Unexpected --count-matches result #1573
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bug
A bug.
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BurntSushi
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May 8, 2020
In order to implement --count-matches, we simply re-execute the regex on the spans reported by the searcher. The spans always correspond to the lines that participated in the match. This is the correct thing to do, except when the regex contains look-ahead (or look-behind). In particular, the look-around permits the regex's match success to depends on an arbitrary point before or after the lines actually reported as participating in the match. Since only the matched lines are reported to the printer, it is possible for subsequent searching on those lines to fail. A true fix for this would somehow make the total span available to the printer. But that seems tricky since it isn't always available. For PCRE2's case in multiline mode, it is available because we force it to be so for correctness. For now, we simply detect this corner case heuristically. If the match count is zero, then it necessarily means there is some kind of look-around that isn't matching. So we set the match count to 1. This is probably incorrect in some cases, although my brain can't quite come up with a concrete example. Nevertheless, this is strictly better than the status quo. Fixes #1573
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What version of ripgrep are you using?
How did you install ripgrep?
Choco
What operating system are you using ripgrep on?
Windows 10
Describe your bug.
I have a pattern (with look-around) which with
--countreports2but with--count-matchesreports0. This doesn't appear to make sense. I would expect ``--count-matchesto report a number at least as high as--count`.What are the steps to reproduce the behavior?
File
test.txtwith contents:Ripgrep usage:
rg --pcre2 -U '(?s)def (\w+);(?=.*use \w+)' test.txt --count-matchesWhat is the actual behavior?
The output is
0whereas the output for the same command with--countinstead of--count-matchesis2.What is the expected behavior?
I would expect an output of
2and generally the result of--count-matchesto be equal to or greater than that of--count.The text was updated successfully, but these errors were encountered: