add FIFO dict

michaelliao · michaelliao · commit feb9b03f3071 · 2014-09-18T18:15:33.000+08:00
diff --git a/collections/fifodict.py b/collections/fifodict.py
@@ -0,0 +1,34 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+from collections import OrderedDict
+
+class LastUpdatedOrderedDict(OrderedDict):
+
+    def __init__(self, capacity):
+        super(LastUpdatedOrderedDict, self).__init__()
+        self._capacity = capacity
+
+    def __setitem__(self, key, value):
+        containsKey = 1 if key in self else 0
+        if len(self) - containsKey >= self._capacity:
+            last = self.popitem(last=False)
+            print 'remove:', last
+        if containsKey:
+            del self[key]
+            print 'set:', (key, value)
+        else:
+            print 'add:', (key, value)
+        OrderedDict.__setitem__(self, key, value)
+
+# test
+
+d = LastUpdatedOrderedDict(capacity=3)
+
+d['A'] = 100
+d['B'] = 200
+d['C'] = 300
+d['D'] = 400
+d['E'] = 500
+
+print d
