AuROXTL/Include/auROXTL/STLShims/ExtendStlLikeSharedPtr.hpp

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

    File: ExtendStlLikeSharedPtr.hpp
    Date: 2022-1-25
    Author: Reece
***/
#pragma once

//#include <auROXTL/auCastUtils.hpp>
#include <auROXTL/auCopyMoveUtils.hpp>

namespace Aurora::Memory
{
    inline void ThrowNullException();

    namespace _detail
    {
        struct IPtrGet
        {
            virtual void *Get() = 0;
        };

        struct IPtrNoOpGet : IPtrGet
        {
            inline virtual void *Get() override
            {
                ThrowNullException();
                return {};
            }
        };

        inline IPtrNoOpGet gNoop;
    }

    template <class TType_t, class Base_t>
    struct ExSharedPtr : Base_t
    #if !defined(_AURORA_NULLEXPT_ENABLE_UB) && !defined(_AURORA_NULLEXPT_BRANCH) 
        , private _detail::IPtrGet
    #endif
    {
        using element_type = typename Base_t::element_type;
        using weak_type = typename Base_t::weak_type;
        using base_type = Base_t;
        using Base_t::Base_t;

        ExSharedPtr() : Base_t()
        {
        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
        }

        ExSharedPtr(Base_t &&in) : Base_t(AuMove(in))
        {
        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
        }
       
        ExSharedPtr(ExSharedPtr &&in) : Base_t(AuMove(in.BasePointerType()))
        {
        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
        }

        ExSharedPtr(const ExSharedPtr &in) : Base_t(in)
        {
        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
        }

        template <class T_t, typename B_t>
        ExSharedPtr(const ExSharedPtr<T_t, B_t> &in) : Base_t(in.BasePointerType(), static_cast<T_t *>(in.get()))
        {
        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
        }

        template <class T_t, typename B_t>
        ExSharedPtr(ExSharedPtr<T_t, B_t> &&in) : Base_t(in.BasePointerType(), static_cast<T_t *>(in.get()))
        {
        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
        }

        template <class T_t, typename B_t>
        ExSharedPtr(ExSharedPtr<T_t, B_t> &&in, element_type *ptr) : Base_t(AuMove(in.BasePointerType()), ptr)
        {
        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
        }

        ExSharedPtr(Base_t &&in, element_type *ptr) : Base_t(AuMove(in), ptr)
        {
        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
        }

        template <class T_t, typename B_t>
        ExSharedPtr(const ExSharedPtr<T_t, B_t> &in, element_type *ptr) : Base_t(in.BasePointerType(), ptr)
        {
        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
        }

        ExSharedPtr(const Base_t &in, element_type *ptr) : Base_t(in, ptr)
        {
        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
        }

        ExSharedPtr(const Base_t &in) : Base_t(in)
        {
        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
        }

        template <class Y = element_type, class Deleter_t, class Alloc_t>
        ExSharedPtr(Y *in, Deleter_t del, Alloc_t alloc) : Base_t(in, del, alloc)
        {
        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
        }

        template <class Y = element_type, class Deleter_t>
        ExSharedPtr(Y *in, Deleter_t del) : Base_t(in, del)
        {
        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
        }

        template < class Y, class Deleter >
        ExSharedPtr(AURORA_RUNTIME_AU_UNIQUE_PTR<Y, Deleter> &&r) : Base_t(AuMove(r))
        {
        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
        }


        template <class T_t, typename B_t>
        void swap(ExSharedPtr<T_t, B_t> &in)
        {
            Base_t::swap(in.BasePointerType());

        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
        }

        void swap(Base_t &r)
        {
            Base_t::swap(r);

        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
        }

        void reset()
        {
            Base_t::reset();
        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
        #if !defined(_AURORA_NULLEXPT_BRANCH)
            ptr = &_detail::gNoop;
        #endif
        #endif
        }

        operator const Base_t &() const noexcept
        {
            return *this;
        }

        // required for move casts 
        operator Base_t &() noexcept
        {
            return *this;
        }

        const Base_t &BasePointerType() const noexcept
        {
            return *this;
        }

        Base_t &BasePointerType() noexcept
        {
            return *this;
        }

        operator bool() const noexcept
        {
            return Base_t::operator bool();
        }

        ExSharedPtr &operator =(const Base_t &in) noexcept
        {
            Base_t::operator=(in);

        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
            return *this;
        }

        template <class T_t, typename B_t>
        ExSharedPtr &operator =(ExSharedPtr<T_t, B_t> &&in) noexcept
        {
            Base_t::operator=(AuMove(in.BasePointerType()));

        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
            return *this;
        }

        ExSharedPtr &operator =(Base_t &&in) noexcept
        {
            Base_t::operator=(in);

        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
            return *this;
        }

        ExSharedPtr &operator =(const ExSharedPtr &in) noexcept
        {
            Base_t::operator=(in);

        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
            return *this;
        }

        template <class T_t, typename B_t>
        ExSharedPtr &operator =(const ExSharedPtr<T_t, B_t> &in) noexcept
        {
            Base_t::operator=(in.BasePointerType());

        #if !defined(_AURORA_NULLEXPT_ENABLE_UB)
            _cache();
        #endif
            return *this;
        }

        template <class TType2_t = TType_t>
        TType2_t &operator*() const
        {
            return *operator->();
        }

        template <class TType2_t = TType_t>
        TType2_t *operator->() const
        {
        #if defined(_AURORA_NULLEXPT_ENABLE_UB)
            return Base_t::operator->();
        #elif !defined(_AURORA_NULLEXPT_BRANCH)
            return reinterpret_cast<TType2_t *>(ptr->Get());
        #else
            throwif();
            return Base_t::operator->();
        #endif
        }

        template <class TType2_t = TType_t>
        TType2_t &operator*()
        {
            return *operator->();
        }

        template <class TType2_t = TType_t>
        TType2_t *operator->()
        {
        #if defined(_AURORA_NULLEXPT_ENABLE_UB)
            return Base_t::operator->();
        #elif !defined(_AURORA_NULLEXPT_BRANCH)
            return reinterpret_cast<TType2_t *>(ptr->Get());
        #else
            throwif();
            return Base_t::operator->();
        #endif
        }

        element_type *get() const
        {
            return Base_t::get();
        }

    #define ADD_OPERATOR(op)                                           \
        template <class T >                                             \
        bool operator op(const T &rhs) noexcept                        \
        {                                                              \
            return static_cast<Base_t &>(*this) op(rhs);               \
        }                                                              \
                                                                       \
        template < class T >                                            \
        bool operator op(std::nullptr_t rhs) noexcept                  \
        {                                                              \
            return static_cast<Base_t &>(*this) op(rhs);               \
        }


        ADD_OPERATOR(==)
        ADD_OPERATOR(!=)
        #if defined(AU_LANG_CPP_20)
            template < class T >
            std::strong_ordering operator<=>(const T &rhs) noexcept
            {
                return Base_t::operator<=>(rhs);
            }
        #else
            ADD_OPERATOR(>)
            ADD_OPERATOR(<)
            ADD_OPERATOR(<=)
            ADD_OPERATOR(=>)
        #endif

    private:

    #if defined(_AURORA_NULLEXPT_ENABLE_UB)
        void _cache()
        {}
    #elif !defined(_AURORA_NULLEXPT_BRANCH)
        _detail::IPtrGet * ptr;

        inline virtual void *Get() override
        {
            return (void *)Base_t::operator->();
        }

        auline void _cache()
        {
            if (Base_t::operator bool())
            {
                ptr = this;
            }
            else
            {

                ptr = &_detail::gNoop;
            }
        }
    #else
        bool cached {};
        auline void throwif() const
        {
            if (!cached) [[unlikely]]
            {
            #if defined(_AURORA_NULLEXPT_BRANCH_BUG_CHECK)
                if (!Base_t::operator bool()) [[likely]]
            #endif
                {
                    AU_THROW_STRING("ExSharedPointer Null Access Violation");
                }
            }
        }

        auline void throwif()
        {
            if (!cached) [[unlikely]]
            {
            #if defined(_AURORA_NULLEXPT_BRANCH_BUG_CHECK)
                cached = Base_t::operator bool();
                if (!cached) [[likely]]
            #endif
                {
                    AU_THROW_STRING("ExSharedPointer Null Access Violation");
                }
            }
        }

        auline void _cache()
        {
            cached = Base_t::operator bool();
        }
    #endif
    };

    template <class TType_t, class Base_t>
    struct ExSharedFromThis : Base_t
    {
        ExSharedPtr<TType_t, AURORA_RUNTIME_AU_SHARED_PTR<TType_t>> SharedFromThis()
        {
            return Base_t::shared_from_this();
        }
    };
}