//*-- Author : Valeriy Onuchin 11/09/2000 
//
//
////////////////////////////////////////////////////////////////////////////////
//
// rooMetaObject corresponds to d_Meta_Object Class
//
// The class rooMetaObject is the abstract base class for descriptor classes 
// that describe named entities (modules, classes, attributes, and so on) in 
// the federated database schema, and for descriptor classes that describe 
// proposed additions or modifications to the schema. Each concrete class 
// derived from this class describes one particular kind of schema entity or
// proposal. An instance of any concrete class derived from rooMetaObject is 
// called a descriptor.
//
//______________________________________________________________________________
//
//             About Descriptors
//
// As the name of this class implies, a descriptor is a meta-object -- that is,
// an object that provides information about a "real" object. Each descriptor 
// provides information about a particular named entity in a federated database
// called its described entity. In addition to the persistent information from 
// the federated database schema, a descriptor can have a transient comment. 
// The comment is associated with a descriptor only during the interaction in 
// which the descriptor was obtained; it is not saved persistently with the 
// described entity in the federated database schema.
// Because this class is abstract, you never instantiate it; instead, you work
// with instances of its concrete derived classes. You should not derive your 
// own classes from this class.
//
////////////////////////////////////////////////////////////////////////////////
//
// rooMetaObject( aka d_Meta_Object) is part of the ODMG standard.  
// A rooMetaObject has a name which can be looked up in a scope.  Types, 
// including classes, are meta-objects named in rooModule(aka d_Module,schema) 
// scope and class attributes are meta-objects named in 
// rooClass(aka d_Class) scope.
// All rooMetaObjects have a name string returned by name().  Comments
// added with set_comment() are transient only; they are not saved in
// the database.  The id() method returns an unsigned integer unique to
// the meta-object within its scope; for subclasses of rooType(aka d_Type), 
// its return value will be the same as for type_number(), and for subclasses 
// of rooProperty(aka d_Property), its return value will be the Objectivity 
// member ID.  The method defined_in() returns the scope of the object.
//
// rooMetaObjects are never constructed, only returned by scope methods.
// For example:
//
//   const rooMetaObject &metaObjConstRef = module.resolve("typeName");
//
////////////////////////////////////////////////////////////////////////////////

#include "rooObjy.h"
#include <ooas.h>
#include <oo.h>

ClassImp(rooMetaObject)

////////////////////////////////////////////////////////////////////////////////
//______________________________________________________________________________
 rooMetaObject::rooMetaObject()
{
   // internal use only
   
   fImp = new d_Meta_Object();
}

//______________________________________________________________________________
 rooMetaObject::~rooMetaObject()
{
   // dtor.

//   if(fImp) delete ((d_Meta_Object*)fImp);
//   fImp = 0;
//   if(fScope) delete (d_Scope*)fScope;
//   fScope = 0;
}

//______________________________________________________________________________
 TString rooMetaObject::name() const
{
   //  Gets the name of the described entity.
 
   return fImp ? TString(((d_Meta_Object*)fImp)->name()) : TString();
}

//______________________________________________________________________________
 TString rooMetaObject::comment() const
{
   //  Gets the transient comment associated with this descriptor.
   //
   // See also set_comment()

   return fImp ? TString(((d_Meta_Object*)fImp)->comment()) : TString();
}

//______________________________________________________________________________
//rooScope & rooMetaObject::defined_in()
//{
   //
//
//   if(!fScope) fScope = new rooScope(&((d_Meta_Object*)fImp)->defined_in());
//   else fScope->setScopeImp((void*)&((d_Meta_Object*)fImp)->defined_in());
//
//   return *fScope;
//}

//______________________________________________________________________________
 UInt_t rooMetaObject::id() const
{
   // Gets the unique ID that identifies the described entity within its scope.
   // Returns The ID for the described entity, or kooNoID if the described 
   // entity does  not have an ID. If this is the null descriptor, this member
   // function returns 0.
   //    Existing entities in the schema have IDs; proposed changes to the 
   // schema do not. Active Schema uses an ID to identify an existing entity 
   // uniquely within its scope. If the described entity is a class or 
   // non-class type, its ID is the same as its type number. If the described 
   // entity is a property, its ID is the same as its Objectivity
   // attribute ID.

   return fImp ? ((d_Meta_Object*)fImp)->id() : 0;
}

//______________________________________________________________________________
 Bool_t rooMetaObject::is_type() const
{
   // Tests whether the described entity is a type.

   return fImp ? ((d_Meta_Object*)fImp)->is_type() : 0;
}

//______________________________________________________________________________
 Bool_t rooMetaObject::is_class() const
{
   // ests whether the described entity is a class.

   return fImp ? ((d_Meta_Object*)fImp)->is_class() : 0;
}

//______________________________________________________________________________
 Bool_t rooMetaObject::is_module() const
{
   // Tests whether the described entity is a module.

   return fImp ? ((d_Meta_Object*)fImp)->is_module() : 0;
}

//______________________________________________________________________________
 void rooMetaObject::set_comment(const TString& comm)
{
   // Sets the transient comment for this descriptor, replacing any
   // existing comment.
   //
   // The comment is associated with this descriptor only during the 
   // interaction in which this descriptor was obtained; it is not saved 
   // persistently with the described entity in the federated database schema.
   //
   // See also comment() 

   if(fImp) ((d_Meta_Object*)fImp)->set_comment(comm.Data());
}

//______________________________________________________________________________
rooMetaObject::operator size_t() const
{
   // Returns zero if this descriptor is null; otherwise, nonzero.
   //
   // Any member function that looks up a descriptor returns a descriptor 
   // object; unsuccessful searches return a null descriptor. This operator 
   // allows you to use a descriptor as an integer expression to test whether 
   // that descriptor is valid (not null).
   //
   // When this member function is called for a valid descriptor of an entity 
   // in the schema, it returns the unique ID of that entity.


   return fImp ? (size_t)(*((d_Meta_Object*)fImp)) : 0;
}