Extract text from string in php with regex

Question

I am struggling with a regex in php to extract function arguments from a string. I am parsing a javascript file in php and want to extract 2 function arguments from a line. Here is an example of how the lines may look:

"Backbone.Radio( 'comments ').trigger("added:comment " ,function(){});"

From this line I want to extract the word comments and added:comment without any whitespaces or quotes.

I have tried with:

$arrMatches = array();
$strRegEx = "/\\(\\s*['\"]\\s*([^)]+?)\\s*['\"]\\s*/";
$nMatches = preg_match_all($strRegEx, $strLine, $arrMatches);

But this will give me something like: ( 'comments ' and ("added:comment "

I would appreciate some help with how to solve this.

is it not possible to 'clean' them after extraction. So just remove ( and ' and " after you've gotten your results? Or will this method affect it, as the comments itself may contain brackets? — A. L
– A. L, Commented Sep 5, 2016 at 12:37
I could clean them after extraction but i would prefer to have the regex only extract the parts i need so i do not need that extra step. — sudden01
– sudden01, Commented Sep 6, 2016 at 6:32

Jan · Accepted Answer · 2016-09-05 13:02:31Z

2

You could use:

<?php

$regex = '~\(\h*([\'"])(.+?)\h*(?!\\\\)(?=\1)~';
$string = "Backbone.Radio( 'comments ').trigger(\"added:comment \" ,function(){});";

preg_match_all($regex, $string, $matches);
print_r($matches[2]);
/*
Array
(
    [0] => comments
    [1] => added:comment
)
*/
?>

The regex looks for single/double quotes, captures them and looks for the next single/double quote which is not escaped. See a demo on regex101.com.

^{Warning: While this might work in this particular example, it is usually the last way to use a regex - have you considered using a parser instead?}

answered Sep 5, 2016 at 13:02

Jan

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3 Comments

sudden01 Over a year ago

Thank you! This works great. But what is the benefits of using if i use a parser and what parser could i use for this example?

Jan Over a year ago

@sudden01: Well, it totally depends on your Input strings. If they are all of the mentioned format, this will very likely work. Problems will only occur if you face nested brackets, e.g. Backbone.Radio('comment_function("testparam")') which is totally JS valid.

sudden01 Over a year ago

Ok, then i think regex will do fine. The lines i am checking will always have this format. Thanks again for your help i will mark your answer as accepted.

SierraOscar · Accepted Answer · 2016-09-05 12:39:11Z

1

Based on your example, something like this would work:

$re = "/(?<=\\()(?:[ '\"]*)([\\w\\d\\:]+)(?=[ ]*['\"]*)/"; 
$str = "\"Backbone.Radio( 'comments ').trigger(\"added:comment \" ,function(){});\""; 

preg_match_all($re, $str, $matches);

you can add other items to the matching group as required.

answered Sep 5, 2016 at 12:39

SierraOscar

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1 Comment

sudden01 Over a year ago

Thanks for the response, this also works. Since i am no regex expert i do not know which solution is the best but they both work for my case.

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