cache blueprint path calculation

src/flask/app.py

@@ -36,6 +36,7 @@
 from .globals import g
 from .globals import request
 from .globals import session
+from .helpers import _split_blueprint_path
 from .helpers import get_debug_flag
 from .helpers import get_env
 from .helpers import get_flashed_messages
@@ -1790,13 +1791,11 @@ def inject_url_defaults(self, endpoint: str, values: dict) -> None:
         funcs: t.Iterable[URLDefaultCallable] = self.url_default_functions[None]
 
         if "." in endpoint:
-            bps: t.List[str] = [endpoint.rsplit(".", 1)[0]]
-
-            while "." in bps[-1]:
-                bps.append(bps[-1].rpartition(".")[0])
-
-            for bp in bps:
-                funcs = chain(funcs, self.url_default_functions[bp])
+            # This is called by url_for, which can be called outside a
+            # request, can't use request.blueprints.
+            bps = _split_blueprint_path(endpoint.rpartition(".")[0])
+            bp_funcs = chain.from_iterable(self.url_default_functions[bp] for bp in bps)
+            funcs = chain(funcs, bp_funcs)
 
         for func in funcs:
             func(endpoint, values)

src/flask/helpers.py

@@ -6,6 +6,7 @@
 import warnings
 from datetime import datetime
 from datetime import timedelta
+from functools import lru_cache
 from functools import update_wrapper
 from threading import RLock
 
@@ -821,3 +822,13 @@ def is_ip(value: str) -> bool:
             return True
 
     return False
+
+
+@lru_cache(maxsize=None)
+def _split_blueprint_path(name: str) -> t.List[str]:
+    out: t.List[str] = [name]
+
+    if "." in name:
+        out.extend(_split_blueprint_path(name.rpartition(".")[0]))
+
+    return out

src/flask/wrappers.py

@@ -1,12 +1,12 @@
 import typing as t
 
 from werkzeug.exceptions import BadRequest
-from werkzeug.utils import cached_property
 from werkzeug.wrappers import Request as RequestBase
 from werkzeug.wrappers import Response as ResponseBase
 
 from . import json
 from .globals import current_app
+from .helpers import _split_blueprint_path
 
 if t.TYPE_CHECKING:
     import typing_extensions as te
@@ -60,38 +60,54 @@ def max_content_length(self) -> t.Optional[int]:  # type: ignore
 
     @property
     def endpoint(self) -> t.Optional[str]:
-        """The endpoint that matched the request.  This in combination with
-        :attr:`view_args` can be used to reconstruct the same or a
-        modified URL.  If an exception happened when matching, this will
-        be ``None``.
+        """The endpoint that matched the request URL.
+
+        This will be ``None`` if matching failed or has not been
+        performed yet.
+
+        This in combination with :attr:`view_args` can be used to
+        reconstruct the same URL or a modified URL.
         """
         if self.url_rule is not None:
             return self.url_rule.endpoint
-        else:
-            return None
+
+        return None
 
     @property
     def blueprint(self) -> t.Optional[str]:
-        """The name of the current blueprint"""
-        if self.url_rule and "." in self.url_rule.endpoint:
-            return self.url_rule.endpoint.rsplit(".", 1)[0]
-        else:
-            return None
+        """The registered name of the current blueprint.
 
-    @cached_property
-    def blueprints(self) -> t.List[str]:
-        """The names of the current blueprint upwards through parent
-        blueprints.
+        This will be ``None`` if the endpoint is not part of a
+        blueprint, or if URL matching failed or has not been performed
+        yet.
+
+        This does not necessarily match the name the blueprint was
+        created with. It may have been nested, or registered with a
+        different name.
         """
-        if self.blueprint is None:
-            return []
+        endpoint = self.endpoint
+
+        if endpoint is not None and "." in endpoint:
+            return endpoint.rpartition(".")[0]
+
+        return None
 
-        bps: t.List[str] = [self.blueprint]
+    @property
+    def blueprints(self) -> t.List[str]:
+        """The registered names of the current blueprint upwards through
+        parent blueprints.
 
-        while "." in bps[-1]:
-            bps.append(bps[-1].rpartition(".")[0])
+        This will be an empty list if there is no current blueprint, or
+        if URL matching failed.
+
+        .. versionadded:: 2.0.1
+        """
+        name = self.blueprint
+
+        if name is None:
+            return []
 
-        return bps
+        return _split_blueprint_path(name)
 
     def _load_form_data(self) -> None:
         RequestBase._load_form_data(self)