Add RestServlet base class in synapse/http/servlet.py

synapse/http/servlet.py

+# -*- coding: utf-8 -*-
+# Copyright 2014, 2015 OpenMarket Ltd
+#
+# 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.
+
+""" This module contains base REST classes for constructing REST servlets. """
+
+import logging
+
+
+logger = logging.getLogger(__name__)
+
+
+class RestServlet(object):
+
+    """ A Synapse REST Servlet.
+
+    An implementing class can either provide its own custom 'register' method,
+    or use the automatic pattern handling provided by the base class.
+
+    To use this latter, the implementing class instead provides a `PATTERN`
+    class attribute containing a pre-compiled regular expression. The automatic
+    register method will then use this method to register any of the following
+    instance methods associated with the corresponding HTTP method:
+
+      on_GET
+      on_PUT
+      on_POST
+      on_DELETE
+      on_OPTIONS
+
+    Automatically handles turning CodeMessageExceptions thrown by these methods
+    into the appropriate HTTP response.
+    """
+
+    def register(self, http_server):
+        """ Register this servlet with the given HTTP server. """
+        if hasattr(self, "PATTERN"):
+            pattern = self.PATTERN
+
+            for method in ("GET", "PUT", "POST", "OPTIONS", "DELETE"):
+                if hasattr(self, "on_%s" % (method)):
+                    method_handler = getattr(self, "on_%s" % (method))
+                    http_server.register_path(method, pattern, method_handler)
+        else:
+            raise NotImplementedError("RestServlet must register something.")