Scissors - Araceli

stacks_queues/queue.py

@@ -1,11 +1,13 @@
 
+from sqlalchemy import null
+
 INITIAL_QUEUE_SIZE = 20
 
 class QueueFullException(Exception):
     pass
 
 class QueueEmptyException(Exception):
-    pass
+    pass 
 
 class Queue:
 
@@ -23,39 +25,74 @@ def enqueue(self, element):
             In the store are occupied
             returns None
         """
-        pass
+
+        if self.front == (self.rear + 1) % self.buffer_size:
+            raise QueueFullException()
+
+        if self.front == -1:
+            self.front = 0
+
+        self.rear = (self.rear +1) % self.buffer_size
+        self.store[self.rear] = element
+        self.size += 1
 
     def dequeue(self):
         """ Removes and returns an element from the Queue
             Raises a QueueEmptyException if 
             The Queue is empty.
         """
-        pass
+
+        if self.front == -1:
+            raise QueueEmptyException()
+        else:
+            element = self.store[self.front]
+            self.front = (self.front + 1) % self.buffer_size
+            self.size -= 1
+
+        return element 
 
     def front(self):
         """ Returns an element from the front
             of the Queue and None if the Queue
             is empty.  Does not remove anything.
         """
-        pass
-
+        if self.size == 0:
+            return None
+
+        return self.store[self.front]
 
     def size(self):
         """ Returns the number of elements in
             The Queue
         """
-        pass
+        return self.size 
 
     def empty(self):
         """ Returns True if the Queue is empty
             And False otherwise.
         """
-        pass
+        return self.size == 0
+
 
     def __str__(self):
         """ Returns the Queue in String form like:
             [3, 4, 7]
             Starting with the front of the Queue and
             ending with the rear of the Queue.
         """
-        pass
+
+        queue_list = []
+
+        if self.size == 0:
+            return queue_list
+
+        current = self.front
+
+        while current != self.rear:
+            if current != None:
+                queue_list.append(self.store[current])
+                current = (current + 1) % self.buffer_size
+
+        queue_list.append(self.store[self.rear])
+
+        return str(queue_list)

stacks_queues/stack.py

@@ -12,7 +12,8 @@ def push(self, element):
         """ Adds an element to the top of the Stack.
             Returns None
         """
-        pass
+        self.store.add_first(element); 
+        return None
 
     def pop(self):
         """ Removes an element from the top
@@ -21,18 +22,20 @@ def pop(self):
             The Stack is empty.
             returns None
         """
-        pass
+        if not self.empty():
+            return self.store.remove_first()
 
     def empty(self):
         """ Returns True if the Stack is empty
             And False otherwise
         """
-        pass
+
+        return self.store.empty()
 
     def __str__(self):
         """ Returns the Stack in String form like:
             [3, 4, 7]
             Starting with the top of the Stack and
             ending with the bottom of the Stack.
         """
-        pass
+        return str(self.store)