LinkList.H

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/* Copyright 1998-2018 Matt Flax <flatmax@flatmax.org>
   This file is now part of MFFM VectorBass.

   MFFM VectorBass is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   MFFM VectorBass is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You have received a copy of the GNU General Public License
   along with MFFM VectorBass
 */

#ifndef LINKLIST_H
#define LINKLIST_H

#include <sys/types.h>
#include <iostream>

//#define LINKLIST_DEBUG

template <class TYPE>
class Lug {

protected:

public:

    Lug<TYPE> * next, * prev;

    TYPE ptr; // The element to point to

    Lug(void) {
        next = this;
        prev = this;
#ifdef LINKLIST_DEBUG
        std::cout <<"LinkList: Adding first "<<this<<" with previous "<< prev << " next " << next <<std::endl;
#endif
    }
    Lug(Lug<TYPE> * oldOne) {
        next = (*oldOne).getNext();
        prev = oldOne;
#ifdef LINKLIST_DEBUG
        std::cout <<"LinkList: Adding "<<this<<" with previous "<< prev << " next " << next <<std::endl;
#endif
        (*oldOne).getNext()->prev = this;
        (*oldOne).next = this;
    }

    //  ~Lug(void){}

    Lug *
    getNext(void) {
#ifdef LINKLIST_DEBUG
        std::cout <<"LinkList: getNext =  "<< next <<std::endl;
#endif
        return next;
    }

    Lug *
    getPrev(void) {
#ifdef LINKLIST_DEBUG
        std::cout <<"LinkList: getPrev =  "<< prev <<std::endl;
#endif
        return prev;
    }
};

template <class TYPE>
class LinkList {

    Lug<TYPE>* lug; 
    Lug<TYPE>* startLug; 
    long count; 
public:
    // Direction ...
    typedef enum {FWD, REV} direction; 
    direction dir; 

    LinkList(void) {
        lug = (Lug<TYPE>*)NULL;
        dir = FWD;
        count =0;
    }

    virtual ~LinkList(void) {
#ifdef LINKLIST_DEBUG
        std::cout <<"LinkList:~LinkList  removing "<<std::endl;
#endif

        while (lug != (Lug<TYPE>*)NULL)
            remove();
    }


    void add(TYPE newElement) { // Add the ptr
#ifdef LINKLIST_DEBUG
        std::cout <<"LinkList:add "<< newElement <<std::endl;
#endif
        if (lug == (Lug<TYPE>*)NULL) { // create the first ...
            lug = new Lug<TYPE>;
            startLug = lug;
        } else // Add infront of the current lug
            lug = new Lug<TYPE>(lug);
        lug->ptr = newElement;
        count++;
    }

    TYPE change(TYPE changeElement) { // exchange ptr's
#ifdef LINKLIST_DEBUG
        std::cout <<"LinkList:change "<< changeElement <<std::endl;
#endif
        if (lug != (Lug<TYPE>*)NULL) {
            TYPE tempPtr = lug->ptr;
            lug->ptr = changeElement;
            return tempPtr;
        } else
            return (TYPE)NULL;
    }

    TYPE remove(void) { // Remove the current lug and return the ptr
        if (lug != (Lug<TYPE>*)NULL) {
            if (lug == startLug)
                startLug = lug->getNext();
            Lug<TYPE>* tempLug = lug;
            TYPE tempPtr = lug->ptr;

            if (lug->getNext() == lug) { // Only one lug exists !
                lug = (Lug<TYPE>*)NULL;
            } else {
                lug->getPrev()->next = lug->getNext();
                lug->getNext()->prev = lug->getPrev();
                if (dir == FWD)
                    lug = lug->getNext();
                else
                    lug = lug->getPrev();
            }
            count--;
            delete tempLug;
            return tempPtr;
        } else {
            return (TYPE)0;//NULL;
        }
    }

    /* BAD IDEA ! - what if the lug->ptr is not a ptr !
    void delAll(void){
      while (getCount())
        del();
    }

    void del(void){ // Delete the current lug
      if (lug != (Lug<TYPE>*)NULL){
        if (lug == startLug)
    startLug = lug->getNext();
        Lug<TYPE>* tempLug = lug;
        TYPE tempPtr = lug->ptr;

        if (lug->getNext() == lug){ // Only one lug exists !
    lug = (Lug<TYPE>*)NULL;
        } else {
    lug->getPrev()->next = lug->getNext();
    lug->getNext()->prev = lug->getPrev();
    if (dir == FWD)
      lug = lug->getNext();
    else
      lug = lug->getPrev();
        }
        count--;
        delete tempLug;
        delete tempPtr;
        //      return tempPtr;
      }
    }
    */

    TYPE current(void) { // Return the current ptr
#ifdef LINKLIST_DEBUG
        std::cout <<"LinkList:current " <<std::endl;
#endif
        if (lug != (Lug<TYPE>*)NULL)
            return lug->ptr;
        else
            return (TYPE)NULL;
    }

    TYPE next(void) { // return the next ptr
#ifdef LINKLIST_DEBUG
        std::cout <<"LinkList:next "<<std::endl;
#endif
        if (lug != (Lug<TYPE>*)NULL) {
            if (dir == FWD)
                lug = lug->getNext();
            else
                lug = lug->getPrev();
            return lug->ptr;
        } else
            return (TYPE)0;//NULL;
    }

    TYPE prev(void) { // return the previous ptr
        if (lug != (Lug<TYPE>*)NULL) {
            if (dir == FWD)
                lug = lug->getPrev();
            else
                lug = lug->getNext();
            return lug->ptr;
        } else
            return (TYPE)0;//NULL;
    }

    TYPE grab(int i) { // return the i'th lug in the chain
#ifdef LINKLIST_DEBUG
        std::cout <<"LinkList:grab "<< i <<std::endl;
#endif
        if (i<=0) {
            std::cerr<<"LinkList: grab: index is less then or equal to zero"<<std::endl;
            return (TYPE)0;// NULL;
        } else if (i>count) {
            std::cerr<<"LinkList: grab: index exceeds count"<<std::endl;
            return (TYPE)0;// NULL;
        } else {
            lug = startLug;

            while (--i)
                lug = lug->getNext();
            return lug->ptr;
        }
    }

    int getCount(void) {
#ifdef LINKLIST_DEBUG
        std::cout <<"LinkList:getCount "<< count <<std::endl;
#endif
        return count;    
    }

    friend std::ostream& operator <<(std::ostream& o, LinkList* l) {
        if (l->getCount()==0) return o;
        l->grab(1);
        l->prev();
        for (int j=0; j<l->getCount(); j++)
            o<<l->next()<<' ';
        o<<std::endl;
        return o;
    }
    friend std::ostream& operator <<(std::ostream& o, LinkList& l) {
        if (l.getCount()==0) return o;
        l.grab(1);
        l.prev();
        for (int j=0; j<l.getCount(); j++)
            o<<l.next()<<' ';
        o<<std::endl;
        return o;
    }

    TYPE getEnd(){
        grab(1); // get the head.
        return prev(); // get the end element
    }
};
#endif // LINKLIST_H