Added stack example.

README.md

@@ -7,6 +7,7 @@ SecureUML.
 
 ## Models
 * **[Royals and Loyals:](./royals_and_loyals)** The famous royals-and-loyals example.
+* **[Stack:](./stack)** A simple stack.
 
 ## Team
 * [Achim D. Brucker](http://www.brucker.ch/)

stack/README.md

@@ -0,0 +1,9 @@
+# A Simple Stack
+A very simple stack example.
+
+## Data Sheet
+* Format:               ArgoUML 0.26
+* Language:             UML/OCL
+
+For further information (license, citation, etc.), please look at the [README.md](../)
+of the main directory. 

stack/stack.ocl

@@ -0,0 +1,48 @@
+-- Copyright (c) 2003-2007 ETH Zurich, Switzerland
+--                    2016 The University of Sheffield, UK
+-- 
+-- All rights reserved.
+-- 
+-- Redistribution and use in source and binary forms, with or without
+-- modification, are permitted provided that the following conditions are met:
+-- 
+-- * Redistributions of source code must retain the above copyright notice, this
+--   list of conditions and the following disclaimer.
+-- 
+-- * Redistributions in binary form must reproduce the above copyright notice,
+--   this list of conditions and the following disclaimer in the documentation
+--   and/or other materials provided with the distribution.
+-- 
+-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+-- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+-- IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+-- DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+-- FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+-- DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+-- SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+-- CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+-- OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+-- OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+-- 
+package Stack
+
+context Stack::pop(): Stack
+    pre notEmpty: isEmpty() = false
+    post topElementRemoved: top() <> self.top@pre()
+    post: elements = elements@pre->subSequence(2,self@pre->size())
+    post: elements->size() = elements@pre->size() -1
+ 
+context Stack::top(): ElemType
+    pre   notEmpty: isEmpty() = false
+    post: result = elements->first()
+--    post: self=self@pre
+ 
+context Stack::push(e: ElemType): Stack
+    post pushedElemTypeIsOnTop: top() = e
+    post: elements = elements@pre->prepend(e)
+    post: result = self
+
+context Stack::isEmpty(): Boolean
+    post: result = (elements->size() <> 0)
+
+endpackage