php一个自定义的WordPress导航助手类，使用我内置的WordPress在自定义主题中完全实现Bootstrap3.0+导航样式

/**
* WP Bootstrap Navwalker
*
* @package WP-Bootstrap-Navwalker
*/
/*
* Class Name: WP_Bootstrap_Navwalker
* Plugin Name: WP Bootstrap Navwalker
* Plugin URI: https://github.com/wp-bootstrap/wp-bootstrap-navwalker
* Description: A custom WordPress nav walker class to implement the Bootstrap 3 navigation style in a custom theme using the WordPress built in menu manager.
* Author: Edward McIntyre - @twittem, WP Bootstrap
* Version: 2.0.5
* Author URI: https://github.com/wp-bootstrap
* GitHub Plugin URI: https://github.com/wp-bootstrap/wp-bootstrap-navwalker
* GitHub Branch: master
* License: GPL-3.0+
* License URI: http://www.gnu.org/licenses/gpl-3.0.txt
*/
/* Check if Class Exists. */
if ( ! class_exists( &＃39;WP_Bootstrap_Navwalker&＃39; ) ) {
/**
* WP_Bootstrap_Navwalker class.
*
* @extends Walker_Nav_Menu
*/
class WP_Bootstrap_Navwalker extends Walker_Nav_Menu {
/**
* Start Level.
*
* @see Walker::start_lvl()
* @since 3.0.0
*
* @access public
* @param mixed $output Passed by reference. Used to append additional content.
* @param int $depth (default: 0) Depth of page. Used for padding.
* @param array $args (default: array()) Arguments.
* @return void
*/
public function start_lvl( &$output, $depth = 0, $args = array() ) {
$indent = str_repeat( "\t", $depth );
$output .= "\n$indent

\n";
}
/**
* Start El.
*
* @see Walker::start_el()
* @since 3.0.0
*
* @access public
* @param mixed $output Passed by reference. Used to append additional content.
* @param mixed $item Menu item data object.
* @param int $depth (default: 0) Depth of menu item. Used for padding.
* @param array $args (default: array()) Arguments.
* @param int $id (default: 0) Menu item ID.
* @return void
*/
public function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {
$indent = ( $depth ) ? str_repeat( "\t", $depth ) : &＃39;&＃39;;
/**
* Dividers, Headers or Disabled
* =============================
* Determine whether the item is a Divider, Header, Disabled or regular
* menu item. To prevent errors we use the strcasecmp() function to so a
* comparison that is not case sensitive. The strcasecmp() function returns
* a 0 if the strings are equal.
*/
if ( 0 === strcasecmp( $item->attr_title, &＃39;divider&＃39; ) && 1 === $depth ) {
$output .= $indent . &＃39;
• &＃39;;
  } elseif ( 0 === strcasecmp( $item->title, &＃39;divider&＃39; ) && 1 === $depth ) {
  $output .= $indent . &＃39;
• &＃39;;
  } elseif ( 0 === strcasecmp( $item->attr_title, &＃39;dropdown-header&＃39; ) && 1 === $depth ) {
  $output .= $indent . &＃39;
• &＃39; . esc_attr( $item->title );
  } elseif ( 0 === strcasecmp( $item->attr_title, &＃39;disabled&＃39; ) ) {
  $output .= $indent . &＃39;
• &＃39; . esc_attr( $item->title ) . &＃39;&＃39;;
  } else {
  $value = &＃39;&＃39;;
  $class_names = $value;
  $classes = empty( $item->classes ) ? array() : (array) $item->classes;
  $classes[] = &＃39;menu-item-&＃39; . $item->ID;
  $class_names = join( &＃39; &＃39;, apply_filters( &＃39;nav_menu_css_class&＃39;, array_filter( $classes ), $item, $args ) );
  if ( $args->has_children ) {
  $class_names .= &＃39; dropdown&＃39;;
  }
  if ( in_array( &＃39;current-menu-item&＃39;, $classes, true ) ) {
  $class_names .= &＃39; active&＃39;;
  }
  $class_names = $class_names ? &＃39; class="&＃39; . esc_attr( $class_names ) . &＃39;"&＃39; : &＃39;&＃39;;
  $id = apply_filters( &＃39;nav_menu_item_id&＃39;, &＃39;menu-item-&＃39; . $item->ID, $item, $args );
  $id = $id ? &＃39; id="&＃39; . esc_attr( $id ) . &＃39;"&＃39; : &＃39;&＃39;;
  $output .= $indent . &＃39;
• &＃39;;
  $atts = array();
  if ( empty( $item->attr_title ) ) {
  $atts[&＃39;title&＃39;] = ! empty( $item->title ) ? strip_tags( $item->title ) : &＃39;&＃39;;
  } else {
  $atts[&＃39;title&＃39;] = $item->attr_title;
  }
  $atts[&＃39;target&＃39;] = ! empty( $item->target ) ? $item->target : &＃39;&＃39;;
  $atts[&＃39;rel&＃39;] = ! empty( $item->xfn ) ? $item->xfn : &＃39;&＃39;;
  // If item has_children add atts to a.
  if ( $args->has_children && 0 === $depth ) {
  $atts[&＃39;href&＃39;] = &＃39;#&＃39;;
  $atts[&＃39;data-toggle&＃39;] = &＃39;dropdown&＃39;;
  $atts[&＃39;class&＃39;] = &＃39;dropdown-toggle&＃39;;
  $atts[&＃39;aria-haspopup&＃39;] = &＃39;true&＃39;;
  } else {
  $atts[&＃39;href&＃39;] = ! empty( $item->url ) ? $item->url : &＃39;&＃39;;
  }
  $atts = apply_filters( &＃39;nav_menu_link_attributes&＃39;, $atts, $item, $args );
  $attributes = &＃39;&＃39;;
  foreach ( $atts as $attr => $value ) {
  if ( ! empty( $value ) ) {
  $value = ( &＃39;href&＃39; === $attr ) ? esc_url( $value ) : esc_attr( $value );
  $attributes .= &＃39; &＃39; . $attr . &＃39;="&＃39; . $value . &＃39;"&＃39;;
  }
  }
  $item_output = $args->before;
  /*
  * Glyphicons/Font-Awesome
  * ===========
  * Since the the menu item is NOT a Divider or Header we check the see
  * if there is a value in the attr_title property. If the attr_title
  * property is NOT null we apply it as the class name for the glyphicon.
  */
  if ( ! empty( $item->attr_title ) ) {
  $pos = strpos( esc_attr( $item->attr_title ), &＃39;glyphicon&＃39; );
  if ( false !== $pos ) {
  $item_output .= &＃39; &＃39;;
  } else {
  $item_output .= &＃39; &＃39;;
  }
  } else {
  $item_output .= &＃39;&＃39;;
  }
  $item_output .= $args->link_before . apply_filters( &＃39;the_title&＃39;, $item->title, $item->ID ) . $args->link_after;
  $item_output .= ( $args->has_children && 0 === $depth ) ? &＃39; &＃39; : &＃39;&＃39;;
  $item_output .= $args->after;
  $output .= apply_filters( &＃39;walker_nav_menu_start_el&＃39;, $item_output, $item, $depth, $args );
  } // End if().
  }
  /**
  * Traverse elements to create list from elements.
  *
  * Display one element if the element doesn&＃39;t have any children otherwise,
  * display the element and its children. Will only traverse up to the max
  * depth and no ignore elements under that depth.
  *
  * This method shouldn&＃39;t be called directly, use the walk() method instead.
  *
  * @see Walker::start_el()
  * @since 2.5.0
  *
  * @access public
  * @param mixed $element Data object.
  * @param mixed $children_elements List of elements to continue traversing.
  * @param mixed $max_depth Max depth to traverse.
  * @param mixed $depth Depth of current element.
  * @param mixed $args Arguments.
  * @param mixed $output Passed by reference. Used to append additional content.
  * @return null Null on failure with no changes to parameters.
  */
  public function display_element( $element, &$children_elements, $max_depth, $depth, $args, &$output ) {
  if ( ! $element ) {
  return; }
  $id_field = $this->db_fields[&＃39;id&＃39;];
  // Display this element.
  if ( is_object( $args[0] ) ) {
  $args[0]->has_children = ! empty( $children_elements[ $element->$id_field ] ); }
  parent::display_element( $element, $children_elements, $max_depth, $depth, $args, $output );
  }
  /**
  * Menu Fallback
  * =============
  * If this function is assigned to the wp_nav_menu&＃39;s fallback_cb variable
  * and a menu has not been assigned to the theme location in the WordPress
  * menu manager the function with display nothing to a non-logged in user,
  * and will add a link to the WordPress menu manager if logged in as an admin.
  *
  * @param array $args passed from the wp_nav_menu function.
  */
  public static function fallback( $args ) {
  if ( current_user_can( &＃39;edit_theme_options&＃39; ) ) {
  /* Get Arguments. */
  $cOntainer= $args[&＃39;container&＃39;];
  $container_id = $args[&＃39;container_id&＃39;];
  $container_class = $args[&＃39;container_class&＃39;];
  $menu_class = $args[&＃39;menu_class&＃39;];
  $menu_id = $args[&＃39;menu_id&＃39;];
  if ( $container ) {
  echo &＃39;<&＃39; . esc_attr( $container );
  if ( $container_id ) {
  echo &＃39; id="&＃39; . esc_attr( $container_id ) . &＃39;"&＃39;;
  }
  if ( $container_class ) {
  echo &＃39; class="&＃39; . sanitize_html_class( $container_class ) . &＃39;"&＃39;; }
  echo &＃39;>&＃39;;
  }
  echo &＃39; if ( $menu_id ) {
  echo &＃39; id="&＃39; . esc_attr( $menu_id ) . &＃39;"&＃39;; }
  if ( $menu_class ) {
  echo &＃39; class="&＃39; . esc_attr( $menu_class ) . &＃39;"&＃39;; }
  echo &＃39;>&＃39;;
  echo &＃39;
• &＃39; . esc_attr( &＃39;Add a menu&＃39;, &＃39;&＃39; ) . &＃39;
&＃39;;
echo &＃39;