Improve static_cfref_cast so that it can be used without causing an unnecessary retain/release in the case when one is only using the cast to convert to a more-derived raw CF ref type.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@47384 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
David Elliott
parent
aa25b7f983
commit
64dfdfa28b
@ -58,6 +58,92 @@ inline Type* wxCFRetain(Type *r)
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return r;
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}
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template <class refType>
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class wxCFRef;
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/*! @class wxCFWeakRef
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@templatefield refType The CF reference type (e.g. CFStringRef, CFRunLoopRef, etc.)
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It should already be a pointer. This is different from
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shared_ptr where the template parameter is the pointee type.
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@discussion Wraps a raw pointer without any retain or release.
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Provides a way to get what amounts to a raw pointer from a wxCFRef without
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using a raw pointer. Unlike a raw pointer, constructing a wxCFRef from this
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class will cause it to be retained because it is assumed that a wxCFWeakRef
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does not own its pointer.
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*/
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template <class refType>
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class wxCFWeakRef
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{
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template <class refTypeA, class otherRefType>
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friend wxCFWeakRef<refTypeA> static_cfref_cast(const wxCFRef<otherRefType> &otherRef);
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public:
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/*! @method wxCFWeakRef
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@abstract Creates a NULL reference
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*/
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wxCFWeakRef()
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: m_ptr(NULL)
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{}
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// Default copy constructor is fine.
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// Default destructor is fine but we'll set NULL to avoid bugs
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~wxCFWeakRef()
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{ m_ptr = NULL; }
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// Do not implement a raw-pointer constructor.
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/*! @method wxCFWeakRef
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@abstract Copies another ref holder where its type can be converted to ours
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@templatefield otherRefType Any type held by another wxCFWeakRef.
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@param otherRef The other weak ref holder to copy.
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@discussion This is merely a copy or implicit cast.
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*/
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template <class otherRefType>
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wxCFWeakRef(const wxCFWeakRef<otherRefType>& otherRef)
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: m_ptr(otherRef.get()) // Implicit conversion from otherRefType to refType should occur
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{}
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/*! @method wxCFWeakRef
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@abstract Copies a strong ref holder where its type can be converted to ours
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@templatefield otherRefType Any type held by a wxCFRef.
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@param otherRef The strong ref holder to copy.
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@discussion This ref is merely a pointer copy, the strong ref still holds the pointer.
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*/
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template <class otherRefType>
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wxCFWeakRef(const wxCFRef<otherRefType>& otherRef)
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: m_ptr(otherRef.get()) // Implicit conversion from otherRefType to refType should occur
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{}
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/*! @method get
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@abstract Explicit conversion to the underlying pointer type
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@discussion Allows the caller to explicitly get the underlying pointer.
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*/
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refType get() const
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{ return m_ptr; }
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/*! @method operator refType
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@abstract Implicit conversion to the underlying pointer type
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@discussion Allows the ref to be used in CF function calls.
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*/
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operator refType() const
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{ return m_ptr; }
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protected:
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/*! @method wxCFWeakRef
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@abstract Constructs a weak reference to the raw pointer
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@templatefield otherType Any type.
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@param p The raw pointer to assume ownership of. May be NULL.
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@discussion This method is private so that the friend static_cfref_cast can use it
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*/
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template <class otherType>
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explicit wxCFWeakRef(otherType *p)
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: m_ptr(p) // Implicit conversion from otherType* to refType should occur.
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{}
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/*! @var m_ptr The raw pointer.
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*/
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refType m_ptr;
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};
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/*! @class wxCFRef
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@templatefield refType The CF reference type (e.g. CFStringRef, CFRunLoopRef, etc.)
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It should already be a pointer. This is different from
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@ -114,6 +200,19 @@ public:
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: m_ptr(wxCFRetain(otherRef.get())) // Implicit conversion from otherRefType to refType should occur
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{}
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/*! @method wxCFRef
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@abstract Copies a weak ref holder where its type can be converted to ours
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@templatefield otherRefType Any type held by a wxCFWeakRef.
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@param otherRef The weak ref holder to copy.
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@discussion Ownership will be taken by this newly created ref. That is,
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the object will be explicitly retained by this new ref.
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Ownership is most likely shared with some other ref as well.
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*/
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template <class otherRefType>
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wxCFRef(const wxCFWeakRef<otherRefType>& otherRef)
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: m_ptr(wxCFRetain(otherRef.get())) // Implicit conversion from otherRefType to refType should occur
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{}
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/*! @method ~wxCFRef
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@abstract Releases (potentially shared) ownership of the ref.
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@discussion A ref holder instance is always assumed to have ownership so ownership is always
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@ -225,21 +324,26 @@ inline wxCFRef<Type*> wxCFRefFromGet(Type *p)
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}
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/*! @function static_cfref_cast
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@abstract Works like static_cast but from one wxCFRef to another
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@abstract Works like static_cast but with a wxCFRef as the argument.
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@param refType Template parameter. The destination raw pointer type
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@param otherRef Normal parameter. The source wxCFRef<> object.
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@discussion This is modeled after shared_ptr's static_pointer_cast. Just as wxCFRef is
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@discussion This is intended to be a clever way to make static_cast work while allowing
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the return value to be converted to either a strong ref or a raw pointer
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while ensuring that the retain count is updated appropriately.
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This is modeled after shared_ptr's static_pointer_cast. Just as wxCFRef is
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parameterized on a pointer to an opaque type so is this class. Note that
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this differs from shared_ptr which is parameterized on the pointee type.
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FIXME: Anybody got a better name?
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*/
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template <class refType, class otherRefType>
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inline wxCFRef<refType> static_cfref_cast(const wxCFRef<otherRefType> &otherRef);
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inline wxCFWeakRef<refType> static_cfref_cast(const wxCFRef<otherRefType> &otherRef);
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template <class refType, class otherRefType>
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inline wxCFRef<refType> static_cfref_cast(const wxCFRef<otherRefType> &otherRef)
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inline wxCFWeakRef<refType> static_cfref_cast(const wxCFRef<otherRefType> &otherRef)
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{
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return wxCFRef<refType>(static_cast<refType>(wxCFRetain(otherRef.get())));
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return wxCFWeakRef<refType>(static_cast<refType>(otherRef.get()));
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}
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/*! @function CFRelease
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