nostalgia/deps/ox/src/ox/std/anyptr.hpp

/*
 * Copyright 2015 - 2025 gary@drinkingtea.net
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

#pragma once

#include "assert.hpp"
#include "array.hpp"
#include "def.hpp"
#include "span.hpp"

namespace ox {

namespace detail {

template<bool unique>
class AnyPtrT {
	private:
		struct WrapBase {
			virtual constexpr ~WrapBase() = default;
			virtual constexpr WrapBase *copyTo(ox::Span<char> s) noexcept = 0;
			virtual constexpr operator bool() const noexcept = 0;
			virtual void free() noexcept = 0;
		};

		template<typename T>
		struct Wrap final: WrapBase {
			T *data{};
			explicit constexpr Wrap(T *pData) noexcept: data(pData) {
			}
			constexpr WrapBase *copyTo(ox::Span<char> s) noexcept override {
				oxAssert(s.size() >= sizeof(Wrap), "too small buffer");
				if (std::is_constant_evaluated()) {
					return new Wrap(data);
				} else {
					return new(s.data()) Wrap(data);
				}
			}
			constexpr operator bool() const noexcept override {
				return data != nullptr;
			}
			constexpr void free() noexcept override {
				safeDelete(data);
				data = {};
			}
		};

		WrapBase *m_wrapPtr{};
		ox::Array<char, sizeof(Wrap<void*>)> m_wrapData;

	public:
		constexpr AnyPtrT() noexcept = default;

		template<typename T>
		constexpr AnyPtrT(T *ptr) noexcept {
			if (std::is_constant_evaluated()) {
				m_wrapPtr = new Wrap<T>(ptr);
			} else {
				m_wrapPtr = new(m_wrapData.data()) Wrap<T>(ptr);
			}
		}

		constexpr AnyPtrT(AnyPtrT const&other) noexcept requires(!unique) {
			if (other) {
				m_wrapPtr = other.m_wrapPtr->copyTo(m_wrapData);
			}
		}

		constexpr AnyPtrT(AnyPtrT &&other) noexcept {
			if (other) {
				m_wrapPtr = other.m_wrapPtr->copyTo(m_wrapData);
				if (std::is_constant_evaluated()) {
					ox::safeDelete(m_wrapPtr);
				}
				other.m_wrapPtr = {};
			}
		}

		constexpr ~AnyPtrT() noexcept {
			if constexpr(unique) {
				free();
			}
			if (std::is_constant_evaluated()) {
				ox::safeDelete(m_wrapPtr);
			}
		}

		template<typename T>
		constexpr AnyPtrT &operator=(T *ptr) noexcept {
			if constexpr(unique) {
				free();
			} else if (std::is_constant_evaluated()) {
				ox::safeDelete(m_wrapPtr);
			}
			if (std::is_constant_evaluated()) {
				m_wrapPtr = new Wrap(ptr);
			} else {
				m_wrapPtr = new(m_wrapData.data()) Wrap(ptr);
			}
			return *this;
		}

		constexpr AnyPtrT &operator=(AnyPtrT const&ptr) noexcept requires(!unique) {
			if (this != &ptr) {
				if (std::is_constant_evaluated()) {
					ox::safeDelete(m_wrapPtr);
				}
				if (ptr) {
					m_wrapPtr = ptr.m_wrapPtr->copyTo(m_wrapData);
				} else {
					m_wrapPtr = nullptr;
				}
			}
			return *this;
		}

		constexpr AnyPtrT &operator=(AnyPtrT &&ptr) noexcept {
			if (this != &ptr) {
				if constexpr(unique) {
					free();
				} else if (std::is_constant_evaluated()) {
					ox::safeDelete(m_wrapPtr);
				}
				if (ptr) {
					m_wrapPtr = ptr.m_wrapPtr->copyTo(m_wrapData);
					if (std::is_constant_evaluated()) {
						ox::safeDelete(ptr.m_wrapPtr);
						ptr.m_wrapPtr = nullptr;
					}
				} else {
					m_wrapPtr = nullptr;
				}
			}
			return *this;
		}

		constexpr operator bool() const noexcept {
			return m_wrapPtr && *m_wrapPtr;
		}

		constexpr void free() noexcept {
			if (m_wrapPtr) {
				m_wrapPtr->free();
			}
			if (std::is_constant_evaluated()) {
				ox::safeDelete(m_wrapPtr);
			}
			m_wrapPtr = nullptr;
		}

		template<typename T>
		[[nodiscard]]
		constexpr T *get() const noexcept {
#ifdef OX_BARE_METAL
			return static_cast<Wrap<T>*>(m_wrapPtr)->data;
#else
			return dynamic_cast<Wrap<T>*>(m_wrapPtr)->data;
#endif
		}

};

}

using AnyPtr = detail::AnyPtrT<false>;
using UAnyPtr = detail::AnyPtrT<true>;

}