initial commit

pig_lite/datastructures/priority_queue.py

@@ -0,0 +1,61 @@
+import heapq
+from functools import total_ordering
+
+
+# this annotation saves us some implementation work
+@total_ordering
+class Item(object):
+    def __init__(self, insertion, priority, value):
+        self.insertion = insertion
+        self.priority = priority
+        self.value = value
+
+    def __lt__(self, other):
+        # if the decision "self < other" can be done
+        # based on the priority, do that
+        if self.priority < other.priority:
+            return True
+        elif self.priority == other.priority:
+            # in case the priorities are equal, we
+            # fall back on the insertion order,
+            # which establishes a total ordering
+            return self.insertion < other.insertion
+        return False
+
+    def __eq__(self, other):
+        return self.priority == other.priority and self.insertion == other.insertion
+
+    def __repr__(self):
+        return '({}, {}, {})'.format(self.priority, self.insertion, self.value)
+
+
+class PriorityQueue(object):
+    def __init__(self):
+        self.insertion = 0
+        self.heap = []
+
+    def has_elements(self):
+        return len(self.heap) > 0
+
+    def put(self, priority, value):
+        heapq.heappush(self.heap, Item(self.insertion, priority, value))
+        self.insertion += 1
+
+    def get(self, include_priority=False):
+        item = heapq.heappop(self.heap)
+        if include_priority:
+            return item.priority, item.value
+        else:
+            return item.value
+
+    def __iter__(self):
+        return iter([item.value for item in self.heap])
+
+    def __str__(self):
+        return self.__repr__()
+
+    def __repr__(self):
+        return ('PriorityQueue [' + ','.join((str(item.value) for item in self.heap)) + ']')
+
+    def __len__(self):
+        return len(self.heap)

pig_lite/datastructures/queue.py

@@ -0,0 +1,27 @@
+from collections import deque
+
+
+class Queue(object):
+    def __init__(self):
+        self.d = deque()
+
+    def put(self, v):
+        self.d.append(v)
+
+    def get(self):
+        return self.d.popleft()
+
+    def has_elements(self):
+        return len(self.d) > 0
+
+    def __iter__(self):
+        return iter(self.d)
+
+    def __str__(self):
+        return self.__repr__()
+
+    def __repr__(self):
+        return ('Queue [' + ','.join((str(item) for item in self.d)) + ']')
+
+    def __len__(self):
+        return len(self.d)

pig_lite/datastructures/stack.py

@@ -0,0 +1,21 @@
+from collections import deque
+
+
+class Stack(object):
+    def __init__(self):
+        self.d = deque()
+
+    def put(self, v):
+        self.d.append(v)
+
+    def get(self):
+        return self.d.pop()
+
+    def has_elements(self):
+        return len(self.d) > 0
+
+    def __iter__(self):
+        return iter(self.d)
+
+    def __repr__(self):
+        return ('Stack [' + ','.join((str(item) for item in self.d)) + ']')