'
'Class description:
'
!short:Stack class structure
Class Stack:
~~~~~~~~~~~~~
Stack is defined as an object.


Common use:
~~~~~~~~~~~~~~~~~
LOCAL OBJECT Stack OF Stack
Stack:Push(...)  //can be used repeatedly
...
x:=Stack:Pop()   //can be repeated

Source code of class Stack is in C_Stack.prg

!seealso: c_menu.ngo:Menu c_color.ngo:Color ob_class.ngo:"Class hierarchy"

!short:~~~~~~~~~~~~~~~~~~~~~~~
!short:create class Stack
!short:  export:
!short:  var Data    //{}
^BStack:Data^N: private: array
  Array which data is filled by Push(val) method and retrieved by
  Pop() method.

!short:  method New=StackNew           //o:New() --> self
^BStack:New()^N: public: return self
  Object is filled with default values.

!short:  method Init=StackInit         //o:Init() --> true
^BStack:Init()^N: public: return true
  The stack is initialised, i.e. the instvar variable is set to {}
  (empty array).

!short:  method Push=StackPush         //o:Push(val) --> xVal
^BStack:Push(xVal)^N: public: return xVal
  The value xVal is stored on top of the stack.

!short:  method Pop=StackPop           //o:Pop() --> xVal
^BStack:Pop()^N: public: return xVal
  The last stored value is retrieved as result and stack is lowered by one.

!short:  method Top=StackTop           //o:Top() --> xVal
^BStack:Top()^N: public: return xVal
  The last stored value is returned, no stack size change.

!short:  method IsEmpty=StackIsEmpty   //o:IsEmpty() --> true/false
^BStack:IsEmpty()^N: public: return true/false
  If empty true is returned, else false is returned.

!short:  method Done=StackDone         //o:Done() --> true
^BStack:Done()^N: public: return true
  Nothing to do because the memory becomes free when the object is destroyed.
  When the object of class Stack is destroyed, its instvar variable
  Stack:data is also destroyed.

!short:  endclass