htmlpurifier/library/HTMLPurifier/AttrDef/HTML/FrameTarget.php

<?php

/**
 * Special-case enum attribute definition that lazy loads allowed frame targets
 */
class HTMLPurifier_AttrDef_HTML_FrameTarget extends HTMLPurifier_AttrDef_Enum
{
    
    public $valid_values = false; // uninitialized value
    protected $case_sensitive = false;
    
    public function __construct() {}
    
    public function validate($string, $config, $context) {
        if ($this->valid_values === false) $this->valid_values = $config->get('Attr', 'AllowedFrameTargets');
        return parent::validate($string, $config, $context);
    }
    
}