Regex Match string

Question

This should be a nice easy one for a regex expert.

I have a group name <APP>_<Resource>_<Action> the action segment contains a combination or CRUD. There are 13 possible combinations that these can appear in.

CRUD, CRU, CRD, CUD, RUD, CR, CU, CD, RU, RD, UD, C, R, U, D

I just want a regex to match on of those patterns within the action segment of the group name. The application and resources can change to various different strings.

Example Group Names

PM_folder1_cru, PM_folder2_ud, PM_folder3_cr, PM_folder4_cu, PM_personalFolder_crud

Thanks in advance

EDIT

This is currently done using:

$allowedActions = ['CRUD', 'CRU', 'CRD', 'CUD', 'RUD', 'CR', 'CU', 'CD', 'RU', 'RD', 'UD', 'C', 'R', 'U', 'D'];

if (in_array(strtoupper($action), $allowedActions)) {

CRD ah yeah, its still early i will just edit the post. and no it doesn't need to match an empty string. — mic
– mic, Commented Jun 13, 2013 at 8:02

grc · Accepted Answer · 2013-06-13 08:05:41Z

2

I think something like this would work:

^C?R?U?D?$

To avoid matching empty strings, you can use a lookahead assertion:

^(?!$)C?R?U?D?$

edited Jun 13, 2013 at 8:05

answered Jun 13, 2013 at 7:57

grc

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Toto · Accepted Answer · 2013-06-13 08:15:43Z

1

How about:

/^.*_(?=[CRUD]{1,4})C?R?U?D?$/i

usage:

$arr = array(
'PM_folder1_cru',
'PM_folder2_ud',
'PM_folder3_cr',
'PM_folder4_cu',
'PM_personalFolder_crud',
);

foreach ($arr as $str) {
    if (preg_match('/^.*_(?=[CRUD]{1,4})C?R?U?D?$/i', $str)) 
        echo "OK : $str\n";
    else
        echo "KO : $arr\n";
}

output:

OK : PM_folder1_cru
OK : PM_folder2_ud
OK : PM_folder3_cr
OK : PM_folder4_cu
OK : PM_personalFolder_crud

answered Jun 13, 2013 at 8:15

Toto

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Comments

HamZa · Accepted Answer · 2013-06-13 08:18:42Z

_{Note: This answer is assuming that APP contains only letters and Resource contains only letters and numbers.}

You could do a more general matching by using a character class:
(?i)[a-z]+_[a-z0-9]+_[crud]{1,4}. Note that this will also match DRUC, DDDD, RRC for example.

If you don't want that, then you could use something more specific:
(?i)[a-z]+_[a-z0-9]+_(?:c?r?ud?|cr?d?|r?d|r)

What does this mean ?

(?i) : set the i modifier to match case insensitive
[a-z]+ : match letters one or more times
_ : match one underscore
[a-z0-9]+ : match letters and numbers one or more times
_ : match one underscore
(?:c?r?ud?|cr?d?|r?d|r) : match crud, cru, rud, c, r, d etc...

PHP code:
If you want to get the action in a separate (sub)array, you'll may add a named group and remove ?::

$string = 'PM_folder1_cru,
PM_folder2_ud,
PM_folder3_cr,
PM_folder4_cu,
PM_personalFolder_crud';
preg_match_all('#(?i)[a-z]+_[a-z0-9]+_(?P<action>c?r?ud?|cr?d?|r?d|r)#', $string, $m);
print_r($m['action']); // Get actions
print_r($m); // everything ?

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