Function parse_list_header

src/werkzeug/http.py:303–361

Parse a header value that consists of a list of comma separated items according to `RFC 9110 <https://httpwg.org/specs/rfc9110.html#abnf.extension>`__. Surrounding quotes are removed from items, but internal quotes are left for future parsing. Empty values are discarded. .. code-bl

(value: str)

def parse_list_header(value: str) -> list[str]:
    """Parse a header value that consists of a list of comma separated items according
    to `RFC 9110 <https://httpwg.org/specs/rfc9110.html#abnf.extension>`__.

    Surrounding quotes are removed from items, but internal quotes are left for
    future parsing. Empty values are discarded.

    .. code-block:: python

        parse_list_header('token, "quoted value"')
        ['token', 'quoted value']

    This is the reverse of :func:`dump_header`.

    :param value: The header value to parse.

    .. versionchanged:: 3.2
        Quotes and escapes are kept if only part of an item is quoted. Empty
        values are omitted. An empty list is returned if the value contains an
        unclosed quoted string.
    """
    items = []
    item = ""
    escape = False
    quote = False

    for char in value:
        if escape:
            escape = False
            item += char
            continue

        if quote:
            if char == "\\":
                escape = True
            elif char == '"':
                quote = False

            item += char
            continue

        if char == ",":
            items.append(item)
            item = ""
            continue

        if char == '"':
            quote = True

        item += char

    if quote:
        # invalid, unclosed quoted string
        return []

    items.append(item)
    return [
        unquote_header_value(item) for item in (item.strip() for item in items) if item