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183 lines
5.9 KiB
C++
183 lines
5.9 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* 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
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 1998
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* the Initial Developer. All 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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* Alternatively, the contents of this file may be used under the terms of
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* either of the GNU General Public License Version 2 or later (the "GPL"),
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* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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/**
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*
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* A sample of XPConnect. This file contains an implementation nsSample
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* of the interface nsISample.
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*
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*/
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#include <stdio.h>
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#include "nsSample.h"
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#include "nsMemory.h"
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#include "nsEmbedString.h"
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#include "nsIClassInfoImpl.h"
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////////////////////////////////////////////////////////////////////////
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nsSampleImpl::nsSampleImpl() : mValue(nsnull)
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{
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mValue = (char*)nsMemory::Clone("initial value", 14);
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}
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nsSampleImpl::~nsSampleImpl()
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{
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if (mValue)
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nsMemory::Free(mValue);
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}
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/**
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* NS_IMPL_ISUPPORTS1 expands to a simple implementation of the nsISupports
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* interface. This includes a proper implementation of AddRef, Release,
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* and QueryInterface. If this class supported more interfaces than just
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* nsISupports,
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* you could use NS_IMPL_ADDREF() and NS_IMPL_RELEASE() to take care of the
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* simple stuff, but you would have to create QueryInterface on your own.
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* nsSampleFactory.cpp is an example of this approach.
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* Notice that the second parameter to the macro is name of the interface, and
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* NOT the #defined IID.
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*
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* The _CI variant adds support for nsIClassInfo, which permits introspection
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* and interface flattening.
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*/
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NS_IMPL_ISUPPORTS1_CI(nsSampleImpl, nsISample)
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/**
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* Notice that in the protoype for this function, the NS_IMETHOD macro was
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* used to declare the return type. For the implementation, the return
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* type is declared by NS_IMETHODIMP
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*/
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NS_IMETHODIMP
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nsSampleImpl::GetValue(char** aValue)
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{
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NS_PRECONDITION(aValue != nsnull, "null ptr");
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if (! aValue)
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return NS_ERROR_NULL_POINTER;
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if (mValue) {
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/**
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* GetValue's job is to return data known by an instance of
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* nsSampleImpl to the outside world. If we were to simply return
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* a pointer to data owned by this instance, and the client were to
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* free it, bad things would surely follow.
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* On the other hand, if we create a new copy of the data for our
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* client, and it turns out that client is implemented in JavaScript,
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* there would be no way to free the buffer. The solution to the
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* buffer ownership problem is the nsMemory singleton. Any buffer
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* returned by an XPCOM method should be allocated by the nsMemory.
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* This convention lets things like JavaScript reflection do their
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* job, and simplifies the way C++ clients deal with returned buffers.
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*/
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*aValue = (char*) nsMemory::Clone(mValue, strlen(mValue) + 1);
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if (! *aValue)
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return NS_ERROR_NULL_POINTER;
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}
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else {
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*aValue = nsnull;
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}
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return NS_OK;
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}
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NS_IMETHODIMP
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nsSampleImpl::SetValue(const char* aValue)
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{
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NS_PRECONDITION(aValue != nsnull, "null ptr");
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if (! aValue)
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return NS_ERROR_NULL_POINTER;
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if (mValue) {
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nsMemory::Free(mValue);
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}
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/**
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* Another buffer passing convention is that buffers passed INTO your
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* object ARE NOT YOURS. Keep your hands off them, unless they are
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* declared "inout". If you want to keep the value for posterity,
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* you will have to make a copy of it.
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*/
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mValue = (char*) nsMemory::Clone(aValue, strlen(aValue) + 1);
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return NS_OK;
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}
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NS_IMETHODIMP
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nsSampleImpl::Poke(const char* aValue)
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{
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return SetValue((char*) aValue);
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}
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static void GetStringValue(nsACString& aValue)
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{
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NS_CStringSetData(aValue, "GetValue");
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}
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NS_IMETHODIMP
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nsSampleImpl::WriteValue(const char* aPrefix)
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{
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NS_PRECONDITION(aPrefix != nsnull, "null ptr");
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if (! aPrefix)
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return NS_ERROR_NULL_POINTER;
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printf("%s %s\n", aPrefix, mValue);
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// This next part illustrates the nsEmbedString:
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nsEmbedString foopy;
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foopy.Append(PRUnichar('f'));
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foopy.Append(PRUnichar('o'));
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foopy.Append(PRUnichar('o'));
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foopy.Append(PRUnichar('p'));
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foopy.Append(PRUnichar('y'));
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const PRUnichar* f = foopy.get();
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PRUint32 l = foopy.Length();
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printf("%c%c%c%c%c %d\n", char(f[0]), char(f[1]), char(f[2]), char(f[3]), char(f[4]), l);
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nsEmbedCString foopy2;
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GetStringValue(foopy2);
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//foopy2.AppendLiteral("foopy");
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const char* f2 = foopy2.get();
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PRUint32 l2 = foopy2.Length();
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printf("%s %d\n", f2, l2);
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return NS_OK;
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}
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