.TH "stack" 3 "Oct 12, 2003"
.SH Stack
.PP
.B
Inherits from:

Cltn
.SH Class Description
.PP
.B
Stack
instances are collections that maintain their entries in LIFO (last in first out) order\&.  Although Stacks are most often controlled by the 
.B
push:
and 
.B
pop
methods, the class also provides for random access of the stack, through the 
.B
at:
and 
.B
removeAt:
methods\&.  Note that the indices are relative to the top (last added) item on the stack, which is the opposite of how the 
.B
OrdCltn
class works\&.
.SH Method types
.PP 
.B
Creation
.RS 3
.br
* new
.br
* new:
.br
* copy
.br
* deepCopy
.br
* emptyYourself
.br
* freeContents
.br
* free
.RE
.PP 
.B
Interrogation
.RS 3
.br
* depth
.br
* isEmpty
.br
* eachElement
.br
* topElement
.RE
.PP 
.B
Adding
.RS 3
.br
* push:
.br
* pop
.br
* swap
.br
* at:
.br
* removeAt:
.RE
.PP 
.B
Printing
.RS 3
.br
* printOn:
.RE
.SH Methods
.PP 
new
.RS 1
+
.B
new
.RE
.PP
Returns a new empty stack\&.
.PP 
new:
.RS 1
+
.B
new
:(unsigned)
.I
n
.RE
.PP
Returns a new empty stack, that can hold 
.I
n
objects\&.
.PP 
copy
.RS 1
-
.B
copy
.RE
.PP
Returns a new copy of the stack\&.
.PP 
deepCopy
.RS 1
-
.B
deepCopy
.RE
.PP
Returns a new copy of the stack\&.  The members in the new stack are deep copies of the members in the original stack\&.
.PP 
emptyYourself
.RS 1
-
.B
emptyYourself
.RE
.PP
Removes all the members of the stack (without freeing them)\&.  Returns the receiver\&.
.PP 
freeContents
.RS 1
-
.B
freeContents
.RE
.PP
Removes and frees all the members of the receiver, but doesn\&'t free the receiver itself\&.  Returns the receiver\&.
.PP 
free
.RS 1
-
.B
free
.RE
.PP
Frees the stack, but not its contents\&.  Returns 
.B
nil
\&.  Do :
.RS 3

aCltn = [[aCltn freeContents] free];
.br

.RE
.PP
if you want to free the collection and its contents\&.
.PP 
depth
.RS 1
- (
unsigned
)
.B
depth
.RE
.PP
Returns the number of objects on the stack\&.
.PP 
isEmpty
.RS 1
- (
BOOL
)
.B
isEmpty
.RE
.PP
Whether the number of objects on the stack is equal to zero\&.
.PP 
eachElement
.RS 1
-
.B
eachElement
.RE
.PP
Returns a sequence of the elements in the collection\&.
.RS 3

aSeq = [myStack eachElement];
.br
while ((anElement = [aSeq next])) {
.br
/* do something */
.br
}
.br
aSeq = [aSeq free];
.br

.RE
.PP 
topElement
.RS 1
-
.B
topElement
.RE
.PP
Returns the top element on the stack, without removing it\&.  Returns 
.B
nil
if there are no elements on the stack\&.
.PP 
push:
.RS 1
-
.B
push
:
.I
anObject
.RE
.PP
Pushes 
.I
anObject
on the stack, so that it becomes the top of the stack\&.  Returns 
.B
self
\&.
.PP 
pop
.RS 1
-
.B
pop
.RE
.PP
Pops the top of the stack and returns it\&.  Returns 
.B
nil
if the stack is empty\&.
.PP 
swap
.RS 1
-
.B
swap
.RE
.PP
Exchanges the top two stack items and returns the receiver\&.  Generates an exception if the stack is not at least two items deep\&.
.PP 
at:
.RS 1
-
.B
at
:(unsigned )
.I
anOffset
.RE
.PP
Returns the object at 
.I
anOffset
\&.  Note that the top of the stack is at offset 0\&.
.PP 
removeAt:
.RS 1
-
.B
removeAt
:(unsigned )
.I
anOffset
.RE
.PP
Removes the object at 
.I
anOffset
\&.  Note that the top of the stack is at offset 0\&.
.PP 
printOn:
.RS 1
-
.B
printOn
:(IOD)
.I
aFile
.RE
.PP
Prints a list of the objects in the objects by sending each individual object a 
.B
printOn:
message\&.  Returns the receiver\&.