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/*
* linkedlist.cc
* Copyright (C) 2000 Frank Hale
* frankhale@yahoo.com
* http://sapphire.sourceforge.net/
*
* Updated: 17 Jan 2002
*
* This program 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 any later version.
*
* This program 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 should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include "linkedlist.hh"
using namespace std;
_LinkedList::_LinkedList()
{
// Get our linked list started.
// Do our default initialization here.
head = NULL;
tail = NULL;
elements=0;
}
_LinkedList::~_LinkedList()
{
// remove each element
removeAll();
}
void _LinkedList::removeAll()
{
Element *temp; //holds the element to be deleted
while(head != NULL) //while anything is in the LL
{
temp = head; //grab the top item
head=head->next; //move the next up
delete temp; //and delete the old top.
}
//now we know everything is gone, so reset to empty state
tail=0;
elements=0;
}
// Inserts an element onto the end of the list.
void _LinkedList::insert(void *data)
{
// We want to add an element by its data. We
// don't want the user of the list to be concerned
// about creating a new element his/her self.
// Allocate memory for a new Element.
Element *temp = new Element();
// Set the temp element data to the data passed
// to this function.
temp->data = data;
// If head is NULL we have an empty list.
if(head==NULL)
{
// If the list is empty then insert it at
// the beginning of the list.
head = tail = temp;
temp->prev = NULL;
} else {
// List has elements in it already,
// Insert onto the end of the list.
tail->next = temp;
temp->prev = tail;
}
// Remember that this element is
// at the end of the list.
tail = temp;
temp->next = NULL;
// Add one to the number of elements.
elements++;
}
Element* _LinkedList::find(void *data)
{
Element *temp;
temp = head;
// This for loop iterates through the elements
// so we can check for the data. If we find data
// then we found our element.
for (; temp != NULL;)
{
// Return the element if we find its data
if (temp->data == data)
return temp;
temp = temp->next;
}
// The data doesn't belong to any element in
// our list.
return NULL;
}
void _LinkedList::remove(void *data)
{
// We can't delete an element if
// that element doesn't exist in
// the first place.
Element *temp = find(data);
// If temp element is NULL that means
// we didn't find the element we were
// looking for.
if(temp == NULL)
{
cerr << "_LinkedList::remove : element not found" << endl;
return;
} else {
if(temp==head) head = temp->next; //if head just drop off
else temp->prev->next = temp->next; //else drop out.
if(temp==tail) tail = temp->prev; //if tail just drop off
else temp->next->prev = temp->prev; //else drop out
delete temp;
// Subtract one from total elements.
elements--;
temp = NULL;
}
}
/* _LinkedListIterator Below */
_LinkedListIterator::_LinkedListIterator()
{
iter = NULL;
}
void _LinkedListIterator::setList(_LinkedList *l, int direction)
{
if(l != NULL)
{
list = l;
element = NULL;
iter = NULL;
reset(direction);
} else {
cerr << "_LinkedListIterator: List is NULL" << endl;
exit(-1);
}
}
void _LinkedListIterator::reset(int direction)
{
switch(direction)
{
case FORWARD:
setForward();
element = list->head;
break;
case BACKWARD:
setBackward();
element = list->tail;
break;
default:
cerr << "_LinkedListIterator: Illegal direction for list traversal using FORWARD" << endl;
setForward();
element = list->head;
break;
}
}
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