Class HTTPHeaderDictItemView

src/urllib3/_collections.py:156–201

HTTPHeaderDict is unusual for a Mapping[str, str] in that it has two modes of address. If we directly try to get an item with a particular name, we will get a string back that is the concatenated version of all the values: >>> d['X-Header-Name'] 'Value1, Value2, Value3'

class HTTPHeaderDictItemView(set[tuple[str, str]]):
    """
    HTTPHeaderDict is unusual for a Mapping[str, str] in that it has two modes of
    address.

    If we directly try to get an item with a particular name, we will get a string
    back that is the concatenated version of all the values:

    >>> d['X-Header-Name']
    'Value1, Value2, Value3'

    However, if we iterate over an HTTPHeaderDict's items, we will optionally combine
    these values based on whether combine=True was called when building up the dictionary

    >>> d = HTTPHeaderDict({"A": "1", "B": "foo"})
    >>> d.add("A", "2", combine=True)
    >>> d.add("B", "bar")
    >>> list(d.items())
    [
        ('A', '1, 2'),
        ('B', 'foo'),
        ('B', 'bar'),
    ]

    This class conforms to the interface required by the MutableMapping ABC while
    also giving us the nonstandard iteration behavior we want; items with duplicate
    keys, ordered by time of first insertion.
    """

    _headers: HTTPHeaderDict

    def __init__(self, headers: HTTPHeaderDict) -> None:
        self._headers = headers

    def __len__(self) -> int:
        return len(list(self._headers.iteritems()))

    def __iter__(self) -> typing.Iterator[tuple[str, str]]:
        return self._headers.iteritems()

    def __contains__(self, item: object) -> bool:
        if isinstance(item, tuple) and len(item) == 2:
            passed_key, passed_val = item
            if isinstance(passed_key, str) and isinstance(passed_val, str):
                return self._headers._has_value_for_header(passed_key, passed_val)
        return False


class HTTPHeaderDict(typing.MutableMapping[str, str]):