WordPress 4.7
[autoinstalls/wordpress.git] / wp-admin / includes / class-wp-list-table.php
index 8a22bd4e0dd886b1b876db0f62d925d96851ac67..bf642acb2572d9ab52e0de6f8695c9d50e3910a4 100644 (file)
@@ -1,6 +1,6 @@
 <?php
 /**
- * Base class for displaying a list of items in an ajaxified HTML table.
+ * Administration API: WP_List_Table class
  *
  * @package WordPress
  * @subpackage List_Table
 /**
  * Base class for displaying a list of items in an ajaxified HTML table.
  *
- * @package WordPress
- * @subpackage List_Table
  * @since 3.1.0
  * @access private
  */
 class WP_List_Table {
 
        /**
-        * The current list of items
+        * The current list of items.
         *
         * @since 3.1.0
+        * @access public
         * @var array
-        * @access protected
         */
-       var $items;
+       public $items;
 
        /**
-        * Various information about the current table
+        * Various information about the current table.
         *
         * @since 3.1.0
+        * @access protected
         * @var array
-        * @access private
         */
-       var $_args;
+       protected $_args;
 
        /**
-        * Various information needed for displaying the pagination
+        * Various information needed for displaying the pagination.
         *
         * @since 3.1.0
+        * @access protected
         * @var array
-        * @access private
         */
-       var $_pagination_args = array();
+       protected $_pagination_args = array();
 
        /**
-        * The current screen
+        * The current screen.
         *
         * @since 3.1.0
-        * @var object
         * @access protected
+        * @var object
         */
-       var $screen;
+       protected $screen;
 
        /**
-        * Cached bulk actions
+        * Cached bulk actions.
         *
         * @since 3.1.0
-        * @var array
         * @access private
+        * @var array
         */
-       var $_actions;
+       private $_actions;
 
        /**
-        * Cached pagination output
+        * Cached pagination output.
         *
         * @since 3.1.0
-        * @var string
         * @access private
+        * @var string
+        */
+       private $_pagination;
+
+       /**
+        * The view switcher modes.
+        *
+        * @since 4.1.0
+        * @access protected
+        * @var array
+        */
+       protected $modes = array();
+
+       /**
+        * Stores the value returned by ->get_column_info().
+        *
+        * @since 4.1.0
+        * @access protected
+        * @var array
         */
-       var $_pagination;
+       protected $_column_headers;
 
        /**
-        * Constructor. The child class should call this constructor from it's own constructor
+        * {@internal Missing Summary}
         *
-        * @param array $args An associative array with information about the current table
         * @access protected
+        * @var array
         */
-       function __construct( $args = array() ) {
+       protected $compat_fields = array( '_args', '_pagination_args', 'screen', '_actions', '_pagination' );
+
+       /**
+        * {@internal Missing Summary}
+        *
+        * @access protected
+        * @var array
+        */
+       protected $compat_methods = array( 'set_pagination_args', 'get_views', 'get_bulk_actions', 'bulk_actions',
+               'row_actions', 'months_dropdown', 'view_switcher', 'comments_bubble', 'get_items_per_page', 'pagination',
+               'get_sortable_columns', 'get_column_info', 'get_table_classes', 'display_tablenav', 'extra_tablenav',
+               'single_row_columns' );
+
+       /**
+        * Constructor.
+        *
+        * The child class should call this constructor from its own constructor to override
+        * the default $args.
+        *
+        * @since 3.1.0
+        * @access public
+        *
+        * @param array|string $args {
+        *     Array or string of arguments.
+        *
+        *     @type string $plural   Plural value used for labels and the objects being listed.
+        *                            This affects things such as CSS class-names and nonces used
+        *                            in the list table, e.g. 'posts'. Default empty.
+        *     @type string $singular Singular label for an object being listed, e.g. 'post'.
+        *                            Default empty
+        *     @type bool   $ajax     Whether the list table supports Ajax. This includes loading
+        *                            and sorting data, for example. If true, the class will call
+        *                            the _js_vars() method in the footer to provide variables
+        *                            to any scripts handling Ajax events. Default false.
+        *     @type string $screen   String containing the hook name used to determine the current
+        *                            screen. If left null, the current screen will be automatically set.
+        *                            Default null.
+        * }
+        */
+       public function __construct( $args = array() ) {
                $args = wp_parse_args( $args, array(
                        'plural' => '',
                        'singular' => '',
@@ -87,7 +142,7 @@ class WP_List_Table {
 
                $this->screen = convert_to_screen( $args['screen'] );
 
-               add_filter( "manage_{$this->screen->id}_columns", array( &$this, 'get_columns' ), 0 );
+               add_filter( "manage_{$this->screen->id}_columns", array( $this, 'get_columns' ), 0 );
 
                if ( !$args['plural'] )
                        $args['plural'] = $this->screen->base;
@@ -99,19 +154,102 @@ class WP_List_Table {
 
                if ( $args['ajax'] ) {
                        // wp_enqueue_script( 'list-table' );
-                       add_action( 'admin_footer', array( &$this, '_js_vars' ) );
+                       add_action( 'admin_footer', array( $this, '_js_vars' ) );
+               }
+
+               if ( empty( $this->modes ) ) {
+                       $this->modes = array(
+                               'list'    => __( 'List View' ),
+                               'excerpt' => __( 'Excerpt View' )
+                       );
                }
        }
 
+       /**
+        * Make private properties readable for backward compatibility.
+        *
+        * @since 4.0.0
+        * @access public
+        *
+        * @param string $name Property to get.
+        * @return mixed Property.
+        */
+       public function __get( $name ) {
+               if ( in_array( $name, $this->compat_fields ) ) {
+                       return $this->$name;
+               }
+       }
+
+       /**
+        * Make private properties settable for backward compatibility.
+        *
+        * @since 4.0.0
+        * @access public
+        *
+        * @param string $name  Property to check if set.
+        * @param mixed  $value Property value.
+        * @return mixed Newly-set property.
+        */
+       public function __set( $name, $value ) {
+               if ( in_array( $name, $this->compat_fields ) ) {
+                       return $this->$name = $value;
+               }
+       }
+
+       /**
+        * Make private properties checkable for backward compatibility.
+        *
+        * @since 4.0.0
+        * @access public
+        *
+        * @param string $name Property to check if set.
+        * @return bool Whether the property is set.
+        */
+       public function __isset( $name ) {
+               if ( in_array( $name, $this->compat_fields ) ) {
+                       return isset( $this->$name );
+               }
+       }
+
+       /**
+        * Make private properties un-settable for backward compatibility.
+        *
+        * @since 4.0.0
+        * @access public
+        *
+        * @param string $name Property to unset.
+        */
+       public function __unset( $name ) {
+               if ( in_array( $name, $this->compat_fields ) ) {
+                       unset( $this->$name );
+               }
+       }
+
+       /**
+        * Make private/protected methods readable for backward compatibility.
+        *
+        * @since 4.0.0
+        * @access public
+        *
+        * @param callable $name      Method to call.
+        * @param array    $arguments Arguments to pass when calling.
+        * @return mixed|bool Return value of the callback, false otherwise.
+        */
+       public function __call( $name, $arguments ) {
+               if ( in_array( $name, $this->compat_methods ) ) {
+                       return call_user_func_array( array( $this, $name ), $arguments );
+               }
+               return false;
+       }
+
        /**
         * Checks the current user's permissions
-        * @uses wp_die()
         *
         * @since 3.1.0
         * @access public
         * @abstract
         */
-       function ajax_user_can() {
+       public function ajax_user_can() {
                die( 'function WP_List_Table::ajax_user_can() must be over-ridden in a sub-class.' );
        }
 
@@ -123,17 +261,19 @@ class WP_List_Table {
         * @access public
         * @abstract
         */
-       function prepare_items() {
+       public function prepare_items() {
                die( 'function WP_List_Table::prepare_items() must be over-ridden in a sub-class.' );
        }
 
        /**
         * An internal method that sets all the necessary pagination arguments
         *
-        * @param array $args An associative array with information about the pagination
+        * @since 3.1.0
         * @access protected
+        *
+        * @param array|string $args Array or string of arguments with information about the pagination.
         */
-       function set_pagination_args( $args ) {
+       protected function set_pagination_args( $args ) {
                $args = wp_parse_args( $args, array(
                        'total_items' => 0,
                        'total_pages' => 0,
@@ -143,8 +283,8 @@ class WP_List_Table {
                if ( !$args['total_pages'] && $args['per_page'] > 0 )
                        $args['total_pages'] = ceil( $args['total_items'] / $args['per_page'] );
 
-               // redirect if page number is invalid and headers are not already sent
-               if ( ! headers_sent() && ( ! defined( 'DOING_AJAX' ) || ! DOING_AJAX ) && $args['total_pages'] > 0 && $this->get_pagenum() > $args['total_pages'] ) {
+               // Redirect if page number is invalid and headers are not already sent.
+               if ( ! headers_sent() && ! wp_doing_ajax() && $args['total_pages'] > 0 && $this->get_pagenum() > $args['total_pages'] ) {
                        wp_redirect( add_query_arg( 'paged', $args['total_pages'] ) );
                        exit;
                }
@@ -153,20 +293,23 @@ class WP_List_Table {
        }
 
        /**
-        * Access the pagination args
+        * Access the pagination args.
         *
         * @since 3.1.0
         * @access public
         *
-        * @param string $key
-        * @return array
+        * @param string $key Pagination argument to retrieve. Common values include 'total_items',
+        *                    'total_pages', 'per_page', or 'infinite_scroll'.
+        * @return int Number of items that correspond to the given pagination argument.
         */
-       function get_pagination_arg( $key ) {
-               if ( 'page' == $key )
+       public function get_pagination_arg( $key ) {
+               if ( 'page' === $key ) {
                        return $this->get_pagenum();
+               }
 
-               if ( isset( $this->_pagination_args[$key] ) )
+               if ( isset( $this->_pagination_args[$key] ) ) {
                        return $this->_pagination_args[$key];
+               }
        }
 
        /**
@@ -177,7 +320,7 @@ class WP_List_Table {
         *
         * @return bool
         */
-       function has_items() {
+       public function has_items() {
                return !empty( $this->items );
        }
 
@@ -187,20 +330,20 @@ class WP_List_Table {
         * @since 3.1.0
         * @access public
         */
-       function no_items() {
+       public function no_items() {
                _e( 'No items found.' );
        }
 
        /**
-        * Display the search box.
+        * Displays the search box.
         *
         * @since 3.1.0
         * @access public
         *
-        * @param string $text The search button text
-        * @param string $input_id The search input id
+        * @param string $text     The 'submit' button label.
+        * @param string $input_id ID attribute value for the search input field.
         */
-       function search_box( $text, $input_id ) {
+       public function search_box( $text, $input_id ) {
                if ( empty( $_REQUEST['s'] ) && !$this->has_items() )
                        return;
 
@@ -216,9 +359,9 @@ class WP_List_Table {
                        echo '<input type="hidden" name="detached" value="' . esc_attr( $_REQUEST['detached'] ) . '" />';
 ?>
 <p class="search-box">
-       <label class="screen-reader-text" for="<?php echo $input_id ?>"><?php echo $text; ?>:</label>
-       <input type="search" id="<?php echo $input_id ?>" name="s" value="<?php _admin_search_query(); ?>" />
-       <?php submit_button( $text, 'button', false, false, array('id' => 'search-submit') ); ?>
+       <label class="screen-reader-text" for="<?php echo esc_attr( $input_id ); ?>"><?php echo $text; ?>:</label>
+       <input type="search" id="<?php echo esc_attr( $input_id ); ?>" name="s" value="<?php _admin_search_query(); ?>" />
+       <?php submit_button( $text, '', '', false, array( 'id' => 'search-submit' ) ); ?>
 </p>
 <?php
        }
@@ -232,7 +375,7 @@ class WP_List_Table {
         *
         * @return array
         */
-       function get_views() {
+       protected function get_views() {
                return array();
        }
 
@@ -242,13 +385,25 @@ class WP_List_Table {
         * @since 3.1.0
         * @access public
         */
-       function views() {
+       public function views() {
                $views = $this->get_views();
-               $views = apply_filters( 'views_' . $this->screen->id, $views );
+               /**
+                * Filters the list of available list table views.
+                *
+                * The dynamic portion of the hook name, `$this->screen->id`, refers
+                * to the ID of the current screen, usually a string.
+                *
+                * @since 3.5.0
+                *
+                * @param array $views An array of available list table views.
+                */
+               $views = apply_filters( "views_{$this->screen->id}", $views );
 
                if ( empty( $views ) )
                        return;
 
+               $this->screen->render_screen_reader_content( 'heading_views' );
+
                echo "<ul class='subsubsub'>\n";
                foreach ( $views as $class => $view ) {
                        $views[ $class ] = "\t<li class='$class'>$view";
@@ -266,7 +421,7 @@ class WP_List_Table {
         *
         * @return array
         */
-       function get_bulk_actions() {
+       protected function get_bulk_actions() {
                return array();
        }
 
@@ -274,14 +429,27 @@ class WP_List_Table {
         * Display the bulk actions dropdown.
         *
         * @since 3.1.0
-        * @access public
+        * @access protected
+        *
+        * @param string $which The location of the bulk actions: 'top' or 'bottom'.
+        *                      This is designated as optional for backward compatibility.
         */
-       function bulk_actions() {
+       protected function bulk_actions( $which = '' ) {
                if ( is_null( $this->_actions ) ) {
-                       $no_new_actions = $this->_actions = $this->get_bulk_actions();
-                       // This filter can currently only be used to remove actions.
-                       $this->_actions = apply_filters( 'bulk_actions-' . $this->screen->id, $this->_actions );
-                       $this->_actions = array_intersect_assoc( $this->_actions, $no_new_actions );
+                       $this->_actions = $this->get_bulk_actions();
+                       /**
+                        * Filters the list table Bulk Actions drop-down.
+                        *
+                        * The dynamic portion of the hook name, `$this->screen->id`, refers
+                        * to the ID of the current screen, usually a string.
+                        *
+                        * This filter can currently only be used to remove bulk actions.
+                        *
+                        * @since 3.5.0
+                        *
+                        * @param array $actions An array of the available bulk actions.
+                        */
+                       $this->_actions = apply_filters( "bulk_actions-{$this->screen->id}", $this->_actions );
                        $two = '';
                } else {
                        $two = '2';
@@ -290,18 +458,19 @@ class WP_List_Table {
                if ( empty( $this->_actions ) )
                        return;
 
-               echo "<select name='action$two'>\n";
-               echo "<option value='-1' selected='selected'>" . __( 'Bulk Actions' ) . "</option>\n";
+               echo '<label for="bulk-action-selector-' . esc_attr( $which ) . '" class="screen-reader-text">' . __( 'Select bulk action' ) . '</label>';
+               echo '<select name="action' . $two . '" id="bulk-action-selector-' . esc_attr( $which ) . "\">\n";
+               echo '<option value="-1">' . __( 'Bulk Actions' ) . "</option>\n";
 
                foreach ( $this->_actions as $name => $title ) {
-                       $class = 'edit' == $name ? ' class="hide-if-no-js"' : '';
+                       $class = 'edit' === $name ? ' class="hide-if-no-js"' : '';
 
-                       echo "\t<option value='$name'$class>$title</option>\n";
+                       echo "\t" . '<option value="' . $name . '"' . $class . '>' . $title . "</option>\n";
                }
 
                echo "</select>\n";
 
-               submit_button( __( 'Apply' ), 'action', false, false, array( 'id' => "doaction$two" ) );
+               submit_button( __( 'Apply' ), 'action', '', false, array( 'id' => "doaction$two" ) );
                echo "\n";
        }
 
@@ -311,9 +480,12 @@ class WP_List_Table {
         * @since 3.1.0
         * @access public
         *
-        * @return string|bool The action name or False if no action was selected
+        * @return string|false The action name or False if no action was selected
         */
-       function current_action() {
+       public function current_action() {
+               if ( isset( $_REQUEST['filter_action'] ) && ! empty( $_REQUEST['filter_action'] ) )
+                       return false;
+
                if ( isset( $_REQUEST['action'] ) && -1 != $_REQUEST['action'] )
                        return $_REQUEST['action'];
 
@@ -333,14 +505,14 @@ class WP_List_Table {
         * @param bool $always_visible Whether the actions should be always visible
         * @return string
         */
-       function row_actions( $actions, $always_visible = false ) {
+       protected function row_actions( $actions, $always_visible = false ) {
                $action_count = count( $actions );
                $i = 0;
 
                if ( !$action_count )
                        return '';
 
-               $out = '<div class="' . ( $always_visible ? 'row-actions-visible' : 'row-actions' ) . '">';
+               $out = '<div class="' . ( $always_visible ? 'row-actions visible' : 'row-actions' ) . '">';
                foreach ( $actions as $action => $link ) {
                        ++$i;
                        ( $i == $action_count ) ? $sep = '' : $sep = ' | ';
@@ -348,6 +520,8 @@ class WP_List_Table {
                }
                $out .= '</div>';
 
+               $out .= '<button type="button" class="toggle-row"><span class="screen-reader-text">' . __( 'Show more details' ) . '</span></button>';
+
                return $out;
        }
 
@@ -356,17 +530,52 @@ class WP_List_Table {
         *
         * @since 3.1.0
         * @access protected
+        *
+        * @global wpdb      $wpdb
+        * @global WP_Locale $wp_locale
+        *
+        * @param string $post_type
         */
-       function months_dropdown( $post_type ) {
+       protected function months_dropdown( $post_type ) {
                global $wpdb, $wp_locale;
 
+               /**
+                * Filters whether to remove the 'Months' drop-down from the post list table.
+                *
+                * @since 4.2.0
+                *
+                * @param bool   $disable   Whether to disable the drop-down. Default false.
+                * @param string $post_type The post type.
+                */
+               if ( apply_filters( 'disable_months_dropdown', false, $post_type ) ) {
+                       return;
+               }
+
+               $extra_checks = "AND post_status != 'auto-draft'";
+               if ( ! isset( $_GET['post_status'] ) || 'trash' !== $_GET['post_status'] ) {
+                       $extra_checks .= " AND post_status != 'trash'";
+               } elseif ( isset( $_GET['post_status'] ) ) {
+                       $extra_checks = $wpdb->prepare( ' AND post_status = %s', $_GET['post_status'] );
+               }
+
                $months = $wpdb->get_results( $wpdb->prepare( "
                        SELECT DISTINCT YEAR( post_date ) AS year, MONTH( post_date ) AS month
                        FROM $wpdb->posts
                        WHERE post_type = %s
+                       $extra_checks
                        ORDER BY post_date DESC
                ", $post_type ) );
 
+               /**
+                * Filters the 'Months' drop-down results.
+                *
+                * @since 3.7.0
+                *
+                * @param object $months    The months drop-down query results.
+                * @param string $post_type The post type.
+                */
+               $months = apply_filters( 'months_dropdown_results', $months, $post_type );
+
                $month_count = count( $months );
 
                if ( !$month_count || ( 1 == $month_count && 0 == $months[0]->month ) )
@@ -374,8 +583,9 @@ class WP_List_Table {
 
                $m = isset( $_GET['m'] ) ? (int) $_GET['m'] : 0;
 ?>
-               <select name='m'>
-                       <option<?php selected( $m, 0 ); ?> value='0'><?php _e( 'Show all dates' ); ?></option>
+               <label for="filter-by-date" class="screen-reader-text"><?php _e( 'Filter by date' ); ?></label>
+               <select name="m" id="filter-by-date">
+                       <option<?php selected( $m, 0 ); ?> value="0"><?php _e( 'All dates' ); ?></option>
 <?php
                foreach ( $months as $arc_row ) {
                        if ( 0 == $arc_row->year )
@@ -401,20 +611,24 @@ class WP_List_Table {
         *
         * @since 3.1.0
         * @access protected
+        *
+        * @param string $current_mode
         */
-       function view_switcher( $current_mode ) {
-               $modes = array(
-                       'list'    => __( 'List View' ),
-                       'excerpt' => __( 'Excerpt View' )
-               );
-
+       protected function view_switcher( $current_mode ) {
 ?>
                <input type="hidden" name="mode" value="<?php echo esc_attr( $current_mode ); ?>" />
                <div class="view-switch">
 <?php
-                       foreach ( $modes as $mode => $title ) {
-                               $class = ( $current_mode == $mode ) ? 'class="current"' : '';
-                               echo "<a href='" . esc_url( add_query_arg( 'mode', $mode, $_SERVER['REQUEST_URI'] ) ) . "' $class><img id='view-switch-$mode' src='" . esc_url( includes_url( 'images/blank.gif' ) ) . "' width='20' height='20' title='$title' alt='$title' /></a>\n";
+                       foreach ( $this->modes as $mode => $title ) {
+                               $classes = array( 'view-' . $mode );
+                               if ( $current_mode === $mode )
+                                       $classes[] = 'current';
+                               printf(
+                                       "<a href='%s' class='%s' id='view-switch-$mode'><span class='screen-reader-text'>%s</span></a>\n",
+                                       esc_url( add_query_arg( 'mode', $mode ) ),
+                                       implode( ' ', $classes ),
+                                       $title
+                               );
                        }
                ?>
                </div>
@@ -427,33 +641,64 @@ class WP_List_Table {
         * @since 3.1.0
         * @access protected
         *
-        * @param int $post_id
-        * @param int $pending_comments
+        * @param int $post_id          The post ID.
+        * @param int $pending_comments Number of pending comments.
         */
-       function comments_bubble( $post_id, $pending_comments ) {
-               $pending_phrase = sprintf( __( '%s pending' ), number_format( $pending_comments ) );
+       protected function comments_bubble( $post_id, $pending_comments ) {
+               $approved_comments = get_comments_number();
 
-               if ( $pending_comments )
-                       echo '<strong>';
+               $approved_comments_number = number_format_i18n( $approved_comments );
+               $pending_comments_number = number_format_i18n( $pending_comments );
 
-               echo "<a href='" . esc_url( add_query_arg( 'p', $post_id, admin_url( 'edit-comments.php' ) ) ) . "' title='" . esc_attr( $pending_phrase ) . "' class='post-com-count'><span class='comment-count'>" . number_format_i18n( get_comments_number() ) . "</span></a>";
+               $approved_only_phrase = sprintf( _n( '%s comment', '%s comments', $approved_comments ), $approved_comments_number );
+               $approved_phrase = sprintf( _n( '%s approved comment', '%s approved comments', $approved_comments ), $approved_comments_number );
+               $pending_phrase = sprintf( _n( '%s pending comment', '%s pending comments', $pending_comments ), $pending_comments_number );
 
-               if ( $pending_comments )
-                       echo '</strong>';
+               // No comments at all.
+               if ( ! $approved_comments && ! $pending_comments ) {
+                       printf( '<span aria-hidden="true">—</span><span class="screen-reader-text">%s</span>',
+                               __( 'No comments' )
+                       );
+               // Approved comments have different display depending on some conditions.
+               } elseif ( $approved_comments ) {
+                       printf( '<a href="%s" class="post-com-count post-com-count-approved"><span class="comment-count-approved" aria-hidden="true">%s</span><span class="screen-reader-text">%s</span></a>',
+                               esc_url( add_query_arg( array( 'p' => $post_id, 'comment_status' => 'approved' ), admin_url( 'edit-comments.php' ) ) ),
+                               $approved_comments_number,
+                               $pending_comments ? $approved_phrase : $approved_only_phrase
+                       );
+               } else {
+                       printf( '<span class="post-com-count post-com-count-no-comments"><span class="comment-count comment-count-no-comments" aria-hidden="true">%s</span><span class="screen-reader-text">%s</span></span>',
+                               $approved_comments_number,
+                               $pending_comments ? __( 'No approved comments' ) : __( 'No comments' )
+                       );
+               }
+
+               if ( $pending_comments ) {
+                       printf( '<a href="%s" class="post-com-count post-com-count-pending"><span class="comment-count-pending" aria-hidden="true">%s</span><span class="screen-reader-text">%s</span></a>',
+                               esc_url( add_query_arg( array( 'p' => $post_id, 'comment_status' => 'moderated' ), admin_url( 'edit-comments.php' ) ) ),
+                               $pending_comments_number,
+                               $pending_phrase
+                       );
+               } else {
+                       printf( '<span class="post-com-count post-com-count-pending post-com-count-no-pending"><span class="comment-count comment-count-no-pending" aria-hidden="true">%s</span><span class="screen-reader-text">%s</span></span>',
+                               $pending_comments_number,
+                               $approved_comments ? __( 'No pending comments' ) : __( 'No comments' )
+                       );
+               }
        }
 
        /**
         * Get the current page number
         *
         * @since 3.1.0
-        * @access protected
+        * @access public
         *
         * @return int
         */
-       function get_pagenum() {
+       public function get_pagenum() {
                $pagenum = isset( $_REQUEST['paged'] ) ? absint( $_REQUEST['paged'] ) : 0;
 
-               if( isset( $this->_pagination_args['total_pages'] ) && $pagenum > $this->_pagination_args['total_pages'] )
+               if ( isset( $this->_pagination_args['total_pages'] ) && $pagenum > $this->_pagination_args['total_pages'] )
                        $pagenum = $this->_pagination_args['total_pages'];
 
                return max( 1, $pagenum );
@@ -465,13 +710,28 @@ class WP_List_Table {
         * @since 3.1.0
         * @access protected
         *
+        * @param string $option
+        * @param int    $default
         * @return int
         */
-       function get_items_per_page( $option, $default = 20 ) {
+       protected function get_items_per_page( $option, $default = 20 ) {
                $per_page = (int) get_user_option( $option );
                if ( empty( $per_page ) || $per_page < 1 )
                        $per_page = $default;
 
+               /**
+                * Filters the number of items to be displayed on each page of the list table.
+                *
+                * The dynamic hook name, $option, refers to the `per_page` option depending
+                * on the type of list table in use. Possible values include: 'edit_comments_per_page',
+                * 'sites_network_per_page', 'site_themes_network_per_page', 'themes_network_per_page',
+                * 'users_network_per_page', 'edit_post_per_page', 'edit_page_per_page',
+                * 'edit_{$post_type}_per_page', etc.
+                *
+                * @since 2.9.0
+                *
+                * @param int $per_page Number of items to be displayed. Default 20.
+                */
                return (int) apply_filters( $option, $per_page );
        }
 
@@ -480,79 +740,120 @@ class WP_List_Table {
         *
         * @since 3.1.0
         * @access protected
+        *
+        * @param string $which
         */
-       function pagination( $which ) {
-               if ( empty( $this->_pagination_args ) )
+       protected function pagination( $which ) {
+               if ( empty( $this->_pagination_args ) ) {
                        return;
+               }
+
+               $total_items = $this->_pagination_args['total_items'];
+               $total_pages = $this->_pagination_args['total_pages'];
+               $infinite_scroll = false;
+               if ( isset( $this->_pagination_args['infinite_scroll'] ) ) {
+                       $infinite_scroll = $this->_pagination_args['infinite_scroll'];
+               }
 
-               extract( $this->_pagination_args, EXTR_SKIP );
+               if ( 'top' === $which && $total_pages > 1 ) {
+                       $this->screen->render_screen_reader_content( 'heading_pagination' );
+               }
 
-               $output = '<span class="displaying-num">' . sprintf( _n( '1 item', '%s items', $total_items ), number_format_i18n( $total_items ) ) . '</span>';
+               $output = '<span class="displaying-num">' . sprintf( _n( '%s item', '%s items', $total_items ), number_format_i18n( $total_items ) ) . '</span>';
 
                $current = $this->get_pagenum();
+               $removable_query_args = wp_removable_query_args();
 
                $current_url = set_url_scheme( 'http://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'] );
 
-               $current_url = remove_query_arg( array( 'hotkeys_highlight_last', 'hotkeys_highlight_first' ), $current_url );
+               $current_url = remove_query_arg( $removable_query_args, $current_url );
 
                $page_links = array();
 
-               $disable_first = $disable_last = '';
-               if ( $current == 1 )
-                       $disable_first = ' disabled';
-               if ( $current == $total_pages )
-                       $disable_last = ' disabled';
-
-               $page_links[] = sprintf( "<a class='%s' title='%s' href='%s'>%s</a>",
-                       'first-page' . $disable_first,
-                       esc_attr__( 'Go to the first page' ),
-                       esc_url( remove_query_arg( 'paged', $current_url ) ),
-                       '&laquo;'
-               );
+               $total_pages_before = '<span class="paging-input">';
+               $total_pages_after  = '</span></span>';
 
-               $page_links[] = sprintf( "<a class='%s' title='%s' href='%s'>%s</a>",
-                       'prev-page' . $disable_first,
-                       esc_attr__( 'Go to the previous page' ),
-                       esc_url( add_query_arg( 'paged', max( 1, $current-1 ), $current_url ) ),
-                       '&lsaquo;'
-               );
+               $disable_first = $disable_last = $disable_prev = $disable_next = false;
+
+               if ( $current == 1 ) {
+                       $disable_first = true;
+                       $disable_prev = true;
+               }
+               if ( $current == 2 ) {
+                       $disable_first = true;
+               }
+               if ( $current == $total_pages ) {
+                       $disable_last = true;
+                       $disable_next = true;
+               }
+               if ( $current == $total_pages - 1 ) {
+                       $disable_last = true;
+               }
+
+               if ( $disable_first ) {
+                       $page_links[] = '<span class="tablenav-pages-navspan" aria-hidden="true">&laquo;</span>';
+               } else {
+                       $page_links[] = sprintf( "<a class='first-page' href='%s'><span class='screen-reader-text'>%s</span><span aria-hidden='true'>%s</span></a>",
+                               esc_url( remove_query_arg( 'paged', $current_url ) ),
+                               __( 'First page' ),
+                               '&laquo;'
+                       );
+               }
+
+               if ( $disable_prev ) {
+                       $page_links[] = '<span class="tablenav-pages-navspan" aria-hidden="true">&lsaquo;</span>';
+               } else {
+                       $page_links[] = sprintf( "<a class='prev-page' href='%s'><span class='screen-reader-text'>%s</span><span aria-hidden='true'>%s</span></a>",
+                               esc_url( add_query_arg( 'paged', max( 1, $current-1 ), $current_url ) ),
+                               __( 'Previous page' ),
+                               '&lsaquo;'
+                       );
+               }
 
-               if ( 'bottom' == $which )
-                       $html_current_page = $current;
-               else
-                       $html_current_page = sprintf( "<input class='current-page' title='%s' type='text' name='paged' value='%s' size='%d' />",
-                               esc_attr__( 'Current page' ),
+               if ( 'bottom' === $which ) {
+                       $html_current_page  = $current;
+                       $total_pages_before = '<span class="screen-reader-text">' . __( 'Current Page' ) . '</span><span id="table-paging" class="paging-input"><span class="tablenav-paging-text">';
+               } else {
+                       $html_current_page = sprintf( "%s<input class='current-page' id='current-page-selector' type='text' name='paged' value='%s' size='%d' aria-describedby='table-paging' /><span class='tablenav-paging-text'>",
+                               '<label for="current-page-selector" class="screen-reader-text">' . __( 'Current Page' ) . '</label>',
                                $current,
                                strlen( $total_pages )
                        );
-
+               }
                $html_total_pages = sprintf( "<span class='total-pages'>%s</span>", number_format_i18n( $total_pages ) );
-               $page_links[] = '<span class="paging-input">' . sprintf( _x( '%1$s of %2$s', 'paging' ), $html_current_page, $html_total_pages ) . '</span>';
+               $page_links[] = $total_pages_before . sprintf( _x( '%1$s of %2$s', 'paging' ), $html_current_page, $html_total_pages ) . $total_pages_after;
 
-               $page_links[] = sprintf( "<a class='%s' title='%s' href='%s'>%s</a>",
-                       'next-page' . $disable_last,
-                       esc_attr__( 'Go to the next page' ),
-                       esc_url( add_query_arg( 'paged', min( $total_pages, $current+1 ), $current_url ) ),
-                       '&rsaquo;'
-               );
+               if ( $disable_next ) {
+                       $page_links[] = '<span class="tablenav-pages-navspan" aria-hidden="true">&rsaquo;</span>';
+               } else {
+                       $page_links[] = sprintf( "<a class='next-page' href='%s'><span class='screen-reader-text'>%s</span><span aria-hidden='true'>%s</span></a>",
+                               esc_url( add_query_arg( 'paged', min( $total_pages, $current+1 ), $current_url ) ),
+                               __( 'Next page' ),
+                               '&rsaquo;'
+                       );
+               }
 
-               $page_links[] = sprintf( "<a class='%s' title='%s' href='%s'>%s</a>",
-                       'last-page' . $disable_last,
-                       esc_attr__( 'Go to the last page' ),
-                       esc_url( add_query_arg( 'paged', $total_pages, $current_url ) ),
-                       '&raquo;'
-               );
+               if ( $disable_last ) {
+                       $page_links[] = '<span class="tablenav-pages-navspan" aria-hidden="true">&raquo;</span>';
+               } else {
+                       $page_links[] = sprintf( "<a class='last-page' href='%s'><span class='screen-reader-text'>%s</span><span aria-hidden='true'>%s</span></a>",
+                               esc_url( add_query_arg( 'paged', $total_pages, $current_url ) ),
+                               __( 'Last page' ),
+                               '&raquo;'
+                       );
+               }
 
                $pagination_links_class = 'pagination-links';
-               if ( ! empty( $infinite_scroll ) )
+               if ( ! empty( $infinite_scroll ) ) {
                        $pagination_links_class = ' hide-if-js';
+               }
                $output .= "\n<span class='$pagination_links_class'>" . join( "\n", $page_links ) . '</span>';
 
-               if ( $total_pages )
+               if ( $total_pages ) {
                        $page_class = $total_pages < 2 ? ' one-page' : '';
-               else
+               } else {
                        $page_class = ' no-pages';
-
+               }
                $this->_pagination = "<div class='tablenav-pages{$page_class}'>$output</div>";
 
                echo $this->_pagination;
@@ -563,12 +864,12 @@ class WP_List_Table {
         * 'internal-name' => 'Title'
         *
         * @since 3.1.0
-        * @access protected
+        * @access public
         * @abstract
         *
         * @return array
         */
-       function get_columns() {
+       public function get_columns() {
                die( 'function WP_List_Table::get_columns() must be over-ridden in a sub-class.' );
        }
 
@@ -585,10 +886,87 @@ class WP_List_Table {
         *
         * @return array
         */
-       function get_sortable_columns() {
+       protected function get_sortable_columns() {
                return array();
        }
 
+       /**
+        * Gets the name of the default primary column.
+        *
+        * @since 4.3.0
+        * @access protected
+        *
+        * @return string Name of the default primary column, in this case, an empty string.
+        */
+       protected function get_default_primary_column_name() {
+               $columns = $this->get_columns();
+               $column = '';
+
+               if ( empty( $columns ) ) {
+                       return $column;
+               }
+
+               // We need a primary defined so responsive views show something,
+               // so let's fall back to the first non-checkbox column.
+               foreach ( $columns as $col => $column_name ) {
+                       if ( 'cb' === $col ) {
+                               continue;
+                       }
+
+                       $column = $col;
+                       break;
+               }
+
+               return $column;
+       }
+
+       /**
+        * Public wrapper for WP_List_Table::get_default_primary_column_name().
+        *
+        * @since 4.4.0
+        * @access public
+        *
+        * @return string Name of the default primary column.
+        */
+       public function get_primary_column() {
+               return $this->get_primary_column_name();
+       }
+
+       /**
+        * Gets the name of the primary column.
+        *
+        * @since 4.3.0
+        * @access protected
+        *
+        * @return string The name of the primary column.
+        */
+       protected function get_primary_column_name() {
+               $columns = get_column_headers( $this->screen );
+               $default = $this->get_default_primary_column_name();
+
+               // If the primary column doesn't exist fall back to the
+               // first non-checkbox column.
+               if ( ! isset( $columns[ $default ] ) ) {
+                       $default = WP_List_Table::get_default_primary_column_name();
+               }
+
+               /**
+                * Filters the name of the primary column for the current list table.
+                *
+                * @since 4.3.0
+                *
+                * @param string $default Column name default for the specific list table, e.g. 'name'.
+                * @param string $context Screen ID for specific list table, e.g. 'plugins'.
+                */
+               $column  = apply_filters( 'list_table_primary_column', $default, $this->screen->id );
+
+               if ( empty( $column ) || ! isset( $columns[ $column ] ) ) {
+                       $column = $default;
+               }
+
+               return $column;
+       }
+
        /**
         * Get a list of all, hidden and sortable columns, with filter applied
         *
@@ -597,14 +975,34 @@ class WP_List_Table {
         *
         * @return array
         */
-       function get_column_info() {
-               if ( isset( $this->_column_headers ) )
-                       return $this->_column_headers;
+       protected function get_column_info() {
+               // $_column_headers is already set / cached
+               if ( isset( $this->_column_headers ) && is_array( $this->_column_headers ) ) {
+                       // Back-compat for list tables that have been manually setting $_column_headers for horse reasons.
+                       // In 4.3, we added a fourth argument for primary column.
+                       $column_headers = array( array(), array(), array(), $this->get_primary_column_name() );
+                       foreach ( $this->_column_headers as $key => $value ) {
+                               $column_headers[ $key ] = $value;
+                       }
+
+                       return $column_headers;
+               }
 
                $columns = get_column_headers( $this->screen );
                $hidden = get_hidden_columns( $this->screen );
 
-               $_sortable = apply_filters( "manage_{$this->screen->id}_sortable_columns", $this->get_sortable_columns() );
+               $sortable_columns = $this->get_sortable_columns();
+               /**
+                * Filters the list table sortable columns for a specific screen.
+                *
+                * The dynamic portion of the hook name, `$this->screen->id`, refers
+                * to the ID of the current screen, usually a string.
+                *
+                * @since 3.5.0
+                *
+                * @param array $sortable_columns An array of sortable columns.
+                */
+               $_sortable = apply_filters( "manage_{$this->screen->id}_sortable_columns", $sortable_columns );
 
                $sortable = array();
                foreach ( $_sortable as $id => $data ) {
@@ -618,7 +1016,8 @@ class WP_List_Table {
                        $sortable[$id] = $data;
                }
 
-               $this->_column_headers = array( $columns, $hidden, $sortable );
+               $primary = $this->get_primary_column_name();
+               $this->_column_headers = array( $columns, $hidden, $sortable, $primary );
 
                return $this->_column_headers;
        }
@@ -631,7 +1030,7 @@ class WP_List_Table {
         *
         * @return int
         */
-       function get_column_count() {
+       public function get_column_count() {
                list ( $columns, $hidden ) = $this->get_column_info();
                $hidden = array_intersect( array_keys( $columns ), array_filter( $hidden ) );
                return count( $columns ) - count( $hidden );
@@ -641,25 +1040,29 @@ class WP_List_Table {
         * Print column headers, accounting for hidden and sortable columns.
         *
         * @since 3.1.0
-        * @access protected
+        * @access public
+        *
+        * @staticvar int $cb_counter
         *
         * @param bool $with_id Whether to set the id attribute or not
         */
-       function print_column_headers( $with_id = true ) {
-               list( $columns, $hidden, $sortable ) = $this->get_column_info();
+       public function print_column_headers( $with_id = true ) {
+               list( $columns, $hidden, $sortable, $primary ) = $this->get_column_info();
 
                $current_url = set_url_scheme( 'http://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'] );
                $current_url = remove_query_arg( 'paged', $current_url );
 
-               if ( isset( $_GET['orderby'] ) )
+               if ( isset( $_GET['orderby'] ) ) {
                        $current_orderby = $_GET['orderby'];
-               else
+               } else {
                        $current_orderby = '';
+               }
 
-               if ( isset( $_GET['order'] ) && 'desc' == $_GET['order'] )
+               if ( isset( $_GET['order'] ) && 'desc' === $_GET['order'] ) {
                        $current_order = 'desc';
-               else
+               } else {
                        $current_order = 'asc';
+               }
 
                if ( ! empty( $columns['cb'] ) ) {
                        static $cb_counter = 1;
@@ -671,22 +1074,24 @@ class WP_List_Table {
                foreach ( $columns as $column_key => $column_display_name ) {
                        $class = array( 'manage-column', "column-$column_key" );
 
-                       $style = '';
-                       if ( in_array( $column_key, $hidden ) )
-                               $style = 'display:none;';
-
-                       $style = ' style="' . $style . '"';
+                       if ( in_array( $column_key, $hidden ) ) {
+                               $class[] = 'hidden';
+                       }
 
-                       if ( 'cb' == $column_key )
+                       if ( 'cb' === $column_key )
                                $class[] = 'check-column';
                        elseif ( in_array( $column_key, array( 'posts', 'comments', 'links' ) ) )
                                $class[] = 'num';
 
+                       if ( $column_key === $primary ) {
+                               $class[] = 'column-primary';
+                       }
+
                        if ( isset( $sortable[$column_key] ) ) {
                                list( $orderby, $desc_first ) = $sortable[$column_key];
 
-                               if ( $current_orderby == $orderby ) {
-                                       $order = 'asc' == $current_order ? 'desc' : 'asc';
+                               if ( $current_orderby === $orderby ) {
+                                       $order = 'asc' === $current_order ? 'desc' : 'asc';
                                        $class[] = 'sorted';
                                        $class[] = $current_order;
                                } else {
@@ -698,12 +1103,14 @@ class WP_List_Table {
                                $column_display_name = '<a href="' . esc_url( add_query_arg( compact( 'orderby', 'order' ), $current_url ) ) . '"><span>' . $column_display_name . '</span><span class="sorting-indicator"></span></a>';
                        }
 
+                       $tag = ( 'cb' === $column_key ) ? 'td' : 'th';
+                       $scope = ( 'th' === $tag ) ? 'scope="col"' : '';
                        $id = $with_id ? "id='$column_key'" : '';
 
                        if ( !empty( $class ) )
                                $class = "class='" . join( ' ', $class ) . "'";
 
-                       echo "<th scope='col' $id $class $style>$column_display_name</th>";
+                       echo "<$tag $scope $id $class>$column_display_name</$tag>";
                }
        }
 
@@ -713,43 +1120,48 @@ class WP_List_Table {
         * @since 3.1.0
         * @access public
         */
-       function display() {
-               extract( $this->_args );
+       public function display() {
+               $singular = $this->_args['singular'];
 
                $this->display_tablenav( 'top' );
 
+               $this->screen->render_screen_reader_content( 'heading_list' );
 ?>
-<table class="wp-list-table <?php echo implode( ' ', $this->get_table_classes() ); ?>" cellspacing="0">
+<table class="wp-list-table <?php echo implode( ' ', $this->get_table_classes() ); ?>">
        <thead>
        <tr>
                <?php $this->print_column_headers(); ?>
        </tr>
        </thead>
 
+       <tbody id="the-list"<?php
+               if ( $singular ) {
+                       echo " data-wp-lists='list:$singular'";
+               } ?>>
+               <?php $this->display_rows_or_placeholder(); ?>
+       </tbody>
+
        <tfoot>
        <tr>
                <?php $this->print_column_headers( false ); ?>
        </tr>
        </tfoot>
 
-       <tbody id="the-list"<?php if ( $singular ) echo " data-wp-lists='list:$singular'"; ?>>
-               <?php $this->display_rows_or_placeholder(); ?>
-       </tbody>
 </table>
 <?php
                $this->display_tablenav( 'bottom' );
        }
 
        /**
-        * Get a list of CSS classes for the <table> tag
+        * Get a list of CSS classes for the WP_List_Table table tag.
         *
         * @since 3.1.0
         * @access protected
         *
-        * @return array
+        * @return array List of CSS classes for the table tag.
         */
-       function get_table_classes() {
-               return array( 'widefat', 'fixed', $this->_args['plural'] );
+       protected function get_table_classes() {
+               return array( 'widefat', 'fixed', 'striped', $this->_args['plural'] );
        }
 
        /**
@@ -757,17 +1169,20 @@ class WP_List_Table {
         *
         * @since 3.1.0
         * @access protected
+        * @param string $which
         */
-       function display_tablenav( $which ) {
-               if ( 'top' == $which )
+       protected function display_tablenav( $which ) {
+               if ( 'top' === $which ) {
                        wp_nonce_field( 'bulk-' . $this->_args['plural'] );
-?>
+               }
+               ?>
        <div class="tablenav <?php echo esc_attr( $which ); ?>">
 
-               <div class="alignleft actions">
-                       <?php $this->bulk_actions(); ?>
+               <?php if ( $this->has_items() ): ?>
+               <div class="alignleft actions bulkactions">
+                       <?php $this->bulk_actions( $which ); ?>
                </div>
-<?php
+               <?php endif;
                $this->extra_tablenav( $which );
                $this->pagination( $which );
 ?>
@@ -782,20 +1197,21 @@ class WP_List_Table {
         *
         * @since 3.1.0
         * @access protected
+        *
+        * @param string $which
         */
-       function extra_tablenav( $which ) {}
+       protected function extra_tablenav( $which ) {}
 
        /**
-        * Generate the <tbody> part of the table
+        * Generate the tbody element for the list table.
         *
         * @since 3.1.0
-        * @access protected
+        * @access public
         */
-       function display_rows_or_placeholder() {
+       public function display_rows_or_placeholder() {
                if ( $this->has_items() ) {
                        $this->display_rows();
                } else {
-                       list( $columns, $hidden ) = $this->get_column_info();
                        echo '<tr class="no-items"><td class="colspanchange" colspan="' . $this->get_column_count() . '">';
                        $this->no_items();
                        echo '</td></tr>';
@@ -806,9 +1222,9 @@ class WP_List_Table {
         * Generate the table rows
         *
         * @since 3.1.0
-        * @access protected
+        * @access public
         */
-       function display_rows() {
+       public function display_rows() {
                foreach ( $this->items as $item )
                        $this->single_row( $item );
        }
@@ -817,19 +1233,29 @@ class WP_List_Table {
         * Generates content for a single row of the table
         *
         * @since 3.1.0
-        * @access protected
+        * @access public
         *
         * @param object $item The current item
         */
-       function single_row( $item ) {
-               static $row_class = '';
-               $row_class = ( $row_class == '' ? ' class="alternate"' : '' );
-
-               echo '<tr' . $row_class . '>';
-               echo $this->single_row_columns( $item );
+       public function single_row( $item ) {
+               echo '<tr>';
+               $this->single_row_columns( $item );
                echo '</tr>';
        }
 
+       /**
+        *
+        * @param object $item
+        * @param string $column_name
+        */
+       protected function column_default( $item, $column_name ) {}
+
+       /**
+        *
+        * @param object $item
+        */
+       protected function column_cb( $item ) {}
+
        /**
         * Generates the columns for a single row of the table
         *
@@ -838,75 +1264,106 @@ class WP_List_Table {
         *
         * @param object $item The current item
         */
-       function single_row_columns( $item ) {
-               list( $columns, $hidden ) = $this->get_column_info();
+       protected function single_row_columns( $item ) {
+               list( $columns, $hidden, $sortable, $primary ) = $this->get_column_info();
 
                foreach ( $columns as $column_name => $column_display_name ) {
-                       $class = "class='$column_name column-$column_name'";
+                       $classes = "$column_name column-$column_name";
+                       if ( $primary === $column_name ) {
+                               $classes .= ' has-row-actions column-primary';
+                       }
+
+                       if ( in_array( $column_name, $hidden ) ) {
+                               $classes .= ' hidden';
+                       }
 
-                       $style = '';
-                       if ( in_array( $column_name, $hidden ) )
-                               $style = ' style="display:none;"';
+                       // Comments column uses HTML in the display name with screen reader text.
+                       // Instead of using esc_attr(), we strip tags to get closer to a user-friendly string.
+                       $data = 'data-colname="' . wp_strip_all_tags( $column_display_name ) . '"';
 
-                       $attributes = "$class$style";
+                       $attributes = "class='$classes' $data";
 
-                       if ( 'cb' == $column_name ) {
+                       if ( 'cb' === $column_name ) {
                                echo '<th scope="row" class="check-column">';
                                echo $this->column_cb( $item );
                                echo '</th>';
-                       }
-                       elseif ( method_exists( $this, 'column_' . $column_name ) ) {
+                       } elseif ( method_exists( $this, '_column_' . $column_name ) ) {
+                               echo call_user_func(
+                                       array( $this, '_column_' . $column_name ),
+                                       $item,
+                                       $classes,
+                                       $data,
+                                       $primary
+                               );
+                       } elseif ( method_exists( $this, 'column_' . $column_name ) ) {
                                echo "<td $attributes>";
-                               echo call_user_func( array( &$this, 'column_' . $column_name ), $item );
+                               echo call_user_func( array( $this, 'column_' . $column_name ), $item );
+                               echo $this->handle_row_actions( $item, $column_name, $primary );
                                echo "</td>";
-                       }
-                       else {
+                       } else {
                                echo "<td $attributes>";
                                echo $this->column_default( $item, $column_name );
+                               echo $this->handle_row_actions( $item, $column_name, $primary );
                                echo "</td>";
                        }
                }
        }
 
+       /**
+        * Generates and display row actions links for the list table.
+        *
+        * @since 4.3.0
+        * @access protected
+        *
+        * @param object $item        The item being acted upon.
+        * @param string $column_name Current column name.
+        * @param string $primary     Primary column name.
+        * @return string The row actions HTML, or an empty string if the current column is the primary column.
+        */
+       protected function handle_row_actions( $item, $column_name, $primary ) {
+               return $column_name === $primary ? '<button type="button" class="toggle-row"><span class="screen-reader-text">' . __( 'Show more details' ) . '</span></button>' : '';
+       }
+
        /**
         * Handle an incoming ajax request (called from admin-ajax.php)
         *
         * @since 3.1.0
         * @access public
         */
-       function ajax_response() {
+       public function ajax_response() {
                $this->prepare_items();
 
-               extract( $this->_args );
-               extract( $this->_pagination_args, EXTR_SKIP );
-
                ob_start();
-               if ( ! empty( $_REQUEST['no_placeholder'] ) )
+               if ( ! empty( $_REQUEST['no_placeholder'] ) ) {
                        $this->display_rows();
-               else
+               } else {
                        $this->display_rows_or_placeholder();
+               }
 
                $rows = ob_get_clean();
 
                $response = array( 'rows' => $rows );
 
-               if ( isset( $total_items ) )
-                       $response['total_items_i18n'] = sprintf( _n( '1 item', '%s items', $total_items ), number_format_i18n( $total_items ) );
-
-               if ( isset( $total_pages ) ) {
-                       $response['total_pages'] = $total_pages;
-                       $response['total_pages_i18n'] = number_format_i18n( $total_pages );
+               if ( isset( $this->_pagination_args['total_items'] ) ) {
+                       $response['total_items_i18n'] = sprintf(
+                               _n( '%s item', '%s items', $this->_pagination_args['total_items'] ),
+                               number_format_i18n( $this->_pagination_args['total_items'] )
+                       );
+               }
+               if ( isset( $this->_pagination_args['total_pages'] ) ) {
+                       $response['total_pages'] = $this->_pagination_args['total_pages'];
+                       $response['total_pages_i18n'] = number_format_i18n( $this->_pagination_args['total_pages'] );
                }
 
-               die( json_encode( $response ) );
+               die( wp_json_encode( $response ) );
        }
 
        /**
         * Send required variables to JavaScript land
         *
-        * @access private
+        * @access public
         */
-       function _js_vars() {
+       public function _js_vars() {
                $args = array(
                        'class'  => get_class( $this ),
                        'screen' => array(
@@ -915,6 +1372,6 @@ class WP_List_Table {
                        )
                );
 
-               printf( "<script type='text/javascript'>list_args = %s;</script>\n", json_encode( $args ) );
+               printf( "<script type='text/javascript'>list_args = %s;</script>\n", wp_json_encode( $args ) );
        }
 }