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#include "stdafx.h" 
 
cStateManager::cStateManager()  
{  
  m_StateParent = NULL;  
} 
 
cStateManager::~cStateManager()  
{ 
  PopAll(); 
} 
 
// Push a function on to the stack 
void cStateManager::Push(void (*Function)(void *Ptr, long Purpose), void *DataPtr) 
{ 
  sState *StatePtr; 
 
  // Don't push a NULL value 
  if(Function != NULL) { 
    // Allocate a new state and push it on stack 
    StatePtr = new sState(); 
 
    StatePtr->Function = Function; 
    StatePtr->Next = m_StateParent; 
 
    m_StateParent = StatePtr; 
 
    // Call state with init purpose 
    StatePtr->Function(DataPtr, INITPURPOSE); 
  } 
} 
 
BOOL cStateManager::Pop(void *DataPtr) 
{ 
  sState *StatePtr; 
 
  // Remove the head of stack (if any) 
  if((StatePtr = m_StateParent) != NULL) { 
    // First call with shutdown purpose 
    m_StateParent->Function(DataPtr, SHUTDOWNPURPOSE); 
 
    m_StateParent = StatePtr->Next; 
    StatePtr->Next = NULL; 
    delete StatePtr; 
  } 
 
  // return TRUE if more states exist, FALSE otherwise 
  if(m_StateParent == NULL) 
    return FALSE; 
  return TRUE; 
} 
 
void cStateManager::PopAll(void *DataPtr) 
{ 
  while(Pop(DataPtr) == TRUE); 
} 
 
BOOL cStateManager::Process(void *DataPtr) 
{  
  // return an error if no more states 
  if(m_StateParent == NULL) 
    return FALSE; 
 
  // Process the top-most state 
  m_StateParent->Function(DataPtr, FRAMEPURPOSE);  
 
  return TRUE; 
}