Glasgow | 25 SDC NOV | Katarzyna Kazimierczuk | Sprint 2 | Lru cache

Sprint-2/implement_lru_cache/lru_cache.py

@@ -0,0 +1,101 @@
+import time
+
+our_list = []  
+lookup_map = {} 
+limit = 0
+
+#  `LruCache(limit)` should construct 
+# an LRU cache which never stores more than `limit` entries.
+def LruCache(user_limit):
+    global limit, our_list, lookup_map
+    limit = user_limit
+    our_list = []
+    lookup_map = {}
+
+# * `set(key, value)` should associate `value` with the passed `key`.
+def set(key, value):
+    global our_list, lookup_map
+
+    if key in lookup_map:
+        old_item = lookup_map[key]
+        our_list.remove(old_item)
+
+    wrapped_item = {
+        "key": key,
+        "value": value,
+        "tracker": time.time()
+    }
+
+#add to list and map
+    our_list.insert(0, wrapped_item)
+    lookup_map[key] = wrapped_item
+
+#if full remove oldest timestamp so last
+    if len(our_list) > limit:
+        oldest_item = our_list.pop() 
+
+        del lookup_map[oldest_item["key"]]
+
+
+# * `get(key)` should look-up the value previously associated with `key`.
+def get(key):
+    global our_list, lookup_map
+#check map instead of for loop    
+    if key in lookup_map:
+        # find by key
+        item = lookup_map[key]
+
+        # // tracker to now timestamp updaed
+        item["tracker"] = time.time()
+
+        #move to front
+        our_list.remove(item)
+        our_list.insert(0, item)
+
+        return item["value"]
+    return None
+
+
+#before i did it this was but was looping over each item and did not 
+#fit the required complexity
+# def get_old(key):
+#     for item in our_list: 
+#         if item["key"] == key:
+#             item["tracker"] = time.time()
+#             our_list.remove(item)
+#             our_list.insert(0, item)
+#             return item["value"]
+#     return None
+
+#and before tried with an id not timestamp 
+# tracker_number = 0  
+
+# def set(key, value):
+#     global tracker_number, our_list, lookup_map
+
+
+#     wrapped_item = {
+#         "key": key,
+#         "value": value,
+#         "tracker": tracker_number 
+#     }
+
+
+#     tracker_number += 1 
+
+#     our_list.insert(0, wrapped_item)
+#     lookup_map[key] = wrapped_item
+
+# and the loop
+# def get_old(key):
+#     global tracker_number, our_list
+#     for item in our_list: 
+#         if item["key"] == key:
+#             item["tracker"] = tracker_number
+#             tracker_number += 1
+
+#             our_list.remove(item)
+#             our_list.insert(0, item)
+
+#             return item["value"]
+#     return None