Category : C Source Code
Archive   : TCPPTECH.ZIP
Filename : CREALIST.CPP

// ECOSYSTEM SIMULATION PROGRAM
// crealist.cpp v2.00 08-Aug-1990
// Turbo C++ 1.0
//
// A list of Creature pointers
//
// Written by Scott Robert Ladd

#include "crealist.h"
#include "creature.h"
#include "stddef.h"
#include "stdlib.h"
#include "stdio.h"

// constructor
CreatureList::CreatureList()
{
Bottom = NULL;
Top = NULL;
Current = NULL;
}

// destructor
CreatureList::~CreatureList()
{
CreatureListNode * nextNode;

Current = Bottom;

while (Current != NULL)
{
nextNode = Current->Next;
delete Current;
Current = nextNode;
}
}

// add node to tope of list
void CreatureList::Add(Creature * w)
{
if (w == NULL)
return;

if (Top == NULL)
{
Top = new CreatureListNode;

if (Top == NULL)
{
printf("unable to allocate Top list item");
exit(255);
}

Top->Prev = NULL;
Top->Next = NULL;

Top->CreaturePtr = w;

Bottom = Top;
}
else
{
Top->Next = new CreatureListNode;

if (Top->Next == NULL)
{
printf("unable to allocate new list item");
exit(255);
}

Top->Next->Next = NULL;
Top->Next->Prev = Top;
Top = Top->Next;

Top->CreaturePtr = w;
}
}

// delete node from list
void CreatureList::Delete(Creature * w)
{
CreatureListNode * Temp;

if (w == NULL)
return;

Temp = Bottom;

while ((Temp != NULL) && (Temp->CreaturePtr != w))
Temp = Temp->Next;

if (Temp->CreaturePtr == w)
{
if (Temp == Current)
if (Temp == Bottom)
Current = Current->Next;
else
Current = Current->Prev;

if (Temp->Prev == NULL)
Bottom = Temp->Next;
else
Temp->Prev->Next = Temp->Next;

if (Temp->Next == NULL)
Top = Temp->Prev;
else
Temp->Next->Prev = Temp->Prev;

delete Temp;
}
}

// goto the bottom Creature in list
Creature * CreatureList::AtBottom()
{
Current = Bottom;

if (Current == NULL)
return NULL;
else
return Current->CreaturePtr;
}

// get next Creature in list
Creature * CreatureList::NextCreature()
{
if (Current == NULL)
return NULL;
else
{
Current = Current->Next;

if (Current == NULL)
return NULL;
else
return Current->CreaturePtr;
}
}