What's new?

• a minor improvement of the regex syntax to allow escaped spaces #360
• updated POSIX regex lazy quantifier matching in linear time using an advanced DFA transformation algorithm #174

Notes

Lazy quantifier POSIX regex matching with efficient DFAs is/was claimed to be impossible in the past, when in fact I wrote a new algorithm for the high-performance RE/flex regex matcher in 2015/2016. This latest installment of the DFA construction algorithm makes the syntax and behavior of POSIX regex lazy quantifier matching align with Perl regex lazy quantifier matching. Lazy quantifiers are of the form ?? (lazy optional) and *? and +? (lazy repetitions) to match no more than necessary, typically by backtracking until matching (Perl). Note that ugrep and RE/flex pattern matching is efficiently performed with a DFA in linear time, i.e. matching is backtrack-free. Pattern searching also uses match predictions to avoid backtracking.