include/AD/csp/logicalterm.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 (leunga@valis.cs.nyu.edu)
  22 // 1994-1996
  23 //////////////////////////////////////////////////////////////////////////////
  24 #ifndef logical_term_h
  25 #define logical_term_h
  26
  27 #include <new.h>
  28 #include <AD/generic/generic.h>
  29 #include <AD/csp/trail.h>
  30
  31 //////////////////////////////////////////////////////////////////////////////
  32 //
  33 //  Definition of a logical term object.  All unifiable objects will
  34 //  be derived from this class.
  35 //
  36 //////////////////////////////////////////////////////////////////////////////
  37
  38 class LogicalTerm {
  39 public:
  40    virtual ~LogicalTerm() {}
  41
  42    ///////////////////////////////////////////////////////////////////////////
  43    //
  44    //  The instantiation/uninstantiation methods must be redefined by
  45    //  subclasses.
  46    //
  47    ///////////////////////////////////////////////////////////////////////////
  48    virtual void uninstantiate ();
  49    virtual Bool is_instantiable () const;
  50    virtual Bool is_instantiated () const;
  51
  52    ///////////////////////////////////////////////////////////////////////////
  53    //
  54    //  Memory management is handled by the trail class.
  55    //
  56    ///////////////////////////////////////////////////////////////////////////
  57    static UnificationTrail& trail; // current trail
  58    inline static void * operator new (size_t n) { return trail.m_alloc(n); }
  59    inline static void operator delete (void *) {} // no-op
  60 };
  61
  62 #endif