include/AD/persist/ptype.h

   1 //////////////////////////////////////////////////////////////////////////////
   2 // NOTICE:
   3 //
   4 // ADLib, Prop and their related set of tools and documentation are in the
   5 // public domain.   The author(s) of this software reserve no copyrights on
   6 // the source code and any code generated using the tools.  You are encouraged
   7 // to use ADLib and Prop to develop software, in both academic and commercial
   8 // settings, and are welcomed to incorporate any part of ADLib and Prop into
   9 // your programs.
  10 //
  11 // Although you are under no obligation to do so, we strongly recommend that
  12 // you give away all software developed using our tools.
  13 //
  14 // We also ask that credit be given to us when ADLib and/or Prop are used in
  15 // your programs, and that this notice be preserved intact in all the source
  16 // code.
  17 //
  18 // This software is still under development and we welcome(read crave for)
  19 // any suggestions and help from the users.
  20 //
  21 // Allen Leung
  22 // 1994
  23 //////////////////////////////////////////////////////////////////////////////
  24
  25 #ifndef persistent_objects_type_h
  26 #define persistent_objects_type_h
  27
  28 //////////////////////////////////////////////////////////////////////////////
  29 //  This file describes the class PObjectType, which describes the type
  30 //  of a persistent object.
  31 //////////////////////////////////////////////////////////////////////////////
  32
  33 #include <AD/generic/generic.h>
  34 #include <AD/persist/pconfig.h>
  35 #include <iostream>
  36
  37 //////////////////////////////////////////////////////////////////////////////
  38 //
  39 //  Opaque definitions
  40 //
  41 //////////////////////////////////////////////////////////////////////////////
  42 class Pistream;
  43 class Postream;
  44 class PBaseFactory;
  45
  46 //////////////////////////////////////////////////////////////////////////////
  47 //
  48 //  Persistent objects types.
  49 //
  50 //////////////////////////////////////////////////////////////////////////////
  51 class PObjectType {
  52    PObjectType (const PObjectType&);
  53    void operator = (const PObjectType&);
  54
  55 public:
  56    struct Entry
  57    {  P_OBJECT_TYPEID unique_id;     // unique id for each type
  58       const char *    type_name;     // name of object type
  59       int             type_name_len; // length of type name
  60       PBaseFactory *  factory;       // object factory
  61    };
  62
  63 protected:
  64    // index into a table of unique id during execution
  65    friend class PBaseFactory;
  66    Entry * entry;
  67
  68    static Entry * lookup_entry (const char *);
  69 public:
  70
  71    //////////////////////////////////////////////////////////////////////////
  72    //  Constructor and destructor
  73    //////////////////////////////////////////////////////////////////////////
  74    inline   PObjectType (Entry * e = 0) : entry(e) {}
  75             PObjectType (const char * name);
  76    virtual ~PObjectType ();
  77
  78    friend std::ostream&  operator << ( std::ostream&, const PObjectType& );
  79    inline Bool operator == (const PObjectType& id) const
  80       {  return entry == id.entry; }
  81    inline Bool operator != (const PObjectType& id) const
  82       {  return entry != id.entry; }
  83    const char * name () const;
  84    static int number_of_types ();
  85
  86    //////////////////////////////////////////////////////////////////////////
  87    //
  88    //  Interface to the persistent object classes
  89    //
  90    //////////////////////////////////////////////////////////////////////////
  91
  92    //////////////////////////////////////////////////////////////////////////
  93    //
  94    //  Read and write methods.  We can't read and write PObjectType
  95    //  arbitrarily from and to the persistent streams.
  96    //
  97    //////////////////////////////////////////////////////////////////////////
  98    void write ( Postream& ) const;
  99    void read  ( Pistream& );
 100 };
 101
 102 #endif