зеркало из https://github.com/mozilla/gecko-dev.git
334 строки
11 KiB
C++
334 строки
11 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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*
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* The contents of this file are subject to the Netscape Public
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* License Version 1.1 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* the License at http://www.mozilla.org/NPL/
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*
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* Software distributed under the License is distributed on an "AS
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* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
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* implied. See the License for the specific language governing
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* rights and limitations under the License.
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*
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* The Original Code is mozilla.org code.
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*
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* The Initial Developer of the Original Code is Netscape
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* Communications Corporation. Portions created by Netscape are
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* Copyright (C) 1998 Netscape Communications Corporation. All
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* Rights Reserved.
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*
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* Contributor(s):
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* Pierre Phaneuf <pp@ludusdesign.com>
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*/
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/*
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A sample of XPConnect. This file contains the XPCOM factory the
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creates for SampleImpl objects.
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*/
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#include "nsCOMPtr.h"
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#include "nscore.h"
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#include "nsISample.h"
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#include "nsIComponentManager.h"
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#include "nsIServiceManager.h"
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#include "nsXPComFactory.h"
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/**
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* IIDs and CIDs (aka CLSIDs) are 32 digit hexadecimal numbers, called Globally
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* Unique IDs (GUIDs) as a whole. They should only be generated by a trusted
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* guid generator. GUID generation algorithms rely on parameters such as
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* the MAC address of your NIC, and the date/time of GUID creation to ensure
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* that no two GUIDs are ever the same. The Windows program 'uuidgen' is one
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* way to create these numbers. The Unix alternative is probably out there
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* somewhere.
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*
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* NS_DEFINE_IID and NS_DEFINE_CID expand to define static IID/CID objects
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* that will be used later. IID and CID objects are of the same form, so the
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* distinction between InterfaceID and ClassID is made strictly by what the
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* ID represents, and not by any binary differences.
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*
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* Note: NS_DEFINE_IID is now deprecated by NS_GET_IID.
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*/
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static NS_DEFINE_CID(kComponentManagerCID, NS_COMPONENTMANAGER_CID);
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static NS_DEFINE_CID(kSampleCID, NS_SAMPLE_CID);
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/**
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* SampleFactoryImpl is a factory capable of creating nsSampleImpl objects.
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* It is the factory, as opposed to the class, which actually registers itself
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* with the XPCOM runtime, in a conversation that goes something like,
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* XPCOM: "Hello factory at <path-name>, what can you do for me?",
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* FACTORY: "Hello XPCOM, I can create the classes named <progID>:<CID>,
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* and <progID>:<CID> and ...". This conversation is initiated when XPCOM calls
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* into the static |NSRegisterSelf| function of the shared library that houses this
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* factory. Once this factory is properly registered, XPCOM can work it's magic.
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* After registration, any call into the Service Manager or Component Manager's
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* |CreateInstance| method requesting a progID or CID that this factory has
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* registered will cause XPCOM to call the static |NSGetFactory| function in
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* the .so, .dll, .whatever associated with this factory (if it hasn't already
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* done so), and then invoke the |CreateInstance| method of the resulting factory.
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*/
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class SampleFactoryImpl : public nsIFactory
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{
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public:
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SampleFactoryImpl(const nsCID &aClass, const char* className,
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const char* progID);
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/**
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* This macro expands into a declaration of the nsISupports interface.
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* Every XPCOM component needs to implement nsISupports, as it acts
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* as the gateway to other interfaces this component implements. You
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* could manually declare QueryInterface, AddRef, and Release instead
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* of using this macro, but why?
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*/
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// nsISupports methods
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NS_DECL_ISUPPORTS
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// nsIFactory methods
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NS_IMETHOD CreateInstance(nsISupports *aOuter,
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const nsIID &aIID,
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void **aResult);
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NS_IMETHOD LockFactory(PRBool aLock);
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protected:
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virtual ~SampleFactoryImpl();
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protected:
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/**
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* When XPCOM calls |NSGetFactory|, it informs us what kind of class
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* it intends to create with this factory. |CreateInstance| does NOT get
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* this information, so we need to record what kind of class |CreateInstance|
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* should return for later reference.
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*/
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nsCID mClassID;
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const char* mClassName;
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const char* mProgID;
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};
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////////////////////////////////////////////////////////////////////////
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/**
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* The constructor needs to initailize reference counting and
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* record the CID / ProgID of the object it should return when
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* |CreateInstance| is called.
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*/
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SampleFactoryImpl::SampleFactoryImpl(const nsCID &aClass,
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const char* className,
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const char* progID)
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: mClassID(aClass), mClassName(className), mProgID(progID)
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{
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NS_INIT_REFCNT();
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}
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SampleFactoryImpl::~SampleFactoryImpl()
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{
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}
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/**
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* This is what a normal implementation of |QueryInterface| (often
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* abbreviated QI) actually looks like. Because this QI only supports
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* nsISupports and nsIFactory, it, and the two NS_IMPL_* macros
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* that follow it could actually be replaced with the macro
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* |NS_IMPL_ISUPPORTS(nsIFactory, NS_GET_IID(nsIFactory))| as nsSample does
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* in nsSample.cpp.
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* The XPCOM homepage (www.mozilla.org/projects/xpcom) has another reference
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* implementation of QueryInterface.
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*/
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NS_IMETHODIMP
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SampleFactoryImpl::QueryInterface(const nsIID &aIID, void **aResult)
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{
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if (! aResult)
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return NS_ERROR_NULL_POINTER;
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// Always NULL result, in case of failure
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*aResult = nsnull;
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if (aIID.Equals(NS_GET_IID(nsISupports))) {
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*aResult = NS_STATIC_CAST(nsISupports*, this);
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AddRef();
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return NS_OK;
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} else if (aIID.Equals(NS_GET_IID(nsIFactory))) {
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*aResult = NS_STATIC_CAST(nsIFactory*, this);
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AddRef();
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return NS_OK;
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}
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return NS_NOINTERFACE;
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}
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/*
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* These macros expand to implementations of AddRef and Release
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*/
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NS_IMPL_ADDREF(SampleFactoryImpl);
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NS_IMPL_RELEASE(SampleFactoryImpl);
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/**
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* The IID passed in here is for COM Aggregation. Aggregation deals with
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* classes contained within other classes, a topic outside the scope of
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* this sample.
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*
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* Notice that this |CreateInstance| is very methodical. It verifies that it
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* has been asked to create a supported class and calls QI on the newly
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* created object, verifying that the created class can actually support
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* the interface that was asked for.
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*/
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NS_IMETHODIMP
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SampleFactoryImpl::CreateInstance(nsISupports *aOuter,
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const nsIID &aIID,
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void **aResult)
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{
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if (! aResult)
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return NS_ERROR_NULL_POINTER;
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// Our example does not support COM Aggregation
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if (aOuter)
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return NS_ERROR_NO_AGGREGATION;
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*aResult = nsnull;
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nsresult rv;
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nsISupports *inst = nsnull;
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if (mClassID.Equals(kSampleCID)) {
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/* Try to create a new nsSampleImpl instance. If this
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fails, then return the error code */
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if (NS_FAILED(rv = NS_NewSample((nsISample**) &inst)))
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return rv;
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}
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else {
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// We don't know how to create objects with the ClassID asked for
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return NS_ERROR_NO_INTERFACE;
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}
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if (! inst)
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return NS_ERROR_OUT_OF_MEMORY;
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if (NS_FAILED(rv = inst->QueryInterface(aIID, aResult))) {
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// We didn't get the right interface.
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NS_ERROR("didn't support the interface you wanted");
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}
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/*
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* We must call |Release| on the interface pointer that was
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* returned from |QueryInterface|. The "interface release"
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* macro checks for a null pointer, calls |Release|, then
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* sets the pointer to null. This macro should be
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* used instead of a direct |inst->Release()| call since
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* the macro records tracing information if
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* NS_BUILD_REFCNT_LOGGING is defined.
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*/
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NS_IF_RELEASE(inst);
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return rv;
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}
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nsresult SampleFactoryImpl::LockFactory(PRBool aLock)
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{
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// Not implemented in simplest case.
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return NS_OK;
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}
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////////////////////////////////////////////////////////////////////////
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/**
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* The XPCOM runtime will call this to get a new factory object for the
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* CID/progID it passes in. XPCOM is responsible for caching the resulting
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* factory.
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*/
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// return the proper factory to the caller
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extern "C" PR_IMPLEMENT(nsresult)
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NSGetFactory(nsISupports* aServMgr,
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const nsCID &aClass,
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const char *aClassName,
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const char *aProgID,
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nsIFactory **aFactory)
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{
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if (! aFactory)
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return NS_ERROR_NULL_POINTER;
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SampleFactoryImpl* factory = new SampleFactoryImpl(aClass, aClassName,
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aProgID);
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if (factory == nsnull)
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return NS_ERROR_OUT_OF_MEMORY;
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NS_ADDREF(factory);
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*aFactory = factory;
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return NS_OK;
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}
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/**
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* When the XPCOM runtime is initialized, it searches the component directory
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* for shared objects, and attempts to call |NSRegisterSelf| for each one it
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* encounters.
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*
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* Clients create instances of XPCOM objects using the ComponentManager.
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* In order for a Client to be able to create an instance of your
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* object, you must register your object and CLSID with the ComponentManager.
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*
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* The ServiceManager is used to access a "service", which is an object
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* that exists for the lifetime of the program. Notice the distinction
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* between accessing a singleton object using the ServiceManager and
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* creating new instances using the ComponentManager.
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*
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* The ComponentManager is an example of an object which persists for
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* the length of the program. To register with the ComponentManager
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* you first retrieve it using the ServiceManager.
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*
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* If you've got some spare time, and _really_ want to see whats going on
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* behind the scenes at registration time, soak up PlatformPrePopulateRegistry
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* (and all the functions it calls) in
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* mozilla/xpcom/components/nsComponentManager.cpp
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*
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* It is possible to register that your component corresponds to a
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* ProgID, which is a human readable string such as
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* "component://netscape/image/decoder&type=image/gif".
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* Instead of using the 32 digit CLSID, Clients can use the
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* convienient ProgID. ProgIDs are the preferred way of
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* accessing components.
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*/
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extern "C" PR_IMPLEMENT(nsresult)
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NSRegisterSelf(nsISupports* aServMgr , const char* aPath)
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{
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nsresult rv;
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nsCOMPtr<nsIServiceManager> servMgr(do_QueryInterface(aServMgr, &rv));
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if (NS_FAILED(rv)) return rv;
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NS_WITH_SERVICE(nsIComponentManager, compMgr, kComponentManagerCID, &rv);
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if (NS_FAILED(rv)) return rv;
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rv = compMgr->RegisterComponent(kSampleCID,
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"Sample World Component",
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"component://mozilla/sample/sample-world",
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aPath, PR_TRUE, PR_TRUE);
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if (NS_FAILED(rv)) return rv;
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return NS_OK;
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}
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/**
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* |NSUnregisterSelf| is responsible for undoing anything NSRegisterSelf does
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* to the registry.
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*/
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extern "C" PR_IMPLEMENT(nsresult)
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NSUnregisterSelf(nsISupports* aServMgr, const char* aPath)
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{
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nsresult rv;
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nsCOMPtr<nsIServiceManager> servMgr(do_QueryInterface(aServMgr, &rv));
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if (NS_FAILED(rv)) return rv;
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NS_WITH_SERVICE(nsIComponentManager, compMgr, kComponentManagerCID, &rv);
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if (NS_FAILED(rv)) return rv;
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rv = compMgr->UnregisterComponent(kSampleCID, aPath);
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if (NS_FAILED(rv)) return rv;
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return NS_OK;
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}
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