On Tue, 07 Nov 2017 17:10:29 -0800, ddgr...@gmail.com wrote: > On Sun, 15 Oct 2017 05:19:54 -0700, ddgr...@gmail.com wrote: > > On Thu, 31 Dec 2015 05:39:24 -0800, ju...@jules.uk wrote: > > > > > > > > > On 29/12/2015 23:05, Timo Paulssen via RT wrote: > > > > On 12/29/2015 12:46 AM, Jules Field (via RT) wrote: > > > >> # New Ticket Created by Jules Field > > > >> # Please include the string: [perl #127064] > > > >> # in the subject line of all future correspondence about this > > > >> issue. > > > >> # <URL: https://rt.perl.org/Ticket/Display.html?id=127064 > > > > >> > > > >> > > > >> Given > > > >> my @lines = "some-text.txt".IO.lines; > > > >> my $s = 'Jules'; > > > >> (some-text.txt is about 43k lines) > > > >> > > > >> Doing > > > >> my @matching = @lines.grep(/ $s /); > > > >> is about 50 times slower than > > > >> my @matching = @lines.grep(/ Jules /); > > > >> > > > >> And if $s happened to contain anything other than literals, so I > > > >> had > > > >> to us > > > >> my @matching = @lines.grep(/ <$s> /); > > > >> then it's nearly 150 times slower. > > > >> > > > >> my @matching = @lines.grep($s); > > > >> doesn't appear to work. It matches 0 lines but doesn't die. > > > >> > > > >> The lack of Perl5's straightforward variable interpolation in > > > >> regexs > > > >> is crippling the speed. > > > >> Is there a faster alternative? (other than EVAL to build the > > > >> regex) > > > >> > > > > For now, you can use @lines.grep(*.contains($s)), which will be > > > > sufficiently fast. > > > > > > > > Ideally, our regex optimizer would turn this simple regex into a > > > > code > > > > that uses .index to find a literal string and construct a match > > > > object > > > > for that. Or even - if you put a literal "so" in front - turn it > > > > into > > > > .contains($literal) if it knows that the match object will only > > > > be > > > > inspected for true/false. > > > > > > > > Until then, we ought to be able to make interpolation a bit > > > > faster. > > > > - Timo > > > Many thanks for that. I hadn't thought to use Whatever. > > > > > > I would ideally also be doing case-insensitive regexps, but they > > > are > > > 50 > > > times slower than case-sensitive ones, even in trivial cases. > > > Maybe a :adverb for rx// that says "give me static (i.e. Perl5- > > > style) > > > interpolation in this regex"? > > > I can see the advantage of passing the variables to the regex > > > engine, > > > as > > > then they can change over time. > > > > > > But that's not something I want to do very often, far more > > > frequently > > > I > > > just need to construct the regex at run-time and have it go as fast > > > as > > > possible. > > > > > > Just thoughts from a big Perl5 user (e.g. MailScanner is 50k lines > > > of > > > it!). > > > > > > Jules > > > > > > I recently attempted to make interpolating into regexes a little > > faster. This is what I was using for a benchmark: > > perl6 -e 'my @l = "sm.sql".IO.lines; my $s = "Perl6"; my $t = now; my > > @m = @l.grep(/ $s /); say @m.elems; say now - $t' > > sm.sql is 10k lines, of which 1283 contain the text "Perl6". > > > > This is Rakudo version 2017.09 built on MoarVM version 2017.09.1: > > / $s / took 5.3s and / <$s> / took 16.5s. > > > > This is Rakudo version 2017.09-427-gd23a9ba9d built on MoarVM version > > 2017.09.1-595-g716f2277f: > > / $s / took 3.2s and / <$s> / took 14.5s. > > > > However, if you type the string to interpolate it is *much* faster > > for > > literal interpolation. > > perl6 -e 'my @l = "sm.sql".IO.lines; my Str $s = "Perl6"; my $t = > > now; > > my @m = @l.grep(/ $s /); say @m.elems; say now - $t' > > This takes only 0.33s. > > > > This is still nowhere near as fast as grep(*.contains($s)) though, > > which only takes 0.037s. > > > This is Rakudo version 2017.10-143-g0e50993f4 built on MoarVM version > 2017.10-58-gad8618468: > / $s / took 2.7s and / <$s> / took 7.0s.
Adding :i (case insensitive adverb), /:i $s / took 3.0s and /:i <$s> / took 7.7s.
