Speed up codespell:ignore check by skipping the regex in most cases
#3721
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nthykier
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The codespell codebase unsurprisingly spends a vast majority of its runtime in various regex related code such as `search` and `finditer`. The best way to optimize runtime spend in regexes is to not do a regex in the first place, since the regex engine has a rather steep overhead over regular string primitives (that is at the cost of flexibility). If the regex rarely matches and there is a very easy static substring that can be used to rule out the match, then you can speed up the code by using `substring in string` as a conditional to skip the regex. This is assuming the regex is used enough for the performance to matter. An obvious choice here falls on the `codespell:ignore` regex, because it has a very distinctive substring in the form of `codespell:ignore`, which will rule out almost all lines that will not match. With this little trick, runtime goes from ~5.4s to ~4.5s on the corpus mentioned in codespell-project#3419.
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The codespell codebase unsurprisingly spends a vast majority of its runtime in various regex related code such as
searchandfinditer.The best way to optimize runtime spend in regexes is to not do a regex in the first place, since the regex engine has a rather steep overhead over regular string primitives (that is at the cost of flexibility). If the regex rarely matches and there is a very easy static substring that can be used to rule out the match, then you can speed up the code by using
substring in stringas a conditional to skip the regex. This is assuming the regex is used enough for the performance to matter.An obvious choice here falls on the
codespell:ignoreregex, because it has a very distinctive substring in the form ofcodespell:ignore, which will rule out almost all lines that will not match.With this little trick, runtime goes from ~5.4s to ~4.5s on the corpus mentioned in #3419.