! An implementation of the stack datatype. By Fredrik Ramsberg, 15 Jan 2003.
! After each Stack.push() operation, Stack.failure or Stack.success will be
! returned. After each Stack.pop() operation, the value popped or
! Stack.failure will be returned. Stack.failure and Stack.success can both
! be changed by the application creating the Stack object. Also, you can
! choose to read Stack.status after each pop operation, in case there is
! no safe value to use for signaling a failure.
!
! Sample of how to set up a stack:
!
! Array stack1tab table 3; ! Last argument states max # of items on stack
!
! Stack stack1 "Stack 1"
! with
! stacktable stack1tab;
Class Stack
private
stacktable -1,
top 0,
with
failure -2,
success -1,
status -1,
push [ element;
self.status=self.success;
if(self.top>=self.stacktable-->0)
self.status=self.failure;
else
(self.stacktable)-->(++self.top)=element;
return self.status;
],
pop [;
self.status=self.success;
if(self.top<=0)
self.status=self.failure;
else
return (self.stacktable)-->(self.top--);
return self.status;
],
size [;
return self.stacktable-->0;
],
element_count [;
return self.top;
];
