gistobserver.h

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// -*- Mode: C++ -*-
//--------------------------------------------------------------------
//        GiSTobserver.h
//        --------------
//
//        GiST - Generalized Search Tree 
//        June 2001 release, Aalborg University
//        
//        This file is a revised version of a part of the original 
//        libGiST release (version  0.9beta1)     
//        Copyright (c) 1996, Regents of the University of California
//

#ifndef GISTOBSERVER_H
#define GISTOBSERVER_H

#include "GiSTdefs.h"
#include "GiSTentry.h"
#include "GiSTnode.h"
#include "GiSTpredicate.h"

//------------------------------------------------
//   Observer notification codes  (parameters of Inform in comments)
//

enum TNotification
{
   ON_CREATE,
   ON_OPEN,
   ON_CLOSE,
   ON_INSERTSTART,
   ON_INSERTEND,
   ON_WRITENODE,                 // node
   ON_OVERFLOWTSTART,
   ON_OVERFLOWTEND,
   ON_REMOVETOP,                 // entry list
   ON_DELETESTART,
   ON_DELETEEND,
   ON_SHORTENTREE,               // node (new root, the child of the old)
   ON_DEALOCATE,                 // node
   ON_CONDENSETREESTART,
   ON_CONDENSETREEEND,
   ON_CHOOSESUBTREESTART,
   ON_CHOOSENODE,                // entry1, entry2, page  
   ON_CHOOSESUBTREEEND,
   ON_SPLIT,                     // node1, node2
   ON_SPLITSTART,                // node 
   ON_NEWROOT,                   // node (new root, one level higher)
   ON_SEARCH,                    // predicate
   ON_SEARCHEND,  
   ON_SEARCHNODE = 75,           // number of qualifying entries, number of all entries, level 
   ON_SEARCHMINPENALTY           // entry
};

class GiST;

//------------------------------------------------
//  GiSTobserver

class GiSTobserver : public GiSTobject
{
public:

  GiSTobjid IsA    () const     { return GISTOBSERVER_CLASS; }
  void      SetGiST(GiST* gist) { tree = gist; }
  GiST*     GetGiST() { return tree; }

  // GiST calls Inform when something is going on
  virtual void Inform (TNotification nc) {}
  virtual void Inform (TNotification nc, const GiSTentry& entry) {}
  virtual void Inform (TNotification nc, const GiSTentry& entry1, const GiSTentry& entry2, GiSTpage page) {}
  virtual void Inform (TNotification nc, GiSTlist<GiSTentry*>& elist) {}
  virtual void Inform (TNotification nc, const GiSTnode& node) {}
  virtual void Inform (TNotification nc, const GiSTnode& node1,
                                         const GiSTnode& node2) {}
  virtual void Inform (TNotification nc, int qual, int total, int level) {}
  virtual void Inform (TNotification nc, GiSTpage page, int level) {}
  virtual void Inform (TNotification nc, const GiSTpredicate& pred) {}

protected:
  // Giving the ability for the derived classes to access the arbitrary
  // part of the tree being observed
  GiSTnode *ReadNode (const GiSTpath& path) const;
  GiSTnode *CreateNode() const;

private:
  GiST*    tree;         // tree being observed
};

#endif