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|
import email.message
import email.policy
import re
import textwrap
from ._text import FoldedCase
class RawPolicy(email.policy.EmailPolicy):
def fold(self, name, value):
folded = self.linesep.join(
textwrap.indent(value, prefix=' ' * 8, predicate=lambda line: True)
.lstrip()
.splitlines()
)
return f'{name}: {folded}{self.linesep}'
class Message(email.message.Message):
r"""
Specialized Message subclass to handle metadata naturally.
Reads values that may have newlines in them and converts the
payload to the Description.
>>> msg_text = textwrap.dedent('''
... Name: Foo
... Version: 3.0
... License: blah
... de-blah
... <BLANKLINE>
... First line of description.
... Second line of description.
... <BLANKLINE>
... Fourth line!
... ''').lstrip().replace('<BLANKLINE>', '')
>>> msg = Message(email.message_from_string(msg_text))
>>> msg['Description']
'First line of description.\nSecond line of description.\n\nFourth line!\n'
Message should render even if values contain newlines.
>>> print(msg)
Name: Foo
Version: 3.0
License: blah
de-blah
Description: First line of description.
Second line of description.
<BLANKLINE>
Fourth line!
<BLANKLINE>
<BLANKLINE>
"""
multiple_use_keys = set(
map(
FoldedCase,
[
'Classifier',
'Obsoletes-Dist',
'Platform',
'Project-URL',
'Provides-Dist',
'Provides-Extra',
'Requires-Dist',
'Requires-External',
'Supported-Platform',
'Dynamic',
],
)
)
"""
Keys that may be indicated multiple times per PEP 566.
"""
def __new__(cls, orig: email.message.Message):
res = super().__new__(cls)
vars(res).update(vars(orig))
return res
def __init__(self, *args, **kwargs):
self._headers = self._repair_headers()
# suppress spurious error from mypy
def __iter__(self):
return super().__iter__()
def __getitem__(self, item):
"""
Override parent behavior to typical dict behavior.
``email.message.Message`` will emit None values for missing
keys. Typical mappings, including this ``Message``, will raise
a key error for missing keys.
Ref python/importlib_metadata#371.
"""
res = super().__getitem__(item)
if res is None:
raise KeyError(item)
return res
def _repair_headers(self):
def redent(value):
"Correct for RFC822 indentation"
indent = ' ' * 8
if not value or '\n' + indent not in value:
return value
return textwrap.dedent(indent + value)
headers = [(key, redent(value)) for key, value in vars(self)['_headers']]
if self._payload:
headers.append(('Description', self.get_payload()))
self.set_payload('')
return headers
def as_string(self):
return super().as_string(policy=RawPolicy())
@property
def json(self):
"""
Convert PackageMetadata to a JSON-compatible format
per PEP 0566.
"""
def transform(key):
value = self.get_all(key) if key in self.multiple_use_keys else self[key]
if key == 'Keywords':
value = re.split(r'\s+', value)
tk = key.lower().replace('-', '_')
return tk, value
return dict(map(transform, map(FoldedCase, self)))
|
