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37b0f55104
Also add some tests to ensure that they _remain_ constexpr. In general, any runtime assertions, weirdo C casts, pointer aliasing, and such shenanigans should be gated behind the (helpfully newly added) AK::is_constant_evaluated() function when the intention is to write constexpr-capable code. a.k.a. deliver promises of constexpr-ness :P
140 lines
2.6 KiB
C++
140 lines
2.6 KiB
C++
/*
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* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/StdLibExtraDetails.h>
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#include <AK/Assertions.h>
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template<typename T, typename U>
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constexpr auto round_up_to_power_of_two(T value, U power_of_two) requires(IsIntegral<T>&& IsIntegral<U>)
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{
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return ((value - 1) & ~(power_of_two - 1)) + power_of_two;
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}
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namespace std {
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// NOTE: This is in the "std" namespace since some compiler features rely on it.
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template<typename T>
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constexpr T&& move(T& arg)
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{
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return static_cast<T&&>(arg);
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}
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}
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using std::move;
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namespace AK::Detail {
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template<typename T>
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struct _RawPtr {
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using Type = T*;
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};
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}
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namespace AK {
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template<class T>
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constexpr T&& forward(RemoveReference<T>& param)
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{
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return static_cast<T&&>(param);
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}
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template<class T>
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constexpr T&& forward(RemoveReference<T>&& param) noexcept
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{
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static_assert(!IsLvalueReference<T>, "Can't forward an rvalue as an lvalue.");
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return static_cast<T&&>(param);
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}
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template<typename T, typename SizeType = decltype(sizeof(T)), SizeType N>
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constexpr SizeType array_size(T (&)[N])
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{
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return N;
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}
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template<typename T>
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constexpr T min(const T& a, const IdentityType<T>& b)
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{
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return b < a ? b : a;
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}
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template<typename T>
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constexpr T max(const T& a, const IdentityType<T>& b)
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{
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return a < b ? b : a;
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}
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template<typename T>
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constexpr T clamp(const T& value, const IdentityType<T>& min, const IdentityType<T>& max)
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{
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VERIFY(max >= min);
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if (value > max)
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return max;
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if (value < min)
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return min;
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return value;
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}
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template<typename T, typename U>
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constexpr T ceil_div(T a, U b)
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{
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static_assert(sizeof(T) == sizeof(U));
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T result = a / b;
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if ((a % b) != 0)
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++result;
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return result;
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}
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template<typename T, typename U>
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inline void swap(T& a, U& b)
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{
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U tmp = move((U&)a);
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a = (T &&) move(b);
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b = move(tmp);
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}
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template<typename T, typename U = T>
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constexpr T exchange(T& slot, U&& value)
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{
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T old_value = move(slot);
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slot = forward<U>(value);
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return old_value;
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}
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template<typename T>
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using RawPtr = typename Detail::_RawPtr<T>::Type;
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template<typename V>
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constexpr decltype(auto) to_underlying(V value) requires(IsEnum<V>)
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{
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return static_cast<UnderlyingType<V>>(value);
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}
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constexpr bool is_constant_evaluated()
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{
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#if __has_builtin(__builtin_is_constant_evaluated)
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return __builtin_is_constant_evaluated();
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#else
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return false;
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#endif
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}
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}
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using AK::array_size;
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using AK::ceil_div;
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using AK::clamp;
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using AK::exchange;
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using AK::forward;
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using AK::is_constant_evaluated;
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using AK::max;
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using AK::min;
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using AK::RawPtr;
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using AK::swap;
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using AK::to_underlying;
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