/* ------------------------------------------------------------------------- */
/* list1.cc                                                                  */
/* implemen'n module for templated singly linked circular list class         */
/*                       with global memory alloc'n                          */
/* ------------------------------------------------------------------------- */

#include "list1.h"

// Print list to cout,
template <class Dtype>
void List1<Dtype> :: Print ( ) const {
  if ( Back ) {
    Node *temp = Back->Next;
    Node *nptr = temp->Next;
    cout << temp->Datum;
    while ( nptr != temp ) {
      cout << nptr->Datum;
      nptr = nptr->Next; 
    }
  }
  return;
}  // end of Print( )

// delete nodes of list
template <class Dtype>
void List1<Dtype> :: MakeEmpty( ) {
  if ( Back) {
    Node *from = Back, *temp = Back, *to = Back->Next;
    delete temp; 
    while ( to != Back ) {
      temp = to;
      to = to->Next;
      delete temp;
    }
  }
  return;
}  // end of MakeEmpty( )

// Member function push_front
template <class Dtype>
void List1<Dtype> :: push_front(const Dtype& X) {
  if ( !Back ) {
    Back = new Node( X );
    if ( !Back ) {  // check that new Node succeeded
      cerr << "Out of space in free store; exiting." << endl;
      exit(2);
    }
    Back->Next = Back; 
    Count = 1;
    return;
  }
  Node *temp = Back->Next;
  Back->Next = new Node( X, temp);
  if ( !(Back->Next) ) {  // check that new Node succeeded
    cerr << "Out of space in free store; exiting." << endl;
    exit(2);
  }
  Count++;
  return;
}  // end of push_front


// Member function push_back
template <class Dtype>
void List1<Dtype> :: push_back(const Dtype& X) {
  if ( !Back ) {
    Back = new Node( X );
    if ( !Back ) {  // check that new Node succeeded
      cerr << "Out of space in free store; exiting." << endl;
      exit(2);
    }
    Back->Next = Back; 
    Count = 1;
    return;
  }
  Node *temp = Back;
  Back = new Node(X, temp->Next);
  if (Back == NULL) {  // check that new Node succeeded
    cerr << "Out of space in free store; exiting." << endl;
    exit(2);
  }
  temp->Next = Back;
  Count++;
  return;
}  // end of push_back

// Member function pop_front
// Deletes front item in list if list is non-empty
template <class Dtype>
void List1<Dtype> :: pop_front( ) {
  if ( Back ) {
    if ( Back == Back->Next ) {
      delete Back;
      Back = 0;
      Count = 0;
      return;
    }
    Node *temp = Back->Next;
    Back->Next = temp->Next;
    delete temp;
    Count--;
  }
  return;
}  // end of pop_front


template <class Dtype>
Dtype& List1<Dtype> :: front( ) const {
  if ( Back ) return Back->Next->Datum;
  else {
    cerr << "\nERROR -- front of empty queue; exiting." << endl;
    exit(3);
  }
}  // end of front

template <class Dtype>
Dtype& List1<Dtype> :: back( ) const {
  if ( Back ) return Back->Datum;
  else {
    cerr << "ERROR -- back of empty queue; exiting." << endl;
    exit(3);
  }
}  // end of back 

template <class Dtype>
int List1<Dtype> :: IsEmpty( ) const {
  if ( Count ) return 0;
  else return 1;
}  // end of empty 

template <class Dtype>
int List1<Dtype> :: Length( ) const {
  return Count;
}  // end of size

// Reverse ( ) -- link inversion reversal in place
template <class Dtype>
void List1<Dtype> :: Reverse( ) { 
  if ( !Back ) return;
  if ( Back == Back->Next ) return;
  Node *nfront = Back;
  Back = Back->Next;
  if ( Back->Next == nfront ) return;
  Node *from = Back;
  Node *to = Back->Next;
  Node *prev = nfront;
  while ( from != nfront ) {
    from->Next = prev;
    prev = from;
    from = to;
    to = to->Next;
  }
  nfront->Next = prev;
  return;
}  // end of Reverse( )

// Concat( ) -- concatenates two lists, in place
template <class Dtype>
void List1<Dtype> :: Concat( List1<Dtype> & Y ) {
  if ( !Y.Back ) return;
  if ( !Back ) {
    Back = Y.Back;
    Count = Y.Count;
    Y.Back = 0;
    Y.Count = 0;
    return;
  }
  Node *temp = Y.Back->Next;
  Y.Back->Next = Back->Next;
  Back->Next = temp;
  Back = Y.Back;
  Count += Y.Count;
  Y.Back = 0;
  Y.Count = 0;
  return;
}  // end of Concat( )