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# Copyright (C) 2013, Stefan Schwarzer
# and ftputil contributors (see `doc/contributors.txt`)
# See the file LICENSE for licensing terms.
"""
tool.py - helper code
"""
from __future__ import unicode_literals
import ftputil.compat as compat
__all__ = ["same_string_type_as", "as_bytes", "as_unicode",
"as_default_string"]
# Encoding to convert between byte string and unicode string. This is
# a "lossless" encoding: Strings can be encoded/decoded back and forth
# without information loss or causing encoding-related errors. The
# `ftplib` module under Python 3 also uses the "latin1" encoding
# internally. It's important to use the same encoding here, so that users who
# used `ftplib` to create FTP items with non-ASCII characters can access them
# in the same way with ftputil.
LOSSLESS_ENCODING = "latin1"
def same_string_type_as(type_source, content_source):
"""
Return a string of the same type as `type_source` with the content
from `content_source`.
If the `type_source` and `content_source` don't have the same
type, use `LOSSLESS_ENCODING` above to encode or decode, whatever
operation is needed.
"""
if (
isinstance(type_source, compat.bytes_type) and
isinstance(content_source, compat.unicode_type)):
return content_source.encode(LOSSLESS_ENCODING)
elif (
isinstance(type_source, compat.unicode_type) and
isinstance(content_source, compat.bytes_type)):
return content_source.decode(LOSSLESS_ENCODING)
else:
return content_source
def as_bytes(string):
"""
Return the argument `string` converted to a byte string if it's a
unicode string. Otherwise just return the string.
"""
return same_string_type_as(b"", string)
def as_unicode(string):
"""
Return the argument `string` converted to a unicode string if it's
a byte string. Otherwise just return the string.
"""
return same_string_type_as("", string)
def as_default_string(string):
"""
Return the argument `string` converted to a the default string
type for the Python version. For unicode strings,
`LOSSLESS_ENCODING` is used for encoding or decoding.
"""
return same_string_type_as(compat.default_string_type(), string)
def encode_if_unicode(string, encoding):
"""
Return the string `string`, encoded with `encoding` if `string` is
a unicode string. Otherwise return `string` unchanged.
"""
if isinstance(string, compat.unicode_type):
return string.encode(encoding)
else:
return string
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