| 1 | /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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| 2 | /* ***** BEGIN LICENSE BLOCK *****
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| 3 | * Version: MPL 1.1/GPL 2.0/LGPL 2.1
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| 4 | *
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| 5 | * The contents of this file are subject to the Mozilla Public License Version
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| 6 | * 1.1 (the "License"); you may not use this file except in compliance with
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| 7 | * the License. You may obtain a copy of the License at
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| 8 | * http://www.mozilla.org/MPL/
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| 9 | *
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| 10 | * Software distributed under the License is distributed on an "AS IS" basis,
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| 11 | * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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| 12 | * for the specific language governing rights and limitations under the
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| 13 | * License.
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| 14 | *
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| 15 | * The Original Code is Mozilla FastLoad code.
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| 16 | *
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| 17 | * The Initial Developer of the Original Code is
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| 18 | * Netscape Communications Corporation.
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| 19 | * Portions created by the Initial Developer are Copyright (C) 2001
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| 20 | * the Initial Developer. All Rights Reserved.
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| 21 | *
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| 22 | * Contributor(s):
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| 23 | * Brendan Eich <brendan@mozilla.org> (original author)
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| 24 | *
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| 25 | * Alternatively, the contents of this file may be used under the terms of
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| 26 | * either of the GNU General Public License Version 2 or later (the "GPL"),
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| 27 | * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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| 28 | * in which case the provisions of the GPL or the LGPL are applicable instead
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| 29 | * of those above. If you wish to allow use of your version of this file only
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| 30 | * under the terms of either the GPL or the LGPL, and not to allow others to
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| 31 | * use your version of this file under the terms of the MPL, indicate your
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| 32 | * decision by deleting the provisions above and replace them with the notice
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| 33 | * and other provisions required by the GPL or the LGPL. If you do not delete
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| 34 | * the provisions above, a recipient may use your version of this file under
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| 35 | * the terms of any one of the MPL, the GPL or the LGPL.
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| 36 | *
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| 37 | * ***** END LICENSE BLOCK ***** */
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| 38 |
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| 39 | #ifndef nsFastLoadPtr_h___
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| 40 | #define nsFastLoadPtr_h___
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| 41 |
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| 42 | /**
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| 43 | * Mozilla FastLoad file object pointer template type.
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| 44 | *
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| 45 | * Use nsFastLoadPtr<T> rather than nsCOMPtr<T> when declaring a strong XPCOM
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| 46 | * ref member of a data structure that's conditionally loaded at application
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| 47 | * startup. You must be willing to tolerate the null mRawPtr test on every
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| 48 | * dereference of this member pointer, or else copy it to a local to optimize
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| 49 | * away the cost.
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| 50 | */
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| 51 |
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| 52 | #ifndef nsCOMPtr_h___
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| 53 | #include "nsCOMPtr.h"
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| 54 | #endif
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| 55 |
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| 56 | #ifndef nsIFastLoadService_h___
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| 57 | #include "nsIFastLoadService.h"
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| 58 | #endif
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| 59 |
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| 60 | /**
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| 61 | * nsFastLoadPtr is a template class, so we don't want a class static service
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| 62 | * pointer member declared in nsFastLoadPtr, above. Plus, we need special
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| 63 | * declaration magic to export data across DLL/DSO boundaries. So we use an
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| 64 | * old-fashioned global variable that refers weakly to the one true FastLoad
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| 65 | * service. This pointer is maintained by that singleton's ctor and dtor.
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| 66 | */
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| 67 | PR_EXPORT_DATA(nsIFastLoadService*) gFastLoadService_;
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| 68 |
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| 69 | template <class T>
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| 70 | class nsFastLoadPtr : public nsCOMPtr<T> {
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| 71 | public:
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| 72 | nsDerivedSafe<T>* get() const {
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| 73 | if (!this->mRawPtr) {
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| 74 | gFastLoadService_->GetFastLoadReferent(
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| 75 | NS_REINTERPRET_CAST(nsISupports**,
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| 76 | &this->mRawPtr));
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| 77 | }
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| 78 | return NS_REINTERPRET_CAST(nsDerivedSafe<T>*, this->mRawPtr);
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| 79 | }
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| 80 |
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| 81 | /**
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| 82 | * Deserialize an nsFastLoadPtr from aInputStream, skipping the referent
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| 83 | * object, but saving the object's offset for later deserialization.
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| 84 | *
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| 85 | * Lowercase name _a la_ get, because it's called the same way -- not via
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| 86 | * operator->().
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| 87 | */
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| 88 | nsresult read(nsIObjectInputStream* aInputStream) {
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| 89 | return gFastLoadService_->ReadFastLoadPtr(aInputStream,
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| 90 | NS_REINTERPRET_CAST(nsISupports**,
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| 91 | &this->mRawPtr));
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| 92 | }
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| 93 |
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| 94 | /**
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| 95 | * Serialize an nsFastLoadPtr reference and possibly the referent object,
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| 96 | * if that object has not yet been serialized.
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| 97 | *
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| 98 | * Lowercase name _a la_ get, because it's called the same way -- not via
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| 99 | * operator->().
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| 100 | */
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| 101 | nsresult write(nsIObjectOutputStream* aOutputStream) {
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| 102 | return gFastLoadService_->WriteFastLoadPtr(aOutputStream,
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| 103 | NS_REINTERPRET_CAST(nsISupports*,
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| 104 | this->mRawPtr));
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| 105 | }
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| 106 | };
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| 107 |
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| 108 | #endif // nsFastLoadPtr_h___
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