bootstrap-collapse-nav-walker.php

<?php
/**
 * Navigation menu using Bootstrap Collapse
 *
 * @package Bootstrap_Collapse_Nav_Walker
 * @since 1.0.0
 */
class Bootstrap_Collapse_Nav_Walker extends Walker_Nav_Menu {
	/**
	 * What the class handles.
	 *
	 * @see Walker::$tree_type
	 * @since 3.0.0
	 * @var string
	 */
	var $tree_type = array( 'post_type', 'taxonomy', 'custom' );

	/**
	 * Database fields to use.
	 *
	 * @see Walker::$db_fields
	 * @since 3.0.0
	 * @todo Decouple this.
	 * @var array
	 */
	var $db_fields = array( 'parent' => 'menu_item_parent', 'id' => 'db_id' );

	function __construct() {

		/**
		 * Current top level element ID
		 * 
		 * @var integer
		 */
		$this->element_id = 1;

		/**
		 * Item parent ID
		 * 
		 * @var string
		 */
		$this->parent_id = false;

	}

	/**
	 * Starts the list before the elements are added.
	 *
	 * @see Walker::start_lvl()
	 *
	 * @since 3.0.0
	 *
	 * @param string $output Passed by reference. Used to append additional content.
	 * @param int    $depth  Depth of menu item. Used for padding.
	 * @param array  $args   An array of arguments. @see wp_nav_menu()
	 */
	function start_lvl( &$output, $depth = 0, $args = array() ) {
		$indent = str_repeat("\t", $depth);

		$id = ( false !== $this->parent_id ) ? $this->parent_id : '';

		$output .= "<div id=\"$id\" class=\"panel-collapse collapse\">";
		$output .= "\n$indent<ul class=\"nav nav-pills nav-stacked\">\n";
	}

	/**
	 * Ends the list of after the elements are added.
	 *
	 * @see Walker::end_lvl()
	 *
	 * @since 3.0.0
	 *
	 * @param string $output Passed by reference. Used to append additional content.
	 * @param int    $depth  Depth of menu item. Used for padding.
	 * @param array  $args   An array of arguments. @see wp_nav_menu()
	 */
	function end_lvl( &$output, $depth = 0, $args = array() ) {
		$indent = str_repeat("\t", $depth);
		$output .= "$indent</div>\n";
	}

	/**
	 * Start the element output.
	 *
	 * @see Walker::start_el()
	 *
	 * @since 3.0.0
	 *
	 * @param string $output Passed by reference. Used to append additional content.
	 * @param object $item   Menu item data object.
	 * @param int    $depth  Depth of menu item. Used for padding.
	 * @param array  $args   An array of arguments. @see wp_nav_menu()
	 * @param int    $id     Current item ID.
	 */
	function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {
		$indent = ( $depth ) ? str_repeat( "\t", $depth ) : '';

		$class_names = $value = '';

		if( in_array( 'current_page_item', $item->classes ) ) {
			$item->classes[] = 'active';
		}

		$classes = empty( $item->classes ) ? array() : (array) $item->classes;
		$classes[] = 'menu-item-' . $item->ID;

		/**
		 * Filter the CSS class(es) applied to a menu item's <li>.
		 *
		 * @since 3.0.0
		 *
		 * @param array  $classes The CSS classes that are applied to the menu item's <li>.
		 * @param object $item    The current menu item.
		 * @param array  $args    An array of arguments. @see wp_nav_menu()
		 */
		$class_names = join( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item, $args ) );
		$class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';

		/**
		 * Filter the ID applied to a menu item's <li>.
		 *
		 * @since 3.0.1
		 *
		 * @param string The ID that is applied to the menu item's <li>.
		 * @param object $item The current menu item.
		 * @param array $args An array of arguments. @see wp_nav_menu()
		 */
		$id = apply_filters( 'nav_menu_item_id', 'menu-item-'. $item->ID, $item, $args );
		$id = $id ? ' id="' . esc_attr( $id ) . '"' : '';

		if( 0 == $depth ) {

			$output .= '<div class="panel panel-default">';
			$output .= '<div class="panel-heading">';

		} else {

			$output .= $indent . '<li' . $id . $value . $class_names .'>';

		}

		$atts = array();
		$atts['title']  = ! empty( $item->attr_title ) ? $item->attr_title : '';
		$atts['target'] = ! empty( $item->target )     ? $item->target     : '';
		$atts['rel']    = ! empty( $item->xfn )        ? $item->xfn        : '';

		if( 0 == $depth && in_array( 'menu-item-has-children', $item->classes ) ) {

			$atts['href'] 		 = '#' . sanitize_title( $item->title );
			$atts['data-toggle'] = 'collapse';
			$atts['data-parent'] = '#menu-' . wp_get_nav_menu_object( $args->menu )->slug;

			$this->parent_id = sanitize_title( $item->title );

		} else {

			$atts['href']   = ! empty( $item->url )        ? $item->url        : '';

		}

		/**
		 * Filter the HTML attributes applied to a menu item's <a>.
		 *
		 * @since 3.6.0
		 *
		 * @param array $atts {
		 *     The HTML attributes applied to the menu item's <a>, empty strings are ignored.
		 *
		 *     @type string $title  The title attribute.
		 *     @type string $target The target attribute.
		 *     @type string $rel    The rel attribute.
		 *     @type string $href   The href attribute.
		 * }
		 * @param object $item The current menu item.
		 * @param array  $args An array of arguments. @see wp_nav_menu()
		 */
		$atts = apply_filters( 'nav_menu_link_attributes', $atts, $item, $args );

		$attributes = '';
		foreach ( $atts as $attr => $value ) {
			if ( ! empty( $value ) ) {
				$value = ( 'href' === $attr ) ? esc_url( $value ) : esc_attr( $value );
				$attributes .= ' ' . $attr . '="' . $value . '"';
			}
		}

		$item_output = $args->before;
		$item_output .= '<a'. $attributes .'>';
		/** This filter is documented in wp-includes/post-template.php */
		$item_output .= $args->link_before . apply_filters( 'the_title', $item->title, $item->ID ) . $args->link_after;
		$item_output .= '</a>';
		$item_output .= $args->after;

		if( 0 == $depth ) {

			$item_output .= '</div>';

		}

		/**
		 * Filter a menu item's starting output.
		 *
		 * The menu item's starting output only includes $args->before, the opening <a>,
		 * the menu item's title, the closing </a>, and $args->after. Currently, there is
		 * no filter for modifying the opening and closing <li> for a menu item.
		 *
		 * @since 3.0.0
		 *
		 * @param string $item_output The menu item's starting HTML output.
		 * @param object $item        Menu item data object.
		 * @param int    $depth       Depth of menu item. Used for padding.
		 * @param array  $args        An array of arguments. @see wp_nav_menu()
		 */
		$output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
	}

	/**
	 * Ends the element output, if needed.
	 *
	 * @see Walker::end_el()
	 *
	 * @since 3.0.0
	 *
	 * @param string $output Passed by reference. Used to append additional content.
	 * @param object $item   Page data object. Not used.
	 * @param int    $depth  Depth of page. Not Used.
	 * @param array  $args   An array of arguments. @see wp_nav_menu()
	 */
	function end_el( &$output, $item, $depth = 0, $args = array() ) {

		$output .= ( 0 == $depth ) ? "</div>\n" : "</li>\n";

	}

} // Walker_Nav_Menu