124 lines
3.7 KiB
C++
124 lines
3.7 KiB
C++
//This file is part of Bertini 2.
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//
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//bertini2/detail/observer.hpp is free software: you can redistribute it and/or modify
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//it under the terms of the GNU General Public License as published by
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//the Free Software Foundation, either version 3 of the License, or
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//(at your option) any later version.
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//
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//bertini2/detail/observer.hpp is distributed in the hope that it will be useful,
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//but WITHOUT ANY WARRANTY; without even the implied warranty of
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//MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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//GNU General Public License for more details.
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//
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//You should have received a copy of the GNU General Public License
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//along with bertini2/detail/observer.hpp. If not, see <http://www.gnu.org/licenses/>.
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//
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// Copyright(C) 2015 - 2021 by Bertini2 Development Team
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//
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// See <http://www.gnu.org/licenses/> for a copy of the license,
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// as well as COPYING. Bertini2 is provided with permitted
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// additional terms in the b2/licenses/ directory.
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// individual authors of this file include:
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// silviana amethyst, university of wisconsin-eau claire
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//
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/**
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\file bertini2/detail/observer.hpp
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\brief Contains the observer base types.
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*/
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#ifndef BERTINI_DETAIL_OBSERVER_HPP
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#define BERTINI_DETAIL_OBSERVER_HPP
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#include <tuple>
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#include <utility>
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#include <boost/fusion/adapted/std_tuple.hpp>
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#include <boost/fusion/algorithm/iteration/for_each.hpp>
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#include <boost/fusion/include/for_each.hpp>
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#include "bertini2/detail/events.hpp"
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namespace bertini{
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/**
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\brief Strawman base class for Observer objects.
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\see Observer
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*/
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class AnyObserver
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{ BOOST_TYPE_INDEX_REGISTER_CLASS
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public:
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virtual ~AnyObserver() = default;
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/**
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\brief Observe the observable object being observed. This is probably in response to NotifyObservers.
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This virtual function must be overridden by actual observers, defining how they observe the observable they are observing, probably filtering events and doing something specific for different ones.
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\param e The event which was emitted by the observed object.
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*/
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virtual void Observe(AnyEvent const& e) = 0;
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};
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/**
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\brief Actual observer type, which you should derive from to extract custom information from observable types.
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\tparam ObservedT The type of object the observer observes.
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\tparam RetT The type of object the observer returns when it visits.
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\see PrecisionAccumulator, GoryDetailLogger, MultiObserver
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*/
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template<class ObservedT>
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class Observer : public AnyObserver
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{ BOOST_TYPE_INDEX_REGISTER_CLASS
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public:
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virtual ~Observer() = default;
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};
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/**
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\brief A class which can glob together observer types into a new, single observer type.
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If there are pre-existing observers for the object you wish to observe, rather than making one of each, and attaching each to the observable, you can make many things one.
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https://frinkiac.com/?q=many%20guns%20into%20five
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\tparam ObservedT The type of thing the observer types you are gluing together observe. They must all observe the same type of object.
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\tparam ObserverTypes The already-existing observer types you are gluing together. You can put as many of them together as you want!
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*/
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template<class ObservedT, template<class> class... ObserverTypes>
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class MultiObserver : public Observer<ObservedT>
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{ BOOST_TYPE_INDEX_REGISTER_CLASS
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public:
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/**
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\brief Observe override which calls the overrides for the types you glued together.
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\param e The emitted event which caused observation.
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*/
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void Observe(AnyEvent const& e) override
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{
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using namespace boost::fusion;
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auto f = [&e](auto &obs) { obs.Observe(e); };
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for_each(observers_, f);
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}
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std::tuple<ObserverTypes<ObservedT>...> observers_;
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virtual ~MultiObserver() = default;
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};
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}
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#endif
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