wxWidgets/include/wx/mac/corefoundation/cfref.h

259 lines
10 KiB
C++

/////////////////////////////////////////////////////////////////////////////
// Name: wx/mac/corefoundation/cfref.h
// Purpose: wxCFRef template class
// Author: David Elliott <dfe@cox.net>
// Modified by:
// Created: 2007/05/10
// RCS-ID: $Id$
// Copyright: (c) 2007 David Elliott <dfe@cox.net>
// Licence: wxWindows licence
// Notes: See http://developer.apple.com/documentation/CoreFoundation/Conceptual/CFMemoryMgmt/index.html
/////////////////////////////////////////////////////////////////////////////
/*! @header wx/mac/corefoundation/cfref.h
@abstract wxCFRef template class
@discussion FIXME: Convert doc tags to something less buggy with C++
*/
#ifndef _WX_MAC_COREFOUNDATION_CFREF_H__
#define _WX_MAC_COREFOUNDATION_CFREF_H__
#include <CoreFoundation/CFBase.h>
/*! @class wxCFRef
@templatefield refType The CF reference type (e.g. CFStringRef, CFRunLoopRef, etc.)
It should already be a pointer. This is different from
shared_ptr where the template parameter is the pointee type.
@discussion Properly retains/releases reference to CoreFoundation objects
*/
template <class refType>
class wxCFRef
{
// Declare wxCFRef<otherRefType> as a friend so that the conversion constructor can access m_ptr directly
template <class otherRefType>
friend class wxCFRef;
public:
/*! @method wxCFRef
@abstract Creates a NULL reference
*/
wxCFRef()
: m_ptr(NULL)
{}
/*! @method wxCFRef
@abstract Assumes ownership of p and creates a reference to it.
@templatefield otherType Any type.
@param p The raw pointer to assume ownership of. May be NULL.
@discussion Like shared_ptr, it is assumed that the caller has a strong reference to p and intends
to transfer ownership of that reference to this ref holder. If the object comes from
a Create or Copy method then this is the correct behavior. If the object comes from
a Get method then you must CFRetain it yourself before passing it to this constructor.
A handy way to do this is to use the non-member wxCFRefFromGet factory funcion.
This method is templated and takes an otherType *p. This prevents implicit conversion
using an operator refType() in a different ref-holding class type.
*/
template <class otherType>
explicit wxCFRef(otherType *p)
: m_ptr(p) // Implicit conversion from otherType* to refType should occur.
{}
/*! @method wxCFRef
@abstract Copies a ref holder of the same type
@param otherRef The other ref holder to copy.
@discussion Ownership will be shared by the original ref and the newly created ref. That is,
the object will be explicitly retained by this new ref.
*/
wxCFRef(const wxCFRef& otherRef)
: m_ptr(otherRef.m_ptr)
{
if(m_ptr != NULL)
CFRetain(m_ptr);
}
/*! @method wxCFRef
@abstract Copies a ref holder where its type can be converted to ours
@templatefield otherRefType Any type held by another wxCFRef.
@param otherRef The other ref holder to copy.
@discussion Ownership will be shared by the original ref and the newly created ref. That is,
the object will be explicitly retained by this new ref.
*/
template <class otherRefType>
wxCFRef(const wxCFRef<otherRefType>& otherRef)
: m_ptr(otherRef.m_ptr) // Implicit conversion from otherRefType to refType should occur
{
if(m_ptr != NULL)
CFRetain(m_ptr);
}
/*! @method ~wxCFRef
@abstract Releases (potentially shared) ownership of the ref.
@discussion A ref holder instance is always assumed to have ownership so ownership is always
released (CFRelease called) upon destruction.
*/
~wxCFRef()
{ reset(); }
/*! @method operator=
@abstract Assigns the other ref's pointer to us when the otherRef is the same type.
@param otherRef The other ref holder to copy.
@discussion The incoming pointer is retained, the original pointer is released, and this object
is made to point to the new pointer.
*/
wxCFRef& operator=(const wxCFRef& otherRef)
{
if(otherRef.m_ptr != NULL)
CFRetain(otherRef.m_ptr);
if(m_ptr != NULL)
CFRelease(m_ptr);
m_ptr = otherRef.m_ptr;
return *this;
}
/*! @method operator=
@abstract Assigns the other ref's pointer to us when the other ref can be converted to our type.
@templatefield otherRefType Any type held by another wxCFRef
@param otherRef The other ref holder to copy.
@discussion The incoming pointer is retained, the original pointer is released, and this object
is made to point to the new pointer.
*/
template <class otherRefType>
wxCFRef& operator=(const wxCFRef<otherRefType>& otherRef)
{
if(otherRef.m_ptr != NULL)
CFRetain(otherRef.m_ptr);
if(m_ptr != NULL)
CFRelease(m_ptr);
m_ptr = otherRef.m_ptr; // Implicit conversion from otherRefType to refType should occur
return *this;
}
/*! @method get
@abstract Explicit conversion to the underlying pointer type
@discussion Allows the caller to explicitly get the underlying pointer.
*/
refType get() const
{ return m_ptr; }
/*! @method operator refType
@abstract Implicit conversion to the underlying pointer type
@discussion Allows the ref to be used in CF function calls.
*/
operator refType() const
{ return m_ptr; }
#if 0
< // HeaderDoc is retarded and thinks the GT from operator-> is part of a template param.
// So give it that < outside of a comment to fake it out. (if 0 is not a comment to HeaderDoc)
#endif
/*! @method operator-&gt;
@abstract Implicit conversion to the underlying pointer type
@discussion This is nearly useless for CF types which are nearly always opaque
*/
refType operator-> () const
{ return m_ptr; }
/*! @method reset
@abstract Nullifies the reference
@discussion Releases ownership (calls CFRelease) before nullifying the pointer.
*/
void reset()
{
if(m_ptr != NULL)
CFRelease(m_ptr);
m_ptr = NULL;
}
/*! @method reset
@abstract Sets this to a new reference
@templatefield otherType Any type.
@param p The raw pointer to assume ownership of
@discussion The existing reference is released (like destruction). It is assumed that the caller
has a strong reference to the new p and intends to transfer ownership of that reference
to this ref holder. Take care to call CFRetain if you received the object from a Get method.
This method is templated and takes an otherType *p. This prevents implicit conversion
using an operator refType() in a different ref-holding class type.
*/
template <class otherType>
void reset(otherType* p)
{
if(m_ptr != NULL)
CFRelease(m_ptr);
m_ptr = p; // Automatic conversion should occur
}
protected:
/*! @var m_ptr The raw pointer.
*/
refType m_ptr;
};
/*! @function wxCFRefFromGet
@abstract Factory function to create wxCFRef from a raw pointer obtained from a Get-rule function
@param p The pointer to retain and create a wxCFRef from. May be NULL.
@discussion Unlike the wxCFRef raw pointer constructor, this function explicitly retains its
argument. This can be used for functions such as CFDictionaryGetValue() or
CFAttributedStringGetString() which return a temporary reference (Get-rule functions).
FIXME: Anybody got a better name?
*/
template <typename Type>
inline wxCFRef<Type*> wxCFRefFromGet(Type *p)
{
return wxCFRef<Type*>( (p!=NULL) ? (Type*)CFRetain(p) : p );
}
/*! @function static_cfref_cast
@abstract Works like static_cast but from one wxCFRef to another
@param refType Template parameter. The destination raw pointer type
@param otherRef Normal parameter. The source wxCFRef<> object.
@discussion This is modeled after shared_ptr's static_pointer_cast. Just as wxCFRef is
parameterized on a pointer to an opaque type so is this class. Note that
this differs from shared_ptr which is parameterized on the pointee type.
FIXME: Anybody got a better name?
*/
template <class refType, class otherRefType>
inline wxCFRef<refType> static_cfref_cast(const wxCFRef<otherRefType> &otherRef);
template <class refType, class otherRefType>
inline wxCFRef<refType> static_cfref_cast(const wxCFRef<otherRefType> &otherRef)
{
return wxCFRef<refType>(static_cast<refType>(CFRetain(otherRef.get())));
}
/*! @function CFRelease
@abstract Overloads CFRelease so that the user is warned of bad behavior.
@discussion It is rarely appropriate to retain or release a wxCFRef. If one absolutely
must do it he can explicitly get() the raw pointer
Normally, this function is unimplemented resulting in a linker error if used.
*/
template <class T>
inline void CFRelease(const wxCFRef<T*> & cfref) DEPRECATED_ATTRIBUTE;
/*! @function CFRetain
@abstract Overloads CFRetain so that the user is warned of bad behavior.
@discussion It is rarely appropriate to retain or release a wxCFRef. If one absolutely
must do it he can explicitly get() the raw pointer
Normally, this function is unimplemented resulting in a linker error if used.
*/
template <class T>
inline void CFRetain(const wxCFRef<T*>& cfref) DEPRECATED_ATTRIBUTE;
// Change the 0 to a 1 if you want the functions to work (no link errors)
// Neither function will cause retain/release side-effects if implemented.
#if 0
template <class T>
void CFRelease(const wxCFRef<T*> & cfref)
{
CFRelease(cfref.get());
}
template <class T>
void CFRetain(const wxCFRef<T*> & cfref)
{
CFRetain(cfref.get());
}
#endif
#endif //ndef _WX_MAC_COREFOUNDATION_CFREF_H__