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79 lines
2.1 KiB
C++
79 lines
2.1 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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// A wrapper that uses RAII to ensure that a class invariant is checked
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// before and after any public function is called
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#ifndef CHECKINVARIANTWRAPPER_H_
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#define CHECKINVARIANTWRAPPER_H_
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#include "mozilla/Attributes.h"
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#include <utility>
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namespace mozilla {
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//
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// Wraps an object of type T and allows access to its public API by
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// deferencing it using the pointer syntax "->".
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//
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// Using that operator will return a temporary RAII object that
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// calls a method named "CheckInvariant" in its constructor, calls the
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// requested method, and then calls "CheckInvariant" again in its
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// destructor.
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//
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// The only thing your class requires is a method with the following signature:
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//
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// void CheckInvariant() const;
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//
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template <typename T>
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class CheckInvariantWrapper {
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public:
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class Wrapper {
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public:
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explicit Wrapper(T& aObject) : mObject(aObject) {
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mObject.CheckInvariant();
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}
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~Wrapper() { mObject.CheckInvariant(); }
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T* operator->() { return &mObject; }
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private:
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T& mObject;
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};
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class ConstWrapper {
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public:
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explicit ConstWrapper(const T& aObject) : mObject(aObject) {
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mObject.CheckInvariant();
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}
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~ConstWrapper() { mObject.CheckInvariant(); }
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const T* operator->() const { return &mObject; }
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private:
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const T& mObject;
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};
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CheckInvariantWrapper() = default;
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MOZ_IMPLICIT CheckInvariantWrapper(T aObject) : mObject(std::move(aObject)) {}
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template <typename... Args>
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explicit CheckInvariantWrapper(std::in_place_t, Args&&... args)
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: mObject(std::forward<Args>(args)...) {}
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const ConstWrapper operator->() const { return ConstWrapper(mObject); }
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Wrapper operator->() { return Wrapper(mObject); }
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private:
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T mObject;
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};
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} // namespace mozilla
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#endif // CHECKINVARIANTWRAPPER_H_
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