lru cache

Author: TarasMykytiuk

Sprint-2/implement_lru_cache/lru_cache.py

@@ -0,0 +1,73 @@
+class LruCache:
+    def __init__(self, limit):
+        if limit <= 0:
+            raise ValueError("limit must be greater than 0")
+        self.limit = limit
+        self.keys = {}
+        self.linkedList = LinkedList()
+    
+    def get(self, key):
+        if key not in self.keys:
+            return None
+        else:
+            self.linkedList.remove(self.keys[key])
+            self.linkedList.push_head(self.keys[key])
+            return self.keys[key].data
+    
+    def set(self, key, data):
+        if key not in self.keys:
+            if len(self.keys) >= self.limit:
+                node_to_delete = self.linkedList.pop_tail()
+                del self.keys[node_to_delete.key]
+            self.keys[key] = Node(key, data)
+            self.linkedList.push_head(self.keys[key])
+
+        else:
+            self.keys[key].data = data
+            self.linkedList.push_head(self.keys[key])
+
+class Node:
+    def __init__(self, key, data):
+        self.key = key
+        self.data = data
+        self.next = None
+        self.previous = None
+
+
+class LinkedList:
+    def __init__(self):
+        self.head = None
+        self.tail = None
+    
+    def push_head(self, new_node):
+        new_node.previous = None
+        new_node.next = None
+        if self.head is None:
+            self.head = new_node
+            self.tail = new_node
+        else:
+            new_node.next = self.head
+            self.head.previous = new_node
+            self.head = new_node
+        return new_node
+    
+    def remove(self, node):
+        if node is None:
+            return
+        if node == self.head:
+            self.head = node.next
+        if node == self.tail:
+            self.tail = node.previous
+        if node.previous is not None:
+            node.previous.next = node.next
+        if node.next is not None:
+            node.next.previous = node.previous
+        node.next = None
+        node.previous = None
+    
+    def pop_tail(self):
+        if self.tail is None:
+            return None
+        node_to_pop = self.tail
+        self.remove(self.tail)
+        return node_to_pop