ladybird/AK/StdLibExtras.h
Ali Mohammad Pur 37b0f55104 AK: Make the constexpr StringView methods actually constexpr
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
2021-06-27 20:54:59 +01:00

141 lines
2.6 KiB
C++

/*
* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/StdLibExtraDetails.h>
#include <AK/Assertions.h>
template<typename T, typename U>
constexpr auto round_up_to_power_of_two(T value, U power_of_two) requires(IsIntegral<T>&& IsIntegral<U>)
{
return ((value - 1) & ~(power_of_two - 1)) + power_of_two;
}
namespace std {
// NOTE: This is in the "std" namespace since some compiler features rely on it.
template<typename T>
constexpr T&& move(T& arg)
{
return static_cast<T&&>(arg);
}
}
using std::move;
namespace AK::Detail {
template<typename T>
struct _RawPtr {
using Type = T*;
};
}
namespace AK {
template<class T>
constexpr T&& forward(RemoveReference<T>& param)
{
return static_cast<T&&>(param);
}
template<class T>
constexpr T&& forward(RemoveReference<T>&& param) noexcept
{
static_assert(!IsLvalueReference<T>, "Can't forward an rvalue as an lvalue.");
return static_cast<T&&>(param);
}
template<typename T, typename SizeType = decltype(sizeof(T)), SizeType N>
constexpr SizeType array_size(T (&)[N])
{
return N;
}
template<typename T>
constexpr T min(const T& a, const IdentityType<T>& b)
{
return b < a ? b : a;
}
template<typename T>
constexpr T max(const T& a, const IdentityType<T>& b)
{
return a < b ? b : a;
}
template<typename T>
constexpr T clamp(const T& value, const IdentityType<T>& min, const IdentityType<T>& max)
{
VERIFY(max >= min);
if (value > max)
return max;
if (value < min)
return min;
return value;
}
template<typename T, typename U>
constexpr T ceil_div(T a, U b)
{
static_assert(sizeof(T) == sizeof(U));
T result = a / b;
if ((a % b) != 0)
++result;
return result;
}
template<typename T, typename U>
inline void swap(T& a, U& b)
{
U tmp = move((U&)a);
a = (T &&) move(b);
b = move(tmp);
}
template<typename T, typename U = T>
constexpr T exchange(T& slot, U&& value)
{
T old_value = move(slot);
slot = forward<U>(value);
return old_value;
}
template<typename T>
using RawPtr = typename Detail::_RawPtr<T>::Type;
template<typename V>
constexpr decltype(auto) to_underlying(V value) requires(IsEnum<V>)
{
return static_cast<UnderlyingType<V>>(value);
}
constexpr bool is_constant_evaluated()
{
#if __has_builtin(__builtin_is_constant_evaluated)
return __builtin_is_constant_evaluated();
#else
return false;
#endif
}
}
using AK::array_size;
using AK::ceil_div;
using AK::clamp;
using AK::exchange;
using AK::forward;
using AK::is_constant_evaluated;
using AK::max;
using AK::min;
using AK::RawPtr;
using AK::swap;
using AK::to_underlying;