From 3992db4464d8d4eb5a777a8286e4362e4b14ee54 Mon Sep 17 00:00:00 2001
From: Tulir Asokan <tulir@maunium.net>
Date: Sun, 23 Jun 2019 03:08:03 +0300
Subject: [PATCH] Make non-regex matching faster

---
 reactbot.py | 58 ++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 51 insertions(+), 7 deletions(-)

diff --git a/reactbot.py b/reactbot.py
index c391f19..966936f 100644
--- a/reactbot.py
+++ b/reactbot.py
@@ -13,7 +13,8 @@
 #
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
-from typing import NewType, Optional, Pattern, Match, Union, Dict, List, Tuple, Set, Type, Any
+from typing import (NewType, Optional, Callable, Pattern, Match, Union, Dict, List, Tuple, Set,
+                    Type, Any)
 from itertools import chain
 import copy
 import re
@@ -34,10 +35,36 @@ class Config(BaseProxyConfig):
         helper.copy("templates")
 
 
+class ConfigError(Exception):
+    pass
+
+
 class Key(str):
     pass
 
 
+class BlankMatch:
+    @staticmethod
+    def groups() -> List[str]:
+        return []
+
+
+class SimplePattern:
+    _ptm = BlankMatch()
+
+    matcher: Callable[[str], bool]
+
+    def __init__(self, matcher: Callable[[str], bool]) -> None:
+        self.matcher = matcher
+
+    def match(self, val: str) -> BlankMatch:
+        if self.matcher(val):
+            return self._ptm
+
+
+RMatch = Union[Match, BlankMatch]
+RPattern = Union[Pattern, SimplePattern]
+
 Index = NewType("Index", Union[str, int, Key])
 
 variable_regex = re.compile(r"\$\${([0-9A-Za-z-_]+)}")
@@ -102,7 +129,8 @@ class Template:
 @dataclass
 class Rule:
     rooms: Set[RoomID]
-    matches: List[Pattern]
+    matches: List[RPattern]
+    not_matches: List[RPattern]
     template: Template
     type: Optional[EventType]
     variables: Dict[str, JinjaTemplate]
@@ -123,10 +151,6 @@ class Rule:
         await evt.client.send_message_event(evt.room_id, self.type or self.template.type, content)
 
 
-class ConfigError(Exception):
-    pass
-
-
 class ReactBot(Plugin):
     rules: Dict[str, Rule]
     templates: Dict[str, Template]
@@ -154,10 +178,30 @@ class ReactBot(Plugin):
         except Exception as e:
             raise ConfigError(f"Failed to load {name}") from e
 
+    @staticmethod
+    def _compile(pattern: str) -> RPattern:
+        esc = re.escape(pattern)
+        if esc == pattern:
+            return SimplePattern(lambda val: pattern in val)
+        elif pattern[0] == '^' and esc == f"\\^{pattern}":
+            pattern = pattern[1:]
+            return SimplePattern(lambda val: val.startswith(pattern))
+        elif pattern[-1] == '$' and esc == f"{pattern}\\$":
+            pattern = pattern[:-1]
+            return SimplePattern(lambda val: val.endswith(pattern))
+        elif pattern[0] == '^' and pattern[-1] == '$' and esc == f"\\^{pattern}\\$":
+            pattern = pattern[1:-1]
+            return SimplePattern(lambda val: val == pattern)
+        return re.compile(pattern)
+
+    def _compile_all(self, patterns: List[str]) -> List[RPattern]:
+        return [self._compile(pattern) for pattern in patterns]
+
     def _make_rule(self, name: str, rule: Dict[str, Any]) -> Rule:
         try:
             return Rule(rooms=set(rule.get("rooms", [])),
-                        matches=[re.compile(match) for match in rule.get("matches")],
+                        matches=self._compile_all(rule["matches"]),
+                        not_matches=self._compile_all(rule.get("not_matches", [])),
                         type=EventType.find(rule["type"]) if "type" in rule else None,
                         template=self.templates[rule["template"]],
                         variables=self._parse_variables(rule))