php正则表达式匹配shorttags

Question

This is close, but is failing to match successive "attributes":

$string = "single attribute [include file=\"bob.txt\"] multiple attributes [another prop=\"val\" attr=\"one\"] no attributes [tag] etc";
preg_match_all('/\[((\w+)((\s(\w+)="([^"]+)"))*)\]/', $string, $matches, PREG_SET_ORDER);
print '<pre>' . print_r($matches, TRUE) . '</pre>';

Gives back the following:

Array
(
    [0] => Array
        (
            [0] => [include file="bob.txt"]
            [1] => include file="bob.txt"
            [2] => include
            [3] =>  file="bob.txt"
            [4] =>  file="bob.txt"
            [5] => file
            [6] => bob.txt
        )

    [1] => Array
        (
            [0] => [another prop="val" attr="one"]
            [1] => another prop="val" attr="one"
            [2] => another
            [3] =>  attr="one"
            [4] =>  attr="one"
            [5] => attr
            [6] => one
        )

    [2] => Array
        (
            [0] => [tag]
            [1] => tag
            [2] => tag
        )

)

Where [2] is the tag name, [5] is the attribute name and [6] is the attribute value.

The failure is on the second node - it catches attr="one" but not prop="val"

TYIA.

(this is only meant for limited, controlled use - not broad distribution - so I don't need to worry about single quotes or escaped double quotes)

Answer 1

Unfortunately there is no way to repeat capture groups like that. Personally, I would use preg_match to match the tags themselves (i.e. remove all the extra parentheses inside the regex), then foreach match you can then extract the attributes. Something like this:

$string = "single attribute [include file=\"bob.txt\"] multiple attributes [another prop=\"val\" attr=\"one\"] no attributes [tag] etc";
preg_match_all('/\[\w+(?:\s\w+="[^"]+")*\]/', $string, $matches);
foreach($matches[0] as $m) {
    preg_match('/^\w+/', $m, $tagname); $tagname = $tagname[0];
    preg_match_all('/\s(\w+)="([^"]+)"/', $m, $attrs, PREG_SET_ORDER);
    // do something with $tagname and $attrs
}

Note that if you intend to replace the tag with some content, you should use preg_replace_callback like so:

$string = "single attribute [include file=\"bob.txt\"] multiple attributes [another prop=\"val\" attr=\"one\"] no attributes [tag] etc";
$output = preg_replace_callback('/\[\w+(?:\s\w+="[^"]+")*\]/', $string, function($match) {
    preg_match('/^\w+/', $m, $tagname); $tagname = $tagname[0];
    preg_match_all('/\s(\w+)="([^"]+)"/', $m, $attrs, PREG_SET_ORDER);
    $result = // do something with $tagname and $attrs
    return $result;
});