166 lines
3.9 KiB
C++
166 lines
3.9 KiB
C++
//=============================================================================
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// MuseScore
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// Music Composition & Notation
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//
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// Copyright (C) 2018 Werner Schweer
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License version 2
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// as published by the Free Software Foundation and appearing in
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// the file LICENCE.GPL
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//=============================================================================
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#ifndef __NOTIFIER_H__
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#define __NOTIFIER_H__
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namespace Ms {
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template<typename Data> class Notifier;
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//---------------------------------------------------------
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// Listener
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//---------------------------------------------------------
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template<typename Data>
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class Listener
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{
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Notifier<Data>* _notifier = nullptr;
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public:
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Listener() = default;
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Listener(Notifier<Data>* n)
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: _notifier(n) {}
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// do not copy notifier attachment
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Listener(const Listener<Data>&) {}
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Listener(Listener<Data>&&);
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Listener& operator=(const Listener<Data>&) { return *this; }
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Listener& operator=(Listener&&);
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~Listener();
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void setNotifier(Notifier<Data>* n);
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void detachNotifier(Notifier<Data>* n)
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{
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if (_notifier == n) {
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setNotifier(nullptr);
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}
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}
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Notifier<Data>* notifier() { return _notifier; }
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const Notifier<Data>* notifier() const { return _notifier; }
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virtual void receive(Data d) = 0;
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template<typename T>
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friend void swap(Listener<T>& l1, Listener<T>& l2);
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};
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//---------------------------------------------------------
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// Notifier
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//---------------------------------------------------------
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template<typename Data>
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class Notifier
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{
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std::vector<Listener<Data>*> _listeners;
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bool _atChange = false;
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public:
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Notifier() = default;
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// do not copy listeners list
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Notifier(const Notifier<Data>&) {}
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Notifier& operator=(const Notifier<Data>&) { return *this; }
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~Notifier()
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{
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_atChange = true; // we don't need to update listeners list anymore
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for (Listener<Data>* l : _listeners) {
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l->detachNotifier(this);
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}
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}
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void addListener(Listener<Data>* l)
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{
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if (_atChange || !l) {
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return;
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}
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_atChange = true;
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_listeners.push_back(l);
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l->setNotifier(this);
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_atChange = false;
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}
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void removeListener(Listener<Data>* l)
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{
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if (_atChange || !l) {
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return;
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}
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_atChange = true;
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_listeners.erase(std::remove(_listeners.begin(), _listeners.end(), l), _listeners.end());
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l->detachNotifier(this);
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_atChange = false;
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}
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void notify(Data d) const
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{
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for (Listener<Data>* l : _listeners) {
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l->receive(d);
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}
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}
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};
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template<typename Data>
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Listener<Data>::Listener(Listener<Data>&& other)
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{
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if (Notifier<Data>* n = other.notifier()) {
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n->removeListener(other);
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setNotifier(n);
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}
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}
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template<typename Data>
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Listener<Data>& Listener<Data>::operator=(Listener<Data>&& other)
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{
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if (Notifier<Data>* n = other.notifier()) {
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n->removeListener(other);
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setNotifier(n);
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} else {
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setNotifier(nullptr);
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}
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return *this;
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}
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template<typename Data>
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Listener<Data>::~Listener()
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{
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if (_notifier) {
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_notifier->removeListener(this);
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}
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}
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template<typename Data>
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void Listener<Data>::setNotifier(Notifier<Data>* n)
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{
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if (n == _notifier) {
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return;
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}
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Notifier<Data>* oldNotifier = _notifier;
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_notifier = n;
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if (oldNotifier) {
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oldNotifier->removeListener(this);
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}
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if (_notifier) {
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_notifier->addListener(this);
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}
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}
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template<typename Data>
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void swap(Listener<Data>& l1, Listener<Data>& l2)
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{
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Notifier<Data>* n1 = l1.notifier();
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Notifier<Data>* n2 = l2.notifier();
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l1.setNotifier(n2);
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l2.setNotifier(n1);
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}
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} // namespace Ms
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#endif
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