gistpredicate.h

FastDb是高效的内存数据库系统

// -*- Mode: C++ -*-

//        GiSTpredicate.h
//
// Copyright (c) 1996, Regents of the University of California
// $Header: /usr/local/devel/GiST/libGiST/libGiST/GiSTpredicate.h,v 1.1.1.1 1996/08/06 23:47:22 jmh Exp $

#ifndef GISTPREDICATE_H
#define GISTPREDICATE_H

#ifdef PRINTING_OBJECTS
#include <iostream.h>
#endif

#include "GiSTdefs.h"
#include "GiSTentry.h"

// The GiSTpredicate class itself doesn't do much except serve as a
// placeholder for the Consistent method.  However, some handy Boolean
// connectors are here as well (And, Or, Not) and well as True.


class GiSTentry;

class GiSTpredicate : public GiSTobject
{
  public:
    GiSTobjid IsA() const { return GISTPREDICATE_CLASS; }
    virtual int Consistent(const GiSTentry& entry) const = 0;
    virtual ~GiSTpredicate() {}
};

class PtrPredicate : public GiSTpredicate
{
  public:
    PtrPredicate(GiSTpage page) : page(page) {}
    int Consistent(const GiSTentry& entry) const;
    GiSTobject *Copy() const;
#ifdef PRINTING_OBJECTS
    void Print(ostream& os) const;
#endif
  private:
    GiSTpage page;
};

class AndPredicate : public GiSTpredicate
{
  public:
    AndPredicate(GiSTpredicate *q1,
		 GiSTpredicate *q2) : q1(q1), q2(q2) {}
    int Consistent(const GiSTentry& entry) const {
	return q1->Consistent(entry) && q2->Consistent(entry);
    }
#ifdef PRINTING_OBJECTS
    void Print(ostream& os) const {
	os << "(" << *q1 << " and " << *q2 << ")";
    }
#endif
    GiSTobject *Copy() const {
	return new AndPredicate((GiSTpredicate*)q1->Copy(),
				(GiSTpredicate*)q2->Copy());
    }
    ~AndPredicate() {
	if (q1) delete q1;
	if (q2) delete q2;
    }
  private:
    GiSTpredicate *q1, *q2;
};

class OrPredicate : public GiSTpredicate
{
  public:
    OrPredicate(GiSTpredicate *q1,
		GiSTpredicate *q2) : q1(q1), q2(q2) {}
    int Consistent(const GiSTentry& entry) const {
	return q1->Consistent(entry) || q2->Consistent(entry);
    }
#ifdef PRINTING_OBJECTS
    void Print(ostream& os) const {
	os << "(" << *q1 << " or " << *q2 << ")";
    }
#endif
    GiSTobject *Copy() const {
	return new OrPredicate((GiSTpredicate*)q1->Copy(),
			       (GiSTpredicate*)q2->Copy());
    }
    ~OrPredicate() {
	if (q1) delete q1;
	if (q2) delete q2;
    }
  private:
    GiSTpredicate *q1, *q2;
};

class NotPredicate : public GiSTpredicate
{
  public:
    NotPredicate(GiSTpredicate *q) : q(q) {}
    int Consistent(const GiSTentry& entry) const {
	return !q->Consistent(entry);
    }
    GiSTobject *Copy() const {
	return new NotPredicate((GiSTpredicate*)q->Copy());
    }
#ifdef PRINTING_OBJECTS
    void Print(ostream& os) const {
	os << "(not " << *q << ")";
    }
#endif
    ~NotPredicate() { if (q) delete q; }
  private:
    GiSTpredicate *q;
};

class TruePredicate : public GiSTpredicate
{
  public:
    TruePredicate() {}
    int Consistent(const GiSTentry& entry) const {
	return 1;
    }
    GiSTobject *Copy() const {
	return new TruePredicate;
    }
#ifdef PRINTING_OBJECTS
    void Print(ostream& os) const {
	os << "true";
    }
#endif
};

extern TruePredicate truePredicate;

#endif