105 lines
2.1 KiB
C++
105 lines
2.1 KiB
C++
// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
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#pragma once
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#include "Luau/Common.h"
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#include <functional>
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namespace Luau
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{
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/** A non-owning, non-null pointer to a T.
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*
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* A NotNull<T> is notionally identical to a T* with the added restriction that
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* it can never store nullptr.
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*
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* The sole conversion rule from T* to NotNull<T> is the single-argument
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* constructor, which is intentionally marked explicit. This constructor
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* performs a runtime test to verify that the passed pointer is never nullptr.
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*
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* Pointer arithmetic, increment, decrement, and array indexing are all
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* forbidden.
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*
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* An implicit coersion from NotNull<T> to T* is afforded, as are the pointer
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* indirection and member access operators. (*p and p->prop)
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*
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* The explicit delete statement is permitted (but not recommended) on a
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* NotNull<T> through this implicit conversion.
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*/
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template<typename T>
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struct NotNull
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{
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explicit NotNull(T* t)
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: ptr(t)
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{
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LUAU_ASSERT(t);
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}
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explicit NotNull(std::nullptr_t) = delete;
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void operator=(std::nullptr_t) = delete;
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template<typename U>
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NotNull(NotNull<U> other)
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: ptr(other.get())
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{
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}
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operator T*() const noexcept
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{
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return ptr;
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}
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T& operator*() const noexcept
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{
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return *ptr;
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}
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T* operator->() const noexcept
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{
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return ptr;
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}
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template<typename U>
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bool operator==(NotNull<U> other) const noexcept
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{
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return get() == other.get();
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}
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template<typename U>
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bool operator!=(NotNull<U> other) const noexcept
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{
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return get() != other.get();
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}
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operator bool() const noexcept = delete;
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T& operator[](int) = delete;
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T& operator+(int) = delete;
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T& operator-(int) = delete;
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T* get() const noexcept
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{
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return ptr;
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}
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private:
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T* ptr;
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};
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} // namespace Luau
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namespace std
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{
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template<typename T>
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struct hash<Luau::NotNull<T>>
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{
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size_t operator()(const Luau::NotNull<T>& p) const
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{
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return std::hash<T*>()(p.get());
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}
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};
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} // namespace std
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