Re: How to trim a line from leading and trailing blanks without using regex or non-standard modules

s/^\s+|\s+$//g

This is certainly not an "abuse" of regex. This is what regex is is for! The Perl regex engine continually becomes better and usually faster between releases.

[reply]
[d/l]

That benchmark shows s/^\s+|\s+$//g as always being slower than two regexes. It proposes a third option, to extract the inner portion with a match, which is shows as faster in the benchmark given. But that is a very limited benchmark. A more complete benchmark shows that doing two regexes is almost always the fastest.

use strict;
use warnings;
use Benchmark::Dumb qw(cmpthese);

my @strings = (
  no_trim_short         => 'asd',
  no_trim_mid           => 'asdasdasdasdasdasdasd',
  no_trim_long          => 'asd' x 500,
  no_trim_mid_with_ws   => 'asd asd asd asd asd asd asd',
  no_trim_long_with_ws  => (join ' ', ('asd') x 500),

  short         => '    asd    ',
  mid           => '    asdasdasdasdasdasdasd    ',
  long          => '    '.('asd' x 500).'    ',
  mid_with_ws   => '    asd asd asd asd asd asd asd    ',
  long_with_ws  => '    '.(join ' ', ('asd') x 500).'    ',
);

while (my ($name, $string) = splice @strings, 0, 2) {
  print "$name:\n";
  cmpthese(0.0005, {
    global => sub {
      my $s = $string;
      $s =~ s/\A\s+|\s+\z//g;
    },
    startend => sub {
      my $s = $string;
      s/\A\s+//, s/\s+\z// for $s;
    },
    match => sub {
      my $s = $string;
      ($s) = $s =~ /\A\s*(.*?)\s*\z/s;
    },
  });
  print "\n";
}

__END__

no_trim_short:
                       Rate         match      global startend
match    1.42373e+06+-420/s            --      -29.2%   -52.9%
global   2.01075e+06+-840/s         41.2%          --   -33.4%
startend   3.02e+06+-1800/s 112.12+-0.14% 50.2+-0.11%       --

no_trim_mid:
                       Rate global  match startend
global        519190+-150/s     -- -12.3%   -81.1%
match         591890+-290/s  14.0%     --   -78.5%
startend 2.7543e+06+-1400/s 430.5% 365.3%       --

no_trim_long:
                       Rate  global   match startend
global   8420.17+-0.00081/s      --  -31.7%   -97.8%
match          12324.1+-4/s   46.4%      --   -96.8%
startend     384590+-0.95/s 4467.5% 3020.6%       --

no_trim_mid_with_ws:
                      Rate global  match startend
global        388912+-98/s     -- -19.5%   -70.2%
match          482948+-4/s  24.2%     --   -63.0%
startend 1.30366e+06+-19/s 235.2% 169.9%       --

no_trim_long_with_ws:
                     Rate global  match startend
global      5750.5+-2.8/s     -- -33.6%   -81.3%
match       8663.4+-3.4/s  50.7%     --   -71.9%
startend 30807.4+-0.011/s 435.7% 255.6%       --

short:
                       Rate global startend  match
global        968450+-390/s     --   -12.8% -32.0%
startend 1.11124e+06+-460/s  14.7%       -- -22.0%
match    1.42383e+06+-490/s  47.0%    28.1%     --

mid:
                  Rate        global  match startend
global   387160+-190/s            -- -35.3%   -56.4%
match    598710+-260/s   54.64+-0.1%     --   -32.5%
startend 887420+-380/s 129.21+-0.15%  48.2%       --

long:
                      Rate  global   match startend
global   8410.31+-0.0012/s      --  -31.8%   -97.2%
match         12323.2+-4/s   46.5%      --   -95.9%
startend     298990+-140/s 3455.0% 2326.2%       --

mid_with_ws:
                  Rate       global  match startend
global   303500+-130/s           -- -37.2%   -48.5%
match      482925+-4/s        59.1%     --   -18.0%
startend 589220+-300/s 94.14+-0.13%  22.0%       --

long_with_ws:
                  Rate global  match startend
global   5691.4+-2.6/s     -- -34.4%   -81.1%
match      8672.9+-4/s  52.4%     --   -71.1%
startend  30035.1+-0/s 427.7% 246.3%       --
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[reply]
[d/l]
[select]

I re-wrote your benchmark and yes, this does show that using 2 lines of Perl to do this is faster!
I show my code below..

use strict;
use warnings;
use Benchmark qw(cmpthese);
use Data::Dumper;
use List::Util qw(pairmap);

my @strings = (
  no_trim_short         => 'asd',
  no_trim_mid           => 'asdasdasdasdasdasdasd',
  no_trim_long          => 'asd' x 50,
  no_trim_mid_with_ws   => 'asd asd asd asd asd asd asd',
  no_trim_long_with_ws  => (join ' ', ('asd') x 20),

  short         => '    asd    ',
  mid           => '    asdasdasdasdasdasdasd    ',
  long          => '    '.('asd' x 20).'    ',
  mid_with_ws   => '    asd asd asd asd asd asd asd    ',
  long_with_ws  => '    '.(join ' ', ('asd') x 20).'    ',
);


my @test_line_array = pairmap{$b}@strings;
#print "$_\n" for @test_line_array;  #for debug


cmpthese (100000, {
  global => sub{
     my @copy = @test_line_array;
     $_ =~ s/\A\s+|\s+\z//g foreach @copy;
     },
  global2 => sub{
     my @copy = @test_line_array;
     $_ =~ s/^\s+|\s+$//g foreach @copy;
     },   
  twoLines => sub {
      my @copy = @test_line_array;
      s/\A\s+//, s/\s+\z// foreach @copy;
    },
  twoLines2 => sub {
      my @copy = @test_line_array;
      s/^\s+//, s/\s+$// foreach @copy;
    },  
  dollar1 => sub {
      my @copy = @test_line_array;
      s/\A\s*(.*?)\s*\z/$1/ foreach @copy;
    }
});

print "\n";

__END__
              Rate    global   global2   dollar1  twoLines twoLines2
global     33681/s        --        0%      -21%      -68%      -68%
global2    33681/s        0%        --      -21%      -68%      -68%
dollar1    42662/s       27%       27%        --      -60%      -60%
twoLines  106610/s      217%      217%      150%        --       -0%
twoLines2 106724/s      217%      217%      150%        0%        --
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[reply]
[d/l]


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