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Observer.h
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236 lines (189 loc) · 6.06 KB
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// Copyright Sebastian Jeckel 2014.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#pragma once
#include "react/detail/Defs.h"
#include <memory>
#include <unordered_map>
#include "react/detail/IReactiveNode.h"
#include "react/detail/graph/ObserverNodes.h"
/*****************************************/ REACT_BEGIN /*****************************************/
template <typename T>
class Reactive;
template <typename D, typename S>
class Signal;
template <typename D, typename E>
class Events;
enum class EventToken;
///////////////////////////////////////////////////////////////////////////////////////////////////
/// Observer
///////////////////////////////////////////////////////////////////////////////////////////////////
template <typename D>
class Observer
{
public:
using SubjectT = REACT_IMPL::NodeBase<D>;
using ObserverNodeT = REACT_IMPL::ObserverNode<D>;
Observer() :
ptr_{ nullptr },
subject_{ nullptr }
{
}
Observer(ObserverNodeT* ptr, const std::shared_ptr<SubjectT>& subject) :
ptr_{ ptr },
subject_{ subject }
{
}
const ObserverNodeT* GetPtr() const
{
return ptr_;
}
bool Detach()
{
if (ptr_ == nullptr)
return false;
D::Observers().Unregister(ptr_);
return true;
}
private:
// Ownership managed by registry
ObserverNodeT* ptr_;
// While the observer handle exists, the subject is not destroyed
std::shared_ptr<SubjectT> subject_;
};
/******************************************/ REACT_END /******************************************/
/***************************************/ REACT_IMPL_BEGIN /**************************************/
///////////////////////////////////////////////////////////////////////////////////////////////////
/// ObserverRegistry
///////////////////////////////////////////////////////////////////////////////////////////////////
template <typename D>
class ObserverRegistry
{
public:
using SubjectT = NodeBase<D>;
private:
class Entry_
{
public:
Entry_(std::unique_ptr<IObserverNode>&& obs, SubjectT* aSubject) :
obs_{ std::move(obs) },
Subject{ aSubject }
{
}
Entry_(Entry_&& other) :
obs_(std::move(other.obs_)),
Subject(other.Subject)
{
}
SubjectT* Subject;
private:
// Manage lifetime
std::unique_ptr<IObserverNode> obs_;
};
public:
void Register(std::unique_ptr<IObserverNode>&& obs, SubjectT* subject)
{
auto* raw = obs.get();
observerMap_.emplace(raw, Entry_(std::move(obs),subject));
}
void Unregister(IObserverNode* obs)
{
obs->Detach();
observerMap_.erase(obs);
}
void UnregisterFrom(SubjectT* subject)
{
auto it = observerMap_.begin();
while (it != observerMap_.end())
{
if (it->second.Subject == subject)
{
it->first->Detach();
it = observerMap_.erase(it);
}
else
{
++it;
}
}
}
private:
std::unordered_map<IObserverNode*,Entry_> observerMap_;
};
/****************************************/ REACT_IMPL_END /***************************************/
/*****************************************/ REACT_BEGIN /*****************************************/
///////////////////////////////////////////////////////////////////////////////////////////////////
/// Observe
///////////////////////////////////////////////////////////////////////////////////////////////////
template
<
typename D,
typename F,
typename TArg
>
auto Observe(const Signal<D,TArg>& subject, F&& func)
-> Observer<D>
{
std::unique_ptr< REACT_IMPL::ObserverNode<D>> pUnique(
new REACT_IMPL::SignalObserverNode<D,TArg,F>(
subject.GetPtr(), std::forward<F>(func)));
auto* raw = pUnique.get();
D::Observers().Register(std::move(pUnique), subject.GetPtr().get());
return Observer<D>(raw, subject.GetPtr());
}
template
<
typename D,
typename F,
typename TArg,
typename = std::enable_if<
! std::is_same<TArg,EventToken>::value>::type
>
auto Observe(const Events<D,TArg>& subject, F&& func)
-> Observer<D>
{
std::unique_ptr< REACT_IMPL::ObserverNode<D>> pUnique(
new REACT_IMPL::EventObserverNode<D,TArg,F>(
subject.GetPtr(), std::forward<F>(func)));
auto* raw = pUnique.get();
D::Observers().Register(std::move(pUnique), subject.GetPtr().get());
return Observer<D>(raw, subject.GetPtr());
}
template
<
typename D,
typename F
>
auto Observe(const Events<D,EventToken>& subject, F&& func)
-> Observer<D>
{
auto f = [func] (EventToken _) { func(); };
std::unique_ptr< REACT_IMPL::ObserverNode<D>> pUnique(
new REACT_IMPL::EventObserverNode<D,EventToken,decltype(f)>(
subject.GetPtr(), std::move(f)));
auto* raw = pUnique.get();
D::Observers().Register(std::move(pUnique), subject.GetPtr().get());
return Observer<D>(raw, subject.GetPtr());
}
///////////////////////////////////////////////////////////////////////////////////////////////////
/// DetachAllObservers
///////////////////////////////////////////////////////////////////////////////////////////////////
template
<
typename D,
template <typename Domain_, typename Val_> class TNode,
typename TArg
>
void DetachAllObservers(const Reactive<TNode<D,TArg>>& subject)
{
D::Observers().UnregisterFrom(subject.GetPtr().get());
}
///////////////////////////////////////////////////////////////////////////////////////////////////
/// DetachThisObserver
///////////////////////////////////////////////////////////////////////////////////////////////////
inline void DetachThisObserver()
{
REACT_IMPL::current_observer_state_::shouldDetach = true;
}
/******************************************/ REACT_END /******************************************/