May 26, 2018
Perl Incompatible Regular Expressions library
This is PIRE, Perl Incompatible Regular Expressions library.
This library is aimed at checking a huge amount of text against relatively many regular expressions. Roughly speaking, it can just check whether given text maches the certain regexp, but can do it really fast more than 400 MB/s on our hardware is common. Even more, multiple regexps can be combined together, giving capability to check the text against apx.10 regexps in a single pass and mantaining the same speed.
Since Pire examines each character only once, without any lookaheads or rollbacks, spending about five machine instructions per each character, it can be used even in realtime tasks.
On the other hand, Pire has very limited functionality compared to other regexp libraries. Pire does not have any Perlish conditional regexps, lookaheads & backtrackings, greedy/nongreedy matches; neither has it any capturing facilities.