aimacode · norvig · Apr 17, 2017 · Mar 23, 2017 · Mar 23, 2017 · Mar 23, 2017
diff --git a/tests/test_utils.py b/tests/test_utils.py
@@ -1,6 +1,6 @@
 import pytest
 from utils import *  # noqa
-
+import random
 
 def test_removeall_list():
     assert removeall(4, []) == []
@@ -177,6 +177,53 @@ def test_expr():
     assert (expr('GP(x, z) <== P(x, y) & P(y, z)')
             == Expr('<==', GP(x, z), P(x, y) & P(y, z)))
 
+def test_FIFOQueue() :
+    # Create an object
+    queue = FIFOQueue()
+    # Generate an array of number to be used for testing
+    test_data = [ random.choice(range(100)) for i in range(100) ]
+    # Index of the element to be added in the queue
+    front_head = 0
+    # Index of the element to be removed from the queue
+    back_head = 0
+    while front_head < 100 or back_head < 100 :
+        if front_head == 100 : # only possible to remove
+            # check for pop and append method
+            assert queue.pop() == test_data[back_head]
+            back_head += 1
+        elif back_head == front_head : # only possible to push element into queue
+            queue.append(test_data[front_head])
+            front_head += 1
+        # else do it in a random manner
+        elif random.random() < 0.5 :
+            assert queue.pop() == test_data[back_head]
+            back_head += 1
+        else :
+            queue.append(test_data[front_head])
+            front_head += 1
+        # check for __len__ method
+        assert len(queue) == front_head - back_head
+        # chek for __contains__ method
+        if front_head - back_head > 0 :
+            assert random.choice(test_data[back_head:front_head]) in queue
+
+    # check extend method
+    test_data1 = [ random.choice(range(100)) for i in range(50) ]
+    test_data2 = [ random.choice(range(100)) for i in range(50) ]
+    # append elements of test data 1
+    queue.extend(test_data1)
+    # append elements of test data 2
+    queue.extend(test_data2)
+    # reset front_head
+    front_head = 0
+
+    while front_head < 50 :
+        assert test_data1[front_head] == queue.pop()
+        front_head += 1
+
+    while front_head < 100 :
+        assert test_data2[front_head - 50] == queue.pop()
+        front_head += 1
 
 if __name__ == '__main__':
     pytest.main()
diff --git a/utils.py b/utils.py
@@ -571,7 +571,7 @@ def __missing__(self, key):
 # ______________________________________________________________________________
 # Queues: Stack, FIFOQueue, PriorityQueue
 
-# TODO: Possibly use queue.Queue, queue.PriorityQueue
+# TODO: queue.PriorityQueue
 # TODO: Priority queues may not belong here -- see treatment in search.py
 
 
@@ -607,29 +607,32 @@ class FIFOQueue(Queue):
 
     """A First-In-First-Out Queue."""
 
-    def __init__(self):
-        self.A = []
-        self.start = 0
+    def __init__(self, maxlen=None, items=[]):
+        self.queue = collections.deque(items, maxlen)
 
     def append(self, item):
-        self.A.append(item)
-
-    def __len__(self):
-        return len(self.A) - self.start
+        if not self.queue.maxlen or len(self.queue) < self.queue.maxlen:
+            self.queue.append(item)
+        else:
+            raise Exception('FIFOQueue is full')
 
     def extend(self, items):
-        self.A.extend(items)
+        if not self.queue.maxlen or len(self.queue) + len(items) <= self.queue.maxlen:
+            self.queue.extend(items)
+        else:
+            raise Exception('FIFOQueue max length exceeded')
 
     def pop(self):
-        e = self.A[self.start]
-        self.start += 1
-        if self.start > 5 and self.start > len(self.A) / 2:
-            self.A = self.A[self.start:]
-            self.start = 0
-        return e
+        if len(self.queue) > 0:
+            return self.queue.popleft()
+        else :
+            raise Exception('FIFOQueue is empty')
+
+    def __len__(self):
+        return len(self.queue)
 
     def __contains__(self, item):
-        return item in self.A[self.start:]
+        return item in self.queue
 
 
 class PriorityQueue(Queue):