ObjectWriter.h

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//
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#ifndef Alembic_AbcCoreAbstract_ObjectWriter_h
#define Alembic_AbcCoreAbstract_ObjectWriter_h

#include <Alembic/Util/Export.h>
#include <Alembic/AbcCoreAbstract/Foundation.h>
#include <Alembic/AbcCoreAbstract/ForwardDeclarations.h>
#include <Alembic/AbcCoreAbstract/ObjectHeader.h>

namespace Alembic {
namespace AbcCoreAbstract {
namespace ALEMBIC_VERSION_NS {

//-*****************************************************************************
//! An Object consists of a list of children objects, which may be empty,
//! and a single compound property which is the root of any properties
//! which the object may contain.
//! Objects have MetaData, which is identical to the MetaData of the root
//! Compound Property.
class ALEMBIC_EXPORT ObjectWriter
    : private Alembic::Util::noncopyable
{
public:
    //! Virtual destructor
    //! ...
    virtual ~ObjectWriter();

    //-*************************************************************************
    // NEW FUNCTIONS
    //-*************************************************************************

    //! All objects are created from an ObjectHeader, which contains their
    //! name, their full name, and their MetaData. This returns
    //! a const reference to the ObjectHeader which was given upon
    //! creation.
    virtual const ObjectHeader & getHeader() const = 0;

    //! All objects have a name. This name is unique amongst their siblings
    //! Returned by reference, since it is guaranteed to exist and be
    //! unchanging. This is the name that was given when the object was
    //! created.
    const std::string &getName() const
    { return getHeader().getName(); }

    //! The full name of an object is the complete path name all the way
    //! to the root object of the archive. It is guaranteed to be fully
    //! unique within the entire archive.
    const std::string &getFullName() const
    { return getHeader().getFullName(); }

    //! All objects have metadata. This metadata is identical to the
    //! Metadata of the top level compoundProperty "properties".
    //! Because the metadata must exist and be initialized in order to
    //! bootstrap the object, it is guaranteed to exist and is returned
    //! by reference. While MetaData was required to create the object,
    //! additional MetaData may be appended during the writing of the
    //! object. This returns the accumulated MetaData, which may change
    //! as writing occurs. The reference will remain valid, but the
    //! MetaData it points to may change over time.
    const MetaData &getMetaData() const
    { return getHeader().getMetaData(); }
    
    //! All objects have a shared link to the root. This may seem
    //! wasteful, but it is essential in order to allow for the flexible,
    //! reference-counted autonomy of the writer objects. Alembic
    //! allows you to keep references to writers wherever you want,
    //! without requiring you to keep track of (or store) the parental
    //! hierarchy directly. In order to make this possible, we have
    //! the ability to walk upwards. This may be stored as a direct
    //! link, or retrieved by walking up the parent chain, which is
    //! a feature of the individual implementations. (it might not be
    //! cheap, basically).
    //! In order to prevent shared_ptr cycles, it is important
    //! that objects only store their children via weak ptrs.
    virtual ArchiveWriterPtr getArchive() = 0;

    //! All objects have a shared link to their parent. This may seem
    //! wasteful, but it is essential in order to allow for the flexible,
    //! reference-counted autonomy of the writer objects. Alembic
    //! allows you to keep references to writers wherever you want,
    //! without requiring you to keep track of (or store) the parental
    //! hierarchy directly. In order to make this possible, we have
    //! the ability to walk upwards.
    //! In order to prevent shared_ptr cycles, it is important
    //! that objects only store their children via weak ptrs.
    virtual ObjectWriterPtr getParent() = 0;

    //! All objects have a single compound property which is the
    //! root for any properties which are associated with this object.
    //! Guaranteed to exist, even if the compound property itself is
    //! empty. This may change as properties are added.
    virtual CompoundPropertyWriterPtr getProperties() = 0;

    //-*************************************************************************
    // CHILDREN
    //-*************************************************************************

    //! Returns the number of objects that are contained as children.
    //! this number may increase (but not decrease) as objects are
    //! created. This is the number of children object writers that
    //! have ALREADY BEEN ADDED. It may increase.
    virtual size_t getNumChildren() = 0;

    //! Returns the header of an object that has already been added.
    //! Object is selected by index.
    //! This will throw an exception on out-of-range access.
    virtual const ObjectHeader & getChildHeader( size_t i ) = 0;

    //! Returns the header of an object that has already been added,
    //! by name.
    //! This will return NULL pointer if no header by that name is found.
    //! Even if the object assosciated with this header is no longer
    //! existing, the header will be non-null if any such object
    //! had been created. This is a mechanism for testing if something
    //! has already been made.
    virtual const ObjectHeader *
    getChildHeader( const std::string &iName ) = 0;

    //! Returns a pointer to an object writer at the given index,
    //! that has ALREADY BEEN ADDED. It is an error to request a child
    //! with an out of range index, and an exception will be thrown.
    //! In a strange case,
    //! this will return an empty pointer if the writer has been
    //! added in the past, but was closed (deleted). There is really
    //! no distinction between an empty weak pointer and a weak pointer
    //! to an expired object, so we simply return an empty pointer
    //! if the object had been created but no longer exists.
    //! This is just a convenience function that uses getChildHeader
    //! and getChild( name );
    ObjectWriterPtr getChild( size_t i );

    //! Returns a pointer to an object writer of the given name iName,
    //! for an object that has ALREADY BEEN ADDED. This will return
    //! an empty pointer if no object of the given name has been added.
    virtual ObjectWriterPtr getChild( const std::string &iName ) = 0;

    //! Create an object with given header.
    //! the header's "fullName" will be ignored and set by the parent object.
    //! If an object with the given name already exists, an exception will
    //! be thrown, as this is a programming error.
    virtual ObjectWriterPtr createChild( const ObjectHeader &iHeader ) = 0;

    //! Returns shared pointer to myself.
    //! Sometimes this may be a spoofed ptr.
    virtual ObjectWriterPtr asObjectPtr() = 0;
};

} // End namespace ALEMBIC_VERSION_NS

using namespace ALEMBIC_VERSION_NS;

} // End namespace AbcCoreAbstract
} // End namespace Alembic

#endif