Add YAQL expression evaluation

* YAQL evaluate
 * Unit tests

Change-Id: I0853a08234c75853875b42cd8e89819e9b1e431f

mistral/tests/unit/utils/test_yaql.py

@@ -0,0 +1,76 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright 2013 - Mirantis, Inc.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License");
+#    you may not use this file except in compliance with the License.
+#    You may obtain a copy of the License at
+#
+#        http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS,
+#    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#    See the License for the specific language governing permissions and
+#    limitations under the License.
+
+import unittest2
+
+from mistral.utils import yaql_utils
+
+
+DATA = {
+    "server": {
+        "id": "03ea824a-aa24-4105-9131-66c48ae54acf",
+        "name": "cloud-fedora",
+        "status": "ACTIVE"
+    },
+    "status": "OK"
+}
+
+
+SERVERS = {
+    "servers": [
+        {
+            'name': 'centos'
+        },
+        {
+            'name': 'ubuntu'
+        },
+        {
+            'name': 'fedora'
+        }
+    ]
+}
+
+
+class YaqlTest(unittest2.TestCase):
+    def test_expression_result(self):
+        res = yaql_utils.evaluate("$.server", DATA)
+        self.assertEqual(res, {
+            "id": "03ea824a-aa24-4105-9131-66c48ae54acf",
+            "name": "cloud-fedora",
+            "status": "ACTIVE"
+        })
+
+        res = yaql_utils.evaluate("$.server.id", DATA)
+        self.assertEqual(res, "03ea824a-aa24-4105-9131-66c48ae54acf")
+
+        res = yaql_utils.evaluate("$.server.status = 'ACTIVE'", DATA)
+        self.assertTrue(res)
+
+    def test_wrong_expression(self):
+        res = yaql_utils.evaluate("$.status = 'Invalid value'", DATA)
+        self.assertFalse(res)
+
+        res = yaql_utils.evaluate("$.wrong_key", DATA)
+        self.assertIsNone(res)
+
+        expression_str = "invalid_expression_string"
+        res = yaql_utils.evaluate(expression_str, DATA)
+        self.assertEqual(res, expression_str)
+
+    def test_select_result(self):
+        res = yaql_utils.evaluate("$.servers[$.name = ubuntu]", SERVERS)
+        item = list(res)[0]
+        self.assertEqual(item, {'name': 'ubuntu'})

mistral/utils/yaql_utils.py

@@ -14,7 +14,9 @@
 #    See the License for the specific language governing permissions and
 #    limitations under the License.
 
+import yaql
+
 
 def evaluate(expression_str, data):
-    #TODO(nmakhotkin) evaluate YAQL expression and return the result
-    pass
+    expression = yaql.parse(expression_str)
+    return expression.evaluate(data)

requirements.txt

@@ -13,3 +13,4 @@ python-keystoneclient>=0.3.2
 pika>=0.9.13
 networkx
 SQLAlchemy
+yaql==0.2.1