def _encode_field(self, value, param="field"):
"""convert field to internal representation.
internal representation is always bytes. byte strings are left as-is,
unicode strings encoding using file's default encoding (or ``utf-8``
if no encoding has been specified).
:raises UnicodeEncodeError:
if unicode value cannot be encoded using default encoding.
:raises ValueError:
if resulting byte string contains a forbidden character,
or is too long (>255 bytes).
:returns:
encoded identifer as bytes
"""
if isinstance(value, unicode):
value = value.encode(self.encoding)
elif not isinstance(value, bytes):
raise ExpectedStringError(value, param)
if len(value) > 255:
raise ValueError("%s must be at most 255 characters: %r" %
(param, value))
if any(c in _INVALID_FIELD_CHARS for c in value):
raise ValueError("%s contains invalid characters: %r" % (
param,
value,
))
return value
def to_unicode(source, encoding="utf-8", param="value"):
"""Helper to normalize input to unicode.
:arg source:
source bytes/unicode to process.
:arg encoding:
encoding to use when decoding bytes instances.
:param param:
optional name of variable/noun to reference when raising errors.
:raises TypeError: if source is not unicode or bytes.
:returns:
* returns unicode strings unchanged.
* returns bytes strings decoded using *encoding*
"""
assert encoding
if isinstance(source, unicode):
return source
elif isinstance(source, bytes):
return source.decode(encoding)
else:
raise ExpectedStringError(source, param)
def to_native_str(source, encoding="utf-8", param="value"):
if isinstance(source, bytes):
return source
elif isinstance(source, unicode):
return source.encode(encoding)
else:
raise ExpectedStringError(source, param)
def to_bytes(source, encoding="utf-8", param="value", source_encoding=None):
"""Helper to normalize input to bytes.
:arg source:
Source bytes/unicode to process.
:arg encoding:
Target encoding (defaults to ``"utf-8"``).
:param param:
Optional name of variable/noun to reference when raising errors
:param source_encoding:
If this is specified, and the source is bytes,
the source will be transcoded from *source_encoding* to *encoding*
(via unicode).
:raises TypeError: if source is not unicode or bytes.
:returns:
* unicode strings will be encoded using *encoding*, and returned.
* if *source_encoding* is not specified, byte strings will be
returned unchanged.
* if *source_encoding* is specified, byte strings will be transcoded
to *encoding*.
"""
assert encoding
if isinstance(source, bytes):
if source_encoding and not is_same_codec(source_encoding, encoding):
return source.decode(source_encoding).encode(encoding)
else:
return source
elif isinstance(source, unicode):
return source.encode(encoding)
else:
raise ExpectedStringError(source, param)
