forked from qt-creator/qt-creator
72e19c4886
It replaces59c90e00c1andd0c537ca75Task-number: QTCREATORBUG-17048 Change-Id: Ief4b1b72f2e5e7b1711be05d4ea8c03bbbf48fdf Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>
114 lines
3.0 KiB
C++
114 lines
3.0 KiB
C++
/****************************************************************************
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**
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** Copyright (C) 2016 The Qt Company Ltd.
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** Contact: https://www.qt.io/licensing/
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**
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** This file is part of Qt Creator.
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**
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/contact-us.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 3 as published by the Free Software
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** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
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** included in the packaging of this file. Please review the following
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** information to ensure the GNU General Public License requirements will
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** be met: https://www.gnu.org/licenses/gpl-3.0.html.
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**
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****************************************************************************/
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#include "guard.h"
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#include "qtcassert.h"
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/*! \class Utils::Guard
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\brief The Guard class implements a recursive guard with locking mechanism.
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It may be used as an alternative to QSignalBlocker.
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QSignalBlocker blocks all signals of the object
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which is usually not desirable. It may also block signals
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which are needed internally by the object itself.
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The Guard and GuardLocker classes don't block signals at all.
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When calling a object's method which may in turn emit a signal
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which you are connected to, and you want to ignore
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this notification, you should keep the Guard object
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as your class member and declare the GuardLocker object
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just before calling the mentioned method, like:
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\code
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class MyClass : public QObject
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{
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\dots
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private:
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Guard updateGuard; // member of your class
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};
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\dots
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void MyClass::updateOtherObject()
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{
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GuardLocker updatelocker(updateGuard);
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otherObject->update(); // this may trigger a signal
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}
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\endcode
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Inside a slot which is connected to the other's object signal
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you may check if the guard is locked and ignore the further
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operations in this case:
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\code
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void MyClass::otherObjectUpdated()
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{
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if (updateGuard.isLocked)
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return;
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// we didn't trigger the update
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// so do update now
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\dots
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}
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\endcode
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The GuardLock unlocks the Guard in it's destructor.
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The Guard object is recursive, you may declare many GuardLocker
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objects for the same Guard instance and the Guard will be locked
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as long as at least one GuardLocker object created for the Guard
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is in scope.
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*/
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namespace Utils {
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Guard::Guard()
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{
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}
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Guard::~Guard()
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{
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QTC_CHECK(m_lockCount == 0);
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}
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bool Guard::isLocked() const
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{
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return m_lockCount;
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}
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GuardLocker::GuardLocker(Guard &guard)
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: m_guard(guard)
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{
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++m_guard.m_lockCount;
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}
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GuardLocker::~GuardLocker()
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{
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--m_guard.m_lockCount;
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}
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} // namespace Utils
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