AggregateObserverBuilder.h

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#pragma once
#include "ObserverTypes.h"
#include "catapult/utils/NamedObject.h"
#include <vector>
 
namespace catapult { namespace observers {
 
    template<typename TNotification>
    class AggregateObserverBuilder {
    private:
        using NotificationObserverPointer = NotificationObserverPointerT<TNotification>;
        using NotificationObserverPointerVector = std::vector<NotificationObserverPointer>;
 
    public:
        AggregateObserverBuilder& add(NotificationObserverPointer&& pObserver) {
            m_observers.push_back(std::move(pObserver));
            return *this;
        }
 
        AggregateNotificationObserverPointerT<TNotification> build() {
            return std::make_unique<DefaultAggregateNotificationObserver>(std::move(m_observers));
        }
 
    private:
        class DefaultAggregateNotificationObserver : public AggregateNotificationObserverT<TNotification> {
        public:
            explicit DefaultAggregateNotificationObserver(NotificationObserverPointerVector&& observers)
                    : m_observers(std::move(observers))
                    , m_name(utils::ReduceNames(utils::ExtractNames(m_observers)))
            {}
 
        public:
            const std::string& name() const override {
                return m_name;
            }
 
            std::vector<std::string> names() const override {
                return utils::ExtractNames(m_observers);
            }
 
            void notify(const TNotification& notification, ObserverContext& context) const override {
                if (NotifyMode::Commit == context.Mode)
                    notifyAll(m_observers.cbegin(), m_observers.cend(), notification, context);
                else
                    notifyAll(m_observers.crbegin(), m_observers.crend(), notification, context);
            }
 
        private:
            template<typename TIter>
            void notifyAll(TIter begin, TIter end, const TNotification& notification, ObserverContext& context) const {
                for (auto iter = begin; end != iter; ++iter)
                    (*iter)->notify(notification, context);
            }
 
        private:
            NotificationObserverPointerVector m_observers;
            std::string m_name;
        };
 
    private:
        NotificationObserverPointerVector m_observers;
    };
}}