/**
 *
 */
function forum_print_discussion($course, $cm, $forum, $discussion, $post, $mode, $canreply = NULL, $canrate = false)
{
    global $USER, $CFG;
    if (!empty($USER->id)) {
        $ownpost = $USER->id == $post->userid;
    } else {
        $ownpost = false;
    }
    if ($canreply === NULL) {
        $modcontext = get_context_instance(CONTEXT_MODULE, $cm->id);
        $reply = forum_user_can_post($forum, $discussion, $USER, $cm, $course, $modcontext);
    } else {
        $reply = $canreply;
    }
    // $cm holds general cache for forum functions
    $cm->cache = new object();
    $cm->cache->groups = groups_get_all_groups($course->id, 0, $cm->groupingid);
    $cm->cache->usersgroups = array();
    $posters = array();
    // preload all posts - TODO: improve...
    if ($mode == FORUM_MODE_FLATNEWEST) {
        $sort = "p.created DESC";
    } else {
        $sort = "p.created ASC";
    }
    $forumtracked = forum_tp_is_tracked($forum);
    $posts = forum_get_all_discussion_posts($discussion->id, $sort, $forumtracked);
    $post = $posts[$post->id];
    foreach ($posts as $pid => $p) {
        $posters[$p->userid] = $p->userid;
    }
    // preload all groups of ppl that posted in this discussion
    if ($postersgroups = groups_get_all_groups($course->id, $posters, $cm->groupingid, 'gm.id, gm.groupid, gm.userid')) {
        foreach ($postersgroups as $pg) {
            if (!isset($cm->cache->usersgroups[$pg->userid])) {
                $cm->cache->usersgroups[$pg->userid] = array();
            }
            $cm->cache->usersgroups[$pg->userid][$pg->groupid] = $pg->groupid;
        }
        unset($postersgroups);
    }
    $ratings = NULL;
    $ratingsmenuused = false;
    $ratingsformused = false;
    if ($forum->assessed and isloggedin()) {
        if ($ratings->scale = make_grades_menu($forum->scale)) {
            $ratings->assesstimestart = $forum->assesstimestart;
            $ratings->assesstimefinish = $forum->assesstimefinish;
            $ratings->allow = $canrate;
            if ($ratings->allow) {
                echo '<form id="form" method="post" action="rate.php">';
                echo '<div class="ratingform">';
                echo '<input type="hidden" name="forumid" value="' . $forum->id . '" />';
                $ratingsformused = true;
            }
            // preload all ratings - one query only and minimal memory
            $cm->cache->ratings = array();
            $cm->cache->myratings = array();
            if ($postratings = forum_get_all_discussion_ratings($discussion)) {
                foreach ($postratings as $pr) {
                    if (!isset($cm->cache->ratings[$pr->postid])) {
                        $cm->cache->ratings[$pr->postid] = array();
                    }
                    $cm->cache->ratings[$pr->postid][$pr->id] = $pr->rating;
                    if ($pr->userid == $USER->id) {
                        $cm->cache->myratings[$pr->postid] = $pr->rating;
                    }
                }
                unset($postratings);
            }
        }
    }
    $post->forum = $forum->id;
    // Add the forum id to the post object, later used by forum_print_post
    $post->forumtype = $forum->type;
    $post->subject = format_string($post->subject);
    $postread = !empty($post->postread);
    if (forum_print_post($post, $discussion, $forum, $cm, $course, $ownpost, $reply, false, $ratings, '', '', $postread, true, $forumtracked)) {
        $ratingsmenuused = true;
    }
    switch ($mode) {
        case FORUM_MODE_FLATOLDEST:
        case FORUM_MODE_FLATNEWEST:
        default:
            if (forum_print_posts_flat($course, $cm, $forum, $discussion, $post, $mode, $ratings, $reply, $forumtracked, $posts)) {
                $ratingsmenuused = true;
            }
            break;
        case FORUM_MODE_THREADED:
            if (forum_print_posts_threaded($course, $cm, $forum, $discussion, $post, 0, $ratings, $reply, $forumtracked, $posts)) {
                $ratingsmenuused = true;
            }
            break;
        case FORUM_MODE_NESTED:
            if (forum_print_posts_nested($course, $cm, $forum, $discussion, $post, $ratings, $reply, $forumtracked, $posts)) {
                $ratingsmenuused = true;
            }
//.........这里部分代码省略.........

//.........这里部分代码省略.........
 * @param int $mode
 * @param mixed $canreply
 * @param bool $canrate
 */
function forum_print_discussion($course, $cm, $forum, $discussion, $post, $mode, $canreply=NULL, $canrate=false) {
    global $USER, $CFG;

    require_once($CFG->dirroot.'/rating/lib.php');

    $ownpost = (isloggedin() && $USER->id == $post->userid);

    $modcontext = context_module::instance($cm->id);
    if ($canreply === NULL) {
        $reply = forum_user_can_post($forum, $discussion, $USER, $cm, $course, $modcontext);
    } else {
        $reply = $canreply;
    }

    // $cm holds general cache for forum functions
    $cm->cache = new stdClass;
    $cm->cache->groups      = groups_get_all_groups($course->id, 0, $cm->groupingid);
    $cm->cache->usersgroups = array();

    $posters = array();

    // preload all posts - TODO: improve...
    if ($mode == FORUM_MODE_FLATNEWEST) {
        $sort = "p.created DESC";
    } else {
        $sort = "p.created ASC";
    }

    $forumtracked = forum_tp_is_tracked($forum);
    $posts = forum_get_all_discussion_posts($discussion->id, $sort, $forumtracked);
    $post = $posts[$post->id];

    foreach ($posts as $pid=>$p) {
        $posters[$p->userid] = $p->userid;
    }

    // preload all groups of ppl that posted in this discussion
    if ($postersgroups = groups_get_all_groups($course->id, $posters, $cm->groupingid, 'gm.id, gm.groupid, gm.userid')) {
        foreach($postersgroups as $pg) {
            if (!isset($cm->cache->usersgroups[$pg->userid])) {
                $cm->cache->usersgroups[$pg->userid] = array();
            }
            $cm->cache->usersgroups[$pg->userid][$pg->groupid] = $pg->groupid;
        }
        unset($postersgroups);
    }

    //load ratings
    if ($forum->assessed != RATING_AGGREGATE_NONE) {
        $ratingoptions = new stdClass;
        $ratingoptions->context = $modcontext;
        $ratingoptions->component = 'mod_forum';
        $ratingoptions->ratingarea = 'post';
        $ratingoptions->items = $posts;
        $ratingoptions->aggregate = $forum->assessed;//the aggregation method
        $ratingoptions->scaleid = $forum->scale;
        $ratingoptions->userid = $USER->id;
        if ($forum->type == 'single' or !$discussion->id) {
            $ratingoptions->returnurl = "$CFG->wwwroot/mod/forum/view.php?id=$cm->id";
        } else {
            $ratingoptions->returnurl = "$CFG->wwwroot/mod/forum/discuss.php?d=$discussion->id";
        }
        $ratingoptions->assesstimestart = $forum->assesstimestart;
        $ratingoptions->assesstimefinish = $forum->assesstimefinish;

        $rm = new rating_manager();
        $posts = $rm->get_ratings($ratingoptions);
    }


    $post->forum = $forum->id;   // Add the forum id to the post object, later used by forum_print_post
    $post->forumtype = $forum->type;

    $post->subject = format_string($post->subject);

    $postread = !empty($post->postread);

    forum_print_post($post, $discussion, $forum, $cm, $course, $ownpost, $reply, false,
                         '', '', $postread, true, $forumtracked);

    switch ($mode) {
        case FORUM_MODE_FLATOLDEST :
        case FORUM_MODE_FLATNEWEST :
        default:
            forum_print_posts_flat($course, $cm, $forum, $discussion, $post, $mode, $reply, $forumtracked, $posts);
            break;

        case FORUM_MODE_THREADED :
            forum_print_posts_threaded($course, $cm, $forum, $discussion, $post, 0, $reply, $forumtracked, $posts);
            break;

        case FORUM_MODE_NESTED :
            forum_print_posts_nested($course, $cm, $forum, $discussion, $post, $reply, $forumtracked, $posts);
            break;
    }
}