code/libraries/joomlatools/library/filter/timestamp.php
protected function _validateIsoDate($value)
    {
        // Test if value is blank.
        if(trim($value) != '')
        {
            // Test basic date format (yyyy-mm-dd)
            $pattern = '/^([0-9]{4})-([0-9]{2})-([0-9]{2})$/D';
            $return  = preg_match($pattern, $value, $matches) && checkdate($matches[2], $matches[3], $matches[1]);
        }
        else $return = false;

        return $return;
    }
protected function _validateIsoDate($value)
    {
        // Test if value is blank.
        if(trim($value) != '')
        {
            // Test basic date format (yyyy-mm-dd)
            $pattern = '/^([0-9]{4})-([0-9]{2})-([0-9]{2})$/D';
            $return  = preg_match($pattern, $value, $matches) && checkdate($matches[2], $matches[3], $matches[1]);
        }
        else $return = false;

        return $return;
    }
protected function _validateIsoDate ( $ value ) { // Test if value is blank. if ( trim ( $ value ) != '' ) { // Test basic date format (yyyy-mm-dd) $ pattern = '/^([0-9]{4})-([0-9]{2})-([0-9]{2})$/D' ; $ return = preg_match ( $ pattern , $ value , $ matches ) && checkdate ( $ matches [ 2 ] , $ matches [ 3 ] , $ matches [ 1 ] ) ; } else $ return = false ; return $ return ; }
Validates that the value is an ISO 8601 date string.

The format is "yyyy-mm-dd".  Also checks to see that the date itself is valid (for example, no Feb 30).

@param string $value The value to validate.
@return bool True if valid, false if not.
Validates that the value is an ISO 8601 date string .