jpayne@7: """
jpayne@7: requests._internal_utils
jpayne@7: ~~~~~~~~~~~~~~
jpayne@7: 
jpayne@7: Provides utility functions that are consumed internally by Requests
jpayne@7: which depend on extremely few external helpers (such as compat)
jpayne@7: """
jpayne@7: import re
jpayne@7: 
jpayne@7: from .compat import builtin_str
jpayne@7: 
jpayne@7: _VALID_HEADER_NAME_RE_BYTE = re.compile(rb"^[^:\s][^:\r\n]*$")
jpayne@7: _VALID_HEADER_NAME_RE_STR = re.compile(r"^[^:\s][^:\r\n]*$")
jpayne@7: _VALID_HEADER_VALUE_RE_BYTE = re.compile(rb"^\S[^\r\n]*$|^$")
jpayne@7: _VALID_HEADER_VALUE_RE_STR = re.compile(r"^\S[^\r\n]*$|^$")
jpayne@7: 
jpayne@7: _HEADER_VALIDATORS_STR = (_VALID_HEADER_NAME_RE_STR, _VALID_HEADER_VALUE_RE_STR)
jpayne@7: _HEADER_VALIDATORS_BYTE = (_VALID_HEADER_NAME_RE_BYTE, _VALID_HEADER_VALUE_RE_BYTE)
jpayne@7: HEADER_VALIDATORS = {
jpayne@7:     bytes: _HEADER_VALIDATORS_BYTE,
jpayne@7:     str: _HEADER_VALIDATORS_STR,
jpayne@7: }
jpayne@7: 
jpayne@7: 
jpayne@7: def to_native_string(string, encoding="ascii"):
jpayne@7:     """Given a string object, regardless of type, returns a representation of
jpayne@7:     that string in the native string type, encoding and decoding where
jpayne@7:     necessary. This assumes ASCII unless told otherwise.
jpayne@7:     """
jpayne@7:     if isinstance(string, builtin_str):
jpayne@7:         out = string
jpayne@7:     else:
jpayne@7:         out = string.decode(encoding)
jpayne@7: 
jpayne@7:     return out
jpayne@7: 
jpayne@7: 
jpayne@7: def unicode_is_ascii(u_string):
jpayne@7:     """Determine if unicode string only contains ASCII characters.
jpayne@7: 
jpayne@7:     :param str u_string: unicode string to check. Must be unicode
jpayne@7:         and not Python 2 `str`.
jpayne@7:     :rtype: bool
jpayne@7:     """
jpayne@7:     assert isinstance(u_string, str)
jpayne@7:     try:
jpayne@7:         u_string.encode("ascii")
jpayne@7:         return True
jpayne@7:     except UnicodeEncodeError:
jpayne@7:         return False