Hi Alan, On 5/19/06, Alan Campbell wrote:
hello folks,I'm slurping in a large file and seeing a nice speedup versus line by line processing...but I'm losing it in my (likely poorly constructed!) reg-expression match I do: - # # look for potentially problematic code of the following form: - # STW b0, *SP--[3] # The reg exp tries to match: - # - anything up until 'ST' (so that we match STH, STW, STDW etc) followed by # - 1+ non-whitespace chars followed by # - 0+ whitespace chars followed by # - 0+ non-whitespace chars followed by # the string 'B15--' followed by # anything up until an odd single-digit number followed by # the ']' character # Matches all occurrences # my @match_sp = $all_lines =~ /.*ST\S+\s*\S*B15--.*[^02468]]/mg; ...and then I foreach on @match_sp to show all occurrences found... Any speedup tips most welcome. Would also appreciate a brief explanation of why this reg ex is slow (so I dont screw it up next time!)
I think using character classes and nonbacktracking groups can speed up the .* stuff. Maybe something like the following will help? /(?:(?>[^S\n]*)S?)*ST\S+\s*\S*B15--(?:(?>[^02468\n]*)[02468]?)*[^02468]\]/mg David -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] <http://learn.perl.org/> <http://learn.perl.org/first-response>
