Re-organize directory structure (#4971)

See discussion in #2491

Co-authored-by: Ivan Levkivskyi <ilevkivskyi@dropbox.com>

stdlib/email/headerregistry.pyi

@@ -0,0 +1,90 @@
+from datetime import datetime as _datetime
+from email.errors import MessageDefect
+from email.policy import Policy
+from typing import Any, Dict, Mapping, Optional, Tuple, Union
+
+class BaseHeader(str):
+    @property
+    def name(self) -> str: ...
+    @property
+    def defects(self) -> Tuple[MessageDefect, ...]: ...
+    @property
+    def max_count(self) -> Optional[int]: ...
+    def __new__(cls, name: str, value: Any) -> BaseHeader: ...
+    def init(self, *args: Any, **kw: Any) -> None: ...
+    def fold(self, *, policy: Policy) -> str: ...
+
+class UnstructuredHeader:
+    @classmethod
+    def parse(cls, string: str, kwds: Dict[str, Any]) -> None: ...
+
+class UniqueUnstructuredHeader(UnstructuredHeader): ...
+
+class DateHeader:
+    datetime: _datetime
+    @classmethod
+    def parse(cls, string: Union[str, _datetime], kwds: Dict[str, Any]) -> None: ...
+
+class UniqueDateHeader(DateHeader): ...
+
+class AddressHeader:
+    groups: Tuple[Group, ...]
+    addresses: Tuple[Address, ...]
+    @classmethod
+    def parse(cls, string: str, kwds: Dict[str, Any]) -> None: ...
+
+class UniqueAddressHeader(AddressHeader): ...
+
+class SingleAddressHeader(AddressHeader):
+    @property
+    def address(self) -> Address: ...
+
+class UniqueSingleAddressHeader(SingleAddressHeader): ...
+
+class MIMEVersionHeader:
+    version: Optional[str]
+    major: Optional[int]
+    minor: Optional[int]
+    @classmethod
+    def parse(cls, string: str, kwds: Dict[str, Any]) -> None: ...
+
+class ParameterizedMIMEHeader:
+    params: Mapping[str, Any]
+    @classmethod
+    def parse(cls, string: str, kwds: Dict[str, Any]) -> None: ...
+
+class ContentTypeHeader(ParameterizedMIMEHeader):
+    content_type: str
+    maintype: str
+    subtype: str
+
+class ContentDispositionHeader(ParameterizedMIMEHeader):
+    content_disposition: str
+
+class ContentTransferEncodingHeader:
+    cte: str
+    @classmethod
+    def parse(cls, string: str, kwds: Dict[str, Any]) -> None: ...
+
+class HeaderRegistry:
+    def __init__(self, base_class: BaseHeader = ..., default_class: BaseHeader = ..., use_default_map: bool = ...) -> None: ...
+    def map_to_type(self, name: str, cls: BaseHeader) -> None: ...
+    def __getitem__(self, name: str) -> BaseHeader: ...
+    def __call__(self, name: str, value: Any) -> BaseHeader: ...
+
+class Address:
+    display_name: str
+    username: str
+    domain: str
+    @property
+    def addr_spec(self) -> str: ...
+    def __init__(
+        self, display_name: str = ..., username: Optional[str] = ..., domain: Optional[str] = ..., addr_spec: Optional[str] = ...
+    ) -> None: ...
+    def __str__(self) -> str: ...
+
+class Group:
+    display_name: Optional[str]
+    addresses: Tuple[Address, ...]
+    def __init__(self, display_name: Optional[str] = ..., addresses: Optional[Tuple[Address, ...]] = ...) -> None: ...
+    def __str__(self) -> str: ...