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-- File: TCollection_Stack.cdl
-- Created: Mon Jan 18 10:45:24 1993
-- Author: Remi LEQUETTE
-- <rle@phylox>
-- Updated: M. MERCIEN 26, Oct 1994
-- Subject: StackIterator implementation
---Copyright: Matra Datavision 1993
generic class Stack from TCollection (Item as any)
---Purpose: A stack is a structure where item can be added and
-- removed from the top. Like a stack of plates in a
-- kitchen. The last entered item will be be the
-- first removed. This is called a LIFO (last In First Out).
-- Stack is a generic class which depends on Item, the type
-- of element in the structure.
-- Use a StackIterator iterator to explore a Stack structure.
-- Note: An iterator class is automatically instantiated from
-- the TCollection_StackIterator class at the time of
-- instantiation of a Stack structure.
raises
NoSuchObject from Standard
class StackNode from TCollection
inherits MapNode from TCollection
uses MapNodePtr from TCollection
is
Create(I : Item; n : MapNodePtr from TCollection) returns StackNode from TCollection;
---C++: inline
Value(me) returns Item;
---C++: return &
---C++: inline
fields
myValue : Item;
end;
class StackIterator from TCollection
---Purpose: Functions used for iterating the contents of a Stack data structure.
-- Note: an iterator class is automatically instantiated from
-- this generic class at the time of instantiation of a Stack structure.
raises NoSuchObject from Standard
is
Create returns StackIterator from TCollection;
---Purpose: Constructs an empty iterator for a Stack data structure.
-- Use the function Initialize to define the stack to explore.
Create(S : Stack from TCollection) returns StackIterator from TCollection;
---Purpose: Constructs an iterator on the stack stack, and positions it
-- on the first item of the stack stack, if it exists.
-- The current position is undefined if the stack stack is empty.
-- Use in a loop:
-- - the function More to know if there is a current item,
-- - then the function Value to read the value of the current item,
-- - then the function Next to position the iterator on the
-- next item, if it exists.
Initialize(me : in out; S : Stack from TCollection)
---Purpose: Sets, or resets this iterator for the stack stack, and
-- positions it on the first item of the stack stack, if it exists.
-- The current position is undefined if the stack stack is empty.
-- Example
-- TColStd_StackOfInteger stack;
-- TColStd_StackIteratorOfStackOfInteger
-- pos;
-- pos.Initialize(stack);
-- Use in a loop:
-- - the function More to know if there is a current item,
-- - then the function Value to read the value of the current item,
-- - then the function Next to position the iterator on the
-- next item, if it exists.
is static;
More(me) returns Boolean from Standard
---Purpose:Returns true if there is a current item in the stack explored
-- with this iterator (i.e. when the current position is defined).
-- More is false if:
-- - the iterator is not initialized, or
-- - the stack is empty, or
-- - the exploration is finished.
-- Use:
-- - the function Value to read the current item,
-- - the function Next to position this iterator on the next item, if it exists.
---C++: inline
is static;
Next(me: in out)
---Purpose: Sets the iterator to the next item in the explored stack.
-- If the current position of this iterator corresponds to the
-- top of the stack, it becomes undefined.
is static;
Value(me) returns any Item
raises NoSuchObject from Standard
---Purpose: Returns the value of the current item of this iterator in the explored stack.
-- Note: Item is the type of element in the explored Stack stack.
-- Example
-- TColStd_StackOfInteger stack;
-- TColStd_StackIteratorOfStackOfInteger
-- pos(stack);
-- stack.Push(1);
-- assert ( pos.Value() == 1 );
-- Exceptions
-- Standard_NoSuchObject if the current position of this
-- iterator is undefined.
---C++: return const &
is static;
fields
current : Address from Standard;
end StackIterator from TCollection;
is
Create returns Stack from TCollection;
---Purpose: Constructs an empty stack.
-- Use:
-- - the function Push to add an item at the top of the stack,
-- - the function Top to read the item at the top of the stack,
-- - the function ChangeTop to assign a new value to the
-- item at the top of the stack,
-- - the function Pop to remove the item at the top of the stack,
-- - and a stack iterator to explore the stack and read all its items.
-- Warning
-- To copy a stack, you must explicitly call the assignment
-- operator (operator=)..
Create(Other : Stack from TCollection)
returns Stack from TCollection
is private;
---Purpose: Creates by copying an existing Stack.
-- Warning: Prints a message when other is not empty. It is
-- recommanded to use Assign (operator =).
Assign(me : in out; Other : Stack from TCollection)
returns Stack from TCollection
---Purpose: Copies in this stack the content of <Other>.
--If this stack is not empty, it is automatically cleared before copying.
-- Note that this method is an alias of the assignment
-- operator operator =.
---C++: alias operator =
---C++: return const &
is static;
IsEmpty(me) returns Boolean
---Purpose: Returns True when the stack is empty.
-- i.e. Depth() == 0
---C++: inline
is static;
Depth(me) returns Integer
---Level: Public
---Purpose: Returns the number of Items in the stack.
-- The depth of this stack is:
-- - incremented by Push, and
-- - decremented by Pop.
-- Example:
-- me = (A B C)
-- returns 3
---C++: inline
is static;
Top(me) returns any Item
---Level: Public
---Purpose: Returns the Item at the top of the stack.
-- Example:
-- before
-- me = (A B C)
-- after
-- me = (A B C)
-- returns
-- A
-- Trigger: Raises an exception when <me> is empty
---C++: return const &
raises NoSuchObject from Standard
is static;
Push(me : in out; I : Item)
---Level: Public
---Purpose: Adds <I> at the top of the stack. Depth is
-- incremented.
-- Example:
-- before
-- me = (A B C) I = D
-- after
-- me = (D A B C)
is static;
Pop(me : in out)
---Level: Public
---Purpose: Removes the Item at the top of the stack. Depth is
-- decremented.
-- Example:
-- before
-- me = (A B C)
-- after
-- me = (B C)
-- Trigger: Raises an exception when <me> is empty
raises NoSuchObject from Standard
is static;
Clear(me : in out)
---Level: Public
---Purpose: Removes all the items from the stack.
---C++: alias ~
is static;
ChangeTop(me : in out) returns any Item
---Level: Public
---Purpose: Returns a modifiable reference of the top of the stack.
-- Example:
-- before
-- me = (A B C)
-- me.ChangeTop() = D
-- after
-- me = (D B C)
-- Trigger: Raises an exception when <me> is empty
raises NoSuchObject from Standard
---C++: return &
is static;
fields
myTop : Address from Standard;
myDepth : Integer from Standard;
friends
class StackIterator from TCollection
end Stack;
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