source: tags/6.5/src/wp-includes/widgets/class-wp-widget-pages.php

<?php
/**
 * Widget API: WP_Widget_Pages class
 *
 * @package WordPress
 * @subpackage Widgets
 * @since 4.4.0
 */

/**
 * Core class used to implement a Pages widget.
 *
 * @since 2.8.0
 *
 * @see WP_Widget
 */
class WP_Widget_Pages extends WP_Widget {

        /**
         * Sets up a new Pages widget instance.
         *
         * @since 2.8.0
         */
        public function __construct() {
                $widget_ops = array(
                        'classname'                   => 'widget_pages',
                        'description'                 => __( 'A list of your site&#8217;s Pages.' ),
                        'customize_selective_refresh' => true,
                        'show_instance_in_rest'       => true,
                );
                parent::__construct( 'pages', __( 'Pages' ), $widget_ops );
        }

        /**
         * Outputs the content for the current Pages widget instance.
         *
         * @since 2.8.0
         *
         * @param array $args     Display arguments including 'before_title', 'after_title',
         *                        'before_widget', and 'after_widget'.
         * @param array $instance Settings for the current Pages widget instance.
         */
        public function widget( $args, $instance ) {
                $default_title = __( 'Pages' );
                $title         = ! empty( $instance['title'] ) ? $instance['title'] : $default_title;

                /**
                 * Filters the widget title.
                 *
                 * @since 2.6.0
                 *
                 * @param string $title    The widget title. Default 'Pages'.
                 * @param array  $instance Array of settings for the current widget.
                 * @param mixed  $id_base  The widget ID.
                 */
                $title = apply_filters( 'widget_title', $title, $instance, $this->id_base );

                $sortby  = empty( $instance['sortby'] ) ? 'menu_order' : $instance['sortby'];
                $exclude = empty( $instance['exclude'] ) ? '' : $instance['exclude'];

                if ( 'menu_order' === $sortby ) {
                        $sortby = 'menu_order, post_title';
                }

                $output = wp_list_pages(
                        /**
                         * Filters the arguments for the Pages widget.
                         *
                         * @since 2.8.0
                         * @since 4.9.0 Added the `$instance` parameter.
                         *
                         * @see wp_list_pages()
                         *
                         * @param array $args     An array of arguments to retrieve the pages list.
                         * @param array $instance Array of settings for the current widget.
                         */
                        apply_filters(
                                'widget_pages_args',
                                array(
                                        'title_li'    => '',
                                        'echo'        => 0,
                                        'sort_column' => $sortby,
                                        'exclude'     => $exclude,
                                ),
                                $instance
                        )
                );

                if ( ! empty( $output ) ) {
                        echo $args['before_widget'];
                        if ( $title ) {
                                echo $args['before_title'] . $title . $args['after_title'];
                        }

                        $format = current_theme_supports( 'html5', 'navigation-widgets' ) ? 'html5' : 'xhtml';

                        /** This filter is documented in wp-includes/widgets/class-wp-nav-menu-widget.php */
                        $format = apply_filters( 'navigation_widgets_format', $format );

                        if ( 'html5' === $format ) {
                                // The title may be filtered: Strip out HTML and make sure the aria-label is never empty.
                                $title      = trim( strip_tags( $title ) );
                                $aria_label = $title ? $title : $default_title;
                                echo '<nav aria-label="' . esc_attr( $aria_label ) . '">';
                        }
                        ?>

                        <ul>
                                <?php echo $output; ?>
                        </ul>

                        <?php
                        if ( 'html5' === $format ) {
                                echo '</nav>';
                        }

                        echo $args['after_widget'];
                }
        }

        /**
         * Handles updating settings for the current Pages widget instance.
         *
         * @since 2.8.0
         *
         * @param array $new_instance New settings for this instance as input by the user via
         *                            WP_Widget::form().
         * @param array $old_instance Old settings for this instance.
         * @return array Updated settings to save.
         */
        public function update( $new_instance, $old_instance ) {
                $instance          = $old_instance;
                $instance['title'] = sanitize_text_field( $new_instance['title'] );
                if ( in_array( $new_instance['sortby'], array( 'post_title', 'menu_order', 'ID' ), true ) ) {
                        $instance['sortby'] = $new_instance['sortby'];
                } else {
                        $instance['sortby'] = 'menu_order';
                }

                $instance['exclude'] = sanitize_text_field( $new_instance['exclude'] );

                return $instance;
        }

        /**
         * Outputs the settings form for the Pages widget.
         *
         * @since 2.8.0
         *
         * @param array $instance Current settings.
         */
        public function form( $instance ) {
                // Defaults.
                $instance = wp_parse_args(
                        (array) $instance,
                        array(
                                'sortby'  => 'post_title',
    ��                           'title'   => '',
                                'exclude' => '',
                        )
                );
                ?>
                <p>
                        <label for="<?php echo esc_attr( $this->get_field_id( 'title' ) ); ?>"><?php _e( 'Title:' ); ?></label>
                        <input class="widefat" id="<?php echo esc_attr( $this->get_field_id( 'title' ) ); ?>" name="<?php echo esc_attr( $this->get_field_name( 'title' ) ); ?>" type="text" value="<?php echo esc_attr( $instance['title'] ); ?>" />
                </p>

                <p>
                        <label for="<?php echo esc_attr( $this->get_field_id( 'sortby' ) ); ?>"><?php _e( 'Sort by:' ); ?></label>
                        <select name="<?php echo esc_attr( $this->get_field_name( 'sortby' ) ); ?>" id="<?php echo esc_attr( $this->get_field_id( 'sortby' ) ); ?>" class="widefat">
                                <option value="post_title"<?php selected( $instance['sortby'], 'post_title' ); ?>><?php _e( 'Page title' ); ?></option>
                                <option value="menu_order"<?php selected( $instance['sortby'], 'menu_order' ); ?>><?php _e( 'Page order' ); ?></option>
                                <option value="ID"<?php selected( $instance['sortby'], 'ID' ); ?>><?php _e( 'Page ID' ); ?></option>
                        </select>
                </p>

                <p>
                        <label for="<?php echo esc_attr( $this->get_field_id( 'exclude' ) ); ?>"><?php _e( 'Exclude:' ); ?></label>
                        <input type="text" value="<?php echo esc_attr( $instance['exclude'] ); ?>" name="<?php echo esc_attr( $this->get_field_name( 'exclude' ) ); ?>" id="<?php echo esc_attr( $this->get_field_id( 'exclude' ) ); ?>" class="widefat" />
                        <br />
                        <small><?php _e( 'Page IDs, separated by commas.' ); ?></small>
                </p>
                <?php
        }
}