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Improve irr_ptr (#10808)
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@ -27,9 +27,14 @@ with this program; if not, write to the Free Software Foundation, Inc.,
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* It should only be used for user-managed objects, i.e. those created with
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* the @c new operator or @c create* functions, like:
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* `irr_ptr<scene::IMeshBuffer> buf{new scene::SMeshBuffer()};`
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* The reference counting is *not* balanced as new objects have reference
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* count set to one, and the @c irr_ptr constructor (and @c reset) assumes
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* ownership of that reference.
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*
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* It should *never* be used for engine-managed objects, including
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* those created with @c addTexture and similar methods.
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* It shouldn’t be used for engine-managed objects, including those created
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* with @c addTexture and similar methods. Constructing @c irr_ptr directly
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* from such object is a bug and may lead to a crash. Indirect construction
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* is possible though; see the @c grab free function for details and use cases.
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*/
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template <class ReferenceCounted,
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class = typename std::enable_if<std::is_base_of<IReferenceCounted,
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@ -38,16 +43,6 @@ class irr_ptr
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{
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ReferenceCounted *value = nullptr;
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/** Drops stored pointer replacing it with the given one.
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* @note Copy semantics: reference counter *is* increased.
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*/
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void grab(ReferenceCounted *object)
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{
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if (object)
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object->grab();
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reset(object);
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}
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public:
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irr_ptr() {}
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@ -71,8 +66,10 @@ public:
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reset(b.release());
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}
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/** Constructs a shared pointer out of a plain one
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/** Constructs a shared pointer out of a plain one to control object lifetime.
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* @param object The object, usually returned by some @c create* function.
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* @note Move semantics: reference counter is *not* increased.
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* @warning Never wrap any @c add* function with this!
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*/
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explicit irr_ptr(ReferenceCounted *object) noexcept { reset(object); }
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@ -134,4 +131,70 @@ public:
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value->drop();
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value = object;
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}
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/** Drops stored pointer replacing it with the given one.
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* @note Copy semantics: reference counter *is* increased.
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*/
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void grab(ReferenceCounted *object) noexcept
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{
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if (object)
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object->grab();
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reset(object);
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}
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};
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// clang-format off
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// ^ dislikes long lines
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/** Constructs a shared pointer as a *secondary* reference to an object
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*
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* This function is intended to make a temporary reference to an object which
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* is owned elsewhere so that it is not destroyed too early. To acheive that
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* it does balanced reference counting, i.e. reference count is increased
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* in this function and decreased when the returned pointer is destroyed.
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*/
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template <class ReferenceCounted>
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irr_ptr<ReferenceCounted> grab(ReferenceCounted *object) noexcept
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{
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irr_ptr<ReferenceCounted> ptr;
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ptr.grab(object);
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return ptr;
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}
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template <typename ReferenceCounted>
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bool operator==(const irr_ptr<ReferenceCounted> &a, const irr_ptr<ReferenceCounted> &b) noexcept
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{
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return a.get() == b.get();
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}
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template <typename ReferenceCounted>
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bool operator==(const irr_ptr<ReferenceCounted> &a, const ReferenceCounted *b) noexcept
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{
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return a.get() == b;
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}
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template <typename ReferenceCounted>
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bool operator==(const ReferenceCounted *a, const irr_ptr<ReferenceCounted> &b) noexcept
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{
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return a == b.get();
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}
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template <typename ReferenceCounted>
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bool operator!=(const irr_ptr<ReferenceCounted> &a, const irr_ptr<ReferenceCounted> &b) noexcept
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{
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return a.get() != b.get();
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}
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template <typename ReferenceCounted>
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bool operator!=(const irr_ptr<ReferenceCounted> &a, const ReferenceCounted *b) noexcept
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{
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return a.get() != b;
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}
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template <typename ReferenceCounted>
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bool operator!=(const ReferenceCounted *a, const irr_ptr<ReferenceCounted> &b) noexcept
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{
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return a != b.get();
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}
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// clang-format on
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