I was curious about the efficiency of the generated regular expression from my previous post. I run some benchmarks, and the results are somewhat unexpected, at least for me!:
my $len = 300;
my @lines;
push @lines, join('', (map { 'f' . ('o' x rand $len * 1.5), (rand > .8
+ ? '. ' : ' ') } 0..rand 20 ), "\n")
for 0 .. 1000;
sub make_re {
my $len = shift;
my $re = "\\b"
. join('|', map("\\w(?:\\s[\\s\\w]{$_,}?", reverse 1 .. (
+$len - 3)), "\\w+\\s+")
. (")" x ($len - 3))
. "\\w+";
qr/($re)/;
}
# match maximal length sentence
my $len_minus_two = $len - 2;
sub max { my @m = grep /\s*\b\w(?=\w*\s+\w+)[\w\s]{$len_minus_two,}\w/
+o, @lines }
# match minimal length sentence
my $re = make_re $len;
sub min { my @m = grep /$re/, @lines }
use Benchmark qw(cmpthese);
cmpthese(-1, { max => \&max,
min => \&min } );
__OUTPUT__
Rate max min
max 24.3/s -- -26%
min 33.0/s 36% --
Note that the two regexps used match different things. |