tdesktop/Telegram/SourceFiles/base/observer.h

465 lines
11 KiB
C++

/*
This file is part of Telegram Desktop,
the official desktop version of Telegram messaging app, see https://telegram.org
Telegram Desktop is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
It is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
In addition, as a special exception, the copyright holders give permission
to link the code of portions of this program with the OpenSSL library.
Full license: https://github.com/telegramdesktop/tdesktop/blob/master/LICENSE
Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
*/
#pragma once
#include <vector>
#include <deque>
#include "base/type_traits.h"
namespace base {
namespace internal {
using ObservableCallHandlers = base::lambda<void()>;
void RegisterPendingObservable(ObservableCallHandlers *handlers);
void UnregisterActiveObservable(ObservableCallHandlers *handlers);
void UnregisterObservable(ObservableCallHandlers *handlers);
template <typename EventType>
struct SubscriptionHandlerHelper {
using type = base::lambda<void(parameter_type<EventType>)>;
};
template <>
struct SubscriptionHandlerHelper<void> {
using type = base::lambda<void()>;
};
template <typename EventType>
using SubscriptionHandler = typename SubscriptionHandlerHelper<EventType>::type;
// Required because QShared/WeakPointer can't point to void.
class BaseObservableData {
};
template <typename EventType, typename Handler>
class CommonObservableData;
template <typename EventType, typename Handler>
class ObservableData;
} // namespace internal
class Subscription {
public:
Subscription() = default;
Subscription(const Subscription &) = delete;
Subscription &operator=(const Subscription &) = delete;
Subscription(Subscription &&other) : _node(base::take(other._node)), _removeMethod(other._removeMethod) {
}
Subscription &operator=(Subscription &&other) {
qSwap(_node, other._node);
qSwap(_removeMethod, other._removeMethod);
return *this;
}
explicit operator bool() const {
return (_node != nullptr);
}
void destroy() {
if (_node) {
(*_removeMethod)(_node);
delete _node;
_node = nullptr;
}
}
~Subscription() {
destroy();
}
private:
struct Node {
Node(const QSharedPointer<internal::BaseObservableData> &observable) : observable(observable) {
}
Node *next = nullptr;
Node *prev = nullptr;
QWeakPointer<internal::BaseObservableData> observable;
};
using RemoveMethod = void(*)(Node*);
Subscription(Node *node, RemoveMethod removeMethod) : _node(node), _removeMethod(removeMethod) {
}
Node *_node = nullptr;
RemoveMethod _removeMethod;
template <typename EventType, typename Handler>
friend class internal::CommonObservableData;
template <typename EventType, typename Handler>
friend class internal::ObservableData;
};
namespace internal {
template <typename EventType, typename Handler, bool EventTypeIsSimple>
class BaseObservable;
template <typename EventType, typename Handler>
class CommonObservable {
public:
Subscription add_subscription(Handler &&handler) {
if (!_data) {
_data = MakeShared<ObservableData<EventType, Handler>>(this);
}
return _data->append(std::move(handler));
}
private:
QSharedPointer<ObservableData<EventType, Handler>> _data;
friend class CommonObservableData<EventType, Handler>;
friend class BaseObservable<EventType, Handler, base::type_traits<EventType>::is_fast_copy_type::value>;
};
template <typename EventType, typename Handler>
class BaseObservable<EventType, Handler, true> : public internal::CommonObservable<EventType, Handler> {
public:
void notify(EventType event, bool sync = false) {
if (this->_data) {
this->_data->notify(std::move(event), sync);
}
}
};
template <typename EventType, typename Handler>
class BaseObservable<EventType, Handler, false> : public internal::CommonObservable<EventType, Handler> {
public:
void notify(EventType &&event, bool sync = false) {
if (this->_data) {
this->_data->notify(std::move(event), sync);
}
}
void notify(const EventType &event, bool sync = false) {
if (this->_data) {
auto event_copy = event;
this->_data->notify(std::move(event_copy), sync);
}
}
};
} // namespace internal
namespace internal {
template <typename EventType, typename Handler>
class CommonObservableData : public BaseObservableData {
public:
CommonObservableData(CommonObservable<EventType, Handler> *observable) : _observable(observable) {
}
Subscription append(Handler &&handler) {
auto node = new Node(_observable->_data, std::move(handler));
if (_begin) {
_end->next = node;
node->prev = _end;
_end = node;
} else {
_begin = _end = node;
}
return { _end, &CommonObservableData::destroyNode };
}
bool empty() const {
return !_begin;
}
private:
struct Node : public Subscription::Node {
Node(const QSharedPointer<BaseObservableData> &observer, Handler &&handler) : Subscription::Node(observer), handler(std::move(handler)) {
}
Handler handler;
};
void remove(Subscription::Node *node) {
if (node->prev) {
node->prev->next = node->next;
}
if (node->next) {
node->next->prev = node->prev;
}
if (_begin == node) {
_begin = static_cast<Node*>(node->next);
}
if (_end == node) {
_end = static_cast<Node*>(node->prev);
}
if (_current == node) {
_current = static_cast<Node*>(node->prev);
} else if (!_begin) {
_observable->_data.reset();
}
}
static void destroyNode(Subscription::Node *node) {
if (auto that = node->observable.toStrongRef()) {
static_cast<CommonObservableData*>(that.data())->remove(node);
}
}
template <typename CallCurrent>
void notifyEnumerate(CallCurrent callCurrent) {
_current = _begin;
do {
callCurrent();
if (_current) {
_current = static_cast<Node*>(_current->next);
} else if (_begin) {
_current = _begin;
} else {
break;
}
} while (_current);
}
bool destroyMeIfEmpty() const {
if (empty()) {
_observable->_data.reset();
return true;
}
return false;
}
CommonObservable<EventType, Handler> *_observable = nullptr;
Node *_begin = nullptr;
Node *_current = nullptr;
Node *_end = nullptr;
ObservableCallHandlers _callHandlers;
friend class ObservableData<EventType, Handler>;
};
template <typename EventType, typename Handler>
class ObservableData : public CommonObservableData<EventType, Handler> {
public:
using CommonObservableData<EventType, Handler>::CommonObservableData;
void notify(EventType &&event, bool sync) {
if (_handling) {
sync = false;
}
if (sync) {
_events.push_back(std::move(event));
callHandlers();
} else {
if (!this->_callHandlers) {
this->_callHandlers = [this]() {
callHandlers();
};
}
if (_events.empty()) {
RegisterPendingObservable(&this->_callHandlers);
}
_events.push_back(std::move(event));
}
}
~ObservableData() {
UnregisterObservable(&this->_callHandlers);
}
private:
void callHandlers() {
_handling = true;
auto events = base::take(_events);
for (auto &event : events) {
this->notifyEnumerate([this, &event]() {
this->_current->handler(event);
});
if (this->destroyMeIfEmpty()) {
return;
}
}
_handling = false;
UnregisterActiveObservable(&this->_callHandlers);
}
std::deque<EventType> _events;
bool _handling = false;
};
template <class Handler>
class ObservableData<void, Handler> : public CommonObservableData<void, Handler> {
public:
using CommonObservableData<void, Handler>::CommonObservableData;
void notify(bool sync) {
if (_handling) {
sync = false;
}
if (sync) {
++_eventsCount;
callHandlers();
} else {
if (!this->_callHandlers) {
this->_callHandlers = [this]() {
callHandlers();
};
}
if (!_eventsCount) {
RegisterPendingObservable(&this->_callHandlers);
}
++_eventsCount;
}
}
~ObservableData() {
UnregisterObservable(&this->_callHandlers);
}
private:
void callHandlers() {
_handling = true;
auto eventsCount = base::take(_eventsCount);
for (int i = 0; i != eventsCount; ++i) {
this->notifyEnumerate([this]() {
this->_current->handler();
});
if (this->destroyMeIfEmpty()) {
return;
}
}
_handling = false;
UnregisterActiveObservable(&this->_callHandlers);
}
int _eventsCount = 0;
bool _handling = false;
};
template <typename Handler>
class BaseObservable<void, Handler, base::type_traits<void>::is_fast_copy_type::value> : public internal::CommonObservable<void, Handler> {
public:
void notify(bool sync = false) {
if (this->_data) {
this->_data->notify(sync);
}
}
};
} // namespace internal
template <typename EventType, typename Handler = internal::SubscriptionHandler<EventType>>
class Observable : public internal::BaseObservable<EventType, Handler, base::type_traits<EventType>::is_fast_copy_type::value> {
public:
Observable() = default;
Observable(const Observable &other) = delete;
Observable(Observable &&other) = delete;
Observable &operator=(const Observable &other) = delete;
Observable &operator=(Observable &&other) = delete;
};
template <typename Type>
class Variable {
public:
Variable(parameter_type<Type> startValue = Type()) : _value(startValue) {
}
Variable(Variable &&other) = default;
Variable &operator=(Variable &&other) = default;
parameter_type<Type> value() const {
return _value;
}
void setForced(parameter_type<Type> newValue, bool sync = false) {
_value = newValue;
changed().notify(_value, sync);
}
void set(parameter_type<Type> newValue, bool sync = false) {
if (_value != newValue) {
setForced(newValue, sync);
}
}
template <typename Callback>
void process(Callback callback, bool sync = false) {
callback(_value);
changed().notify(_value, sync);
}
Observable<Type> &changed() const {
return _changed;
}
private:
Type _value;
mutable Observable<Type> _changed;
};
class Subscriber {
protected:
template <typename EventType, typename Handler, typename Lambda>
int subscribe(base::Observable<EventType, Handler> &observable, Lambda &&handler) {
_subscriptions.push_back(observable.add_subscription(std::forward<Lambda>(handler)));
return _subscriptions.size();
}
template <typename EventType, typename Handler, typename Lambda>
int subscribe(base::Observable<EventType, Handler> *observable, Lambda &&handler) {
return subscribe(*observable, std::forward<Lambda>(handler));
}
template <typename Type, typename Lambda>
int subscribe(const base::Variable<Type> &variable, Lambda &&handler) {
return subscribe(variable.changed(), std::forward<Lambda>(handler));
}
template <typename Type, typename Lambda>
int subscribe(const base::Variable<Type> *variable, Lambda &&handler) {
return subscribe(variable->changed(), std::forward<Lambda>(handler));
}
void unsubscribe(int index) {
if (!index) return;
auto count = static_cast<int>(_subscriptions.size());
t_assert(index > 0 && index <= count);
_subscriptions[index - 1].destroy();
if (index == count) {
while (index > 0 && !_subscriptions[--index]) {
_subscriptions.pop_back();
}
}
}
~Subscriber() {
auto subscriptions = base::take(_subscriptions);
for (auto &subscription : subscriptions) {
subscription.destroy();
}
}
private:
std::vector<base::Subscription> _subscriptions;
};
void HandleObservables();
} // namespace base