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// Template List class definition
// for illustration purposes only, no robust implementation ( no error-ckecking, etc)
#ifndef LIST_H
#define LIST_H
#include <iostream>
using std::cout;
#include <new>
template< class NODETYPE >
class List {
public:
List(); // constructor
~List(); // destructor
void insertAtFront( const NODETYPE & );
void insertAtBack( const NODETYPE & );
bool removeFromFront( NODETYPE & );
bool removeFromBack( NODETYPE & );
bool isEmpty() const;
void print() const;
private:
struct ListNode {
ListNode( const NODETYPE & info ): data( info ), nextPtr( 0 ) { } // constructor
NODETYPE data; // data
ListNode* nextPtr; // next node in list
}; // end struct ListNode
ListNode* firstPtr; // pointer to first node
ListNode* lastPtr; // pointer to last node
public:
class Iterator { // public access!
public:
friend class List< NODETYPE >;
Iterator( ListNode* initPos = 0 ) : currentPos( initPos ) { }
Iterator( const List< NODETYPE >& currentList )
{
*this = currentList.begin();
}
const NODETYPE& operator*() const
{
return currentPos->data;
}
NODETYPE& operator*()
{
return currentPos->data;
}
Iterator& operator++() // prefix
{
if( currentPos )
currentPos = currentPos->nextPtr;
return *this;
}
Iterator operator++( int ) // postfix
{
Iterator temp = *this;
++*this;
return temp;
}
bool operator==( const Iterator& x ) const
{
return currentPos == x.currentPos;
}
bool operator!=( const Iterator& x ) const
{
return currentPos != x.currentPos;
}
private:
ListNode* currentPos;
}; // end class Iterator
Iterator begin() const
{
return Iterator( firstPtr );
}
Iterator end() const
{
return Iterator();
}
}; // end class List
// default constructor
template< class NODETYPE >
List< NODETYPE >::List()
: firstPtr( 0 ),
lastPtr( 0 )
{
// empty body
} // end List constructor
// destructor
template< class NODETYPE >
List< NODETYPE >::~List()
{
if ( !isEmpty() ) { // List is not empty
cout << "Destroying nodes ...\n";
ListNode *currentPtr = firstPtr;
ListNode *tempPtr;
while ( currentPtr != 0 ) { // delete remaining nodes
tempPtr = currentPtr;
cout << tempPtr->data << '\n';
currentPtr = currentPtr->nextPtr;
delete tempPtr;
} // end while
} // end if
cout << "All nodes destroyed\n\n";
} // end List destructor
// insert node at front of list
template< class NODETYPE >
void List< NODETYPE >::insertAtFront( const NODETYPE &value )
{
ListNode *newPtr = new ListNode( value );
if ( isEmpty() ) // List is empty
firstPtr = lastPtr = newPtr;
else { // List is not empty
newPtr->nextPtr = firstPtr;
firstPtr = newPtr;
} // end else
} // end function insertAtFront
// insert node at back of list
template< class NODETYPE >
void List< NODETYPE >::insertAtBack( const NODETYPE &value )
{
ListNode *newPtr = new ListNode( value );
if ( isEmpty() ) // List is empty
firstPtr = lastPtr = newPtr;
else { // List is not empty
lastPtr->nextPtr = newPtr;
lastPtr = newPtr;
} // end else
} // end function insertAtBack
// delete node from front of list
template< class NODETYPE >
bool List< NODETYPE >::removeFromFront( NODETYPE &value )
{
if ( isEmpty() ) // List is empty
return false; // delete unsuccessful
else {
ListNode *tempPtr = firstPtr;
if ( firstPtr == lastPtr )
firstPtr = lastPtr = 0;
else
firstPtr = firstPtr->nextPtr;
value = tempPtr->data; // data being removed
delete tempPtr;
return true; // delete successful
} // end else
} // end function removeFromFront
// delete node from back of list
template< class NODETYPE >
bool List< NODETYPE >::removeFromBack( NODETYPE &value )
{
if ( isEmpty() )
return false; // delete unsuccessful
else {
ListNode *tempPtr = lastPtr;
if ( firstPtr == lastPtr )
firstPtr = lastPtr = 0;
else {
ListNode *currentPtr = firstPtr;
// locate second-to-last element
while ( currentPtr->nextPtr != lastPtr )
currentPtr = currentPtr->nextPtr;
lastPtr = currentPtr;
currentPtr->nextPtr = 0;
} // end else
value = tempPtr->data;
delete tempPtr;
return true; // delete successful
} // end else
} // end function removeFromBack
// is List empty?
template< class NODETYPE >
bool List< NODETYPE >::isEmpty() const
{
return firstPtr == 0;
} // end function isEmpty
// display contents of List
template< class NODETYPE >
void List< NODETYPE >::print() const
{
if ( isEmpty() ) {
cout << "The list is empty\n\n";
return;
} // end if
ListNode *currentPtr = firstPtr;
cout << "The list is: ";
while ( currentPtr != 0 ) {
cout << currentPtr->data << ' ';
currentPtr = currentPtr->nextPtr;
} // end while
cout << "\n\n";
} // end function print
#endif
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