extract html element name with perl regexp

Question

I try to be able to extract the html element name that comes in 2 form in one regexp in perl for example i have this :

document.all.ElemName.

and also

document.all["ElemName"].

and this

document.all['ElemName'].

and i need to get the ElemName , i can only capture one opetion , is it posible to extract it in 1 regexp ? this is what i have :

document.all[\.\w|\[](\w+)

that capture only the first example

I can sense a lecture on parsing HTML with regexes on its way... — Zaid, Jan 14 '13 at 13:42
No lecture could be better than http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags/1732454#1732454 ;) — creaktive, Jan 14 '13 at 13:47
And `document.all[variable + or + expression]`? @creaktive, that's a pretty bad lecture by the way. — Qtax, Jan 14 '13 at 14:12
yeah i know this post , and its true but here i have some need i have to solve — user63898, Jan 14 '13 at 14:12

score 1 · Answer 1 · answered Jan 14 '13 at 14:16

You can use named captures, available since Perl v5.10:

#!/usr/bin/env perl
use strict;
use warnings;

my @array = qw{
    document.all.ElemName1.
    document.all["ElemName2"].
    document.all['ElemName3'].
};

for (@array) {
    /
        \b
        document\.all
        (?:
            \.(?<elem>\w+)
            | \["(?<elem>\w+)"\]
            | \['(?<elem>\w+)'\]
        )
        \.
    /x;

    print $+{elem}, "\n";
}

score 1 · Accepted Answer · answered Jan 14 '13 at 14:43

1

This will match all three cases with ElemName in the first capture group:

document\.all\.?(?:\[["'])?(\w+)(?:['"]\])?

Demo here.

answered Jan 14 '13 at 14:43

Chris Seymour

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1

This will also match the following incorrect strings: `document.all.ElemName"]`, `document.all["ElemName']`, `document.all.["ElemName"]` ... – Zaid Jan 14 '13 at 14:54
@Zaid that is true but you shouldn't parse html with regexp at all but the OP seems determine to, I don't think it's a problem as the incorrect *(unbalanced)* examples won't exist in the document, if they do the OP has more problems than just trying to parsing a non-regular language with regexp. – Chris Seymour Jan 14 '13 at 14:59

score 0 · Answer 3 · answered Jan 14 '13 at 14:43

you could use a character class containing a single and a double quote to match the quotes:

$a = 'document.all.Element["ElemNamea"]';
$b = "document.all.Element['ElemNameb']";
print "a : $a\n";
print "b : $b\n\n";

$a =~ /document.all.Element\[['"](\w+)['"]\]/;  # ["'] matches ' or "
print "result: $a and $1\n";                    # result is in $1
$b =~ /document.all.Element\[['"](\w+)['"]\]/;
print "result: $b and $1\n";

output:

a : document.all.Element["ElemNamea"]
b : document.all.Element['ElemNameb']

result: document.all.Element["ElemNamea"] and ElemNamea
result: document.all.Element['ElemNameb'] and ElemNameb

extract html element name with perl regexp

3 Answers3