Re^2: string pattern match, limited to first 1000 characters?

What do you make of this benchmark? :)

#!/usr/bin/perl

use Benchmark qw(cmpthese);

$substr = join('','a'..'j');
$str = $substr x 90 . 'hTmL'. $substr x 2000;
print "length of search string: ",length $str, "\n";
cmpthese(-3, {
    ' regex ' => sub {
        $str =~ /^\A.{0,996}?html/si
     or $str =~ /^\A.{0,996}?sgml/si;
     },
    ' substr' => sub {
        substr( $str, 0, 1000) =~ /html/i
     or substr( $str, 0, 1000) =~ /sgml/i;
     },
    'index'   => sub {
        1+index( lc substr( $str, 0, 1000 ), 'html' )
     or 1+index( lc substr( $str, 0, 1000 ), 'sgml' )
     } ,
});
print substr $str, 900, 10;;
__END__
C:\test>junk
length of search string: 20904
            Rate  regex   substr   index
 regex   93505/s      --    -54%    -65%
 substr 204367/s    119%      --    -23%
index   266809/s    185%     31%      --
hTmLabcdef
[download]

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Comment on Re^2: string pattern match, limited to first 1000 characters? Download Code

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Re^3: string pattern match, limited to first 1000 characters? by shmem (Chancellor) on Jun 23, 2007 at 10:27 UTC
The conlusions are obvious, aren't they? don't use a regexp when all you need is index don't use a regexp with a quantifier pattern if you can substr simple tools are fastest for simple tasks Did I miss some? Nice that you combined the positive and negative searches into one, so one can see the average of both. --shmem _($_=" "x(1<<5)."?\n".q·/)Oo. G°\ / /\_¯/(q / ---------------------------- \__(m.====·.(_("always off the crowd"))."· ");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}	[reply]
Re^3: string pattern match, limited to first 1000 characters? by roboticus (Chancellor) on Jun 23, 2007 at 12:34 UTC
BrowserUk: Ummm ... you want to reverse those `or` clauses, otherwise the second clause in your `or` won't run. #!/usr/bin/perl use Benchmark qw(cmpthese); $substr = join('','a'..'j'); $str = $substr x 90 . 'hTmL'. $substr x 2000; print "length of search string: ",length $str, "\n"; cmpthese(-3, { 'Fregex ' => sub { $str =~ /^\A.{0,996}?html/si or $str =~ /^\A.{0,996}?sgml/si; }, 'Fsubstr' => sub { substr( $str, 0, 1000) =~ /sgml/i or substr( $str, 0, 1000) =~ /html/i; }, 'Findex ' => sub { 1+index( lc substr( $str, 0, 1000 ), 'sgml' ) or 1+index( lc substr( $str, 0, 1000 ), 'html' ) }, 'Rregex ' => sub { $str =~ /^\A.{0,996}?sgml/si or $str =~ /^\A.{0,996}?html/si; }, 'Rsubstr' => sub { substr( $str, 0, 1000) =~ /sgml/i or substr( $str, 0, 1000) =~ /html/i; }, 'Rindex' => sub { 1+index( lc substr( $str, 0, 1000 ), 'sgml' ) or 1+index( lc substr( $str, 0, 1000 ), 'html' ) }, }); print substr $str, 900, 10; __END__ root@swill ~/PerlMonks$ ./string_search2.pl length of search string: 20904 Rate Rregex Fregex Rsubstr Fsubstr Findex Rindex Rregex 48562/s -- -35% -54% -54% -55% -55% Fregex 75225/s 55% -- -28% -29% -30% -30% Rsubstr 104700/s 116% 39% -- -1% -2% -3% Fsubstr 105896/s 118% 41% 1% -- -1% -1% Findex 107056/s 120% 42% 2% 1% -- -0% Rindex 107434/s 121% 43% 3% 1% 0% -- hTmLabcdef root@swill ~/PerlMonks$ [download] Update: Had I used my brain, I'd've changed the `$str` definition to use 'sGmL' rather than edit the function definitions.... ...roboticus There are lies, damned lies, and benchmarks.	[reply] [d/l] [select]
Re^4: string pattern match, limited to first 1000 characters? by johngg (Canon) on Jun 23, 2007 at 17:40 UTC
It looks from your code that, apart from `Fregex` and `Rregex`, your subroutine pairs are identical as you haven't swapped the 'sgml' and 'html' around. When I run your code with them swapped around I get these results. (Rates are slow as the machine is a quite elderly SPARC.) `length of search string: 20904 Rate Rregex Fregex Rsubstr Rindex Fsubstr Findex Rregex 11708/s -- -16% -41% -45% -61% -70% Fregex 14005/s 20% -- -29% -35% -54% -64% Rsubstr 19721/s 68% 41% -- -8% -35% -50% Rindex 21423/s 83% 53% 9% -- -29% -45% Fsubstr 30362/s 159% 117% 54% 42% -- -22% Findex 39142/s 234% 179% 98% 83% 29% --` [download] Cheers, JohnGG Update: Fixed typo.	[reply] [d/l] [select]
Re^5: string pattern match, limited to first 1000 characters? by roboticus (Chancellor) on Jun 24, 2007 at 14:04 UTC
johngg: D'oh!++ and I thought I had. I wonder what I was thinking? I know I changed the lines, but I guess I changed 'sgml' to 'sgml' and 'html' to 'html'... (Or did I change it twice during my confusion? I guess we'll never know.) Thanks for catching that! ...roboticus	[reply]