inkscape/src/composite-undo-stack-observer.h

/*
 * Authors:
 * David Yip <yipdw@rose-hulman.edu>
 *
 * Copyright (c) 2005 Authors
 *
 * Released under GNU GPL, read the file 'COPYING' for more information
 */

#ifndef SEEN_COMPOSITE_UNDO_COMMIT_OBSERVER_H
#define SEEN_COMPOSITE_UNDO_COMMIT_OBSERVER_H

#include "inkgc/gc-alloc.h"
#include "undo-stack-observer.h"

#include <list>

namespace Inkscape {

struct Event;

/**
 * Aggregates UndoStackObservers for management and triggering in an SPDocument's undo/redo
 * system.
 *
 * Heavily inspired by Inkscape::XML::CompositeNodeObserver.
 */
class CompositeUndoStackObserver : public UndoStackObserver {
public:

    /**
     * Structure for tracking UndoStackObservers.
     */
    struct UndoStackObserverRecord {
    public:
        /**
         * Constructor.
         *
         * \param o Reference to the UndoStackObserver that this UndoStackObserverRecord
         * will track.
         */
        UndoStackObserverRecord(UndoStackObserver& o) : to_remove(false), _observer(o) { }
        bool to_remove;

        /**
         * Overloaded equality test operator to facilitate usage of STL find algorithms.
         */
        bool operator==(UndoStackObserverRecord const& _x) const
        {
            return &(this->_observer) == &(_x._observer);
        }

        /**
         * Issue a redo event to the UndoStackObserver that is associated with this UndoStackObserverRecord.
         *
         * \param log The event log generated by the redo event.
         */
        void issueRedo(Event* log)
        {
            this->_observer.notifyRedoEvent(log);
        }

        /**
         * Issue an undo event to the UndoStackObserver that is associated with this
         * UndoStackObserverRecord.
         *
         * \param log The event log generated by the undo event.
         */
        void issueUndo(Event* log)
        {
            this->_observer.notifyUndoEvent(log);
        }

        /**
         * Issues a committed event to the UndoStackObserver that is associated with this
         * UndoStackObserverRecord.
         *
         * \param log The event log being committed to the undo stack.
         */
        void issueUndoCommit(Event* log)
        {
            this->_observer.notifyUndoCommitEvent(log);
        }

        /**
         * Issue a clear undo event to the UndoStackObserver
         * that is associated with this
         * UndoStackObserverRecord.
         */
        void issueClearUndo()
        {
            this->_observer.notifyClearUndoEvent();
        }

        /**
         * Issue a clear redo event to the UndoStackObserver
         * that is associated with this
         * UndoStackObserverRecord.
         */
        void issueClearRedo()
        {
            this->_observer.notifyClearRedoEvent();
        }

    private:
        UndoStackObserver& _observer;
    };

    /// A list of UndoStackObserverRecords, used to aggregate multiple UndoStackObservers.
    typedef std::list< UndoStackObserverRecord, GC::Alloc< UndoStackObserverRecord, GC::MANUAL > > UndoObserverRecordList;

    /**
     * Constructor.
     */
    CompositeUndoStackObserver();

    virtual ~CompositeUndoStackObserver();

    /**
     * Add an UndoStackObserver.
     *
     * \param observer Reference to an UndoStackObserver to add.
     */
    void add(UndoStackObserver& observer);

    /**
     * Remove an UndoStackObserver.
     *
     * \param observer Reference to an UndoStackObserver to remove.
     */
    void remove(UndoStackObserver& observer);

    /**
     * Notify all registered UndoStackObservers of an undo event.
     *
     * \param log The event log generated by the undo event.
     */
    void notifyUndoEvent(Event* log);

    /**
     * Notify all registered UndoStackObservers of a redo event.
     *
     * \param log The event log generated by the redo event.
     */
    void notifyRedoEvent(Event* log);

    /**
     * Notify all registered UndoStackObservers of an event log being committed to the undo stack.
     *
     * \param log The event log being committed to the undo stack.
     */
    void notifyUndoCommitEvent(Event* log);

    virtual void notifyClearUndoEvent();
    virtual void notifyClearRedoEvent();

private:
    // Remove an observer from a given list
    bool _remove_one(UndoObserverRecordList& list, UndoStackObserver& rec);

    // Mark an observer for removal from a given list
    bool _mark_one(UndoObserverRecordList& list, UndoStackObserver& rec);

    // Keep track of whether or not we are notifying observers
    unsigned int _iterating;

    // Observers in the active list
    UndoObserverRecordList _active;

    // Observers to be added
    UndoObserverRecordList _pending;

    // Prevents the observer vector from modifications during
    // iteration through the vector
    void _lock() { this->_iterating++; }
    void _unlock();
};

}

#endif // SEEN_COMPOSITE_UNDO_COMMIT_OBSERVER_H