473 lines
15 KiB
C
473 lines
15 KiB
C
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/* -*- mode: C++; indent-tabs-mode: nil; -*-
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*
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* This file is a part of LEMON, a generic C++ optimization library.
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*
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* Copyright (C) 2003-2013
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* Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
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* (Egervary Research Group on Combinatorial Optimization, EGRES).
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*
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* Permission to use, modify and distribute this software is granted
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* provided that this copyright notice appears in all copies. For
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* precise terms see the accompanying LICENSE file.
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*
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* This software is provided "AS IS" with no warranty of any kind,
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* express or implied, and with no claim as to its suitability for any
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* purpose.
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*
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*/
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#ifndef LEMON_BITS_ALTERATION_NOTIFIER_H
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#define LEMON_BITS_ALTERATION_NOTIFIER_H
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#include <vector>
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#include <list>
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#include <lemon/core.h>
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#include <lemon/bits/lock.h>
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//\ingroup graphbits
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//\file
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//\brief Observer notifier for graph alteration observers.
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namespace lemon {
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// \ingroup graphbits
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//
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// \brief Notifier class to notify observes about alterations in
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// a container.
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//
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// The simple graphs can be refered as two containers: a node container
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// and an edge container. But they do not store values directly, they
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// are just key continars for more value containers, which are the
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// node and edge maps.
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//
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// The node and edge sets of the graphs can be changed as we add or erase
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// nodes and edges in the graph. LEMON would like to handle easily
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// that the node and edge maps should contain values for all nodes or
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// edges. If we want to check on every indicing if the map contains
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// the current indicing key that cause a drawback in the performance
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// in the library. We use another solution: we notify all maps about
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// an alteration in the graph, which cause only drawback on the
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// alteration of the graph.
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//
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// This class provides an interface to a node or edge container.
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// The first() and next() member functions make possible
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// to iterate on the keys of the container.
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// The id() function returns an integer id for each key.
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// The maxId() function gives back an upper bound of the ids.
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//
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// For the proper functonality of this class, we should notify it
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// about each alteration in the container. The alterations have four type:
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// add(), erase(), build() and clear(). The add() and
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// erase() signal that only one or few items added or erased to or
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// from the graph. If all items are erased from the graph or if a new graph
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// is built from an empty graph, then it can be signaled with the
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// clear() and build() members. Important rule that if we erase items
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// from graphs we should first signal the alteration and after that erase
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// them from the container, on the other way on item addition we should
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// first extend the container and just after that signal the alteration.
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//
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// The alteration can be observed with a class inherited from the
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// ObserverBase nested class. The signals can be handled with
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// overriding the virtual functions defined in the base class. The
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// observer base can be attached to the notifier with the
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// attach() member and can be detached with detach() function. The
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// alteration handlers should not call any function which signals
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// an other alteration in the same notifier and should not
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// detach any observer from the notifier.
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//
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// Alteration observers try to be exception safe. If an add() or
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// a clear() function throws an exception then the remaining
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// observeres will not be notified and the fulfilled additions will
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// be rolled back by calling the erase() or clear() functions.
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// Hence erase() and clear() should not throw exception.
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// Actullay, they can throw only \ref ImmediateDetach exception,
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// which detach the observer from the notifier.
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//
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// There are some cases, when the alteration observing is not completly
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// reliable. If we want to carry out the node degree in the graph
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// as in the \ref InDegMap and we use the reverseArc(), then it cause
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// unreliable functionality. Because the alteration observing signals
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// only erasing and adding but not the reversing, it will stores bad
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// degrees. Apart form that the subgraph adaptors cannot even signal
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// the alterations because just a setting in the filter map can modify
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// the graph and this cannot be watched in any way.
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//
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// \param _Container The container which is observed.
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// \param _Item The item type which is obserbved.
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template <typename _Container, typename _Item>
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class AlterationNotifier {
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public:
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typedef True Notifier;
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typedef _Container Container;
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typedef _Item Item;
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// \brief Exception which can be called from clear() and
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// erase().
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//
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// From the clear() and erase() function only this
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// exception is allowed to throw. The exception immediatly
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// detaches the current observer from the notifier. Because the
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// clear() and erase() should not throw other exceptions
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// it can be used to invalidate the observer.
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struct ImmediateDetach {};
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// \brief ObserverBase is the base class for the observers.
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//
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// ObserverBase is the abstract base class for the observers.
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// It will be notified about an item was inserted into or
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// erased from the graph.
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//
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// The observer interface contains some pure virtual functions
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// to override. The add() and erase() functions are
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// to notify the oberver when one item is added or erased.
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//
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// The build() and clear() members are to notify the observer
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// about the container is built from an empty container or
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// is cleared to an empty container.
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class ObserverBase {
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protected:
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typedef AlterationNotifier Notifier;
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friend class AlterationNotifier;
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// \brief Default constructor.
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//
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// Default constructor for ObserverBase.
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ObserverBase() : _notifier(0) {}
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// \brief Constructor which attach the observer into notifier.
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//
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// Constructor which attach the observer into notifier.
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ObserverBase(AlterationNotifier& nf) {
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attach(nf);
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}
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// \brief Constructor which attach the obserever to the same notifier.
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//
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// Constructor which attach the obserever to the same notifier as
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// the other observer is attached to.
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ObserverBase(const ObserverBase& copy) {
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if (copy.attached()) {
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attach(*copy.notifier());
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}
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}
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// \brief Destructor
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virtual ~ObserverBase() {
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if (attached()) {
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detach();
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}
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}
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// \brief Attaches the observer into an AlterationNotifier.
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//
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// This member attaches the observer into an AlterationNotifier.
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void attach(AlterationNotifier& nf) {
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nf.attach(*this);
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}
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// \brief Detaches the observer into an AlterationNotifier.
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//
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// This member detaches the observer from an AlterationNotifier.
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void detach() {
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_notifier->detach(*this);
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}
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// \brief Gives back a pointer to the notifier which the map
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// attached into.
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//
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// This function gives back a pointer to the notifier which the map
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// attached into.
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Notifier* notifier() const { return const_cast<Notifier*>(_notifier); }
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// Gives back true when the observer is attached into a notifier.
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bool attached() const { return _notifier != 0; }
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private:
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ObserverBase& operator=(const ObserverBase& copy);
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protected:
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Notifier* _notifier;
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typename std::list<ObserverBase*>::iterator _index;
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// \brief The member function to notificate the observer about an
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// item is added to the container.
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//
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// The add() member function notificates the observer about an item
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// is added to the container. It have to be overrided in the
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// subclasses.
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virtual void add(const Item&) = 0;
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// \brief The member function to notificate the observer about
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// more item is added to the container.
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//
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// The add() member function notificates the observer about more item
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// is added to the container. It have to be overrided in the
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// subclasses.
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virtual void add(const std::vector<Item>& items) = 0;
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// \brief The member function to notificate the observer about an
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// item is erased from the container.
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//
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// The erase() member function notificates the observer about an
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// item is erased from the container. It have to be overrided in
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// the subclasses.
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virtual void erase(const Item&) = 0;
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// \brief The member function to notificate the observer about
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// more item is erased from the container.
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//
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// The erase() member function notificates the observer about more item
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// is erased from the container. It have to be overrided in the
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// subclasses.
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virtual void erase(const std::vector<Item>& items) = 0;
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// \brief The member function to notificate the observer about the
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// container is built.
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//
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// The build() member function notificates the observer about the
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// container is built from an empty container. It have to be
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// overrided in the subclasses.
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virtual void build() = 0;
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// \brief The member function to notificate the observer about all
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// items are erased from the container.
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//
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// The clear() member function notificates the observer about all
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// items are erased from the container. It have to be overrided in
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// the subclasses.
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virtual void clear() = 0;
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};
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protected:
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const Container* container;
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typedef std::list<ObserverBase*> Observers;
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Observers _observers;
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lemon::bits::Lock _lock;
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public:
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// \brief Default constructor.
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//
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// The default constructor of the AlterationNotifier.
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// It creates an empty notifier.
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AlterationNotifier()
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: container(0) {}
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// \brief Constructor.
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//
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// Constructor with the observed container parameter.
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AlterationNotifier(const Container& _container)
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: container(&_container) {}
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// \brief Copy Constructor of the AlterationNotifier.
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//
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// Copy constructor of the AlterationNotifier.
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// It creates only an empty notifier because the copiable
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// notifier's observers have to be registered still into that notifier.
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AlterationNotifier(const AlterationNotifier& _notifier)
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: container(_notifier.container) {}
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// \brief Destructor.
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//
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// Destructor of the AlterationNotifier.
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~AlterationNotifier() {
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typename Observers::iterator it;
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for (it = _observers.begin(); it != _observers.end(); ++it) {
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(*it)->_notifier = 0;
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}
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}
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// \brief Sets the container.
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//
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// Sets the container.
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void setContainer(const Container& _container) {
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container = &_container;
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}
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protected:
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AlterationNotifier& operator=(const AlterationNotifier&);
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public:
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// \brief First item in the container.
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//
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// Returns the first item in the container. It is
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// for start the iteration on the container.
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void first(Item& item) const {
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container->first(item);
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}
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// \brief Next item in the container.
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//
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// Returns the next item in the container. It is
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// for iterate on the container.
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void next(Item& item) const {
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container->next(item);
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}
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// \brief Returns the id of the item.
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//
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// Returns the id of the item provided by the container.
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int id(const Item& item) const {
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return container->id(item);
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}
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// \brief Returns the maximum id of the container.
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//
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// Returns the maximum id of the container.
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int maxId() const {
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return container->maxId(Item());
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}
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protected:
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void attach(ObserverBase& observer) {
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_lock.lock();
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observer._index = _observers.insert(_observers.begin(), &observer);
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observer._notifier = this;
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_lock.unlock();
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}
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void detach(ObserverBase& observer) {
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_lock.lock();
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_observers.erase(observer._index);
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observer._index = _observers.end();
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observer._notifier = 0;
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_lock.unlock();
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}
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public:
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// \brief Notifies all the registed observers about an item added to
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// the container.
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//
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// It notifies all the registed observers about an item added to
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// the container.
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void add(const Item& item) {
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typename Observers::reverse_iterator it;
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try {
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for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
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(*it)->add(item);
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}
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} catch (...) {
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typename Observers::iterator jt;
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for (jt = it.base(); jt != _observers.end(); ++jt) {
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(*jt)->erase(item);
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}
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throw;
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}
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}
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// \brief Notifies all the registed observers about more item added to
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// the container.
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//
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// It notifies all the registed observers about more item added to
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// the container.
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void add(const std::vector<Item>& items) {
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typename Observers::reverse_iterator it;
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try {
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for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
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(*it)->add(items);
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}
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} catch (...) {
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typename Observers::iterator jt;
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for (jt = it.base(); jt != _observers.end(); ++jt) {
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(*jt)->erase(items);
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}
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throw;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// \brief Notifies all the registed observers about an item erased from
|
||
|
|
// the container.
|
||
|
|
//
|
||
|
|
// It notifies all the registed observers about an item erased from
|
||
|
|
// the container.
|
||
|
|
void erase(const Item& item) throw() {
|
||
|
|
typename Observers::iterator it = _observers.begin();
|
||
|
|
while (it != _observers.end()) {
|
||
|
|
try {
|
||
|
|
(*it)->erase(item);
|
||
|
|
++it;
|
||
|
|
} catch (const ImmediateDetach&) {
|
||
|
|
(*it)->_index = _observers.end();
|
||
|
|
(*it)->_notifier = 0;
|
||
|
|
it = _observers.erase(it);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// \brief Notifies all the registed observers about more item erased
|
||
|
|
// from the container.
|
||
|
|
//
|
||
|
|
// It notifies all the registed observers about more item erased from
|
||
|
|
// the container.
|
||
|
|
void erase(const std::vector<Item>& items) {
|
||
|
|
typename Observers::iterator it = _observers.begin();
|
||
|
|
while (it != _observers.end()) {
|
||
|
|
try {
|
||
|
|
(*it)->erase(items);
|
||
|
|
++it;
|
||
|
|
} catch (const ImmediateDetach&) {
|
||
|
|
(*it)->_index = _observers.end();
|
||
|
|
(*it)->_notifier = 0;
|
||
|
|
it = _observers.erase(it);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// \brief Notifies all the registed observers about the container is
|
||
|
|
// built.
|
||
|
|
//
|
||
|
|
// Notifies all the registed observers about the container is built
|
||
|
|
// from an empty container.
|
||
|
|
void build() {
|
||
|
|
typename Observers::reverse_iterator it;
|
||
|
|
try {
|
||
|
|
for (it = _observers.rbegin(); it != _observers.rend(); ++it) {
|
||
|
|
(*it)->build();
|
||
|
|
}
|
||
|
|
} catch (...) {
|
||
|
|
typename Observers::iterator jt;
|
||
|
|
for (jt = it.base(); jt != _observers.end(); ++jt) {
|
||
|
|
(*jt)->clear();
|
||
|
|
}
|
||
|
|
throw;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// \brief Notifies all the registed observers about all items are
|
||
|
|
// erased.
|
||
|
|
//
|
||
|
|
// Notifies all the registed observers about all items are erased
|
||
|
|
// from the container.
|
||
|
|
void clear() {
|
||
|
|
typename Observers::iterator it = _observers.begin();
|
||
|
|
while (it != _observers.end()) {
|
||
|
|
try {
|
||
|
|
(*it)->clear();
|
||
|
|
++it;
|
||
|
|
} catch (const ImmediateDetach&) {
|
||
|
|
(*it)->_index = _observers.end();
|
||
|
|
(*it)->_notifier = 0;
|
||
|
|
it = _observers.erase(it);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif
|