Updated __init__.py as for queue requirement

pydatastructs/miscellaneous_data_structures/__init__.py

@@ -2,7 +2,9 @@
 
 from . import (
     stack,
-    binomial_trees
+    binomial_trees,
+    queue
+
 )
 
 from .binomial_trees import (
@@ -11,6 +13,11 @@
 __all__.extend(binomial_trees.__all__)
 
 from .stack import (
-    Stack,
+    Stack
 )
 __all__.extend(stack.__all__)
+
+from .queue import (
+    Queue
+)
+__all__.extend(queue.__all__)

pydatastructs/miscellaneous_data_structures/queue.py

@@ -0,0 +1,66 @@
+from pydatastructs.linear_data_structures import DynamicOneDimensionalArray
+
+__all__ = [
+    'Queue'
+]
+
+_check_type = lambda a, t: isinstance(a, t)
+NoneType = type(None)
+
+class Queue(objects):
+    def __new__(clas, implementation='array', **kwargs):
+        if implementation == 'array':
+            return ArrayQueue(
+                kwargs.get('item', None),
+                kwargs.get('dtype', int))
+        raise NotImplementedError("%s hasn't been implemented yet."%(implementation))
+
+   def append(self, *args, **kwargs):
+        raise NotImplementedError("This is an abstract method.")
+
+   def popleft(self, **kwargs):
+        raise NotImplementedError("This is an abstract method.")
+
+   def __len__(self, **kwargs):
+        raise NotImplementedError("This is an abstract method.")
+
+
+class ArrayQueue(Queue):
+    __slots__ = ['item','dtype']
+    front= -1
+    count= 0
+    def __new__(clas, item = None, dtype = int):
+        if item is None:
+            item= DynamicOneDimensionalArray(dtype, 0)
+        else:
+            item= DynamicOneDimensionalArray(dtype, item)
+
+        obj = object.__new__(clas)
+        obj.item, obj.dtype = item, items._dtype
+        return obj
+
+    def append(self, x):
+            if self.front == -1:
+                self.front=0
+            self.item.append(x)
+            self.count+=1
+
+    def popleft(self):
+        if (self.front == -1):
+            raise ValueError("Queue is empty.")
+        r = dc(self.item[self.front])
+        self.item.delete(self.front)
+        self.front += 1
+        return r
+
+    def __len__(self):
+        if (self.front == -1):
+            return 0
+        else:
+            return (self.count- self.front)
+
+    def __str__(self):
+        """
+        Used for printing.
+        """
+        return str(self.item._data)