Refactor api.filtering to have a Filter API

2 files changed, 57 insertions, 100 deletions

diff --git a/synapse/api/filtering.py b/synapse/api/filtering.py
index e79e91e7eb..cd7a465e97 100644
--- a/synapse/api/filtering.py
+++ b/synapse/api/filtering.py
@@ -24,7 +24,7 @@ class Filtering(object):
 
     def get_user_filter(self, user_localpart, filter_id):
         result = self.store.get_user_filter(user_localpart, filter_id)
-        result.addCallback(Filter)
+        result.addCallback(FilterCollection)
         return result
 
     def add_user_filter(self, user_localpart, user_filter):
@@ -131,125 +131,82 @@ class Filtering(object):
             raise SynapseError(400, "Bad bundle_updates: expected bool.")
 
 
-class Filter(object):
+class FilterCollection(object):
     def __init__(self, filter_json):
         self.filter_json = filter_json
 
+        self.room_timeline_filter = Filter(
+            self.filter_json.get("room", {}).get("timeline", {})
+        )
+
+        self.room_state_filter = Filter(
+            self.filter_json.get("room", {}).get("state", {})
+        )
+
+        self.room_ephemeral_filter = Filter(
+            self.filter_json.get("room", {}).get("ephemeral", {})
+        )
+
+        self.presence_filter = Filter(
+            self.filter_json.get("presence", {})
+        )
+
     def timeline_limit(self):
-        return self.filter_json.get("room", {}).get("timeline", {}).get("limit", 10)
+        return self.room_timeline_filter.limit()
 
     def presence_limit(self):
-        return self.filter_json.get("presence", {}).get("limit", 10)
+        return self.presence_filter.limit()
 
     def ephemeral_limit(self):
-        return self.filter_json.get("room", {}).get("ephemeral", {}).get("limit", 10)
+        return self.room_ephemeral_filter.limit()
 
     def filter_presence(self, events):
-        return self._filter_on_key(events, ["presence"])
+        return self.presence_filter.filter(events)
 
     def filter_room_state(self, events):
-        return self._filter_on_key(events, ["room", "state"])
+        return self.room_state_filter.filter(events)
 
     def filter_room_timeline(self, events):
-        return self._filter_on_key(events, ["room", "timeline"])
+        return self.room_timeline_filter.filter(events)
 
     def filter_room_ephemeral(self, events):
-        return self._filter_on_key(events, ["room", "ephemeral"])
-
-    def _filter_on_key(self, events, keys):
-        filter_json = self.filter_json
-        if not filter_json:
-            return events
-
-        try:
-            # extract the right definition from the filter
-            definition = filter_json
-            for key in keys:
-                definition = definition[key]
-            return self._filter_with_definition(events, definition)
-        except KeyError:
-            # return all events if definition isn't specified.
-            return events
-
-    def _filter_with_definition(self, events, definition):
-        return [e for e in events if self._passes_definition(definition, e)]
-
-    def _passes_definition(self, definition, event):
-        """Check if the event passes the filter definition
-        Args:
-            definition(dict): The filter definition to check against
-            event(dict or Event): The event to check
-        Returns:
-            True if the event passes the filter in the definition
-        """
-        if type(event) is dict:
-            room_id = event.get("room_id")
-            sender = event.get("sender")
-            event_type = event["type"]
-        else:
-            room_id = getattr(event, "room_id", None)
-            sender = getattr(event, "sender", None)
-            event_type = event.type
-        return self._event_passes_definition(
-            definition, room_id, sender, event_type
-        )
+        return self.room_ephemeral_filter.filter(events)
 
-    def _event_passes_definition(self, definition, room_id, sender,
-                                 event_type):
-        """Check if the event passes through the given definition.
 
-        Args:
-            definition(dict): The definition to check against.
-            room_id(str): The id of the room this event is in or None.
-            sender(str): The sender of the event
-            event_type(str): The type of the event.
-        Returns:
-            True if the event passes through the filter.
-        """
-        # Algorithm notes:
-        # For each key in the definition, check the event meets the criteria:
-        #   * For types: Literal match or prefix match (if ends with wildcard)
-        #   * For senders/rooms: Literal match only
-        #   * "not_" checks take presedence (e.g. if "m.*" is in both 'types'
-        #     and 'not_types' then it is treated as only being in 'not_types')
-
-        # room checks
-        if room_id is not None:
-            allow_rooms = definition.get("rooms", None)
-            reject_rooms = definition.get("not_rooms", None)
-            if reject_rooms and room_id in reject_rooms:
-                return False
-            if allow_rooms and room_id not in allow_rooms:
-                return False
+class Filter(object):
+    def __init__(self, filter_json):
+        self.filter_json = filter_json
 
-        # sender checks
-        if sender is not None:
-            allow_senders = definition.get("senders", None)
-            reject_senders = definition.get("not_senders", None)
-            if reject_senders and sender in reject_senders:
-                return False
-            if allow_senders and sender not in allow_senders:
+    def check(self, event):
+        literal_keys = {
+            "rooms": lambda v: event.room_id == v,
+            "senders": lambda v: event.sender == v,
+            "types": lambda v: _matches_wildcard(event.type, v)
+        }
+
+        for name, match_func in literal_keys.items():
+            not_name = "not_%s" % (name,)
+            disallowed_values = self.filter_json.get(not_name, [])
+            if any(map(match_func, disallowed_values)):
                 return False
 
-        # type checks
-        if "not_types" in definition:
-            for def_type in definition["not_types"]:
-                if self._event_matches_type(event_type, def_type):
+            allowed_values = self.filter_json.get(name, None)
+            if allowed_values is not None:
+                if not any(map(match_func, allowed_values)):
                     return False
-        if "types" in definition:
-            included = False
-            for def_type in definition["types"]:
-                if self._event_matches_type(event_type, def_type):
-                    included = True
-                    break
-            if not included:
-                return False
 
         return True
 
-    def _event_matches_type(self, event_type, def_type):
-        if def_type.endswith("*"):
-            type_prefix = def_type[:-1]
-            return event_type.startswith(type_prefix)
-        else:
-            return event_type == def_type
+    def filter(self, events):
+        return filter(self.check, events)
+
+    def limit(self):
+        return self.filter_json.get("limit", 10)
+
+
+def _matches_wildcard(actual_value, filter_value):
+    if filter_value.endswith("*"):
+        type_prefix = filter_value[:-1]
+        return actual_value.startswith(type_prefix)
+    else:
+        return actual_value == filter_value
diff --git a/synapse/rest/client/v2_alpha/sync.py b/synapse/rest/client/v2_alpha/sync.py
index fffecb24f5..5e27a859f9 100644
--- a/synapse/rest/client/v2_alpha/sync.py
+++ b/synapse/rest/client/v2_alpha/sync.py
@@ -23,7 +23,7 @@ from synapse.types import StreamToken
 from synapse.events.utils import (
     serialize_event, format_event_for_client_v2_without_event_id,
 )
-from synapse.api.filtering import Filter
+from synapse.api.filtering import FilterCollection
 from ._base import client_v2_pattern
 
 import copy
@@ -103,7 +103,7 @@ class SyncRestServlet(RestServlet):
                 user.localpart, filter_id
             )
         except:
-            filter = Filter({})
+            filter = FilterCollection({})
 
         sync_config = SyncConfig(
             user=user,