AuROXTL/Include/auROXTL/auTemplateMeta.hpp

/***
    Copyright (C) 2022 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: auTemplateMeta.hpp
    Date: 2022-2-1
    Author: Reece
***/
#pragma once

template <bool v>
struct AuBoolType
{
    static constexpr bool value = v;
    using value_type = bool;
    using type = AuBoolType;

    constexpr operator value_type() const noexcept
    {
        return value;
    }

    constexpr value_type operator()() const noexcept
    {
        return value;
    }
};

using AuFalseType = AuBoolType<false>;
using AuTrueType = AuBoolType<true>;

#include "auTemplateMetaIsFunction.hpp"

template <class T>
using AuToValueType_t = typename T::value_type;

template <class T>
using AuToElementType_t = typename T::element_type;

template <class T>
using AuToIterator_t = typename T::iterator;

template <typename T>
static AuToIterator_t<T> AuToIterator(const T &a); // intended use case: screwing over nasty ass lines of `AuToIterator_t<decltype(muh member)>` or worse.
                                                   // example usage: `decltype(AuToIterator(myHashMap)) itr;`
template <typename T>
static AuToElementType_t<T> AuToElementType(const T &a);

template <typename T>
static AuToValueType_t<T> AuToValueType(const T &a);

template <class T, class U>
struct AuIsSame : AuFalseType
{};

template <class T>
struct AuIsSame<T, T> : AuTrueType
{};

template <class T, class U>
inline constexpr bool AuIsSame_v = AuIsSame<T, U>::value;

namespace _audetail
{
    template <class T>
    AuBoolType<!__is_union(T)> IsClass(int T:: *);

    template <class>
    AuFalseType IsClass(...);

    template <class B>
    AuTrueType TestIsPtrConvertible(const volatile B *);
    template <class>
    AuFalseType TestIsPtrConvertible(const volatile void *);

    template <class, typename>
    auto TestIsBaseOf(...)->AuTrueType;

    template <class B, typename D>
    auto TestIsBaseOf(int) -> decltype(TestIsPtrConvertible<B>(static_cast<D *>(nullptr)));

    // yoinked: https://stackoverflow.com/a/40867906
    template<typename Func, typename...Params> static auto IsCallable(int) -> decltype((void)AuDeclVal<Func>()(AuDeclVal<Params>()...), AuTrueType {});
    template<typename Func, typename...Params> static AuFalseType IsCallable(...);
}

template <class T>
struct AuIsClass : decltype(_audetail::IsClass<T>(nullptr))
{};

template <class T>
inline constexpr bool AuIsClass_v = AuIsClass<T>::value;

template <class Base, typename Derived>
struct AuIsBaseOf :
    AuBoolType<
        AuIsClass_v<Base> &&
        AuIsClass_v<Derived> &&
        decltype(_audetail::TestIsBaseOf<Base, Derived>(0))::value
    >
{};

template <class Base, typename Derived>
inline constexpr bool AuIsBaseOf_v = AuIsBaseOf<Base, Derived>::value;

template <class>
inline constexpr bool AuIsPointer_v = false;

template <class T>
inline constexpr bool AuIsPointer_v<T *> = true;

template <class T>
inline constexpr bool AuIsPointer_v<T *const> = true;

template <class T>
inline constexpr bool AuIsPointer_v<T *volatile> = true;

template <class T>
inline constexpr bool AuIsPointer_v<T *const volatile> = true;

template <class>
inline constexpr bool AuIsReference_v = false;

template <class T>
inline constexpr bool AuIsReference_v<T &> = true;

template <class T>
inline constexpr bool AuIsReference_v<T &&> = true;

template <class>
inline constexpr bool AuIsLValueReference_v = false;

template <class T>
inline constexpr bool AuIsLValueReference_v<T &> = true;

template <class>
inline constexpr bool AuIsRValueReference_v = false;

template <class T>
inline constexpr bool AuIsRValueReference_v<T &&> = true;

template <class T>
struct AuRemovePointer
{
    typedef T type;
};

template <class T>
struct AuRemovePointer<T *>
{
    typedef T type;
};

template <class T>
struct AuRemovePointer<T *const>
{
    typedef T type;
};

template <class T>
struct AuRemovePointer<T *volatile>
{
    typedef T type;
};

template <class T>
struct AuRemovePointer<T *const volatile>
{
    typedef T type;
};

template <class T>
using AuRemovePointer_t = typename AuRemovePointer<T>::type;

template <class T>
using AuIsVoid = AuIsSame<void, T>;

template <class T>
inline constexpr bool AuIsVoid_v = AuIsVoid<T>::value;

template <class T>
struct AuRemoveReference
{
    using type = T;
};

template <class T>
struct AuRemoveReference<T &>
{
    using type = T;
};

template <class T>
struct AuRemoveReference<T &&>
{
    using type = T;
};

template <class T>
using AuRemoveReference_t = typename AuRemoveReference<T>::type;

template <class T>
struct AuRemoveConst
{
    typedef T type;
};

template <class T>
struct AuRemoveConst<const T>
{
    typedef T type;
};

template <class T>
using AuRemoveConst_t = typename AuRemoveConst<T>::type;

template <class T>
struct AuRemoveVolatile
{
    typedef T type;
};

template <class T>
struct AuRemoveVolatile<volatile T>
{
    typedef T type;
};

template <class T>
using AuRemoveVolatile_t = typename AuRemoveVolatile<T>::type;

template <bool Test, class T = void>
struct AuEnableIf
{};

template <class T>
struct AuEnableIf<true, T>
{
    using type = T;
};

template <class T>
struct AuAddPointer
{
    using type = AuRemoveReference_t<T> *;
};

template <class T>
using AuAddPointer_t = typename AuAddPointer<T>::type;

template <class T>
struct AuAddLReference
{
    using type = AuRemoveReference_t<T> &;
};

template <class T>
using AuAddLReference_t = typename AuAddLReference<T>::type;

template <class T>
struct AuAddRReference
{
    using type = AuRemoveReference_t<T> &&;
};

template <class T>
using AuAddRReference_t = typename AuAddRReference<T>::type;

template <class T>
T &&AuDeclVal();

template <class T>
struct AuAddConst
{
    using type = const T;
};

template <class T>
using AuAddConst_t = typename AuAddConst<T>::type;

template <class T>
using AuRemoveCV_t = AuRemoveConst_t<AuRemoveReference_t<T>>;

template <class T>
struct AuRemoveExtent
{
    using type = T;
};

template <class T>
struct AuRemoveExtent<T[]>
{
    using type = T;
};

template <class T, AuUInt Len>
struct AuRemoveExtent<T[Len]>
{
    using type = T;
};

template <class T>
using AuRemoveExtent_t = typename AuRemoveExtent<T>::type;

template <class>
constexpr inline bool AuIsArray_v = false;

template <class T, size_t Len>
inline constexpr bool AuIsArray_v<T[Len]> = true;

template <class T>
inline constexpr bool AuIsArray_v<T[]> = true;

template <bool Test, class T = void>
using AuEnableIf_t = typename AuEnableIf<Test, T>::type;

template <class T, class ... Args>
struct AuIsConstructible
{
    template <class C, class ... Args2> static constexpr AuTrueType  Test(decltype(::new C(AuDeclVal<Args2>()...)));
    template <class C, class ... Args2> static constexpr AuFalseType Test(...);
    using type = decltype(Test<T, Args...>(0));
};

template <class T, class ... Args>
using AuIsConstructible_t = typename AuIsConstructible<T, Args ...>::type;

template <class T, class ... Args>
inline constexpr bool AuIsConstructible_v = AuIsConstructible<T, Args ...>::type::value;

template <bool Test, class T, class T2>
struct AuConditional
{
    using type = T;
};

template <class T, class T2>
struct AuConditional<false, T, T2>
{
    using type = T2;
};

template <bool Test, class T, class T2>
using AuConditional_t = typename AuConditional<Test, T, T2>::type;

template <class T>
using AuDecay_t = AuConditional_t<
    AuIsArray_v<T>,
    AuAddPointer_t<AuRemoveExtent_t<T>>,
    AuConditional_t<
        AuIsFunction_v<T>,
        AuAddPointer_t<T>,
        AuRemoveCV_t<T>
    >
>;

template <template <class...> class Base, typename Derived>
struct AuIsBaseOfTemplateImpl
{
    template <class... Ts>
    static constexpr AuTrueType  Test(const Base<Ts...> *);
    static constexpr AuFalseType Test(...);
    using type = decltype(Test(AuDeclVal<AuRemoveReference_t<Derived> *>()));
};

template <template <class...> class Base, typename Derived>
using AuIsBaseOfTemplate = typename AuIsBaseOfTemplateImpl<Base, Derived>::type;

template <template <class...> class Base, typename Derived>
inline constexpr bool AuIsBaseOfTemplate_v = AuIsBaseOfTemplateImpl<Base, Derived>::type::value;

// :(
// we have a boost licensed call traits in auv8pp
#include <type_traits>

#if defined(AU_LANG_CPP_14)
    template <class T, class... Args>
    using AuResultOf_t = typename std::result_of_t<T, Args...>;
#else
    template <class T, class... Args>
    using AuResultOf_t = typename std::invoke_result_t<T, Args...>;
#endif

template <class Func, class ...Params>
struct AuCallable : decltype(_audetail::IsCallable<Func, Params...>(0))
{
};

template <class F, class... Args>
constexpr auto AuIsCallable_v = AuCallable<F, Args...>::value;