53 lines
1.5 KiB
C++
53 lines
1.5 KiB
C++
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// Copyright 2015, Tobias Hermann and the FunctionalPlus contributors.
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// https://github.com/Dobiasd/FunctionalPlus
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#pragma once
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#include <memory>
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namespace fplus
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{
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// A std::shared_ptr expresses
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// optionality of the contained value (can be nullptr)
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// and shared ownership that can be transferred.
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// A std::optional expresses optionality only.
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// The standard does not provide a class to
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// express only shared ownership without optionality.
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// shared_ref fills this gap.
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template <typename T>
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class shared_ref
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{
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public:
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shared_ref(const shared_ref&) = default;
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shared_ref(shared_ref&&) = default;
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shared_ref& operator=(const shared_ref&) = default;
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shared_ref& operator=(shared_ref&&) = default;
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~shared_ref() = default;
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T* operator->() { return m_ptr.get(); }
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const T* operator->() const { return m_ptr.get(); }
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T& operator*() { return *m_ptr.get(); }
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const T& operator*() const { return *m_ptr.get(); }
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template <typename XT, typename...XTypes>
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friend shared_ref<XT> make_shared_ref(XTypes&&...args);
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private:
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std::shared_ptr<T> m_ptr;
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shared_ref(T* value) :m_ptr(value) { assert(value != nullptr); }
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};
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// http://stackoverflow.com/a/41976419/1866775
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template <typename T, typename...Types>
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shared_ref<T> make_shared_ref(Types&&...args)
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{
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return shared_ref<T>(new T(std::forward<Types>(args)...));
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}
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} // namespace fplus
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