зеркало из https://github.com/mozilla/pjs.git
494 строки
12 KiB
C++
494 строки
12 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/*
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* The contents of this file are subject to the Netscape Public License
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* Version 1.0 (the "NPL"); you may not use this file except in
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* compliance with the NPL. You may obtain a copy of the NPL at
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* http://www.mozilla.org/NPL/
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*
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* Software distributed under the NPL is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
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* for the specific language governing rights and limitations under the
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* NPL.
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*
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* The Initial Developer of this code under the NPL is Netscape
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* Communications Corporation. Portions created by Netscape are
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* Copyright (C) 1998 Netscape Communications Corporation. All Rights
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* Reserved.
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*/
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#ifndef nsCOMPtr_h___
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#define nsCOMPtr_h___
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// Wrapping includes can speed up compiles (see "Large Scale C++ Software Design")
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#ifndef nsDebug_h___
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#include "nsDebug.h"
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// for |NS_PRECONDITION|
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#endif
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#ifndef nsISupports_h___
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#include "nsISupports.h"
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// for |nsresult|, |NS_ADDREF|, et al
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#endif
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/*
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Having problems?
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See the User Manual at:
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<http://www.meer.net/ScottCollins/doc/nsCOMPtr.html>, or
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<http://www.mozilla.org/projects/xpcom/nsCOMPtr.html>
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*/
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/*
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TO DO...
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+ make StartAssignment optionally inlined
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+ make constructor for |nsQueryInterface| explicit (suddenly construct/assign from raw pointer becomes illegal)
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+ Improve internal documentation
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+ mention *&
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+ alternatives for comparison
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+ do_QueryInterface
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*/
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/*
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WARNING:
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This file defines several macros for internal use only. These macros begin with the
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prefix |NSCAP_|. Do not use these macros in your own code. They are for internal use
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only for cross-platform compatibility, and are subject to change without notice.
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*/
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/*
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Set up some |#define|s to turn off a couple of troublesome C++ features.
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Interestingly, none of the compilers barf on template stuff. These are set up automatically
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by the autoconf system for all Unixes. (Temporarily, I hope) I have to define them
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myself for Mac and Windows.
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*/
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// under Metrowerks (Mac), we don't have autoconf yet
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#ifdef __MWERKS__
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#define HAVE_CPP_USING
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#define HAVE_CPP_EXPLICIT
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#define HAVE_CPP_NEW_CASTS
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#endif
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// under VC++ (Windows), we don't have autoconf yet
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#ifdef _MSC_VER
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#define HAVE_CPP_EXPLICIT
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#define HAVE_CPP_USING
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#define HAVE_CPP_NEW_CASTS
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#if (_MSC_VER<1100)
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// before 5.0, VC++ couldn't handle explicit
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#undef HAVE_CPP_EXPLICIT
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#elif (_MSC_VER==1100)
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// VC++5.0 has an internal compiler error (sometimes) without this
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#undef HAVE_CPP_USING
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#endif
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#define NSCAP_FEATURE_INLINE_STARTASSIGNMENT
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// under VC++, we win by inlining StartAssignment
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#endif
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/*
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If the compiler doesn't support |explicit|, we'll just make it go away, trusting
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that the builds under compilers that do have it will keep us on the straight and narrow.
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*/
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#ifndef HAVE_CPP_EXPLICIT
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#define explicit
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#endif
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#ifdef HAVE_CPP_NEW_CASTS
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#define NSCAP_REINTERPRET_CAST(T,x) reinterpret_cast<T>(x)
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#else
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#define NSCAP_REINTERPRET_CAST(T,x) ((T)(x))
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#endif
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#ifdef NSCAP_FEATURE_DEBUG_MACROS
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#define NSCAP_ADDREF(ptr) NS_ADDREF(ptr)
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#define NSCAP_RELEASE(ptr) NS_RELEASE(ptr)
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#else
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#define NSCAP_ADDREF(ptr) (ptr)->AddRef()
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#define NSCAP_RELEASE(ptr) (ptr)->Release()
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#endif
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/*
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WARNING:
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VC++4.2 is very picky. To compile under VC++4.2, the classes must be defined
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in an order that satisfies:
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nsDerivedSafe < nsCOMPtr
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nsDontAddRef < nsCOMPtr
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nsCOMPtr < nsGetterAddRefs
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The other compilers probably won't complain, so please don't reorder these
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classes, on pain of breaking 4.2 compatibility.
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*/
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template <class T>
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class nsDerivedSafe : public T
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/*
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No client should ever see or have to type the name of this class. It is the
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artifact that makes it a compile-time error to call |AddRef| and |Release|
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on a |nsCOMPtr|.
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See |nsCOMPtr::operator->|, |nsCOMPtr::operator*|, et al.
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*/
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{
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private:
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#ifdef HAVE_CPP_USING
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using T::AddRef;
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using T::Release;
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#else
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NS_IMETHOD_(nsrefcnt) AddRef(void);
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NS_IMETHOD_(nsrefcnt) Release(void);
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#endif
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void operator delete( void*, size_t ); // NOT TO BE IMPLEMENTED
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// declaring |operator delete| private makes calling delete on an interface pointer a compile error
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nsDerivedSafe<T>& operator=( const nsDerivedSafe<T>& ); // NOT TO BE IMPLEMENTED
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// you may not call |operator=()| through a dereferenced |nsCOMPtr|, because you'd get the wrong one
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};
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#if !defined(HAVE_CPP_USING) && defined(NEED_CPP_UNUSED_IMPLEMENTATIONS)
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template <class T>
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nsrefcnt
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nsDerivedSafe<T>::AddRef()
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{
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return 0;
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}
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template <class T>
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nsrefcnt
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nsDerivedSafe<T>::Release()
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{
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return 0;
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}
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#endif
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template <class T>
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struct nsDontQueryInterface
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/*
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...
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*/
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{
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explicit
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nsDontQueryInterface( T* aRawPtr )
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: mRawPtr(aRawPtr)
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{
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// nothing else to do here
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}
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T* mRawPtr;
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};
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template <class T>
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inline
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nsDontQueryInterface<T>
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dont_QueryInterface( T* aRawPtr )
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{
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return nsDontQueryInterface<T>(aRawPtr);
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}
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struct nsQueryInterface
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{
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explicit
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nsQueryInterface( nsISupports* aRawPtr, nsresult* error = 0 )
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: mRawPtr(aRawPtr),
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mErrorPtr(error)
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{
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// nothing else to do here
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}
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nsISupports* mRawPtr;
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nsresult* mErrorPtr;
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};
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inline
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nsQueryInterface
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do_QueryInterface( nsISupports* aRawPtr, nsresult* error = 0 )
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{
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return nsQueryInterface(aRawPtr, error);
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}
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template <class T>
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struct nsDontAddRef
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/*
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...cooperates with |nsCOMPtr| to allow you to assign in a pointer _without_
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|AddRef|ing it. You would rarely use this directly, but rather through the
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machinery of |getter_AddRefs| in the argument list to functions that |AddRef|
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their results before returning them to the caller.
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See also |getter_AddRefs()| and |class nsGetterAddRefs|.
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*/
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{
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explicit
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nsDontAddRef( T* aRawPtr )
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: mRawPtr(aRawPtr)
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{
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// nothing else to do here
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}
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T* mRawPtr;
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};
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// This call is now deprecated. Use |getter_AddRefs()| instead.
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template <class T>
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inline
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nsDontAddRef<T>
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dont_AddRef( T* aRawPtr )
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/*
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...makes typing easier, because it deduces the template type, e.g.,
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you write |dont_AddRef(fooP)| instead of |nsDontAddRef<IFoo>(fooP)|.
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*/
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{
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return nsDontAddRef<T>(aRawPtr);
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}
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template <class T>
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inline
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nsDontAddRef<T>
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getter_AddRefs( T* aRawPtr )
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{
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return nsDontAddRef<T>(aRawPtr);
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}
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class nsCOMPtr_base
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{
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public:
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nsCOMPtr_base( nsISupports* rawPtr = 0 )
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: mRawPtr(rawPtr)
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{
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// nothing else to do here
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}
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~nsCOMPtr_base()
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{
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if ( mRawPtr )
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NSCAP_RELEASE(mRawPtr);
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}
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NS_EXPORT void assign_with_AddRef( nsISupports* );
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NS_EXPORT void assign_with_QueryInterface( nsISupports*, const nsIID&, nsresult* );
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NS_EXPORT void** begin_assignment();
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protected:
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nsISupports* mRawPtr;
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};
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template <class T>
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class nsCOMPtr : private nsCOMPtr_base
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/*
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...
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*/
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{
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public:
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typedef T element_type;
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nsCOMPtr()
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// : nsCOMPtr_base(0)
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{
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// nothing else to do here
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}
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nsCOMPtr( const nsQueryInterface& aSmartPtr )
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// : nsCOMPtr_base(0)
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{
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assign_with_QueryInterface(aSmartPtr.mRawPtr, T::GetIID(), aSmartPtr.mErrorPtr);
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}
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nsCOMPtr( const nsDontAddRef<T>& aSmartPtr )
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: nsCOMPtr_base(aSmartPtr.mRawPtr)
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{
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// nothing else to do here
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}
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nsCOMPtr( const nsDontQueryInterface<T>& aSmartPtr )
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: nsCOMPtr_base(aSmartPtr.mRawPtr)
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{
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if ( mRawPtr )
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NSCAP_ADDREF(mRawPtr);
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}
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nsCOMPtr( const nsCOMPtr<T>& aSmartPtr )
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: nsCOMPtr_base(aSmartPtr.mRawPtr)
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{
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if ( mRawPtr )
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NSCAP_ADDREF(mRawPtr);
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}
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nsCOMPtr<T>&
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operator=( const nsQueryInterface& rhs )
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{
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assign_with_QueryInterface(rhs.mRawPtr, T::GetIID(), rhs.mErrorPtr);
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return *this;
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}
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nsCOMPtr<T>&
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operator=( const nsDontAddRef<T>& rhs )
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{
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if ( mRawPtr )
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NSCAP_RELEASE(mRawPtr);
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mRawPtr = rhs.mRawPtr;
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return *this;
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}
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nsCOMPtr<T>&
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operator=( const nsDontQueryInterface<T>& rhs )
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{
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assign_with_AddRef(rhs.mRawPtr);
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return *this;
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}
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nsCOMPtr<T>&
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operator=( const nsCOMPtr<T>& rhs )
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{
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assign_with_AddRef(rhs.mRawPtr);
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return *this;
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}
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nsDerivedSafe<T>*
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get() const
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// returns a |nsDerivedSafe<T>*| to deny clients the use of |AddRef| and |Release|
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{
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return NSCAP_REINTERPRET_CAST(nsDerivedSafe<T>*, mRawPtr);
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}
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nsDerivedSafe<T>*
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operator->() const
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// returns a |nsDerivedSafe<T>*| to deny clients the use of |AddRef| and |Release|
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{
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NS_PRECONDITION(mRawPtr != 0, "You can't dereference a NULL nsCOMPtr with operator->().");
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return get();
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}
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nsDerivedSafe<T>&
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operator*() const
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// returns a |nsDerivedSafe<T>*| to deny clients the use of |AddRef| and |Release|
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{
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NS_PRECONDITION(mRawPtr != 0, "You can't dereference a NULL nsCOMPtr with operator*().");
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return *get();
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}
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operator nsDerivedSafe<T>*() const
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{
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return get();
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}
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#if 0
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private:
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friend class nsGetterAddRefs<T>;
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/*
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In a perfect world, the following member function, |StartAssignment|, would be private.
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It is and should be only accessed by the closely related class |nsGetterAddRefs<T>|.
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Unfortunately, some compilers---most notably VC++5.0---fail to grok the
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friend declaration above or in any alternate acceptable form. So, physically
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it will be public (until our compilers get smarter); but it is not to be
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considered part of the logical public interface.
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*/
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#endif
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T**
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StartAssignment()
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{
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#ifndef NSCAP_FEATURE_INLINE_STARTASSIGNMENT
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return NSCAP_REINTERPRET_CAST(T**, begin_assignment());
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#else
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if ( mRawPtr )
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NSCAP_RELEASE(mRawPtr);
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mRawPtr = 0;
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return NSCAP_REINTERPRET_CAST(T**, &mRawPtr);
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#endif
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}
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};
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template <class T>
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class nsGetterAddRefs
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/*
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...
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This class is designed to be used for anonymous temporary objects in the
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argument list of calls that return COM interface pointers, e.g.,
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nsCOMPtr<IFoo> fooP;
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...->QueryInterface(iid, nsGetterAddRefs<IFoo>(fooP))
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...->QueryInterface(iid, getter_AddRefs(fooP))
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When initialized with a |nsCOMPtr|, as in the example above, it returns
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a |void**| (or |T**| if needed) that the outer call (|QueryInterface| in this
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case) can fill in.
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*/
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{
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public:
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explicit
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nsGetterAddRefs( nsCOMPtr<T>& aSmartPtr )
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: mTargetSmartPtr(aSmartPtr)
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{
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// nothing else to do
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}
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operator void**()
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{
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// NS_PRECONDITION(mTargetSmartPtr != 0, "getter_AddRefs into no destination");
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return NSCAP_REINTERPRET_CAST(void**, mTargetSmartPtr.StartAssignment());
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}
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T*&
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operator*()
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{
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// NS_PRECONDITION(mTargetSmartPtr != 0, "getter_AddRefs into no destination");
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return *(mTargetSmartPtr.StartAssignment());
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}
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operator T**()
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{
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// NS_PRECONDITION(mTargetSmartPtr != 0, "getter_AddRefs into no destination");
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return mTargetSmartPtr.StartAssignment();
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}
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private:
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nsCOMPtr<T>& mTargetSmartPtr;
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};
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template <class T>
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inline
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nsGetterAddRefs<T>
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getter_AddRefs( nsCOMPtr<T>& aSmartPtr )
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/*
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Used around a |nsCOMPtr| when
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...makes the class |nsGetterAddRefs<T>| invisible.
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*/
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{
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return nsGetterAddRefs<T>(aSmartPtr);
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}
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#endif // !defined(nsCOMPtr_h___)
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