UN_Handle.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * NAME:        UN_Handle.h ( UN Library, C++)
 *
 * COMMENTS:
 *      
 */

#ifndef __UN_Handle_h__
#define __UN_Handle_h__


#include "UN_API.h"
#include "UN_Types.h"

class UN_GraphData;


// ============================================================================
/// A handle class that is the basis for many concrete handle classes.
/// It factors out the behavious of a data object inside a data container.

// Note, no UN_API because all methods are defined in the header.
class UN_Handle
{
public:
    /// Convenience constructor.
    UN_Handle( UN_GraphData *graph_data, UN_DataID data_id )
        : myGraphData( graph_data )
        , myDataID( data_id )
        {}

    /// Default constructor.
    UN_Handle() 
        : UN_Handle( nullptr,  UN_DataID() )
        {}

    /// @{ Default destructor, constructors and assignment operators.
                       ~UN_Handle() = default;
                        UN_Handle( const UN_Handle & ) = default;
                        UN_Handle( UN_Handle && ) = default;
                        UN_Handle& operator=( const UN_Handle & ) = default;
                        UN_Handle& operator=( UN_Handle && ) = default;
    /// @}

    /// @{ Comparison operators
    bool                operator==( const UN_Handle &other ) const
                            { 
                                return myGraphData == other.myGraphData 
                                    && myDataID    == other.myDataID; 
                            }

    bool                operator!=( const UN_Handle &other ) const
                            {   
                                return !( *this == other ); 
                            }

    /// @}


    /// The unique number identifying this data object during the lifespan 
    /// of the owner graph. Used for referring to this object in the graph.
    UN_DataID           dataID() const
                            { return myDataID; }

protected:
    /// The graph that owns, manages, and operates on data object.
    /// Returning a non-const pointer from const method, since the
    /// derived classes have const methods that operate on non-const graph,
    /// but are always constructed with a non-const graph.
    UN_GraphData *      graphData() const
                            { return myGraphData; }

private:
    /// The graph that owns, manages, and operates on data object.
    UN_GraphData *      myGraphData;

    /// The unique identification number of a data object during the lifespan
    /// of the graph above. Used for referring to the data object in a graph.
    UN_DataID           myDataID;
};


#endif