Tim Peters <[email protected]> added the comment:
Sure! The OP was obviously asking about the engine that ships with Python, so
that's what I talked about.
Raphaël, Matthew develops an excellent replacement ("regex") for Python's re
module, which you can install via, e.g., "pip install regex" (or, on Windows,
"python -m pip install regex"). More info here:
https://pypi.python.org/pypi/regex/
Matthew, will that become Python's standard offering some day? I'd be in favor
of that! It has many advantages, although it doesn't always avoid
exponential-time backtracking in failing cases. For example, `re` and `regex`
both take exponential time to fail to match the regexp:
"((xy)+)+$"
against strings of the form:
"xy" * i + "y"
Increase `i` by 1, and both take about twice as long to fail to match (meaning
either .match or .search), and `re` is actually quicker on my box (3.6.3 on
64-bit Win10).
In any case, I'm closing this, since there's no concrete idea on the table for
a change to `re` that would actually help (e.g., people ignore warnings, and
there's really no way to _guess_ whether a regexp is "taking too long" to begin
with - if it's taking minutes, people immediately discover the hangup already
when they interrupt the program and see that it's trying to match a regexp).
----------
resolution: -> wont fix
stage: -> resolved
status: open -> closed
_______________________________________
Python tracker <[email protected]>
<https://bugs.python.org/issue31759>
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