Question

My search text is as follows.

...
...
var strings = ["aaa","bbb","ccc","ddd","eee"];
...
...

It contains many lines(actually a javascript file) but need to parse the values in variable strings , ie aaa , bbb, ccc , ddd , eee

Following is the Perl code, or use PHP at bottom

my $str = <<STR;
    ...
    ...
    var strings = ["aaa","bbb","ccc","ddd","eee"];
    ...
    ...
STR

my @matches = $str =~ /(?:\"(.+?)\",?)/g;
print "@matches";

I know the above script will match all instants, but it will parse strings (“xyz”) in the other lines also. So I need to check the string var strings =

/var strings = \[(?:\"(.+?)\",?)/g

Using above regex it will parse aaa.

/var strings = \[(?:\"(.+?)\",?)(?:\"(.+?)\",?)/g

Using above, will get aaa , and bbb. So to avoid the regex repeating I used ‘+’ quantifier as below.

/var strings = \[(?:\"(.+?)\",?)+/g

But I got only eee, So my question is why I got eee ONLY when I used ‘+’ quantifier?

Update 1: Using PHP preg_match_all (doing it to get more attention 🙂 )

$str = <<<STR
    ...
    ...
    var strings = ["aaa","bbb","ccc","ddd","eee"];
    ...
    ...
STR;

preg_match_all("/var strings = \[(?:\"(.+?)\",?)+/",$str,$matches);
print_r($matches);

Update 2: Why it matched eee ? Because of the greediness of (?:\"(.+?)\",?)+ . By removing greediness /var strings = \[(?:\"(.+?)\",?)+?/ aaa will be matched. But why only one result? Is there any way it can be achieved by using single regex?

Answer 1

Here’s a single-regex solution:

/(?:\bvar\s+strings\s*=\s*\[|\G,)\s*"([^"]*)"/g

\G is a zero-width assertion that matches the position where the previous match ended (or the beginning of the string if it’s the first match attempt). So this acts like:

var\s+strings\s*=\s*[\s*"([^"]*)"

…on the first attempt, then:

,\s*"([^"]*)"

…after that, but each match has to start exactly where the last one left off.

Here’s a demo in PHP, but it will work in Perl, too.