added collection utils

Author: lxhunter

collection_utils.py

@@ -0,0 +1,63 @@
+# -*- coding: utf-8 -*-
+
+import unittest
+
+
+def where(entries, properties):
+    ret = []
+
+    if type(properties) is str:
+        for entry in entries:
+            if properties in entry:
+                ret.append(entry[properties])
+
+    if type(properties) is list:
+        for entry in entries:
+            obj = {}
+            for p in properties:
+                if p in entry:
+                    obj[p] = entry[p]
+
+            ret.append(obj)
+
+    return ret
+
+def initial(array):
+    return array[0:len(array) - 1]
+
+def rest(array):
+    return array[1:len(array)]
+
+
+class FilterModule(object):
+    """ utility filters for operating on hashes """
+
+    def filters(self):
+        return {
+            'where': where,
+            'initial': initial,
+            'rest': rest
+        }
+
+
+class TestCollectionUtils(unittest.TestCase):
+    def test_where(self):
+        l = [
+            {'foo': 'bar', 'bar': 'quuux', 'baz': 'qux'},
+            {'foo': 'baz', 'bar': 'quuuux', 'baz': 'quux'}
+        ]
+        self.assertEqual(where(l, 'foo'), ['bar', 'baz'])
+        self.assertEqual(where(l, ['foo', 'baz']), [
+            {'foo': 'bar', 'baz': 'qux'},
+            {'foo': 'baz', 'baz': 'quux'}
+        ])
+
+    def test_initial(self):
+        self.assertEqual(initial([1, 2, 3]), [1, 2])
+
+    def test_rest(self):
+        self.assertEqual(rest([1, 2, 3]), [2, 3])
+
+
+if __name__ == '__main__':
+    unittest.main()