On Thu, 20 Jun 2019, Zoltán Herczeg wrote: > > (?=x|y) looks much more ergonomical than (?:(?=x)|(?=y)) > > They behave the same way, so pick whatever you prefer.
(?:(?=X)|(?=Y))Z means "if X matches, try to match Z; if that fails, if Y matches try to match Z". In the simple case the second match of Z will be the same as the first, so will always fail. However, if X and Y are complex and contain capturing parentheses, I suppose it is possible to construct Z using back references in such a way that it fails after X matches but succeeds after Y matches. But who would want to constuct such a complicated thing? Philip -- Philip Hazel -- ## List details at https://lists.exim.org/mailman/listinfo/pcre-dev
