comment on

For the cases where you compare multiple regexps against your target string, it may save time if you also study($sequence) before starting the matches.

This will do a scan of the sequence to allow subsequent matches to use the Boyer-Moore algorithm - it builds a linked list of the locations of each different character in the sequence, and then takes advantage of the frequency data to pick the rarest character for which to walk the list.

Because the main benefit of this approach is about rarity, it may not be a big win for a case like this where the string uses only a 4-character alphabet, and (presumably) uses each character roughly 1/4 of the time; I'd be interested to see how it affects the benchmarks.

Hugo

In reply to Re^2: Multiple Regex's on a Big Sequence - Benchmark by hv
in thread Multiple Regex's on a Big Sequence by bernanke01

Are you posting in the right place? Check out Where do I post X? to know for sure.
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
Want more info? How to link or How to display code and escape characters are good places to start.


We don't bite newbies here... much
	PerlMonks