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Merged
corona10 merged 2 commits into from
Jul 13, 2023
Merged

gh-106628: email parsing speedup #106629

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gh-106628: speed up the performance of email multipart parsing
cfbolz Jul 11, 2023
4016142
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cfbolz Jul 11, 2023
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15 changes: 9 additions & 6 deletions Lib/email/feedparser.py
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,8 @@
headerRE = re.compile(r'^(From |[\041-\071\073-\176]*:|[\t ])')
EMPTYSTRING = ''
NL = '\n'
boundaryendRE = re.compile(
r'(?P<end>--)?(?P<ws>[ \t]*)(?P<linesep>\r\n|\r|\n)?$')

NeedMoreData = object()

Expand Down Expand Up @@ -327,9 +329,10 @@ def _parsegen(self):
# this onto the input stream until we've scanned past the
# preamble.
separator = '--' + boundary
boundaryre = re.compile(
'(?P<sep>' + re.escape(separator) +
r')(?P<end>--)?(?P<ws>[ \t]*)(?P<linesep>\r\n|\r|\n)?$')
def boundarymatch(line):
if not line.startswith(separator):
return None
return boundaryendRE.match(line, len(separator))
capturing_preamble = True
preamble = []
linesep = False
Expand All @@ -341,7 +344,7 @@ def _parsegen(self):
continue
if line == '':
break
mo = boundaryre.match(line)
mo = boundarymatch(line)
if mo:
# If we're looking at the end boundary, we're done with
# this multipart. If there was a newline at the end of
Expand Down Expand Up @@ -373,13 +376,13 @@ def _parsegen(self):
if line is NeedMoreData:
yield NeedMoreData
continue
mo = boundaryre.match(line)
mo = boundarymatch(line)
if not mo:
self._input.unreadline(line)
break
# Recurse to parse this subpart; the input stream points
# at the subpart's first line.
self._input.push_eof_matcher(boundaryre.match)
self._input.push_eof_matcher(boundarymatch)
for retval in self._parsegen():
if retval is NeedMoreData:
yield NeedMoreData
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2023-07-11-16-36-22.gh-issue-106628.Kx8Zvc.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Speed up parsing of emails by about 20% by not compiling a new regular
expression for every single email.