampedNumeric operator++(int) {
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ClampedNumeric value = *this;
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*this += 1;
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return value;
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}
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constexpr ClampedNumeric& operator--() {
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*this -= 1;
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return *this;
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}
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constexpr ClampedNumeric operator--(int) {
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ClampedNumeric value = *this;
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*this -= 1;
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return value;
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}
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// These perform the actual math operations on the ClampedNumerics.
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// Binary arithmetic operations.
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template <template <typename, typename, typename> class M,
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typename L,
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typename R>
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static constexpr ClampedNumeric MathOp(const L lhs, const R rhs) {
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using Math = typename MathWrapper<M, L, R>::math;
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return ClampedNumeric<T>(
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Math::template Do<T>(Wrapper<L>::value(lhs), Wrapper<R>::value(rhs)));
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}
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// Assignment arithmetic operations.
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template <template <typename, typename, typename> class M, typename R>
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constexpr ClampedNumeric& MathOp(const R rhs) {
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using Math = typename MathWrapper<M, T, R>::math;
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*this =
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ClampedNumeric<T>(Math::template Do<T>(value_, Wrapper<R>::value(rhs)));
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return *this;
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}
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template <typename Dst>
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constexpr operator Dst() const {
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return saturated_cast<typename ArithmeticOrUnderlyingEnum<Dst>::type>(
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value_);
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}
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// This method extracts the raw integer value without saturating it to the
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// destination type as the conversion operator does. This is useful when
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// e.g. assigning to an auto type or passing as a deduced template parameter.
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constexpr T RawValue() const { return value_; }
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private:
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T value_;
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// These wrappers allow us to handle state the same way for both
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// ClampedNumeric and POD arithmetic types.
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template <typename Src>
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struct Wrapper {
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static constexpr Src value(Src value) {
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return static_cast<typename UnderlyingType<Src>::type>(value);
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}
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};
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};
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// Convience wrapper to return a new ClampedNumeric from the provided arithmetic
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// or ClampedNumericType.
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template <typename T>
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constexpr ClampedNumeric<typename UnderlyingType<T>::type> MakeClampedNum(
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const T value) {
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return value;
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}
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#if !BASE_NUMERICS_DISABLE_OSTREAM_OPERATORS
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// Overload the ostream output operator to make logging work nicely.
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template <typename T>
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std::ostream& operator<<(std::ostream& os, const ClampedNumeric<T>& value) {
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os << static_cast<T>(value);
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return os;
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}
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#endif
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// These implement the variadic wrapper for the math operations.
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template <template <typename, typename, typename> class M,
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typename L,
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typename R>
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constexpr ClampedNumeric<typename MathWrapper<M, L, R>::type> ClampMathOp(
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const L lhs,
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const R rhs) {
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using Math = typename MathWrapper<M, L, R>::math;
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return ClampedNumeric<typename Math::result_type>::template MathOp<M>(lhs,
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rhs);
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}
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// General purpose wrapper template for arithmetic operations.
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template <template <typename, typename, typename> class M,
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typename L,
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typename R,
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typename... Args>
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constexpr ClampedNumeric<typename ResultType<M, L, R, Args...>::type>
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ClampMathOp(const L lhs, const R rhs, const Args... args) {
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return ClampMathOp<M>(ClampMathOp<M>(lhs, rhs), args...);
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}
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BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Add, +, +=)
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BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Sub, -, -=)
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BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Mul, *, *=)
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BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Div, /, /=)
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BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Mod, %, %=)
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BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Lsh, <<, <<=)
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BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Rsh, >>, >>=)
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BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, And, &, &=)
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BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Or, |, |=)
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BASE_NUMERIC_ARITHMETIC_OPERATORS(Clamped, Clamp, Xor, ^, ^=)
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BASE_NUMERIC_ARITHMETIC_VARIADIC(Clamped, Clamp, Max)
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BASE_NUMERIC_ARITHMETIC_VARIADIC(Clamped, Clamp, Min)
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BASE_NUMERIC_COMPARISON_OPERATORS(Clamped, IsLess, <)
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BASE_NUMERIC_COMPARISON_OPERATORS(Clamped, IsLessOrEqual, <=)
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BASE_NUMERIC_COMPARISON_OPERATORS(Clamped, IsGreater, >)
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BASE_NUMERIC_COMPARISON_OPERATORS(Clamped, IsGreaterOrEqual, >=)
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BASE_NUMERIC_COMPARISON_OPERATORS(Clamped, IsEqual, ==)
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BASE_NUMERIC_COMPARISON_OPERATORS(Clamped, IsNotEqual, !=)
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} // namespace internal
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using internal::ClampedNumeric;
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using internal::MakeClampedNum;
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using internal::ClampMax;
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using internal::ClampMin;
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using internal::ClampAdd;
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using internal::ClampSub;
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using internal::ClampMul;
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using internal::ClampDiv;
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using internal::ClampMod;
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using internal::ClampLsh;
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using internal::ClampRsh;
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using internal::ClampAnd;
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using internal::ClampOr;
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using internal::ClampXor;
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} // namespace base
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#endif // BASE_NUMERICS_CLAMPED_MATH_H_
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