Merge pull request #26 from bchaoss/main

add CircularQueue.py

datastax/Arrays/CircularQueue.py

@@ -0,0 +1,45 @@
+# Circular Queue implementation using Lists (Pseudo Arrays)
+from typing import Any, Optional
+
+from datastax.Utils.Exceptions import OverflowException, UnderflowException
+from datastax.Arrays import Queue
+
+
+class CircularQueue(Queue):
+    def __init__(self, *, capacity: Optional[int] = None):
+        super().__init__(capacity=capacity)
+        self._front = 0
+        self._rear = 0 
+
+    def is_full(self) -> bool:
+        if not super().is_full():
+            return False
+        return (self._rear + 1) % self.capacity == self._front
+
+    def is_empty(self) -> bool:
+        if super().is_empty():
+            return True
+        return self._front == self._rear
+
+    def enqueue(self, item: Any) -> int:
+        if self.is_full():
+            raise OverflowException(self)
+
+        if not super().is_full():
+            self._array.append(item) 
+        else:
+            self._array[self._rear] = item
+        self._rear = (self._rear + 1) % self.capacity
+        return 0
+
+    def dequeue(self) -> Any:
+        if self.is_empty():
+            raise UnderflowException(self)
+        deleted_item = self._array[self.front]
+        self._front = (self._front + 1) % self.capacity
+        return deleted_item
+
+    def peek(self) -> Any:
+        if self.is_empty():
+            return "CIRCULAR QUEUE EMPTY"
+        return self._array[self._front]