    //------------------------------------------------------------------------------
    // emContext.h
    //
    // Copyright (C) 2005-2008,2010 Oliver Hamann.
    //
    // Homepage: http://eaglemode.sourceforge.net/
    //
    // This program is free software: you can redistribute it and/or modify it under
    // the terms of the GNU General Public License version 3 as published by the
    // Free Software Foundation.
    //
    // This program is distributed in the hope that it will be useful, but WITHOUT
    // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
    // FOR A PARTICULAR PURPOSE. See the GNU General Public License version 3 for
    // more details.
    //
    // You should have received a copy of the GNU General Public License version 3
    // along with this program. If not, see <http://www.gnu.org/licenses/>.
    //------------------------------------------------------------------------------

    #ifndef emContext_h
    #define emContext_h

    #ifndef emAvlTree_h
    #include <emCore/emAvlTree.h>
    #endif

    #ifndef emCrossPtr_h
    #include <emCore/emCrossPtr.h>
    #endif

    #ifndef emTimer_h
    #include <emCore/emTimer.h>
    #endif

    class emModel;
    class emRootContext;

    //==============================================================================
    //================================= emContext ==================================
    //==============================================================================

    class emContext : public emEngine {

    public:

            // Class for a context of models (read comments on emModel). It manages
            // an AVL tree for quickly refinding common models.

            emContext(emContext & parentContext);
                    // Construct a child context. For constructing a root context
                    // please see emRootContext.

            virtual ~emContext();
                    // Destructor. This even deletes all common models in this
                    // context, in an order respecting references between the
                    // models. Child contexts and private models are not deleted by
                    // this. They must have been destructed before or they must be
                    // managed by common models.

            void LinkCrossPtr(emCrossPtrPrivate & crossPtr);
                    // This means emCrossPtr<emContext> is possible.

            emRootContext & GetRootContext();
                    // Get the root context.

            emContext * GetParentContext();
                    // Get the parent context. Returns NULL if this is the root
                    // context.

            emContext * GetFirstChildContext();
            emContext * GetLastChildContext();
            emContext * GetPrevContext();
            emContext * GetNextContext();
                    // Get the first or last child context, or the previous or next
                    // brother context, NULL if none.

            emModel * Lookup(const type_info & modelClass, const char * name);
                    // Search for a common model within this context.
                    // Arguments:
                    //   modelClass - Final class of the model.
                    //   name       - Name of the model.
                    // Returns: The model, or NULL if not found.

            emModel * LookupInherited(const type_info & modelClass,
                                      const char * name);
                    // Like Lookup, but if the model is not found in this context,
                    // the parent context is searched, then the grad-parent, and so
                    // on.

            emString GetListing() const;
                    // Just for debugging: Get a listing of all common models.

            void GetModelInfo(int * pCommonCount, int * pPrivateCount=NULL,
                              emModel * * * pArrayOfCommon=NULL);
                    // Just for debugging: Get the number of common and private
                    // models, and create an array of pointers to all common models.
                    // The array must be deleted by the caller.

    protected:

            virtual bool Cycle();
                    // emContext has been derived from emEngine for convenience.
                    // This default implementation does nothing and returns false.

    private:

            friend class emModel;
            friend class emRootContext;

            emContext(emScheduler & scheduler);

            void RegisterModel(emModel * model);
            void UnregisterModel(emModel * model);
            static int CalcHashCode(const type_info & modelClass,
                                    const char * name);
            emModel * SearchUnused();
            emModel * SearchUnused(int minHash);
            emModel * SearchGarbage();
            emModel * SearchGarbage(int minHash);
            void CollectGarbage();

            class SharedTimingEngine : public emEngine {
            public:
                    SharedTimingEngine(emRootContext & rootContext,
                                       unsigned int gcPeriod);
                    virtual ~SharedTimingEngine();
                    virtual bool Cycle();
                    emRootContext & RootContext;
                    emTimer SecsTimer;
                    unsigned int GCPeriod;
                    unsigned int SecsCounter;
                    unsigned int TimeOfGC;
            };

            friend class SharedTimingEngine;

            emRootContext & RootContext;
            emCrossPtrList CrossPtrList;
            SharedTimingEngine * SharedTiming;
            emContext * ParentContext;
            emContext * FirstChildContext;
            emContext * LastChildContext;
            emContext * PrevContext;
            emContext * NextContext;
            emAvlTree AvlTree;
            unsigned int ModelCount;
            bool DoGCOnModels;
    };

    //==============================================================================
    //=============================== emRootContext ================================
    //==============================================================================

    class emRootContext : public emContext {

    public:

            emRootContext(emScheduler & scheduler);
                    // Construct a root context.

    };

    //==============================================================================
    //============================== Implementations ===============================
    //==============================================================================

    inline void emContext::LinkCrossPtr(emCrossPtrPrivate & crossPtr)
    {
            CrossPtrList.LinkCrossPtr(crossPtr);
    }

    inline emRootContext & emContext::GetRootContext()
    {
            return RootContext;
    }

    inline emContext * emContext::GetParentContext()
    {
            return ParentContext;
    }

    inline emContext * emContext::GetFirstChildContext()
    {
            return FirstChildContext;
    }

    inline emContext * emContext::GetLastChildContext()
    {
            return LastChildContext;
    }

    inline emContext * emContext::GetPrevContext()
    {
            return PrevContext;
    }

    inline emContext * emContext::GetNextContext()
    {
            return NextContext;
    }

    inline emRootContext::emRootContext(emScheduler & scheduler)
            : emContext(scheduler)
    {
    }

    #endif