Method setField

/**
 * Method to set a field XML element to the form definition.  If the replace flag is set then
 * the field will be set whether it already exists or not.  If it isn't set, then the field
 * will not be replaced if it already exists.
 *
 * @param   \SimpleXMLElement  $element   The XML element object representation of the form field.
 * @param   string             $group     The optional dot-separated form group path on which to set the field.
 * @param   boolean            $replace   True to replace an existing field if one already exists.
 * @param   string             $fieldset  The name of the fieldset we are adding the field to.
 *
 * @return  boolean  True on success.
 *
 * @since   1.7.0
 * @throws  \UnexpectedValueException
 */
public function setField(\SimpleXMLElement $element, $group = null, $replace = true, $fieldset = 'default')
{
    // Make sure there is a valid Form XML document.
    if (!$this->xml instanceof \SimpleXMLElement) {
        throw new \UnexpectedValueException(sprintf('%s::%s `xml` is not an instance of SimpleXMLElement', \get_class($this), __METHOD__));
    }
    // Find the form field element from the definition.
    $old = $this->findField((string) $element['name'], $group);
    // If an existing field is found and replace flag is false do nothing and return true.
    if (!$replace && !empty($old)) {
        return true;
    }
    // If an existing field is found and replace flag is true remove the old field.
    if ($replace && !empty($old) && $old instanceof \SimpleXMLElement) {
        $dom = dom_import_simplexml($old);
        // Get the parent element, this should be the fieldset
        $parent = $dom->parentNode;
        $fieldset = $parent->getAttribute('name');
        $parent->removeChild($dom);
    }
    // Create the search path
    $path = '//';
    if (!empty($group)) {
        $path .= 'fields[@name="' . $group . '"]/';
    }
    $path .= 'fieldset[@name="' . $fieldset . '"]';
    $fs = $this->xml->xpath($path);
    if (isset($fs[0]) && $fs[0] instanceof \SimpleXMLElement) {
        // Add field to the form.
        self::addNode($fs[0], $element);
        // Synchronize any paths found in the load.
        $this->syncPaths();
        return true;
    }
    // We couldn't find a fieldset to add the field. Now we are checking, if we have set only a group
    if (!empty($group)) {
        $fields =& $this->findGroup($group);
        // If an appropriate fields element was found for the group, add the element.
        if (isset($fields[0]) && $fields[0] instanceof \SimpleXMLElement) {
            self::addNode($fields[0], $element);
        }
        // Synchronize any paths found in the load.
        $this->syncPaths();
        return true;
    }
    // We couldn't find a parent so we are adding it at root level
    // Add field to the form.
    self::addNode($this->xml, $element);
    // Synchronize any paths found in the load.
    $this->syncPaths();
    return true;
}