8000 bpo-34002: Minor efficiency and clarity improvements in email package… · python/cpython@2702638 · GitHub
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bpo-34002: Minor efficiency and clarity improvements in email package. (GH-7999)
* Check intersection of two sets explicitly Comparing ``len(a) > ``len(a - b)`` is essentially looking for an intersection between the two sets. If set ``b`` does not intersect ``a`` then ``len(a - b)`` will be equal to ``len(a)``. This logic is more clearly expressed as ``a & b``. * Change while/pop to a for-loop Copying the list, then repeatedly popping the first element was unnecessarily slow. I also cleaned up a couple other inefficiencies. There's no need to unpack a tuple, then re-pack and append it. The list can be created with the first element instead of empty. Secondly, the ``endswith`` method returns a bool, so there's no need for an if- statement to set ``encoding`` to True or False. * Use set.intersection to check for intersections ``a.intersection(b)`` method is more clear of purpose than ``not a.isdisjoint(b)`` and avoids an unnecessary set construction that ``a & set(b)`` performs. * Use not isdisjoint instead of intersection While it reads slightly worse, the isdisjoint method will stop when it finds a counterexample and returns a bool, rather than looping over the entire iterable and constructing a new set.
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‎Lib/email/headerregistry.py

Lines changed: 8 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -69,11 +69,9 @@ def addr_spec(self):
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"""The addr_spec (username@domain) portion of the address, quoted
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according to RFC 5322 rules, but with no Content Transfer Encoding.
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"""
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nameset = set(self.username)
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if len(nameset) > len(nameset-parser.DOT_ATOM_ENDS):
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lp = parser.quote_string(self.username)
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else:
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lp = self.username
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lp = self.username
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if not parser.DOT_ATOM_ENDS.isdisjoint(lp):
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lp = parser.quote_string(lp)
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if self.domain:
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return lp + '@' + self.domain
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if not lp:
@@ -86,11 +84,9 @@ def __repr__(self):
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self.display_name, self.username, self.domain)
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def __str__(self):
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nameset = set(self.display_name)
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if len(nameset) > len(nameset-parser.SPECIALS):
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disp = parser.quote_string(self.display_name)
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else:
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disp = self.display_name
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disp = self.display_name
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if not parser.SPECIALS.isdisjoint(disp):
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disp = parser.quote_string(disp)
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if disp:
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addr_spec = '' if self.addr_spec=='<>' else self.addr_spec
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return "{} <{}>".format(disp, addr_spec)
@@ -141,10 +137,8 @@ def __str__(self):
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if self.display_name is None and len(self.addresses)==1:
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return str(self.addresses[0])
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disp = self.display_name
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if disp is not None:
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nameset = set(disp)
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if len(nameset) > len(nameset-parser.SPECIALS):
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disp = parser.quote_string(disp)
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if disp is not None and not parser.SPECIALS.isdisjoint(disp):
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disp = parser.quote_string(disp)
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adrstr = ", ".join(str(x) for x in self.addresses)
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adrstr = ' ' + adrstr if adrstr else adrstr
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return "{}:{};".format(disp, adrstr)

‎Lib/email/utils.py

Lines changed: 3 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -259,21 +259,13 @@ def decode_params(params):
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params is a sequence of 2-tuples containing (param name, string value).
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"""
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# Copy params so we don't mess with the original
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params = params[:]
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new_params = []
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new_params = [params[0]]
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# Map parameter's name to a list of continuations. The values are a
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# 3-tuple of the continuation number, the string value, and a flag
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# specifying whether a particular segment is %-encoded.
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rfc2231_params = {}
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name, value = params.pop(0)
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new_params.append((name, value))
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while params:
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name, value = params.pop(0)
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if name.endswith('*'):
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encoded = True
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else:
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encoded = False
267+
for name, value in params[1:]:
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encoded = name.endswith('*')
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value = unquote(value)
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mo = rfc2231_continuation.match(name)
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if mo:

‎Misc/NEWS.d/next/Library/2019-09-19-19-58-33.bpo-34002.KBnaVX.rst

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,2 @@
1+
Improve efficiency in parts of email package by changing while-pop to a for
2+
loop, using isdisjoint instead of set intersections.

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