зеркало из https://github.com/mozilla/pjs.git
244 строки
9.0 KiB
C++
244 строки
9.0 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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* vim: set ts=8 sw=4 et tw=99 ft=cpp:
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*
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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 Code.
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*
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* The Initial Developer of the Original Code is
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* The Mozilla Foundation
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* Portions created by the Initial Developer are Copyright (C) 2011
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Jeff Walden <jwalden+code@mit.edu> (original author)
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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 the GNU General Public License Version 2 or later (the "GPL"), or
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* 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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/* Implementations of various C++ class and method modifier attributes. */
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#ifndef mozilla_Attributes_h_
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#define mozilla_Attributes_h_
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/*
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* This header does not include any other headers so that it can be included by
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* code that is (only currently) mfbt-incompatible.
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*/
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#ifndef __cplusplus
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#error "mozilla/Attributes.h is only relevant to C++ code."
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#endif
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/*
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* g++ requires -std=c++0x or -std=gnu++0x to support C++11 functionality
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* without warnings (functionality used by the macros below). These modes are
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* detectable by checking whether __GXX_EXPERIMENTAL_CXX0X__ is defined or, more
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* standardly, by checking whether __cplusplus has a C++11 or greater value.
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* Current versions of g++ do not correctly set __cplusplus, so we check both
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* for forward compatibility.
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*/
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#if defined(__clang__)
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# if __clang_major__ >= 3
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# define MOZ_HAVE_CXX11_DELETE
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# define MOZ_HAVE_CXX11_OVERRIDE
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# define MOZ_HAVE_CXX11_FINAL final
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# elif __clang_major__ == 2
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# if __clang_minor__ >= 9
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# define MOZ_HAVE_CXX11_DELETE
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# endif
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# endif
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#elif defined(__GNUC__)
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# if defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L
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# if __GNUC__ > 4
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# define MOZ_HAVE_CXX11_DELETE
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# define MOZ_HAVE_CXX11_OVERRIDE
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# define MOZ_HAVE CXX11_FINAL final
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# elif __GNUC__ == 4
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# if __GNUC_MINOR__ >= 7
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# define MOZ_HAVE_CXX11_OVERRIDE
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# endif
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# if __GNUC_MINOR__ >= 4
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# define MOZ_HAVE_CXX11_DELETE
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# endif
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# endif
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# else
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/* __final is a non-C++11 GCC synonym for 'final', per GCC r176655. */
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# if __GNUC__ > 4
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# define MOZ_HAVE_CXX11_FINAL __final
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# elif __GNUC__ == 4
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# if __GNUC_MINOR__ >= 7
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# define MOZ_HAVE_CXX11_FINAL __final
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# endif
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# endif
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# endif
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#elif defined(_MSC_VER)
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# if _MSC_VER >= 1400
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# define MOZ_HAVE_CXX11_OVERRIDE
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/* MSVC currently spells "final" as "sealed". */
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# define MOZ_HAVE_CXX11_FINAL sealed
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# endif
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#endif
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/*
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* MOZ_DELETE, specified immediately prior to the ';' terminating an undefined-
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* method declaration, attempts to delete that method from the corresponding
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* class. An attempt to use the method will always produce an error *at compile
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* time* (instead of sometimes as late as link time) when this macro can be
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* implemented. For example, you can use MOZ_DELETE to produce classes with no
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* implicit copy constructor or assignment operator:
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*
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* struct NonCopyable
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* {
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* private:
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* NonCopyable(const NonCopyable& other) MOZ_DELETE;
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* void operator=(const NonCopyable& other) MOZ_DELETE;
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* };
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*
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* If MOZ_DELETE can't be implemented for the current compiler, use of the
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* annotated method will still cause an error, but the error might occur at link
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* time in some cases rather than at compile time.
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*
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* MOZ_DELETE relies on C++11 functionality not universally implemented. As a
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* backstop, method declarations using MOZ_DELETE should be private.
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*/
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#if defined(MOZ_HAVE_CXX11_DELETE)
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# define MOZ_DELETE = delete
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#else
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# define MOZ_DELETE /* no support */
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#endif
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/*
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* MOZ_OVERRIDE explicitly indicates that a virtual member function in a class
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* overrides a member function of a base class, rather than potentially being a
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* new member function. MOZ_OVERRIDE should be placed immediately before the
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* ';' terminating the member function's declaration, or before '= 0;' if the
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* member function is pure. If the member function is defined in the class
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* definition, it should appear before the opening brace of the function body.
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*
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* class Base
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* {
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* public:
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* virtual void f() = 0;
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* };
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* class Derived1 : public Base
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* {
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* public:
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* virtual void f() MOZ_OVERRIDE;
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* };
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* class Derived2 : public Base
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* {
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* public:
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* virtual void f() MOZ_OVERRIDE = 0;
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* };
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* class Derived3 : public Base
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* {
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* public:
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* virtual void f() MOZ_OVERRIDE { }
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* };
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*
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* In compilers supporting C++11 override controls, MOZ_OVERRIDE *requires* that
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* the function marked with it override a member function of a base class: it
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* is a compile error if it does not. Otherwise MOZ_OVERRIDE does not affect
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* semantics and merely documents the override relationship to the reader (but
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* of course must still be used correctly to not break C++11 compilers).
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*/
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#if defined(MOZ_HAVE_CXX11_OVERRIDE)
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# define MOZ_OVERRIDE override
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#else
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# define MOZ_OVERRIDE /* no support */
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#endif
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/*
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* MOZ_FINAL indicates that some functionality cannot be overridden through
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* inheritance. It can be used to annotate either classes/structs or virtual
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* member functions.
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*
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* To annotate a class/struct with MOZ_FINAL, place MOZ_FINAL immediately after
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* the name of the class, before the list of classes from which it derives (if
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* any) and before its opening brace. MOZ_FINAL must not be used to annotate
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* unnamed classes or structs. (With some compilers, and with C++11 proper, the
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* underlying expansion is ambiguous with specifying a class name.)
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*
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* class Base MOZ_FINAL
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* {
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* public:
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* Base();
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* ~Base();
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* virtual void f() { }
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* };
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* // This will be an error in some compilers:
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* class Derived : public Base
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* {
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* public:
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* ~Derived() { }
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* };
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*
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* One particularly common reason to specify MOZ_FINAL upon a class is to tell
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* the compiler that it's not dangerous for it to have a non-virtual destructor
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* yet have one or more virtual functions, silencing the warning it might emit
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* in this case. Suppose Base above weren't annotated with MOZ_FINAL. Because
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* ~Base() is non-virtual, an attempt to delete a Derived* through a Base*
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* wouldn't call ~Derived(), so any cleanup ~Derived() might do wouldn't happen.
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* (Formally C++ says behavior is undefined, but compilers will likely just call
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* ~Base() and not ~Derived().) Specifying MOZ_FINAL tells the compiler that
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* it's safe for the destructor to be non-virtual.
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*
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* In compilers implementing final controls, it is an error to inherit from a
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* class annotated with MOZ_FINAL. In other compilers it serves only as
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* documentation.
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*
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* To annotate a virtual member function with MOZ_FINAL, place MOZ_FINAL
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* immediately before the ';' terminating the member function's declaration, or
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* before '= 0;' if the member function is pure. If the member function is
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* defined in the class definition, it should appear before the opening brace of
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* the function body. (This placement is identical to that for MOZ_OVERRIDE.
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* If both are used, they should appear in the order 'MOZ_FINAL MOZ_OVERRIDE'
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* for consistency.)
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*
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* class Base
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* {
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* public:
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* virtual void f() MOZ_FINAL;
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* };
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* class Derived
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* {
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* public:
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* // This will be an error in some compilers:
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* virtual void f();
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* };
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*
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* In compilers implementing final controls, it is an error for a derived class
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* to override a method annotated with MOZ_FINAL. In other compilers it serves
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* only as documentation.
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*/
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#if defined(MOZ_HAVE_CXX11_FINAL)
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# define MOZ_FINAL MOZ_HAVE_CXX11_FINAL
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#else
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# define MOZ_FINAL /* no support */
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#endif
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#endif /* mozilla_Attributes_h_ */
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