Category : Alternate Operating Systems - Quarterdeck DesqView, CP/M, etc
Archive   : PCCAPP.ZIP
Filename : LIGHTHAS.H

/*
* This file is part of the Choices Operating System
* Developed by: The TAPESTRY Parallel Computing Laboratory
* University of Illinois at Urbana-Champaign
* Department of Computer Science
* 1304 W. Springfield Ave.
* Urbana, IL 61801
*
* Copyright (c) 1987, 1988, 1989 The University of Illinois Board of Trustees.
* All Rights Reserved.
* CONFIDENTIAL INFORMATION. Distribution restricted under license agreement.
*
* Author: Aamod Sane ([email protected])
* Project Manager and Principal Investigator: Roy Campbell ([email protected])
*
* Funded by: NSF TAPESTRY Grant No. 1-5-30035, NASA ICLASS Grant
* No. 1-5-25469 and No. NSG1471 and AT&T Metronet Grant No. 1-5-37411.
*/

#include "GPInclude.h"
#include "LightList.h"

#ifndef LightHashTable_h
#define LightHashTable_h

// Abstract hash table defined for SLink subclasses that have a hash()
// function. An interface can define a proper subclass and hash
// functions for numbers, strings and pointers.

class LightHashTable {
friend class HashVirtualiser;
int nextPrime( int from );
int isPrime( int number );
int divides( int divisor, int number );
protected:

// Internal classes and variables get prepended by underscore
class _lht_table {
protected:
int _numBuckets;
LightList* __table;
public:
_lht_table(LightList * _t, int _n) { __table = _t; _numBuckets = _n; };
virtual ~_lht_table();
virtual LightList* operator[](int i);
};
_lht_table* _table;

int _numBuckets;
PFSV _destructFunction; // Function called on all elements when
// destructing, if defined in ctor

// Virtualiser is used to virtualise the functions for the
// lightlist. What it actually does is to dispatch these to the
// functions defined in the hashtable. Subclasses of hashtable
// never have to bother about the virtualiser again.

class HashVirtualiser : public LightListVirtualiser {
LightHashTable* _t;
public:
HashVirtualiser( LightHashTable * h ) { _t = h; };
virtual ~HashVirtualiser() {};
virtual int compare(SLink * a, SLink * b);
virtual void destroy(SLink * a);
virtual void inspect(SLink * a);
virtual SLink * end(SLink *);
};
HashVirtualiser* _v;

virtual int hash( SLink * entry, int buckets );
virtual int compare( SLink * a, SLink * b );
virtual void deleteEntry( SLink * entry );
virtual void inspectEntry( SLink * entry );
virtual SLink * listType(SLink *);

public:
// Estimated size or nearabouts.
LightHashTable(int size, PFSV f=0);
LightHashTable(int size, PFSV f, int derived);
virtual ~LightHashTable();

// find and remove will return a pointer to the found/removed link
// resp. or 0 for failure. Note,of course, that the SLink class
// defined such a member function

virtual void insert( SLink * entry );
// For nonunique members, search for the nth element. The first
// element is 0
virtual SLink * find( SLink * entry, int n=0 );
virtual SLink * remove( SLink * entry, int n=0 );
virtual void mapcar(PFSV f); // PFSV defined in SLink.h

virtual void inspect();
};

#endif