/*------------------------------------------------------------------------*
 *    programm : C O N T A I N . C P P                                    *
 *        date : 12.06.1992                                               *
 *  created by : (fa)                                                     *
 *               Projekt MEE                                              *
 *                                                                        *
 *------------------------------------------------------------------------*/
//
// Contents -------------------------------------------------
// 
//      Implementation for class Container
//     
//      Memeber functions:
//
//      Container::Container
//      Container::~Container
//      Container::Add
//      Container::Insert
//      Container::Remove
//      Container::Delete
//      Container::Clear
//      Container::First
//      Container::Next
//      Container::Current
//      Container::Previous
//      Container::isEmpty
//
// End ------------------------------------------------------
//
// Implementation Dependencies ------------------------------

#include <stream.hpp>
#include "contain.hpp"
   
// End ------------------------------------------------------

// Implementation -------------------------------------------

Container::Container(){

   current=first=(Container_element*)NULL;
   itemsInContainer = NULL;  
}   

//-----------------------------------------------------------

void Container::Insert(Element &q){
   if(first==(Container_element*)NULL){           // 0 ... 1 element
      current=first=new Container_element(&q);    //
      current->next     = current;                //
      current->previous = current;
   }   
   else{
        if((current->previous==current) & (current->next==current)){
           Container_element *p=new Container_element(&q,current,current);
           current->next     = p;                 // 1 ... 2 elements
           current->previous = p;                 //
           first = current   = p;
        }
        else{
           Container_element *p=new Container_element(&q,current->previous,
                                                                   current);
           current->previous->next = p;           // 2 ... more elements
           current->previous = p;
           if(first==current) first=current=p;
           else current=p;                                            
        }        
   }
   itemsInContainer++;
}

//------------------------------------------------------------

void Container::Add( Element &q){
   if(first != (Container_element *)NULL) First();
   Insert(q);
   first=current->next;
}

//------------------------------------------------------------

Element* Container::Remove(){
   
   Element *elm_tmp;
   
   if(itemsInContainer){                             // ? container empty

      if(first==current) first=current->next;        // shift right for first
   
      if((current->previous==current) & (current->next==current)){
         elm_tmp=current->element;
         delete current;                             // removing last element
         current=first=(Container_element*)NULL;
      }
      else{   
         current->previous->next=current->next;
         current->next->previous=current->previous;
         Container_element *tmp=current;
         current=current->next;
         elm_tmp=tmp->element;
         delete tmp;
      }   
      itemsInContainer--;
      return elm_tmp;
   }
   else return (Element*)NULL;   
}

//------------------------------------------------------------

void  Container::Delete(){
  delete Remove();
}

//------------------------------------------------------------

void  Container::Clear(){
  while(itemsInContainer) Delete();
}
//------------------------------------------------------------

int   Container::itemsNumber(){
  return itemsInContainer;
}

//------------------------------------------------------------

Element * Container::First(){
   current=first;
   return current->element;
}

//------------------------------------------------------------

Element * Container::Next(){
   current=current->next;
   return current->element;
}

//------------------------------------------------------------

Element * Container::Current(){
      return current->element;
}

//------------------------------------------------------------

Element * Container::Previous(){
   current=current->previous;
   return current->element;
}

//------------------------------------------------------------

int Container::isEmpty(){
   return ((itemsInContainer>0)?0:1);
}

//------------------------------------------------------------

int Container::isFirst(){
   return ((first==current)?1:0); 
   
}

//------------------------------------------------------------

Container::~Container(){
   while(itemsInContainer) Remove();
}

// End of implementation -------------------------------------