Enhance the implementation of Queue using list

data_structures/queue/queue_on_list.py

@@ -1,52 +1,132 @@
 """Queue represented by a Python list"""
 
+from typing import Any
+
 
 class Queue:
-    def __init__(self):
-        self.entries = []
-        self.length = 0
-        self.front = 0
+    def __init__(self) -> None:
+        self.entries: list[Any] = []
+
+    def __str__(self) -> str:
+        """
+        >>> queue = Queue()
+        >>> str(queue)
+        '<>'
+        >>> queue.put(10)
+        >>> queue.put(20)
+        >>> queue.put(30)
+        >>> str(queue)
+        '<10, 20, 30>'
+        """
+
+        return "<" + str(self.entries)[1:-1] + ">"
+
+    def __len__(self) -> int:
+        """
+        >>> queue = Queue()
+        >>> queue.put(10)
+        >>> queue.put(20)
+        >>> queue.put(30)
+        >>> len(queue)
+        3
+        """
+
+        return len(self.entries)
 
-    def __str__(self):
-        printed = "<" + str(self.entries)[1:-1] + ">"
-        return printed
+    def put(self, item: Any) -> None:
+        """Put `item` to the Queue
 
-    """Enqueues {@code item}
-    @param item
-        item to enqueue"""
+        >>> queue = Queue()
+        >>> queue.put(10)
+        >>> str(queue)
+        '<10>'
+        >>> queue.put(20)
+        >>> str(queue)
+        '<10, 20>'
+        >>> len(queue)
+        2
+        """
 
-    def put(self, item):
         self.entries.append(item)
-        self.length = self.length + 1
-
-    """Dequeues {@code item}
-    @requirement: |self.length| > 0
-    @return dequeued
-        item that was dequeued"""
-
-    def get(self):
-        self.length = self.length - 1
-        dequeued = self.entries[self.front]
-        # self.front-=1
-        # self.entries = self.entries[self.front:]
-        self.entries = self.entries[1:]
-        return dequeued
-
-    """Rotates the queue {@code rotation} times
-    @param rotation
-        number of times to rotate queue"""
-
-    def rotate(self, rotation):
+
+    def get(self) -> Any:
+        """Get `item` from the Queue
+
+        >>> queue = Queue()
+        >>> queue.put(10)
+        >>> queue.get() == 10
+        True
+        >>> len(queue) == 0
+        True
+        >>> queue.get()
+        Traceback (most recent call last):
+        ...
+        IndexError: Queue is empty
+        """
+
+        if not self.entries:
+            raise IndexError("Queue is empty")
+        return self.entries.pop(0)
+
+    def rotate(self, rotation: int) -> None:
+        """Rotate the items of the Queue `rotation` times
+
+        >>> queue = Queue()
+        >>> for i in (10, 20, 30, 40):
+        ...     queue.put(i)
+        ...
+        >>> str(queue)
+        '<10, 20, 30, 40>'
+        >>> queue.rotate(1)
+        >>> str(queue)
+        '<20, 30, 40, 10>'
+        >>> queue.rotate(2)
+        >>> str(queue)
+        '<40, 10, 20, 30>'
+        """
+
+        # An optimization to reduce the number of attribute look-ups in the for-loop.
+        put = self.entries.append
+        get = self.entries.pop
+
         for _ in range(rotation):
-            self.put(self.get())
+            put(get(0))
+
+    def get_front(self) -> Any:
+        """Get the front item from the Queue
 
-    """Enqueues {@code item}
-    @return item at front of self.entries"""
+        >>> queue = Queue()
+        >>> for i in (10, 20, 30):
+        ...     queue.put(i)
+        ...
+        >>> queue.get_front()
+        10
+        >>> len(queue) == 3
+        True
+        """
 
-    def get_front(self):
         return self.entries[0]
 
-    """Returns the length of this.entries"""
+    def size(self) -> int:
+        """Returns the length of the Queue
+
+        >>> queue = Queue()
+        >>> queue.put(10)
+        >>> queue.size()
+        1
+        >>> queue.put(20)
+        >>> queue.size()
+        2
+        >>> queue.get()
+        10
+        >>> queue.size() == 1
+        True
+        """
+
+        return len(self.entries)
+
+
+if __name__ == "__main__":
+    from doctest import testmod
 
-    def size(self):
-        return self.length
+    testmod()