Warning: This document is for the development version of molten.

Source code for molten.http.headers

# This file is a part of molten.
#
# Copyright (C) 2018 CLEARTYPE SRL <bogdan@cleartype.io>
#
# molten is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or (at
# your option) any later version.
#
# molten is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
# License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

from collections import defaultdict
from typing import Dict, Iterable, Iterator, List, Optional, Tuple, Union

from ..errors import HeaderMissing
from ..typing import Environ

#: An alias representing a dictionary of headers.
HeadersDict = Dict[str, Union[str, List[str]]]

#: WSGI keeps these separate from other headers.
CONTENT_VARS = {"CONTENT_LENGTH", "CONTENT_TYPE"}


[docs]class Headers(Iterable[Tuple[str, str]]): """A mapping from case-insensitive header names to lists of values. """ __slots__ = ["_headers"] def __init__(self, mapping: Optional[HeadersDict] = None) -> None: self._headers: Dict[str, List[str]] = defaultdict(list) self.add_all(mapping or {})
[docs] @classmethod def from_environ(cls, environ: Environ) -> "Headers": """Construct a Headers instance from a WSGI environ. """ headers = {} for name, value in environ.items(): if name in CONTENT_VARS: headers[name.replace("_", "-")] = value elif name.startswith("HTTP_"): headers[_parse_environ_header(name)] = [value] return cls(headers)
[docs] def add(self, header: str, value: Union[str, List[str]]) -> None: """Add values for a particular header. """ if isinstance(value, list): self._headers[header.lower()].extend(value) else: self._headers[header.lower()].append(value)
[docs] def add_all(self, mapping: HeadersDict) -> None: """Add a group of headers. """ for header, value_or_values in mapping.items(): self.add(header, value_or_values)
[docs] def get(self, header: str, default: Optional[str] = None) -> Optional[str]: """Get the last value for a given header. """ try: return self[header] except HeaderMissing: return default
[docs] def get_all(self, header: str) -> List[str]: """Get all the values for a given header. """ return self._headers[header.lower()]
[docs] def get_int(self, header: str, default: Optional[int] = None) -> Optional[int]: """Get the last value for a given header as an integer. """ try: return int(self[header]) except HeaderMissing: return default
def __delitem__(self, header: str) -> None: """Delete all the values for a given header. """ del self._headers[header.lower()] def __getitem__(self, header: str) -> str: """Get the last value for a given header. Raises: HeaderMissing: When the header is missing. """ try: return self._headers[header.lower()][-1] except IndexError: raise HeaderMissing(header) def __setitem__(self, header: str, value: str) -> None: """Replace a header's values. """ self._headers[header.lower()] = [value] def __iter__(self) -> Iterator[Tuple[str, str]]: """Iterate over all the headers. """ for header, values in self._headers.items(): for value in values: yield header, value def __repr__(self) -> str: mapping = ", ".join(f"{repr(name)}: {repr(value)}" for name, value in self._headers.items()) return f"Headers({{{mapping}}})"
#: The number of characters that are stripped from the beginning of #: every header name in a WSGI environ. HEADER_PREFIX_LEN = len("HTTP_") #: A lookup table from WSGI header strings to header names. HEADER_PARSER_CACHE: Dict[str, str] = {} def _parse_environ_header(header: str) -> str: try: return HEADER_PARSER_CACHE[header] except KeyError: HEADER_PARSER_CACHE[header] = parsed_header = header[HEADER_PREFIX_LEN:].replace("_", "-") return parsed_header