[core] Add util.store for store-like get/set

tests/test_store.py

@@ -0,0 +1,47 @@
+import unittest
+
+import util.store
+
+class config(unittest.TestCase):
+    def setUp(self):
+        self.store = util.store.Store()
+
+        self.unusedKey = "someRandomUnusedKey"
+        self.someKey = "someRandomKey"
+        self.someOtherKey = "anotherRandomKey"
+        self.someValue = "someRandomValue"
+        self.someOtherValue = "anotherRandomValue"
+
+    def tearDown(self):
+        pass
+
+    def test_get_of_unset_key(self):
+        self.assertEqual(None, self.store.get(self.unusedKey), 'default value expected to be None')
+        self.assertEqual(self.someValue, self.store.get(self.unusedKey, self.someValue), 'wrong user-provided default value returned')
+
+    def test_get_of_set_key(self):
+        self.assertNotEqual(self.someValue, None)
+
+        self.store.set(self.someKey, self.someValue)
+        self.assertEqual(self.someValue, self.store.get(self.someKey), 'unexpected value for existing key')
+
+    def test_overwrite_set(self):
+        self.assertNotEqual(self.someValue, None)
+        self.assertNotEqual(self.someOtherValue, self.someValue)
+
+        self.store.set(self.someKey, self.someValue)
+        self.store.set(self.someKey, self.someOtherValue)
+        self.assertEqual(self.someOtherValue, self.store.get(self.someKey), 'unexpected value for existing key')
+
+    def test_unused_keys(self):
+        self.assertNotEqual(self.someKey, self.someOtherKey)
+
+        self.store.set(self.someKey, self.someValue)
+        self.store.set(self.someOtherKey, self.someOtherValue)
+
+        self.assertEqual(sorted(self.store.unused_keys()), sorted([self.someKey, self.someOtherKey]))
+
+        self.store.get(self.someKey)
+        self.assertEqual(self.store.unused_keys(), [self.someOtherKey])
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4

util/store.py

@@ -0,0 +1,26 @@
+"""Store interface
+
+Allows arbitrary classes to offer a simple get/set
+store interface by deriving from the Store class in
+this module
+"""
+
+class Store(object):
+    """Interface for storing and retrieving simple values"""
+    def __init__(self):
+        self._data = {}
+
+    def set(self, key, value):
+        """Set 'key' to 'value', overwriting 'key' if it exists already"""
+        self._data[key] = { 'value': value, 'used': False }
+
+    def unused_keys(self):
+        return [ key for key, value in self._data.items() if value['used'] == False ]
+
+    def get(self, key, default=None):
+        """Return the current value of 'key', or 'default' if 'key' is not set"""
+        if key in self._data:
+            self._data[key]['used'] = True
+        return self._data.get(key, { 'value': default })['value']
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4