Added LRU CACHE implementation in python

Author: impiyush83

LRU Cache Implementation/lru.py

@@ -0,0 +1,75 @@
+from lru import LRU
+l = LRU(5)         # Create an LRU container that can hold 5 items
+
+print (l.peek_first_item(), l.peek_last_item())  #return the MRU key and LRU key
+# Would print None None
+
+for i in range(5):
+   l[i] = str(i)
+print(l.items())    # Prints items in MRU order
+# Would print [(4, '4'), (3, '3'), (2, '2'), (1, '1'), (0, '0')]
+
+print(l.peek_first_item(), l.peek_last_item())  #return the MRU key and LRU key
+# Would print (4, '4') (0, '0')
+
+l[5] = '5'         # Inserting one more item should evict the old item
+print(l.items())
+# Would print [(5, '5'), (4, '4'), (3, '3'), (2, '2'), (1, '1')]
+
+l[3]               # Accessing an item would make it MRU
+print(l.items())
+# Would print [(3, '3'), (5, '5'), (4, '4'), (2, '2'), (1, '1')]
+# Now 3 is in front
+
+l.keys()           # Can get keys alone in MRU order
+# Would print [3, 5, 4, 2, 1]
+
+del l[4]           # Delete an item
+print(l.items())
+# Would print [(3, '3'), (5, '5'), (2, '2'), (1, '1')]
+
+print(l.get_size())
+# Would print 5
+
+l.set_size(3)
+print(l.items())
+# Would print [(3, '3'), (5, '5'), (2, '2')]
+print(l.get_size())
+# Would print 3
+print(l.has_key(5))
+# Would print True
+print(2 in l)
+# Would print True
+
+l.get_stats()
+# Would print (1, 0)
+
+
+l.update(5='0')           # Update an item
+print l.items()
+# Would print [(5, '0'), (3, '3'), (2, '2')]
+
+l.clear()
+print l.items()
+# Would print []
+
+def evicted(key, value):
+  print "removing: %s, %s" % (key, value)
+
+l = LRU(1, callback=evicted)
+
+l[1] = '1'
+l[2] = '2'
+# callback would print removing: 1, 1
+
+l[2] = '3'
+# doesn't call the evicted callback
+
+print l.items()
+# would print [(2, '3')]
+
+del l[2]
+# doesn't call the evicted callback
+
+print l.items()
+# would print []