Parsing attributes in PHP using regular expressions

Question

Consider that i have the string,

$string = 'tag2 display="users" limit="5"';

Using the preg_match_all function, i need to get the output

Required o/p

Array
(
    [0] => Array
        (
            [0] => tag2
            [1] => tag2
            [2] => 
        )

    [1] => Array
        (
            [0] => display="users"
            [1] => display
            [2] => users
        )

    [2] => Array
        (
            [0] => limit="5"
            [1] => limit
            [2] => 5
        )

)

I tried using this pattern '/([^=\s]+)="([^"]+)"/' but it is not recognizing the parameter with no value (in this case tag2) Instead it gives the output

What I am getting

Array
(
    [0] => Array
        (
            [0] => display="users"
            [1] => display
            [2] => users
        )

    [1] => Array
        (
            [0] => limit="5"
            [1] => limit
            [2] => 5
        )

)

What will be the pattern for getting the required output ?

EDIT 1: I also need to get the attributes which are not wrapped with quotes ex: attr=val. Sorry for not mentioning before.

deejayy · Accepted Answer · 2011-11-05 09:02:40Z

2

Try this:

<?php

    $string = 'tag2 display="users" limit="5"';
    preg_match_all('/([^=\s]+)(="([^"]+)")?/', $string, $res);

    foreach ($res[0] as $r => $v) {
        $o[] = array($res[0][$r], $res[1][$r], $res[3][$r]);
    }

    print_r($o);

?>

It outputs me:

Array
(
    [0] => Array
        (
            [0] => tag2
            [1] => tag2
            [2] => 
        )

    [1] => Array
        (
            [0] => display="users"
            [1] => display
            [2] => users
        )

    [2] => Array
        (
            [0] => limit="5"
            [1] => limit
            [2] => 5
        )

)

edited Nov 5, 2011 at 9:02

answered Nov 5, 2011 at 8:28

deejayy

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5 Comments

Aakash Chakravarthy Over a year ago

somewhat similar... it will be good if i got the required o/p, since my other functions depend on the exact required array..

deejayy Over a year ago

I made some changes to fit the output you defined.

Aakash Chakravarthy Over a year ago

great answer thank you... but when i tried without quotes, its not working... i.e param=val sorry I should have told this before..

deejayy Over a year ago

No problem, patch with this regexp: /([^=\s]+)(="?([^"]+)"?)?/

Aakash Chakravarthy Over a year ago

i tried hakre's pattern /([^=\s]+)(?:="([^"]+)")?/, which came out really well. But it is not working without quotes... what will be the fix... i am sure it will be easy..

hakre · Accepted Answer · 2011-11-05 10:29:51Z

1

I think it's not fully possible to give you with one call what you're looking for, but this is pretty close:

$string = 'tag2 display="users" limit=5';
preg_match_all('/([^=\s]+)(?:="?([^"]+)"?|())?/', $string, $res, PREG_SET_ORDER);
print_r($res);

Output:

Array
(
    [0] => Array
        (
            [0] => tag2
            [1] => tag2
            [2] => 
            [3] => 
        )

    [1] => Array
        (
            [0] => display="users"
            [1] => display
            [2] => users
        )

    [2] => Array
        (
            [0] => limit=5
            [1] => limit
            [2] => 5
        )

)

As you can see, the first element has no value, I tried to work around that and offer an empty match now. So this builds the array you were asking for, but has an additional entry on the empty attribute.

However the main point is the PREG_SET_ORDER flag of preg_match_all. Maybe you can live with this output already.

edited Nov 5, 2011 at 10:29

answered Nov 5, 2011 at 9:07

hakre

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8 Comments

Aakash Chakravarthy Over a year ago

how to tweak the pattern to get parameters without quotes ?

hakre Over a year ago

@AakashChakravarthy: I added a tweak for those. However, I think if you want something really safe, this needs another update.

Aakash Chakravarthy Over a year ago

still more one issue, when the parameter value is empty, the output is not correct... what will be the tweak ?

hakre Over a year ago

Well it's correct, subindex 2 is an empty string. The only thing that differs is that there is an additional subindex 3. Is that really a problem? And leaving a note in case you need to have escape characters in values, this answer is showing some technique: @AakashChakravarthy: I added a tweak for those. However, I think if you want something really safe, this needs another update, see as well stackoverflow.com/questions/6243778/…

Aakash Chakravarthy Over a year ago

no thats not the problem... when tag param="" -----> param value is empty, in this case i get a varied o/p. i tried tweaking the (?:="?([^"]+)"?|()) section, but its in-vain.... do you have any idea ?

|

rodneyrehm · Accepted Answer · 2011-11-05 09:16:56Z

0

Maybe you're interested in this litte snippet that parses all sorts of attribute styles. <div class="hello" id=foobar style='display:none'> is valid html(5), not pretty, I know…

<?php
$string = '<tag2 display="users" limit="5">';

$attributes = array();
$pattern = "/\s+(?<name>[a-z0-9-]+)=(((?<quotes>['\"])(?<value>.*?)\k<quotes>)|(?<value2>[^'\" ]+))/i";
preg_match_all($pattern, $source, $matches, PREG_SET_ORDER);
foreach ($matches as $match) {
  $attributes[$match['name']] = $match['value'] ?: $match['value2'];
}

var_dump($attributes);

will give you

$attributes = array(
  'display' => 'users',
  'limit' => '5',
);

answered Nov 5, 2011 at 9:16

rodneyrehm

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