forms: Add new 'regex' selection to validators

This allows administrators to define a regular expression to filter content
entered into short answer fields by agents and endusers. With the new
visibility feature, the regular expression input is only shown if the
regular expression validator is selected.

include/class.forms.php

@@ -237,6 +237,16 @@ class FormField {
             $this->_clean = (isset($this->value))
                 ? $this->value : $this->parse($this->getWidget()->value);
 
+            if ($vs = $this->get('cleaners')) {
+                if (is_array($vs)) {
+                    foreach ($vs as $cleaner)
+                        if (is_callable($clenaer))
+                            $this->_clean = $cleaner($this, $this->_clean);
+                }
+                elseif (is_callable($vs))
+                    $this->_clean = $vs($this, $this->_clean);
+            }
+
             if ($this->isVisible())
                 $this->validateEntry($this->_clean);
         }
@@ -640,7 +650,27 @@ class TextboxField extends FormField {
             'validator' => new ChoiceField(array(
                 'id'=>3, 'label'=>__('Validator'), 'required'=>false, 'default'=>'',
                 'choices' => array('phone'=>__('Phone Number'),'email'=>__('Email Address'),
-                    'ip'=>__('IP Address'), 'number'=>__('Number'), ''=>__('None')))),
+                    'ip'=>__('IP Address'), 'number'=>__('Number'),
+                    'regex'=>__('Custom (Regular Expression)'), ''=>__('None')))),
+            'regex' => new TextboxField(array(
+                'id'=>6, 'label'=>__('Regular Expression'), 'required'=>true,
+                'configuration'=>array('size'=>40, 'length'=>100),
+                'visibility' => new VisibilityConstraint(
+                    new Q(array('validator__eq'=>'regex')),
+                    VisibilityConstraint::HIDDEN
+                ),
+                'cleaners' => function ($self, $value) {
+                    $wrapped = "/".$value."/iu";
+                    if (false === @preg_match($value, ' ')
+                            && false !== @preg_match($wrapped, ' ')) {
+                        return $wrapped;
+                    }
+                    return $value;
+                },
+                'validators' => function($self, $v) {
+                    if (false === @preg_match($v, ' '))
+                        $self->addError(__('Cannot compile this regular expression'));
+                })),
             'validator-error' => new TextboxField(array(
                 'id'=>4, 'label'=>__('Validation Error'), 'default'=>'',
                 'configuration'=>array('size'=>40, 'length'=>60),
@@ -668,7 +698,13 @@ class TextboxField extends FormField {
                 __('Enter a valid phone number')),
             'ip' =>     array(array('Validator', 'is_ip'),
                 __('Enter a valid IP address')),
-            'number' => array('is_numeric', __('Enter a number'))
+            'number' => array('is_numeric', __('Enter a number')),
+            'regex' => array(
+                function($v) use ($config) {
+                    $regex = $config['regex'];
+                    return @preg_match($regex, $v);
+                }, __('Value does not match required pattern')
+            ),
         );
         // Support configuration forms, as well as GUI-based form fields
         $valid = $this->get('validator');