SIM/SIM_DataFactory.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.
 *
 * Produced by:
 *      Side Effects Software Inc.
 *      477 Richmond Street West, Suite 1001
 *      Toronto, Ontario
 *      Canada   M5V 3E7
 *      416-504-9876
 */

#ifndef __SIM_DataFactory_h__
#define __SIM_DataFactory_h__

#include "SIM_API.h"
#include <UT/UT_String.h>

class UT_Guid;
class SIM_Data;
class SIM_DataFactory;
class SIM_DopDescription;
class SIM_Engine;
class SIM_DataFactoryCreator;

typedef SIM_Data *(*SIM_DataConstructor)(const SIM_DataFactory *);
typedef void (*SIM_DataDestructor)(SIM_Data *);

/// This class provides a means of creating and destroying SIM_Data objects.
/// Nothing needs to be known about the SIM_Data object except its data
/// type name. It is possible to derive a subclass to use instead of
/// relying on the default implementations used by the DECLARE_DATAFACTORY
/// and IMPLEMENT_DATAFACTORY macros. But generally these macros will be
/// sufficient.
class SIM_API SIM_DataFactory
{
public:
    /// Constructor which receives all the data for this factory.
    /// The constructor arguments contain all the information that may be
    /// required for the new data type without actually requiring an
    /// instance of that data type to be constructed.
                         SIM_DataFactory(const char *datatype,
                                         const char *description,
                                         SIM_DataConstructor constructor,
                                         SIM_DataDestructor destructor,
                                         const SIM_DopDescription *dopdesc,
                                         const SIM_Engine *engine);
    /// Destructor.
    virtual             ~SIM_DataFactory();

    /// Return the SIM_Engine that owns this factory.
    const SIM_Engine                    &getEngine() const;
    /// Get the name of the data type that is created by this factory.
    /// This is the unique identifier that is passed to a SIM_Object to
    /// create a new instance of this data type.
    const UT_String                     &getDataType() const;
    /// Gets a string that describes what this data type does.
    /// This descriptive string is what is presented to the user when
    /// given a menu of data type choices.
    const UT_String                     &getDescription() const;
    /// Returns the name of the DSO or DLL file that defines the data type.
    /// For data types defined internally to Houdini the returned string
    /// will be empty.
    const UT_String                     &getSource() const;

    /// Create a new instance of our particular subclass of SIM_Data.
    virtual SIM_Data                    *newData() const;
    /// Calls newData() to create some new data, then changes the unique id.
    SIM_Data                            *newData(const UT_Guid &uniqueid) const;
    /// Delete an instance of our particular subclass of SIM_Data.
    virtual void                         deleteData(SIM_Data *data) const;
    /// Return our SIM_DopDescription.
    virtual const SIM_DopDescription    *getDopDescription() const;

private:
    /// All our data is set up in the constructor and cannot be modified.
    const UT_String                      myDataType;
    const UT_String                      myDescription;
    const SIM_DataConstructor            myConstructor;
    const SIM_DataDestructor             myDestructor;
    const SIM_DopDescription            *myDopDescription;
    const SIM_Engine                    *myEngine;
    const SIM_DataFactoryCreator        *myCreator;

    friend class                         SIM_DataFactoryCreator;
};

/// This helper class lets each SIM_Engine create an instance of
/// each SIM_DataFactory available on the system.
class SIM_API SIM_DataFactoryCreator
{
public:
    /// Defines a function for creating a SIM_DataFactory.
    typedef void (*SIM_DataFactoryCreateFunc)(SIM_Engine *engine);

    /// Constructor sets the SIM_DataFactory creation function.
    /// It also registers this SIM_DataFactoryCreator instance with the
    /// global list in the SIM_Engine class.
                 SIM_DataFactoryCreator(SIM_DataFactoryCreateFunc createfunc);
    /// Destructor which removes this SIM_DataFactoryCreator from the
    /// global list owned by the SIM_Engine class.
                ~SIM_DataFactoryCreator();

    /// Returns the name of the DSO or DLL file that defines the data type.
    /// For data types defined internally to Houdini the returned string
    /// will be empty.
    const UT_String     &getSource() const;
    /// Call the creation function to make a new SIM_DataFactory instance.
    void                 createDataFactory(SIM_Engine *engine);
    /// Call addDataFactory on the specified SIM_Engine.
    static void          addDataFactory(SIM_Engine *engine,
                                        SIM_DataFactory *factory);

private:
    SIM_DataFactoryCreateFunc            myCreateFunc;
    const UT_String                      mySource;

    static const SIM_DataFactoryCreator *theCreatingFactory;
};

#endif

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