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Setting optional group uses wrong offset #14

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tek opened this issue Mar 14, 2023 · 0 comments

tek commented Mar 14, 2023

This appears to be similar to #7, but since it happens in 1.1.0.0, I thought you might have overlooked something.

ghci> "aaxxc" & [regex|aax(b)?x(c)|] . group 0 .~ "B"
"Baaxxc"
ghci> "aaxxc" & [regex|(aa)x(b)?x(c)|] . group 1 .~ "B"
"aaBxxc"

When the optional group is the last one, nothing is changed:

ghci> "aaxxc" & [regex|(aa)x(b)?xc|] . group 1 .~ "B"
"aaxxc"

Like in the other issue, making the optional group non-capturing and wrapping it in a new group works around the issue:

ghci> "aaxxc" & [regex|(aa)x((?:b)?)xc|] . group 1 .~ "B"
"aaxBxc"

No worries if this is too awkward to implement reliably, the workaround is tolerable 🙂

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