From f7642f2de1b39eecfcf0643b90258bd8cc9feb6a Mon Sep 17 00:00:00 2001
From: Lemonyte <49930425+lemonyte@users.noreply.github.com>
Date: Sun, 12 May 2024 15:42:41 -0700
Subject: [PATCH] Improve route finding performance

---
 src/ferry_planner/route.py | 39 +++++++++++++++++++-------------------
 1 file changed, 19 insertions(+), 20 deletions(-)

diff --git a/src/ferry_planner/route.py b/src/ferry_planner/route.py
index 11bdd68..c7a3c08 100644
--- a/src/ferry_planner/route.py
+++ b/src/ferry_planner/route.py
@@ -2,7 +2,7 @@
 from __future__ import annotations
 
 import hashlib
-from collections.abc import Iterable, Iterator, Sequence
+from collections.abc import Generator, Iterable, Iterator, Sequence
 from copy import deepcopy
 from datetime import datetime, timedelta
 from enum import Enum
@@ -182,21 +182,18 @@ def __init__(self, connection_db: ConnectionDB, /) -> None:
         self._connection_db = connection_db
 
     def find_routes(self, *, origin: Location, destination: Location) -> Iterator[Route]:
-        routes = []
-        self._find_routes_recurse(next_point=origin, end_point=destination, routes=routes)
-        yield from routes
+        return self._find_routes_recurse(next_point=origin, end_point=destination)
 
     def _find_routes_recurse(  # noqa: C901, PLR0912, PLR0913
         self,
         *,
         next_point: Location,
         end_point: Location,
-        routes: list[Route],
         current_route: list[Location] | None = None,
         dead_ends: list[Connection] | None = None,
         lands: list[str] | None = None,
         last_connection_type: type[Connection] = Connection,
-    ) -> bool:
+    ) -> Generator[Route, None, bool]:
         if current_route is None:
             current_route = []
         if dead_ends is None:
@@ -205,7 +202,7 @@ def _find_routes_recurse(  # noqa: C901, PLR0912, PLR0913
             lands = []
         current_route.append(next_point)
         if next_point == end_point:
-            routes.append(current_route.copy())
+            yield current_route.copy()
             del current_route[-1]
             return True
         if isinstance(end_point, City):
@@ -216,7 +213,7 @@ def _find_routes_recurse(  # noqa: C901, PLR0912, PLR0913
                 pass
             else:
                 current_route.append(end_point)
-                routes.append(current_route.copy())
+                yield current_route.copy()
                 del current_route[-2:]
                 return True
         res = False
@@ -235,18 +232,20 @@ def _find_routes_recurse(  # noqa: C901, PLR0912, PLR0913
                 lands.append(connection.origin.land_group)
             else:
                 lands.append("")
-            if self._find_routes_recurse(
-                next_point=connection.destination,
-                end_point=end_point,
-                routes=routes,
-                current_route=current_route,
-                dead_ends=dead_ends,
-                lands=lands,
-                last_connection_type=type(connection),
-            ):
-                res = True
-            else:
-                dead_ends.append(connection)
+            try:
+                yield from self._find_routes_recurse(
+                    next_point=connection.destination,
+                    end_point=end_point,
+                    current_route=current_route,
+                    dead_ends=dead_ends,
+                    lands=lands,
+                    last_connection_type=type(connection),
+                )
+            except StopIteration as exc:
+                if exc.value is True:
+                    res = True
+                else:
+                    dead_ends.append(connection)
             del lands[-1]
         del current_route[-1]
         return res