从WordPress中提取属性，如短代码

I have a string like WordPress shortcodes and need to extract the attributes. :
[prefix action="foo" class="bar"][/prefix]

I need to keep exactly this structure that means I can't i.e. remove quotes to become action=foo

right now i used WordPress regex patterns:

// Grabs [prefix foo="bar"][/prefix] from the $content
$pattern = '/\[(\[?)(' . PREFIX . ')(?![\w-])([^\]\/]*(?:\/(?!\])[^\]\/]*)*?)(?:(\/)\]|\](?:([^\[]*+(?:\[(?!\/\2\])[^\[]*+)*+)\[\/\2\])?)(\]?)/';
preg_match_all($pattern, $content, $matches, PREG_SET_ORDER);

this is the result:

Array
 (
     [0] => [prefix action="foo" class="bar"][/prefix]
     [1] => 
     [2] => prefix
     [3] =>  action="foo" class="bar"
     [4] => 
     [5] => 
     [6] => 
 )

Then I Loop through regex matches

foreach( $matches as $block )
    {
    /*
     * I'm not working on WordPress platform, 
     * But I used function shortcode_parse_atts
     */
    $attr = shortcode_parse_atts( $block[3] );

results:

Array
(
    [action] => "foo"
    [class] => "bar"
)

and in the end extract($attr). but as you can see $class and $action values are between double quotes. so i need to get ride of those quotes.

In short:
I want $class = "bar" becomes $class = bar

In case you think why i don't use str_replace or preg_replace, I did but it did not removed quotes somehow ( which i don't understand why )

This is your attributes array; $array as shown by your print_r() output in the question:

Array (
    [action] => "foo"
    [class] => "bar"
)

print_r() doesnt output quotes unless there actually are quotes as part of the values, which there clearly is in this case. To remove the quotes we can use str_replace() and the array_map() function like this:

$clean = array_map(function($item) {
    return str_replace("\"", "", $item);
}, $array);

print_r($clean);

Then we get:

Array (
    [action] => foo
    [class] => bar
)

If you have something like this,

$array = array ( "action" => "\"foo\"", "class" => "\"bar\"" );

Then you can use (to remove the quotes)

 $arr = array_map(function($i){ 
    return trim($i, '"'); 
}, $array);

But, I think, either I'm miss-understanding or you are just miss-understanding the array, it's the way the array works, look at this (if you have an array like this)

$array = array ( "action" => "foo", "class" => "bar" );
print_r($array);

Result is :

Array
(
    [action] => foo
    [class] => bar
)

Now look at this

$arr = array_map(function($i){ 
    return trim($i, '"'); 
}, $array);
print_r($arr);

Result is :

Array 
(
    [action] => foo
    [class] => bar 
)

Or you can test it as

extract($array);
echo $class; // barArray

So, in this case quotes are part of the array to wrap the string value and in the output, the quotes won't be visible.