<regex>: Properly parse dollar anchors in basic and grep mode
#5362
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muellerj2
commented
Mar 25, 2025
Comment on lines
+3951
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+3955
| const bool _Is_end_of_alternative = | ||
| ((_L_flags & _L_alt_pipe) && _Ch == _Meta_bar) // dollar followed by pipe | | ||
| || ((_L_flags & _L_alt_nl) && _Ch == _Meta_nl && _Disj_count == 0) // dollar followed by pipe \n | ||
| || ((_Escaped || (_L_flags & _L_nex_grp)) && _Ch == _Meta_rpar | ||
| && _Disj_count != 0); // dollar followed by parenthesis closing a group |
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Strictly speaking, _L_flags & _L_alt_pipe and _L_flags & _L_nex_grp are always 0 here, so the first disjunct could be removed completely and _L_flags & _L_nex_grp could be omitted in the third.
I still opted for this expression, though, because it clearly handles all possible cases of "end of an alternative", independent of how the flags for alternatives correlate in practice with the flag _L_anch_rstr.
StephanTLavavej
added
bug
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This PR provides the symmetric change to #5165 for the dollar sign in basic and grep mode. Similar to the handling of the caret anchor, this PR recognizes a dollar sign as an anchor in a basic regular expression if it is at the end of an alternative. It does so by doing a bit of lookahead.
Drive-by: Remove a duplicated test that was accidentally added in #5165.