Regular expression /(ab)?use/: Is a more complex expression worth it?

Question

I'm writing a simple Perl script that translates assembly instruction strings to 32-bit binary code.

I decided to handle translation grouping instruction by type (ADD and SUB are R-Type instructions and so on...) so in my code I'm doing something like this:

my $bin = &r_type($instruction) if $instruction =~ /^(?:add|s(?:ub|lt|gt))\s/;

because I want to handle add, sub, slt and sgt in the same way.

I realized however that maybe using that regular expression could be an 'overkill' for the task I'm supposed to do... could the pattern

/^(?:add|sub|slt|sgt)\s/

represent a better use of regular expressions in this case?

Thanks a lot.

Answer 1

Unless you are using a perl older than 5.10, the simple alternation will perform better anyway (see here), so there is no reason to try to optimize it.