91 lines
3.8 KiB
C++
91 lines
3.8 KiB
C++
#ifndef ARBUTILS_BORROWEDPTR_HPP
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#define ARBUTILS_BORROWEDPTR_HPP
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#include <memory>
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#include "../Assert.hpp"
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namespace ArbUt {
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/// @brief A borrowed pointer is used to indicate a pointer that is not owned by its holder.
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/// @details A borrowed pointer is used to indicate a pointer that is not owned by an object, but instead borrowed
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/// from another owning object that is assumed to always be kept alive during the entire lifetime of the borrowing
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// object.
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template <class T> class BorrowedPtr {
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private:
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T* _raw;
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public:
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/// @brief Initialise a BorrowedPtr with a null pointer.
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inline BorrowedPtr<T>() noexcept : _raw(nullptr){};
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/// @brief Initialise a BorrowedPtr with a specific raw pointer.
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inline BorrowedPtr<T>(T* ptr) noexcept : _raw(ptr){};
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/// @brief Initialise a BorrowedPtr from a copy.
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inline BorrowedPtr<T>(const BorrowedPtr<T>& other) noexcept : _raw(other._raw){};
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/// @brief Initialise a BorrowedPtr with a std unique_ptr.
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inline BorrowedPtr<T>(const std::unique_ptr<T>& other) noexcept : _raw(other.get()){};
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~BorrowedPtr() noexcept = default;
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/// @brief Copy operator.
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inline BorrowedPtr<T>& operator=(const BorrowedPtr<T>& rhs) noexcept {
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if (this == &rhs)
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return *this;
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_raw = rhs._raw;
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return *this;
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}
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/// @brief Operator for access into underlying pointer.
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/// @warning Note that this asserts that the underlying pointer is not null first, to prevent segfaults.
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inline T* operator->() const {
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AssertNotNull(_raw);
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return _raw;
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}
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/// @brief Get the raw underlying pointer.
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inline T* GetRaw() const noexcept { return _raw; }
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/// @brief Check equality of two BorrowedPtr objects
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inline bool operator==(const BorrowedPtr& rhs) const noexcept { return _raw == rhs._raw; }
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/// @brief Check equality of two BorrowedPtr objects
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inline bool operator!=(const BorrowedPtr& rhs) const noexcept { return _raw != rhs._raw; }
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/// @brief Returns whether the underlying pointer is a nullptr or not.
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[[nodiscard]] inline constexpr bool IsNull() const noexcept { return _raw == nullptr; }
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/// @brief Returns a const version of the underlying pointer.
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inline BorrowedPtr<const T> Const() const noexcept { return BorrowedPtr<const T>(_raw); }
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/// @brief Casts the underlying pointer to another type using dynamic_cast.
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template <class TCast> inline BorrowedPtr<TCast> As() const {
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auto cast = dynamic_cast<TCast*>(_raw);
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return BorrowedPtr<TCast>(cast);
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}
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/// @brief Try to cast the underlying pointer to another type using dynamic_cast.
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template <class TCast> inline bool TryAs(BorrowedPtr<TCast>& out) const noexcept {
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auto cast = dynamic_cast<TCast*>(_raw);
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if (cast == nullptr)
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return false;
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out = BorrowedPtr<TCast>(cast);
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return true;
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}
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/// @brief Force cast the underlying pointer to another type using reinterpret_cast.
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template <class TCast> inline BorrowedPtr<TCast> ForceAs() const noexcept {
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auto cast = reinterpret_cast<TCast*>(_raw);
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return BorrowedPtr<TCast>(cast);
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}
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};
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}
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namespace std {
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/// @brief Helper class for allowing hashing of BorrowedPtr.
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template <class T> struct hash<ArbUt::BorrowedPtr<T>> {
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/// @brief Returns a hash of for a borrowed Pointer. Effectively just the raw memory address.
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/// @param k A borrowed pointer.
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/// @return The hash of the borrowed pointer.
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std::size_t operator()(const ArbUt::BorrowedPtr<T>& k) const { return (size_t)k.GetRaw(); }
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};
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}
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#endif // ARBUTILS_BORROWEDPTR_HPP
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