How can I retrieve three parameters from a string using preg_match_all?

Question

I'm trying to get from a text all the occurrences of a code snippet and the 3 parameters. I do this using a regular expression and preg_match_all PHP function.

It works fine if I have just one occurrence of the snippet present in the text. If there are two or more I get a weird result.

I'm not so expert with regular expressions so I have some difficulties to understand what am I missing.

Function

public function getGallerySnippetOccurrences($text) {

    $ptn = '/{# +gallery +(src|width|height)=\[(.*)\] +(src|width|height)=\[(.*)\] +(src|width|height)=\[(.*)\] +#}/';

    if(preg_match_all($ptn,$text,$matches)){
        $turnedMatches = $this->turn_array($matches);
        return $turnedMatches;
    }
    else {
        return null;
    }
}

Text 1 (in this case works as aspected)

Lorem ipsum {# gallery src=[holiday_images/london] width=[400] height=[300] #} sid amet.

Returns:

array(1) {
  [0] =>
  array(7) {
    [0] =>
    string(66) "{# gallery src=[holiday_images/london] width=[400] height=[300] #}"
    [1] =>
    string(3) "src"
    [2] =>
    string(21) "holiday_images/london"
    [3] =>
    string(5) "width"
    [4] =>
    string(3) "400"
    [5] =>
    string(6) "height"
    [6] =>
    string(3) "300"
  }
}

Text 2 (unespected behaviour)

Lorem ipsum {# gallery src=[holiday_images/london] width=[400] height=[300] #} sid amet {# gallery src=[holiday_images/paris] width=[400] height=[300] #}

Returns

array(1) {
  [0] =>
  array(7) {
    [0] =>
    string(141) "{# gallery src=[holiday_images/london] width=[400] height=[300] #} sid amet {# gallery src=[holiday_images/paris] width=[400] height=[300] #}"
    [1] =>
    string(3) "src"
    [2] =>
    string(96) "holiday_images/london] width=[400] height=[300] #} sid amet {# gallery src=[holiday_images/paris"
    [3] =>
    string(5) "width"
    [4] =>
    string(3) "400"
    [5] =>
    string(6) "height"
    [6] =>
    string(3) "300"
  }
}

What am I doing wrong?

Make it non-greedy: /{# +gallery +(src|width|height)=\[(.*?)] +(src|width|height)=\[(.*?)] +(src|width|height)=\[(.*?)] +#}/ — anubhava
– anubhava, Commented Mar 13, 2019 at 17:13

Rinsad Ahmed · Accepted Answer · 2019-03-13 17:25:28Z

2

In your pattern, you are using greedy matches using (.) which should be replaced with non-greedy pattern (.?). Please find the pattern below

$ptn = '/{# +gallery +(src|width|height)=\[(.*?)\] +(src|width|height)=\[(.*?)\] +(src|width|height)=\[(.*?)\] +#}/';

answered Mar 13, 2019 at 17:25

Rinsad Ahmed

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Comments

anubhava · Accepted Answer · 2019-03-13 18:39:45Z

1

As pointed out in my comment below your answer that making quantifier non-greedy will make it work. However that still leaves your regex repetitive and inefficient.

You may consider this approach for both points:

$re = '/{\#
\h+gallery
\h+(src|width|height)=\[([^]]*)]
\h+((?1))=\[([^]]*)]
\h+((?1))=\[([^]]*)]
\h*\#}/x';

preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);

// Print the entire match result
var_dump($matches);

RegEx Demo

Note how this regex is defining a sub-pattern and reusing it all over the regex using (?1) to avoid repetitions
Also note use of more efficient negated class [^]]* instead of inefficient .*? to capture values.

edited Mar 13, 2019 at 18:39

answered Mar 13, 2019 at 17:28

anubhava

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