serenity/AK/StdLibExtras.h

/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#pragma once

constexpr unsigned round_up_to_power_of_two(unsigned value, unsigned power_of_two)
{
    return ((value - 1) & ~(power_of_two - 1)) + power_of_two;
}

namespace AK {

template<typename T>
auto declval() -> T;

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 T& b)
{
    return b < a ? b : a;
}

template<typename T>
constexpr T max(const T& a, const T& b)
{
    return a < b ? b : a;
}

template<typename T>
constexpr T clamp(const T& value, const T& min, const T& max)
{
    ASSERT(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>
constexpr T&& move(T& arg)
{
    return static_cast<T&&>(arg);
}

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<bool B, class T = void>
struct EnableIf {
};

template<class T>
struct EnableIf<true, T> {
    using Type = T;
};

template<class T>
struct AddConst {
    using Type = const T;
};

template<class T>
struct RemoveConst {
    using Type = T;
};

template<class T>
struct RemoveConst<const T> {
    using Type = T;
};

template<class T>
struct RemoveVolatile {
    using Type = T;
};
template<class T>
struct RemoveVolatile<volatile T> {
    using Type = T;
};
template<class T>
struct RemoveCV {
    using Type = typename RemoveVolatile<typename RemoveConst<T>::Type>::Type;
};

template<class T, T v>
struct IntegralConstant {
    static constexpr T value = v;
    using ValueType = T;
    using Type = IntegralConstant;
    constexpr operator ValueType() const { return value; }
    constexpr ValueType operator()() const { return value; }
};

using FalseType = IntegralConstant<bool, false>;
using TrueType = IntegralConstant<bool, true>;
template<typename...>
using VoidType = void;

template<class T>
struct IsLvalueReference : FalseType {
};

template<class T>
struct IsLvalueReference<T&> : TrueType {
};

template<class T>
struct __IsPointerHelper : FalseType {
};

template<class T>
struct __IsPointerHelper<T*> : TrueType {
};

template<class T>
struct IsPointer : __IsPointerHelper<typename RemoveCV<T>::Type> {
};

template<class>
struct IsFunction : FalseType {
};

template<class Ret, class... Args>
struct IsFunction<Ret(Args...)> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args..., ...)> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args...) const> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args..., ...) const> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args...) volatile> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args..., ...) volatile> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args...) const volatile> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args..., ...) const volatile> : TrueType {
};

template<class Ret, class... Args>
struct IsFunction<Ret(Args...)&> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args..., ...)&> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args...) const&> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args..., ...) const&> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args...) volatile&> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args..., ...) volatile&> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args...) const volatile&> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args..., ...) const volatile&> : TrueType {
};

template<class Ret, class... Args>
struct IsFunction<Ret(Args...) &&> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args..., ...) &&> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args...) const&&> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args..., ...) const&&> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args...) volatile&&> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args..., ...) volatile&&> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args...) const volatile&&> : TrueType {
};
template<class Ret, class... Args>
struct IsFunction<Ret(Args..., ...) const volatile&&> : TrueType {
};

template<class T>
struct IsRvalueReference : FalseType {
};
template<class T>
struct IsRvalueReference<T&&> : TrueType {
};

template<class T>
struct RemovePointer {
    using Type = T;
};
template<class T>
struct RemovePointer<T*> {
    using Type = T;
};
template<class T>
struct RemovePointer<T* const> {
    using Type = T;
};
template<class T>
struct RemovePointer<T* volatile> {
    using Type = T;
};
template<class T>
struct RemovePointer<T* const volatile> {
    using Type = T;
};

template<typename T, typename U>
struct IsSame {
    static constexpr bool value = false;
};

template<typename T>
struct IsSame<T, T> {
    static constexpr bool value = true;
};

template<bool condition, class TrueType, class FalseType>
struct Conditional {
    using Type = TrueType;
};

template<class TrueType, class FalseType>
struct Conditional<false, TrueType, FalseType> {
    using Type = FalseType;
};

template<typename T>
struct IsNullPointer : IsSame<decltype(nullptr), typename RemoveCV<T>::Type> {
};

template<typename T>
struct RemoveReference {
    using Type = T;
};
template<class T>
struct RemoveReference<T&> {
    using Type = T;
};
template<class T>
struct RemoveReference<T&&> {
    using Type = T;
};

template<class T>
constexpr T&& forward(typename RemoveReference<T>::Type& param)
{
    return static_cast<T&&>(param);
}

template<class T>
constexpr T&& forward(typename RemoveReference<T>::Type&& param) noexcept
{
    static_assert(!IsLvalueReference<T>::value, "Can't forward an rvalue as an lvalue.");
    return static_cast<T&&>(param);
}

template<typename T>
struct MakeUnsigned {
    using Type = void;
};
template<>
struct MakeUnsigned<signed char> {
    using Type = unsigned char;
};
template<>
struct MakeUnsigned<short> {
    using Type = unsigned short;
};
template<>
struct MakeUnsigned<int> {
    using Type = unsigned int;
};
template<>
struct MakeUnsigned<long> {
    using Type = unsigned long;
};
template<>
struct MakeUnsigned<long long> {
    using Type = unsigned long long;
};
template<>
struct MakeUnsigned<unsigned char> {
    using Type = unsigned char;
};
template<>
struct MakeUnsigned<unsigned short> {
    using Type = unsigned short;
};
template<>
struct MakeUnsigned<unsigned int> {
    using Type = unsigned int;
};
template<>
struct MakeUnsigned<unsigned long> {
    using Type = unsigned long;
};
template<>
struct MakeUnsigned<unsigned long long> {
    using Type = unsigned long long;
};
template<>
struct MakeUnsigned<char> {
    using Type = unsigned char;
};
template<>
struct MakeUnsigned<char8_t> {
    using Type = char8_t;
};
template<>
struct MakeUnsigned<char16_t> {
    using Type = char16_t;
};
template<>
struct MakeUnsigned<char32_t> {
    using Type = char32_t;
};
template<>
struct MakeUnsigned<bool> {
    using Type = bool;
};

template<typename T>
struct MakeSigned {
};
template<>
struct MakeSigned<signed char> {
    using Type = signed char;
};
template<>
struct MakeSigned<short> {
    using Type = short;
};
template<>
struct MakeSigned<int> {
    using Type = int;
};
template<>
struct MakeSigned<long> {
    using Type = long;
};
template<>
struct MakeSigned<long long> {
    using Type = long long;
};
template<>
struct MakeSigned<unsigned char> {
    using Type = char;
};
template<>
struct MakeSigned<unsigned short> {
    using Type = short;
};
template<>
struct MakeSigned<unsigned int> {
    using Type = int;
};
template<>
struct MakeSigned<unsigned long> {
    using Type = long;
};
template<>
struct MakeSigned<unsigned long long> {
    using Type = long long;
};
template<>
struct MakeSigned<char> {
    using Type = signed char;
};

template<class T>
struct IsVoid : IsSame<void, typename RemoveCV<T>::Type> {
};

template<class T>
struct IsConst : FalseType {
};

template<class T>
struct IsConst<const T> : TrueType {
};

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>
struct IsUnion : public IntegralConstant<bool, __is_union(T)> {
};

template<typename T>
struct IsClass : public IntegralConstant<bool, __is_class(T)> {
};

template<typename Base, typename Derived>
struct IsBaseOf : public IntegralConstant<bool, __is_base_of(Base, Derived)> {
};

template<typename T>
constexpr bool is_trivial()
{
    return __is_trivial(T);
}

template<typename T>
constexpr bool is_trivially_copyable()
{
    return __is_trivially_copyable(T);
}

template<typename T>
struct __IsIntegral : FalseType {
};
template<>
struct __IsIntegral<bool> : TrueType {
};
template<>
struct __IsIntegral<unsigned char> : TrueType {
};
template<>
struct __IsIntegral<char8_t> : TrueType {
};
template<>
struct __IsIntegral<char16_t> : TrueType {
};
template<>
struct __IsIntegral<char32_t> : TrueType {
};
template<>
struct __IsIntegral<unsigned short> : TrueType {
};
template<>
struct __IsIntegral<unsigned int> : TrueType {
};
template<>
struct __IsIntegral<unsigned long> : TrueType {
};
template<>
struct __IsIntegral<unsigned long long> : TrueType {
};
template<typename T>
using IsIntegral = __IsIntegral<typename MakeUnsigned<typename RemoveCV<T>::Type>::Type>;

template<typename T>
struct __IsFloatingPoint : FalseType {
};
template<>
struct __IsFloatingPoint<float> : TrueType {
};
template<>
struct __IsFloatingPoint<double> : TrueType {
};
template<>
struct __IsFloatingPoint<long double> : TrueType {
};
template<typename T>
using IsFloatingPoint = __IsFloatingPoint<typename RemoveCV<T>::Type>;

template<typename ReferenceType, typename T>
using CopyConst =
    typename Conditional<IsConst<ReferenceType>::value, typename AddConst<T>::Type, typename RemoveConst<T>::Type>::Type;

template<typename... Ts>
using Void = void;

template<typename... _Ignored>
constexpr auto DependentFalse = false;

template<typename T>
using IsUnsigned = IsSame<T, MakeUnsigned<T>>;

template<typename T>
using IsArithmetic = IntegralConstant<bool, IsIntegral<T>::value || IsFloatingPoint<T>::value>;

template<typename T>
using IsFundamental = IntegralConstant<bool, IsArithmetic<T>::value || IsVoid<T>::value || IsNullPointer<T>::value>;

template<typename T, T... Ts>
struct IntegerSequence {
    using Type = T;
    static constexpr unsigned size() noexcept { return sizeof...(Ts); };
};

template<unsigned... Indices>
using IndexSequence = IntegerSequence<unsigned, Indices...>;

template<typename T, T N, T... Ts>
auto make_integer_sequence_impl()
{
    if constexpr (N == 0)
        return IntegerSequence<T, Ts...> {};
    else
        return make_integer_sequence_impl<T, N - 1, N - 1, Ts...>();
}

template<typename T, T N>
using MakeIntegerSequence = decltype(make_integer_sequence_impl<T, N>());

template<unsigned N>
using MakeIndexSequence = MakeIntegerSequence<unsigned, N>;

template<unsigned long N>
struct StringLiteral {
    constexpr StringLiteral(const char (&in)[N])
        : data {}
        , size { N }
    {
        for (unsigned long i = 0; i < N; ++i)
            data[i] = in[i];
    }

    template<unsigned long Nx>
    constexpr StringLiteral& operator=(const StringLiteral<Nx>& other)
    {
        static_assert(Nx <= N, "Storing a string literal in a smaller one");
        for (unsigned long i = 0; i < Nx; ++i)
            data[i] = other[i];
        return *this;
    }

    template<unsigned long Nx>
    constexpr StringLiteral& operator=(const char (&other)[Nx])
    {
        static_assert(Nx <= N, "Storing a string literal in a smaller one");
        for (unsigned long i = 0; i < Nx; ++i)
            data[i] = other[i];
        return *this;
    }

    char data[N];
    unsigned long size;
};

}

using AK::AddConst;
using AK::array_size;
using AK::ceil_div;
using AK::clamp;
using AK::Conditional;
using AK::declval;
using AK::DependentFalse;
using AK::exchange;
using AK::forward;
using AK::IndexSequence;
using AK::IntegerSequence;
using AK::is_trivial;
using AK::is_trivially_copyable;
using AK::IsArithmetic;
using AK::IsBaseOf;
using AK::IsClass;
using AK::IsConst;
using AK::IsFundamental;
using AK::IsNullPointer;
using AK::IsSame;
using AK::IsUnion;
using AK::IsVoid;
using AK::MakeIndexSequence;
using AK::MakeIntegerSequence;
using AK::MakeSigned;
using AK::MakeUnsigned;
using AK::max;
using AK::min;
using AK::move;
using AK::RemoveConst;
using AK::StringLiteral;
using AK::swap;
using AK::Void;