UNI_GraphHandle.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:        UNI_GraphHandle.h ( UNI Library, C++)
 *
 * COMMENTS:
 *      
 */

#ifndef __UNI_GraphHandle_h__
#define __UNI_GraphHandle_h__

#include "UNI_API.h"
#include "UNI_Graph.h"


// ============================================================================ /// Handle for holding a reference to a const UNI_Graph.
class UNI_API UNI_ConstGraphHandle 
{
public:
    /// @{ Constructor for the graph handle.
                UNI_ConstGraphHandle() = default;
    explicit    UNI_ConstGraphHandle( UNI_GraphID graph_id );
                UNI_ConstGraphHandle( const UNI_ConstGraphPtr &graph_ptr )
                    : myGraphPtr( graph_ptr ) {}
                UNI_ConstGraphHandle( UNI_ConstGraphPtr &&graph_ptr )
                    : myGraphPtr( std::move(graph_ptr) ) {}
    /// @}

    /// @{ Returns true if this handle refers to a valid graph; false otherwise.
    bool                isValid() const
                            { return graph(); } 
    explicit operator   bool() const
                            { return isValid(); }
    /// @}

    /// @{ Comparison operators.
    bool                operator==( const UNI_ConstGraphHandle &other ) const
                            { return graph() == other.graph(); }
    bool                operator!=( const UNI_ConstGraphHandle &other ) const
                            { return graph() != other.graph(); }
    /// @}

    /// @{ Returns the UNI graph referenced by this handle.
    const UNI_Graph *   graph() const
                            { return myGraphPtr.get(); }
    const UNI_Graph *   operator->() const 
                            { return graph(); }
    /// @}

    /// Returns the ID of a UNI graph referenced by this handle.
    UNI_GraphID graphID() const
    { 
        return myGraphPtr ? myGraphPtr->graphID() : UNI_GraphID(); 
    }

private:
    /// Intrusive pointer to the UNI graph.
    UNI_ConstGraphPtr   myGraphPtr;
};

// ============================================================================ /// Handle for holding a reference to UNI_Graph.
class UNI_API UNI_GraphHandle  : public UNI_ConstGraphHandle
{
public:
    /// @{ Constructor for the graph handle.
                UNI_GraphHandle() = default;
    explicit    UNI_GraphHandle( UNI_GraphID graph_id );
                UNI_GraphHandle( const UNI_GraphPtr &graph_ptr )
                    : UNI_ConstGraphHandle( graph_ptr ) {}
                UNI_GraphHandle( UNI_GraphPtr &&graph_ptr )
                    : UNI_ConstGraphHandle( std::move(graph_ptr) ) {}
    /// Takes ownership of a freshly created graph. The graph has already
    /// registered itself in the look-up table in its constructor; this
    /// handle's reference count becomes the sole owner of the graph.
    explicit    UNI_GraphHandle( UT_UniquePtr<UNI_Graph> graph )
                    : UNI_GraphHandle( UNI_GraphPtr( graph.release() )) {}
    /// @}

    /// @{ Returns the UNI graph referenced by this handle.
    UNI_Graph * graph() const
    { 
        // This sub-class constructs the base class always with 
        // a non-const graph, so we can cast away constness here.
        return const_cast<UNI_Graph*>( UNI_ConstGraphHandle::graph() );
    }

    UNI_Graph *operator->() const 
    { 
        return graph(); 
    }
    /// @}

private:
};
#endif