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