Re: Backtracking and eternal loops caused by regular

(b) The specs have nothing to say about performance.

(c) Saxon relies entirely on the regex engines in the underlying platform
(Java or .NET). I dare say there are cases where one regex engine will find
an optimization that another one misses.

(d) I was under the impression that regular expression evaluation will
always terminate, though of course it's possible to construct cases where
that might require extreme patience to observe.

25 char:  2.5 seconds
26 char: 5.3 seconds
27 char: 10.7 seconds
28 char: 21.4 seconds
35 char: 2739 seconds
40 char: 24.4 hours
50 char: almost 3 years
85 char: 97 * 10^9 years (97 billion years)