1 files changed, 113 insertions, 0 deletions
diff --git a/synapse/http/servlet.py b/synapse/http/servlet.py
new file mode 100644
index 0000000000..a4eb6c817c
--- /dev/null
+++ b/synapse/http/servlet.py
@@ -0,0 +1,113 @@
+# -*- 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. """
+
+from synapse.api.errors import SynapseError
+
+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.")
+
+    @staticmethod
+    def parse_integer(request, name, default=None, required=False):
+        if name in request.args:
+            try:
+                return int(request.args[name][0])
+            except:
+                message = "Query parameter %r must be an integer" % (name,)
+                raise SynapseError(400, message)
+        else:
+            if required:
+                message = "Missing integer query parameter %r" % (name,)
+                raise SynapseError(400, message)
+            else:
+                return default
+
+    @staticmethod
+    def parse_boolean(request, name, default=None, required=False):
+        if name in request.args:
+            try:
+                return {
+                    "true": True,
+                    "false": False,
+                }[request.args[name][0]]
+            except:
+                message = (
+                    "Boolean query parameter %r must be one of"
+                    " ['true', 'false']"
+                ) % (name,)
+                raise SynapseError(400, message)
+        else:
+            if required:
+                message = "Missing boolean query parameter %r" % (name,)
+                raise SynapseError(400, message)
+            else:
+                return default
+
+    @staticmethod
+    def parse_string(request, name, default=None, required=False,
+                     allowed_values=None, param_type="string"):
+        if name in request.args:
+            value = request.args[name][0]
+            if allowed_values is not None and value not in allowed_values:
+                message = "Query parameter %r must be one of [%s]" % (
+                    name, ", ".join(repr(v) for v in allowed_values)
+                )
+                raise SynapseError(message)
+            else:
+                return value
+        else:
+            if required:
+                message = "Missing %s query parameter %r" % (param_type, name)
+                raise SynapseError(400, message)
+            else:
+                return default