icingaweb2-module-director/library/Director/PropertyModifier/PropertyModifierSubstring.php

<?php

namespace Icinga\Module\Director\PropertyModifier;

use Icinga\Module\Director\Hook\PropertyModifierHook;
use Icinga\Module\Director\Web\Form\QuickForm;

class PropertyModifierSubstring extends PropertyModifierHook
{
    public static function addSettingsFormFields(QuickForm $form)
    {
        $form->addElement('text', 'start', array(
            'label'       => 'Start',
            'required'    => true,
            'description' => sprintf(
                $form->translate(
                    'Please see %s for detailled instructions of how start and end work'
                ),
                'http://php.net/manual/en/function.substr.php'
            )
        ));

        $form->addElement('text', 'length', array(
            'label'    => 'End',
            'description' => sprintf(
                $form->translate(
                    'Please see %s for detailled instructions of how start and end work'
                ),
                'http://php.net/manual/en/function.substr.php'
            )
        ));
    }

    public function transform($value)
    {
        return substr($value, $this->getSetting('start'), $this->getSetting('length'));
    }
}