Allow nested routes sharing the same path parameter matcher

When two routes share the same parameter at the same node position
(e.g. GET /restaurants/${id} and GET /restaurants/${id}/menu),
reuse the existing equivalent matcher instead of raising a conflict.
Non-equivalent matchers (different names, kinds, or glob patterns)
at the same node for the same method still raise ValueError.

packages/kaya-core/tests/test_asgi.py

@@ -190,3 +190,29 @@ class AsgiTest(unittest.TestCase):
                 'employee_id': 101325
             }, response)
 
+    @async_test
+    async def test_nested_param_routes(self):
+        app = KayaApp()
+
+        @app.GET('/restaurants/${id}')
+        async def restaurant(ctx: HttpContext, id: str) -> None:
+            await ctx.send_str(200, f"restaurant:{id}")
+
+        @app.GET('/restaurants/${id}/menu')
+        async def menu(ctx: HttpContext, id: str) -> None:
+            await ctx.send_str(200, f"menu:{id}")
+
+        transport = httpx.ASGITransport(app=app)
+
+        async with httpx.AsyncClient(transport=transport, base_url="http://127.0.0.1:80") as client:
+            r = await client.get("/restaurants/42")
+            self.assertEqual(200, r.status_code)
+            self.assertEqual("restaurant:42", r.text)
+
+            r = await client.get("/restaurants/42/menu")
+            self.assertEqual(200, r.status_code)
+            self.assertEqual("menu:42", r.text)
+
+            r = await client.get("/restaurants/42/unknown")
+            self.assertEqual(404, r.status_code)
+

packages/kaya-core/tests/test_tree.py

@@ -84,7 +84,14 @@ class TreeTest(unittest.TestCase):
         tree = Tree()
         tree.add((p for p in ('foo', '*')), None, self.handlers[0])
         with self.assertRaises(ValueError):
-            tree.add((p for p in ('foo', '*')), None, self.handlers[1])
+            tree.add((p for p in ('foo', '*.md')), None, self.handlers[1])
+
+    def test_identical_method_agnostic_matchers_reuse(self):
+        tree = Tree()
+        tree.add((p for p in ('foo', '*')), None, self.handlers[0])
+        tree.add((p for p in ('foo', '*')), None, self.handlers[1])
+        handler = Maybe.of_nullable(tree.get_handler('/foo/bar', HttpMethod.GET)).map(lambda it: it[0]).or_none()
+        self.assertIs(self.handlers[0], handler)
 
     def test_two_overlapping_method_specific_matchers_raise(self):
         tree = Tree()
@@ -101,3 +108,51 @@ class TreeTest(unittest.TestCase):
         self.assertIs(self.handlers[0], put_handler)
         self.assertIs(self.handlers[1], get_handler)
 
+    def test_nested_routes_with_same_param_allowed(self):
+        tree = Tree()
+        tree.add((p for p in ('restaurants', '${id}')), HttpMethod.GET, self.handlers[0])
+        tree.add((p for p in ('restaurants', '${id}', 'menu')), HttpMethod.GET, self.handlers[1])
+        h0 = Maybe.of_nullable(tree.get_handler('/restaurants/42', HttpMethod.GET)).map(lambda it: it[0]).or_none()
+        h1 = Maybe.of_nullable(tree.get_handler('/restaurants/42/menu', HttpMethod.GET)).map(lambda it: it[0]).or_none()
+        self.assertIs(self.handlers[0], h0)
+        self.assertIs(self.handlers[1], h1)
+
+    def test_nested_routes_same_param_reverse_order(self):
+        tree = Tree()
+        tree.add((p for p in ('restaurants', '${id}', 'menu')), HttpMethod.GET, self.handlers[1])
+        tree.add((p for p in ('restaurants', '${id}')), HttpMethod.GET, self.handlers[0])
+        h0 = Maybe.of_nullable(tree.get_handler('/restaurants/42', HttpMethod.GET)).map(lambda it: it[0]).or_none()
+        h1 = Maybe.of_nullable(tree.get_handler('/restaurants/42/menu', HttpMethod.GET)).map(lambda it: it[0]).or_none()
+        self.assertIs(self.handlers[0], h0)
+        self.assertIs(self.handlers[1], h1)
+
+    def test_nested_routes_with_same_int_param_allowed(self):
+        tree = Tree()
+        tree.add((p for p in ('restaurants', '${id:int}')), HttpMethod.GET, self.handlers[0])
+        tree.add((p for p in ('restaurants', '${id:int}', 'menu')), HttpMethod.GET, self.handlers[1])
+        h0 = Maybe.of_nullable(tree.get_handler('/restaurants/42', HttpMethod.GET)).map(lambda it: it[0]).or_none()
+        h1 = Maybe.of_nullable(tree.get_handler('/restaurants/42/menu', HttpMethod.GET)).map(lambda it: it[0]).or_none()
+        self.assertIs(self.handlers[0], h0)
+        self.assertIs(self.handlers[1], h1)
+
+    def test_nested_routes_method_agnostic_reuses_matcher(self):
+        tree = Tree()
+        tree.add((p for p in ('restaurants', '${id}')), HttpMethod.GET, self.handlers[0])
+        tree.add((p for p in ('restaurants', '${id}', 'menu')), None, self.handlers[1])
+        h0 = Maybe.of_nullable(tree.get_handler('/restaurants/42', HttpMethod.GET)).map(lambda it: it[0]).or_none()
+        h1 = Maybe.of_nullable(tree.get_handler('/restaurants/42/menu', HttpMethod.POST)).map(lambda it: it[0]).or_none()
+        self.assertIs(self.handlers[0], h0)
+        self.assertIs(self.handlers[1], h1)
+
+    def test_different_param_names_still_raise(self):
+        tree = Tree()
+        tree.add((p for p in ('a', '${id}')), HttpMethod.GET, self.handlers[0])
+        with self.assertRaises(ValueError):
+            tree.add((p for p in ('a', '${name}', 'x')), HttpMethod.GET, self.handlers[1])
+
+    def test_different_param_kinds_still_raise(self):
+        tree = Tree()
+        tree.add((p for p in ('a', '${id}')), HttpMethod.GET, self.handlers[0])
+        with self.assertRaises(ValueError):
+            tree.add((p for p in ('a', '${id:int}', 'x')), HttpMethod.GET, self.handlers[1])
+