function classic_widget_logic_update_callback($instance, $new_instance)
{
  if (isset($new_instance['classic_widget_logic'])) {
    $instance['classic_widget_logic'] = $new_instance['classic_widget_logic'];
  }

  return $instance;
}

function classic_widget_logic_in_widget_form($widget, $return, $instance)
{
  $logic = isset($instance['classic_widget_logic']) ? $instance['classic_widget_logic'] : classic_widget_logic_by_id($widget->id);
  ?>
        <p>
            <label for="<?php echo $widget->get_field_id('classic_widget_logic'); ?>">条件判断</label>
            <textarea class="widefat" name="<?php echo $widget->get_field_name('classic_widget_logic'); ?>" id="<?php echo $widget->get_field_id('classic_widget_logic'); ?>"><?php echo esc_textarea($logic) ?></textarea>
        </p>
    <?php
return;
}
// 
function classic_widget_logic_by_id($widget_id)
{
  global $classic_options;
  if (preg_match('/^(.+)-(\d+)$/', $widget_id, $m)) {
    $widget_class = $m[1];
    $widget_i     = $m[2];
    $info         = get_option('widget_' . $widget_class);
    if (empty($info[$widget_i])) {
      return '';
    }

    $info = $info[$widget_i];
  } else {
    $info = (array) get_option('widget_' . $widget_id, array());
  }

  if (isset($info['classic_widget_logic'])) {
    $logic = $info['classic_widget_logic'];
  } elseif (isset($wl_options[$widget_id])) {
    $logic = stripslashes($wl_options[$widget_id]);
    classic_widget_logic_save($widget_id, $logic);
    unset($wl_options[$widget_id]);
    update_option('classic_widget_logic', $wl_options);
  } else {
    $logic = '';
  }

  return $logic;
}
// 将数据存到options表中
function classic_widget_logic_save($widget_id, $logic)
{
  global $classic_options;
  if (preg_match('/^(.+)-(\d+)$/', $widget_id, $m)) {
    $widget_class = $m[1];
    $widget_i     = $m[2];
    $info         = get_option('widget_' . $widget_class);
    if (!is_array($info[$widget_i])) {
      $info[$widget_i] = array();
    }

    $info[$widget_i]['classic_widget_logic'] = $logic;
    update_option('widget_' . $widget_class, $info);
  } else {
    $info                       = (array) get_option('widget_' . $widget_id, array());
    $info['classic_widget_logic'] = $logic;
    update_option('widget_' . $widget_id, $info);
  }
}

// CALLED ON 'sidebars_widgets' FILTER
function classic_widget_logic_filter_sidebars_widgets($sidebars_widgets)
{
  global $classic_options, $wl_in_customizer;
  if ($wl_in_customizer) {
    return $sidebars_widgets;
  }

  if (!empty($classic_options['classic_widget_logic-options-wp_reset_query'])) {
    wp_reset_query();
  }

  foreach ($sidebars_widgets as $widget_area => $widget_list) {
    if ($widget_area == 'wp_inactive_widgets' || empty($widget_list)) {
      continue;
    }

    foreach ($widget_list as $pos => $widget_id) {
      $logic = classic_widget_logic_by_id($widget_id); // string(11) "is_single()"
      if (!classic_widget_logic_check_logic($logic)) {
        unset($sidebars_widgets[$widget_area][$pos]);
      }

    }
  }
  return $sidebars_widgets;
}

function classic_widget_logic_check_logic($logic)
{
  $logic = @trim((string) $logic);
  $logic = apply_filters('classic_widget_logic_eval_override', $logic);
  if (is_bool($logic)) {
    return $logic;
  }

  if ($logic === '') {
    return true;
  }

  if (stristr($logic, "return") === false) {
    $logic = "return ( $logic );";
  }

  try {
    $show_widget = eval($logic);
  } catch (Error $e) {
    trigger_error($e->getMessage(), E_USER_WARNING);
    $show_widget = false;
  }
  restore_error_handler();
  return $show_widget;
}
//
if (is_admin()) {
  add_filter('in_widget_form', 'classic_widget_logic_in_widget_form', 10, 3);
  add_filter('widget_update_callback', 'classic_widget_logic_update_callback', 10, 4);
} else {
  add_filter('sidebars_widgets', 'classic_widget_logic_filter_sidebars_widgets', 10);
}