Actually at the 4th Ed. of the Camel Book, there is a page or two devoted to rsc's engine
CHAPTER 5 Pattern Matching
Fancy Patterns - Alternate Engines
Starting with v5.10, you can even swap out Perl’s entire regex engine and replace it with an alternate pattern-matching library.
...
Table 5-18. Alternate regex engines
re::engine::RE2 - Russ Cox’s RE2 regex engine
...
One engine of special note is Russ Cox’s RE2 library. It’s a C and C++ library that’s used in the Go programming language, among many other places. The interesting thing is that it maintains a high level Perl compatibility, including good UTF-8 support, while avoiding the potential pitfalls of catastrophic backtracking. It does this because unlike Perl, whose engine is a recursive backtracker, RE2 uses a hybrid NFA/DFA approach that never gets bogged down in pathological cases.
This can be critical in time-sensitive applications where you want to let users provide their own pattern, but you cannot risk letting their search take forever. First written for Google’s Code Search, where time is of the essence, RE2 is also used via its Perl interface at http://grep.cpan.me. This site lets you enter a search pattern that runs over everything in CPAN.
The possibility of exponential runtimes can only be eliminated by limiting the input language in ways that Perl Regular Expressions do not [i.e. eliminating the NP-hard languages]. Swapping out the engine for one that does not bog down means reducing the expressive power. See this answer on SE-Computer Science: http://cs.stackexchange.com/a/46837 or this discussion on lambda-the-ultimate: http://lambda-the-ultimate.org/node/2961
CHAPTER 5 Pattern Matching
Fancy Patterns - Alternate Engines
Starting with v5.10, you can even swap out Perl’s entire regex engine and replace it with an alternate pattern-matching library.
...
Table 5-18. Alternate regex engines
re::engine::RE2 - Russ Cox’s RE2 regex engine
...
One engine of special note is Russ Cox’s RE2 library. It’s a C and C++ library that’s used in the Go programming language, among many other places. The interesting thing is that it maintains a high level Perl compatibility, including good UTF-8 support, while avoiding the potential pitfalls of catastrophic backtracking. It does this because unlike Perl, whose engine is a recursive backtracker, RE2 uses a hybrid NFA/DFA approach that never gets bogged down in pathological cases.
This can be critical in time-sensitive applications where you want to let users provide their own pattern, but you cannot risk letting their search take forever. First written for Google’s Code Search, where time is of the essence, RE2 is also used via its Perl interface at http://grep.cpan.me. This site lets you enter a search pattern that runs over everything in CPAN.
...