Re: Handling escapes while splitting lines

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Re^2: Handling escapes while splitting lines by mikecarlton (Novice) on Jan 19, 2005 at 05:35 UTC
Aha -- that does it. I like the approach much better (matching non-backslash and colon or 2-character escape sequences). Running some quick test code: `my $re = shift or die "re expected\n"; while (<>) { chomp; my ($field, $value) = ($_ =~ $re); print "'$_' -> ('$field', '$value')\n"; }` [download] We see that it handles all these cases correctly: `'a:b:c' -> ('a', 'b:c') 'a\:b:c' -> ('a\:b', 'c') 'a\\:b:c' -> ('a\\', 'b:c') 'a\\\:b:c' -> ('a\\\:b', 'c') 'a:' -> ('a', '') ':b' -> ('', 'b')` [download] The only thing it doesn't handle perfectly is the invalid input case with an escaped colon but no delimiter: `'a\:b' -> ('', 'b')` [download] Notice that this is indistinguishable from the ':b' input. The fix is simple though, just anchor the start of the match: `^((?:[^:\\]+\|\\.)):(.)` [download] For my use this works better, as the match fails, telling me there was no field delimiter present. Thanks --mike	[reply] [d/l] [select]

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Re^2: Handling escapes while splitting lines
by mikecarlton (Novice) on Jan 19, 2005 at 05:35 UTC

Running some quick test code:

    my $re = shift or die "re expected\n";
    while (<>) {
        chomp;
        my ($field, $value) = ($_ =~ $re);
        print "'$_' -> ('$field', '$value')\n";
    }
[download]

 'a:b:c' -> ('a', 'b:c')
 'a\:b:c' -> ('a\:b', 'c')
 'a\\:b:c' -> ('a\\', 'b:c')
 'a\\\:b:c' -> ('a\\\:b', 'c')
 'a:' -> ('a', '')
 ':b' -> ('', 'b')
[download]

 
 'a\:b' -> ('', 'b')
[download]

 ^((?:[^:\\]+|\\.)*):(.*)
[download]

Thanks
--mike

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