Re^6: Parser Performance Question (updated)

Meh, this will teach me about posting when I can't test. I meant q< \\\\" >; but thought the \ wouldn't escape the next one. The case where the \ just before the " is litteral because escaped, so it can't escape the ".

use v5.20;
use Data::Dump qw( pp );
my $str = <<STR;
 " .. \\\\" .. "
STR

print $str;

my %re = (LanX => qr/ " (?: \\\\ | \\" | [^"] )* " /x,
          Eily => qr/ " (?: [^\\] | \\. )* " /x);

$str =~ /$re{$_}/ and say "$_ found $&" for keys %re;
[download]

 " .. \\" .. "
Eily found " .. \\" .. "
LanX found " .. \\"
[download]

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Re^7: Parser Performance Question (updated) by LanX (Saint) on Oct 06, 2017 at 08:37 UTC
> `" .. \\" .. " Eily found " .. \\" .. " LanX found " .. \\"` [download] Well, you proved that my version is correct and yours doesn't work. :p Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :) Je suis Charlie!}	[reply] [d/l]
Re^8: Parser Performance Question (updated) by Eily (Monsignor) on Oct 06, 2017 at 08:45 UTC
Hu, how did I ever reach sainthood in our book? `Eily => qr/ " (?: [^"\\] \| \\. )* " /x);` <= added the missing " in the character class `use Data::Dump qw( pp ); my $str = <<STR; " .. \\" .. STR print $str; my %re = (LanX => qr/ " (?: \\\\ \| \\" \| [^"] )* " /x, Eily => qr/ " (?: [^"\\] \| \\. )* " /x); $str =~ /$re{$_}/ and say "$_ found $&" or say "$_ found nothing" for +keys %re;` [download] `" .. \" .. Eily found nothing LanX found " .. \"` [download]	[reply] [d/l] [select]
Re^9: Parser Performance Question (Atomic grouping) by LanX (Saint) on Oct 06, 2017 at 11:28 UTC
Atomic grouping `(?>...)` seems to fix the problem `use strict; use warnings; use feature 'say'; use Data::Dump qw( pp ); my @strs = qw( "..\\".. "abc" "a\"bc" "a\\\\bc" "a\" ); my %re = ( LanX => qr/ " (?> \\\\ \| \\" \| [^"] )* " /x, Eily => qr/ " (?: [^"\\] \| \\. )* " /x ); for my $str (@strs) { say "\nTesting: <$str> = ", pp ($str); $str =~ /$re{$_}/ and say "$_ found $&" or say "$_ found nothing" for keys %re; }` [download] `Testing: <"..\"..> = "\"..\\\".." LanX found nothing Eily found nothing Testing: <"abc"> = "\"abc\"" LanX found "abc" Eily found "abc" Testing: <"a\"bc"> = "\"a\\\"bc\"" LanX found "a\"bc" Eily found "a\"bc" Testing: <"a\\bc"> = "\"a\\\\bc\"" LanX found "a\\bc" Eily found "a\\bc" Testing: <"a\"> = "\"a\\\"" LanX found nothing Eily found nothing` [download] Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :) Je suis Charlie!}	[reply] [d/l] [select]
Re^10: Parser Performance Question (Atomic grouping) by Eily (Monsignor) on Oct 06, 2017 at 12:37 UTC
Re^11: Parser Performance Question (Atomic grouping) by LanX (Saint) on Oct 06, 2017 at 13:40 UTC
Some notes below your chosen depth have not been shown here
Re^11: Parser Performance Question (Atomic grouping) by songmaster (Beadle) on Oct 20, 2017 at 01:37 UTC
Re^9: Parser Performance Question by LanX (Saint) on Oct 06, 2017 at 10:48 UTC
> Hu, how did I ever reach sainthood in our book? Lots of voting? :p > LanX found " .. \" Oops, you are right!!! This really puzzled me till I used `re "debug"` and saw that I got bitten by backtracking. (Whipping myself while mumbling "mea culpa") Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :) Je suis Charlie!}	[reply] [d/l]