More annotations that I forgot to break up into multiple commits.

- validators.py
 - Finish annotating return types.
 - Change ensure_one_of takes a `Collection`, not a `Container`, since it needs to be iterable within `UnpermittedComponentError.__init__`.
 - Change `authority_is_valid` to permit None as an input; continuation of making sure is_valid allowing None propogates. Also, this behavior is depended on elsewhere in the library (just one spot, I think).
- parseresult.py
 - Add variable annotations to `ParseResultMixin`, and make sure _generate_authority is allowed to return `None`.
 - Fix `ParseResultBytes.copy_with` not accepting an int for port.
 - Annotate return type for `authority_from`.
- misc.py
 - Use common base for `URIReference` and `IRIReference` as annotation for `merge_path` and remove circular import.
- exceptions.py
 - Annotate everything.
- _mixin.py
 - Add variable annotations to `URIMixin`; they're under a TYPE_CHECKING block so that only the subclasse's annotations can be found in cases of introspection. Might be overkill.
 - Use `uri.URIReference` to annotate parameters for various functions.
  - TODO: Check if these are potentially too wide, since `IRIReference` also exists and inherits from `URIMixin`?
  - Use hacky "typing.cast within an elided if block" trick to improve typing within `URIMixin.resolve_with`.

src/rfc3986/_mixin.py

@@ -5,6 +5,7 @@
 from . import exceptions as exc
 from . import misc
 from . import normalizers
+from . import uri
 from . import validators
 from ._typing_compat import Self as _Self
 
@@ -20,6 +21,14 @@ class _AuthorityInfo(t.TypedDict):
 class URIMixin:
     """Mixin with all shared methods for URIs and IRIs."""
 
+    if t.TYPE_CHECKING:
+        scheme: t.Optional[str]
+        authority: t.Optional[str]
+        path: t.Optional[str]
+        query: t.Optional[str]
+        fragment: t.Optional[str]
+        encoding: str
+
     def authority_info(self) -> _AuthorityInfo:
         """Return a dictionary with the ``userinfo``, ``host``, and ``port``.
 
@@ -251,7 +260,7 @@ def fragment_is_valid(self, require: bool = False) -> bool:
         )
         return validators.fragment_is_valid(self.fragment, require)
 
-    def normalized_equality(self, other_ref) -> bool:
+    def normalized_equality(self, other_ref: "uri.URIReference") -> bool:
         """Compare this URIReference to another URIReference.
 
         :param URIReference other_ref: (required), The reference with which
@@ -261,7 +270,11 @@ def normalized_equality(self, other_ref) -> bool:
         """
         return tuple(self.normalize()) == tuple(other_ref.normalize())
 
-    def resolve_with(self, base_uri, strict: bool = False) -> _Self:
+    def resolve_with(
+        self,
+        base_uri: t.Union[str, "uri.URIReference"],
+        strict: bool = False,
+    ) -> _Self:
         """Use an absolute URI Reference to resolve this relative reference.
 
         Assuming this is a relative reference that you would like to resolve,
@@ -280,6 +293,9 @@ def resolve_with(self, base_uri, strict: bool = False) -> _Self:
         if not isinstance(base_uri, URIMixin):
             base_uri = type(self).from_string(base_uri)
 
+        if t.TYPE_CHECKING:
+            base_uri = t.cast(uri.URIReference, base_uri)
+
         try:
             self._validator.validate(base_uri)
         except exc.ValidationError:
@@ -388,6 +404,6 @@ def copy_with(
         for key, value in list(attributes.items()):
             if value is misc.UseExisting:
                 del attributes[key]
-        uri = self._replace(**attributes)
+        uri: "uri.URIReference" = self._replace(**attributes)
         uri.encoding = self.encoding
         return uri

src/rfc3986/exceptions.py

@@ -1,5 +1,8 @@
 """Exceptions module for rfc3986."""
+import typing as t
+
 from . import compat
+from . import uri
 
 
 class RFC3986Exception(Exception):
@@ -11,7 +14,7 @@ class RFC3986Exception(Exception):
 class InvalidAuthority(RFC3986Exception):
     """Exception when the authority string is invalid."""
 
-    def __init__(self, authority):
+    def __init__(self, authority: t.Union[str, bytes]) -> None:
         """Initialize the exception with the invalid authority."""
         super().__init__(
             f"The authority ({compat.to_str(authority)}) is not valid."
@@ -21,15 +24,15 @@ def __init__(self, authority):
 class InvalidPort(RFC3986Exception):
     """Exception when the port is invalid."""
 
-    def __init__(self, port):
+    def __init__(self, port: str) -> None:
         """Initialize the exception with the invalid port."""
         super().__init__(f'The port ("{port}") is not valid.')
 
 
 class ResolutionError(RFC3986Exception):
     """Exception to indicate a failure to resolve a URI."""
 
-    def __init__(self, uri):
+    def __init__(self, uri: "uri.URIReference") -> None:
         """Initialize the error with the failed URI."""
         super().__init__(
             "{} does not meet the requirements for resolution.".format(
@@ -47,7 +50,7 @@ class ValidationError(RFC3986Exception):
 class MissingComponentError(ValidationError):
     """Exception raised when a required component is missing."""
 
-    def __init__(self, uri, *component_names):
+    def __init__(self, uri: "uri.URIReference", *component_names: str) -> None:
         """Initialize the error with the missing component name."""
         verb = "was"
         if len(component_names) > 1:
@@ -66,7 +69,12 @@ def __init__(self, uri, *component_names):
 class UnpermittedComponentError(ValidationError):
     """Exception raised when a component has an unpermitted value."""
 
-    def __init__(self, component_name, component_value, allowed_values):
+    def __init__(
+        self,
+        component_name: str,
+        component_value: t.Any,
+        allowed_values: t.Collection[t.Any],
+    ) -> None:
         """Initialize the error with the unpermitted component."""
         super().__init__(
             "{} was required to be one of {!r} but was {!r}".format(
@@ -86,7 +94,7 @@ def __init__(self, component_name, component_value, allowed_values):
 class PasswordForbidden(ValidationError):
     """Exception raised when a URL has a password in the userinfo section."""
 
-    def __init__(self, uri):
+    def __init__(self, uri: t.Union[str, "uri.URIReference"]) -> None:
         """Initialize the error with the URI that failed validation."""
         unsplit = getattr(uri, "unsplit", lambda: uri)
         super().__init__(
@@ -100,7 +108,7 @@ def __init__(self, uri):
 class InvalidComponentsError(ValidationError):
     """Exception raised when one or more components are invalid."""
 
-    def __init__(self, uri, *component_names):
+    def __init__(self, uri: "uri.URIReference", *component_names: str) -> None:
         """Initialize the error with the invalid component name(s)."""
         verb = "was"
         if len(component_names) > 1:

src/rfc3986/misc.py

@@ -22,10 +22,6 @@
 
 from . import abnf_regexp
 
-if t.TYPE_CHECKING:
-    # Break an import loop.
-    from . import uri
-
 
 class URIReferenceBase(t.NamedTuple):
     """The namedtuple used as a superclass of URIReference and IRIReference."""
@@ -130,7 +126,7 @@ class URIReferenceBase(t.NamedTuple):
 
 
 # Path merger as defined in http://tools.ietf.org/html/rfc3986#section-5.2.3
-def merge_paths(base_uri: "uri.URIReference", relative_path: str) -> str:
+def merge_paths(base_uri: URIReferenceBase, relative_path: str) -> str:
     """Merge a base URI's path with a relative URI's path."""
     if base_uri.path is None and base_uri.authority is not None:
         return "/" + relative_path

src/rfc3986/parseresult.py

@@ -36,10 +36,21 @@
 
 
 class ParseResultMixin(t.Generic[t.AnyStr]):
+    if t.TYPE_CHECKING:
+        userinfo: t.Optional[t.AnyStr]
+        host: t.Optional[t.AnyStr]
+        port: t.Optional[int]
+        query: t.Optional[t.AnyStr]
+        encoding: str
+
+        @property
+        def authority(self) -> t.Optional[t.AnyStr]:
+            ...
+
     def _generate_authority(
         self,
         attributes: t.Dict[str, t.Optional[t.AnyStr]],
-    ) -> str:
+    ) -> t.Optional[str]:
         # I swear I did not align the comparisons below. That's just how they
         # happened to align based on pep8 and attribute lengths.
         userinfo, host, port = (
@@ -402,7 +413,7 @@ def copy_with(
         scheme: t.Optional[t.Union[str, bytes]] = misc.UseExisting,
         userinfo: t.Optional[t.Union[str, bytes]] = misc.UseExisting,
         host: t.Optional[t.Union[str, bytes]] = misc.UseExisting,
-        port: t.Optional[t.Union[str, bytes]] = misc.UseExisting,
+        port: t.Optional[t.Union[int, str, bytes]] = misc.UseExisting,
         path: t.Optional[t.Union[str, bytes]] = misc.UseExisting,
         query: t.Optional[t.Union[str, bytes]] = misc.UseExisting,
         fragment: t.Optional[t.Union[str, bytes]] = misc.UseExisting,
@@ -490,7 +501,10 @@ def split_authority(
     return userinfo, host, port
 
 
-def authority_from(reference: "uri.URIReference", strict: bool):
+def authority_from(
+    reference: "uri.URIReference",
+    strict: bool,
+) -> t.Tuple[t.Optional[str], t.Optional[str], t.Optional[int]]:
     try:
         subauthority = reference.authority_info()
     except exceptions.InvalidAuthority:

src/rfc3986/validators.py

@@ -18,6 +18,7 @@
 from . import misc
 from . import normalizers
 from . import uri
+from ._typing_compat import Self as _Self
 
 
 class Validator:
@@ -51,13 +52,13 @@ class Validator:
         ["scheme", "userinfo", "host", "port", "path", "query", "fragment"]
     )
 
-    def __init__(self):
+    def __init__(self) -> None:
         """Initialize our default validations."""
-        self.allowed_schemes: set[str] = set()
-        self.allowed_hosts: set[str] = set()
-        self.allowed_ports: set[str] = set()
-        self.allow_password = True
-        self.required_components = {
+        self.allowed_schemes: t.Set[str] = set()
+        self.allowed_hosts: t.Set[str] = set()
+        self.allowed_ports: t.Set[str] = set()
+        self.allow_password: bool = True
+        self.required_components: t.Dict[str, bool] = {
             "scheme": False,
             "userinfo": False,
             "host": False,
@@ -66,9 +67,11 @@ def __init__(self):
             "query": False,
             "fragment": False,
         }
-        self.validated_components = self.required_components.copy()
+        self.validated_components: t.Dict[
+            str, bool
+        ] = self.required_components.copy()
 
-    def allow_schemes(self, *schemes: str):
+    def allow_schemes(self, *schemes: str) -> _Self:
         """Require the scheme to be one of the provided schemes.
 
         .. versionadded:: 1.0
@@ -84,7 +87,7 @@ def allow_schemes(self, *schemes: str):
             self.allowed_schemes.add(normalizers.normalize_scheme(scheme))
         return self
 
-    def allow_hosts(self, *hosts: str):
+    def allow_hosts(self, *hosts: str) -> _Self:
         """Require the host to be one of the provided hosts.
 
         .. versionadded:: 1.0
@@ -100,7 +103,7 @@ def allow_hosts(self, *hosts: str):
             self.allowed_hosts.add(normalizers.normalize_host(host))
         return self
 
-    def allow_ports(self, *ports: str):
+    def allow_ports(self, *ports: str) -> _Self:
         """Require the port to be one of the provided ports.
 
         .. versionadded:: 1.0
@@ -118,7 +121,7 @@ def allow_ports(self, *ports: str):
                 self.allowed_ports.add(port)
         return self
 
-    def allow_use_of_password(self):
+    def allow_use_of_password(self) -> _Self:
         """Allow passwords to be present in the URI.
 
         .. versionadded:: 1.0
@@ -131,7 +134,7 @@ def allow_use_of_password(self):
         self.allow_password = True
         return self
 
-    def forbid_use_of_password(self):
+    def forbid_use_of_password(self) -> _Self:
         """Prevent passwords from being included in the URI.
 
         .. versionadded:: 1.0
@@ -144,7 +147,7 @@ def forbid_use_of_password(self):
         self.allow_password = False
         return self
 
-    def check_validity_of(self, *components: str):
+    def check_validity_of(self, *components: str) -> _Self:
         """Check the validity of the components provided.
 
         This can be specified repeatedly.
@@ -167,7 +170,7 @@ def check_validity_of(self, *components: str):
         )
         return self
 
-    def require_presence_of(self, *components: str):
+    def require_presence_of(self, *components: str) -> _Self:
         """Require the components provided.
 
         This can be specified repeatedly.
@@ -190,7 +193,7 @@ def require_presence_of(self, *components: str):
         )
         return self
 
-    def validate(self, uri: "uri.URIReference"):
+    def validate(self, uri: "uri.URIReference") -> None:
         """Check a URI for conditions specified on this validator.
 
         .. versionadded:: 1.0
@@ -244,7 +247,7 @@ def check_password(uri: "uri.URIReference") -> None:
 
 
 def ensure_one_of(
-    allowed_values: t.Container[object],
+    allowed_values: t.Collection[object],
     uri: "uri.URIReference",
     attribute: str,
 ) -> None:
@@ -261,7 +264,7 @@ def ensure_one_of(
 def ensure_required_components_exist(
     uri: "uri.URIReference",
     required_components: t.Iterable[str],
-):
+) -> None:
     """Assert that all required components are present in the URI."""
     missing_components = sorted(
         component
@@ -294,7 +297,7 @@ def is_valid(
 
 
 def authority_is_valid(
-    authority: str,
+    authority: t.Optional[str],
     host: t.Optional[str] = None,
     require: bool = False,
 ) -> bool: