PHP quiz_clean_layout函数代码示例

/**
 * Upgrade states for an attempt to Moodle 1.5 model
 *
 * Any state that does not yet have its timestamp set to nonzero has not yet been
 * upgraded from Moodle 1.4. The reason these are still around is that for large
 * sites it would have taken too long to upgrade all states at once. This function
 * sets the timestamp field and creates an entry in the question_sessions table.
 * @param object $attempt  The attempt whose states need upgrading
 */
function quiz_upgrade_very_old_question_sessions($attempt)
{
    global $DB;
    // The old quiz model only allowed a single response per quiz attempt so that there will be
    // only one state record per question for this attempt.
    // We set the timestamp of all states to the timemodified field of the attempt.
    $DB->execute("UPDATE {question_states} SET timestamp = ? WHERE attempt = ?", array($attempt->timemodified, $attempt->uniqueid));
    // For each state we create an entry in the question_sessions table, with both newest and
    // newgraded pointing to this state.
    // Actually we only do this for states whose question is actually listed in $attempt->layout.
    // We do not do it for states associated to wrapped questions like for example the questions
    // used by a random question
    $session = new stdClass();
    $session->attemptid = $attempt->uniqueid;
    $session->sumpenalty = 0;
    $session->manualcomment = '';
    $session->manualcommentformat = FORMAT_HTML;
    $session->flagged = 0;
    $questionlist = str_replace(',0', '', quiz_clean_layout($attempt->layout, true));
    if (!$questionlist) {
        return;
    }
    list($usql, $question_params) = $DB->get_in_or_equal(explode(',', $questionlist));
    $params = array_merge(array($attempt->uniqueid), $question_params);
    if ($states = $DB->get_records_select('question_states', "attempt = ? AND question {$usql}", $params)) {
        foreach ($states as $state) {
            if ($DB->record_exists('question_sessions', array('attemptid' => $attempt->uniqueid, 'questionid' => $state->question))) {
                // It was possible for the code to get here when some of the necessary
                // question_sessions were already in the database. That lead to a
                // unique key violation, so we manually detect and avoid that.
                continue;
            }
            $session->newgraded = $state->id;
            $session->newest = $state->id;
            $session->questionid = $state->question;
            $DB->insert_record('question_sessions', $session, false);
        }
    }
    // It was possible to have old question_states records for this attempt but
    // pointing to questionids that were no longer in quiz_attempt->layout.
    // That makes no sense, and will break things later in the upgrade, so delete
    // those now.
    list($qidsql, $params) = $DB->get_in_or_equal(explode(',', $questionlist), SQL_PARAMS_QM, 'param', false);
    $params[] = $attempt->uniqueid;
    $DB->delete_records_select('question_states', "question {$usql} AND attempt = ?", $params);
}

 function test_quiz_clean_layout()
 {
     // Without stripping empty pages.
     $this->assertEqual(quiz_clean_layout(',,1,,,2,,'), '1,2,0');
     $this->assertEqual(quiz_clean_layout(''), '0');
     $this->assertEqual(quiz_clean_layout('0'), '0');
     $this->assertEqual(quiz_clean_layout('0,0'), '0,0');
     $this->assertEqual(quiz_clean_layout('0,0,0'), '0,0,0');
     $this->assertEqual(quiz_clean_layout('1'), '1,0');
     $this->assertEqual(quiz_clean_layout('1,2'), '1,2,0');
     $this->assertEqual(quiz_clean_layout('1,0,2'), '1,0,2,0');
     $this->assertEqual(quiz_clean_layout('0,1,0,0,2,0'), '0,1,0,0,2,0');
     // With stripping empty pages.
     $this->assertEqual(quiz_clean_layout('', true), '0');
     $this->assertEqual(quiz_clean_layout('0', true), '0');
     $this->assertEqual(quiz_clean_layout('0,0', true), '0');
     $this->assertEqual(quiz_clean_layout('0,0,0', true), '0');
     $this->assertEqual(quiz_clean_layout('1', true), '1,0');
     $this->assertEqual(quiz_clean_layout('1,2', true), '1,2,0');
     $this->assertEqual(quiz_clean_layout('1,0,2', true), '1,0,2,0');
     $this->assertEqual(quiz_clean_layout('0,1,0,0,2,0', true), '1,0,2,0');
 }

/**
 * Upgrade states for an attempt to Moodle 1.5 model
 *
 * Any state that does not yet have its timestamp set to nonzero has not yet been
 * upgraded from Moodle 1.4. The reason these are still around is that for large
 * sites it would have taken too long to upgrade all states at once. This function
 * sets the timestamp field and creates an entry in the question_sessions table.
 * @param object $attempt  The attempt whose states need upgrading
 */
function quiz_upgrade_very_old_question_sessions($attempt) {
    global $DB;
    // The old quiz model only allowed a single response per quiz attempt so that there will be
    // only one state record per question for this attempt.

    // We set the timestamp of all states to the timemodified field of the attempt.
    $DB->execute("UPDATE {question_states} SET timestamp = ? WHERE attempt = ?",
            array($attempt->timemodified, $attempt->uniqueid));

    // For each state we create an entry in the question_sessions table, with both newest and
    // newgraded pointing to this state.
    // Actually we only do this for states whose question is actually listed in $attempt->layout.
    // We do not do it for states associated to wrapped questions like for example the questions
    // used by a random question
    $session = new stdClass();
    $session->attemptid = $attempt->uniqueid;
    $session->sumpenalty = 0;
    $session->manualcomment = '';
    $session->manualcommentformat = FORMAT_HTML;
    $session->flagged = 0;

    $questionlist = str_replace(',0', '', quiz_clean_layout($layout, true));
    if (!$questionlist) {
        return;
    }
    list($usql, $question_params) = $DB->get_in_or_equal(explode(',', $questionlist));
    $params = array_merge(array($attempt->uniqueid), $question_params);

    if ($states = $DB->get_records_select('question_states',
            "attempt = ? AND question $usql", $params)) {
        foreach ($states as $state) {
            $session->newgraded = $state->id;
            $session->newest = $state->id;
            $session->questionid = $state->question;
            $DB->insert_record('question_sessions', $session, false);
        }
    }
}

        $select = html_writer::select($randomcount, 'randomcount', '1', null, $attributes);
        $out .= get_string('addrandom', 'quiz', $select);
        $out .= '<input type="hidden" name="recurse" value="' . $recurse . '" />';
        $out .= '<input type="hidden" name="categoryid" value="' . $category->id . '" />';
        $out .= ' <input type="submit" name="addrandom" value="' . get_string('addtoquiz', 'quiz') . '"' . $disabled . ' />';
        $out .= $OUTPUT->help_icon('addarandomquestion', 'quiz');
    }
    return $out;
}
// These params are only passed from page request to request while we stay on
// this page otherwise they would go in question_edit_setup.
$quiz_reordertool = optional_param('reordertool', -1, PARAM_BOOL);
$quiz_qbanktool = optional_param('qbanktool', -1, PARAM_BOOL);
$scrollpos = optional_param('scrollpos', '', PARAM_INT);
list($thispageurl, $contexts, $cmid, $cm, $quiz, $pagevars) = question_edit_setup('editq', '/mod/quiz/edit.php', true);
$quiz->questions = quiz_clean_layout($quiz->questions);
$defaultcategoryobj = question_make_default_categories($contexts->all());
$defaultcategory = $defaultcategoryobj->id . ',' . $defaultcategoryobj->contextid;
if ($quiz_qbanktool > -1) {
    $thispageurl->param('qbanktool', $quiz_qbanktool);
    set_user_preference('quiz_qbanktool_open', $quiz_qbanktool);
} else {
    $quiz_qbanktool = get_user_preferences('quiz_qbanktool_open', 0);
}
if ($quiz_reordertool > -1) {
    $thispageurl->param('reordertool', $quiz_reordertool);
    set_user_preference('quiz_reordertab', $quiz_reordertool);
} else {
    $quiz_reordertool = get_user_preferences('quiz_reordertab', 0);
}
$canaddrandom = $contexts->have_cap('moodle/question:useall');

/**
 * Prints a list of quiz questions for the edit.php main view for edit
 * ($reordertool = false) and order and paging ($reordertool = true) tabs
 *
 * @param object $quiz This is not the standard quiz object used elsewhere but
 *     it contains the quiz layout in $quiz->questions and the grades in
 *     $quiz->grades
 * @param moodle_url $pageurl The url of the current page with the parameters required
 *     for links returning to the current page, as a moodle_url object
 * @param bool $allowdelete Indicates whether the delete icons should be displayed
 * @param bool $reordertool  Indicates whether the reorder tool should be displayed
 * @param bool $quiz_qbanktool  Indicates whether the question bank should be displayed
 * @param bool $hasattempts  Indicates whether the quiz has attempts
 * @param object $defaultcategoryobj
 * @param bool $canaddquestion is the user able to add and use questions anywere?
 * @param bool $canaddrandom is the user able to add random questions anywere?
 */
function quiz_print_question_list($quiz, $pageurl, $allowdelete, $reordertool,
        $quiz_qbanktool, $hasattempts, $defaultcategoryobj, $canaddquestion, $canaddrandom) {
    global $CFG, $DB, $OUTPUT;
    $strorder = get_string('order');
    $strquestionname = get_string('questionname', 'quiz');
    $strmaxmark = get_string('markedoutof', 'question');
    $strremove = get_string('remove', 'quiz');
    $stredit = get_string('edit');
    $strview = get_string('view');
    $straction = get_string('action');
    $strmove = get_string('move');
    $strmoveup = get_string('moveup');
    $strmovedown = get_string('movedown');
    $strsave = get_string('save', 'quiz');
    $strreorderquestions = get_string('reorderquestions', 'quiz');

    $strselectall = get_string('selectall', 'quiz');
    $strselectnone = get_string('selectnone', 'quiz');
    $strtype = get_string('type', 'quiz');
    $strpreview = get_string('preview', 'quiz');

    if ($quiz->questions) {
        list($usql, $params) = $DB->get_in_or_equal(explode(',', $quiz->questions));
        $params[] = $quiz->id;
        $questions = $DB->get_records_sql("SELECT q.*, qc.contextid, qqi.grade as maxmark
                              FROM {question} q
                              JOIN {question_categories} qc ON qc.id = q.category
                              JOIN {quiz_question_instances} qqi ON qqi.question = q.id
                             WHERE q.id $usql AND qqi.quiz = ?", $params);
    } else {
        $questions = array();
    }

    $layout = quiz_clean_layout($quiz->questions);
    $order = explode(',', $layout);
    $lastindex = count($order) - 1;

    $disabled = '';
    $pagingdisabled = '';
    if ($hasattempts) {
        $disabled = 'disabled="disabled"';
    }
    if ($hasattempts || $quiz->shufflequestions) {
        $pagingdisabled = 'disabled="disabled"';
    }

    $reordercontrolssetdefaultsubmit = '<div style="display:none;">' .
        '<input type="submit" name="savechanges" value="' .
        $strreorderquestions . '" ' . $pagingdisabled . ' /></div>';
    $reordercontrols1 = '<div class="addnewpagesafterselected">' .
        '<input type="submit" name="addnewpagesafterselected" value="' .
        get_string('addnewpagesafterselected', 'quiz') . '"  ' .
        $pagingdisabled . ' /></div>';
    $reordercontrols1 .= '<div class="quizdeleteselected">' .
        '<input type="submit" name="quizdeleteselected" ' .
        'onclick="return confirm(\'' .
        get_string('areyousureremoveselected', 'quiz') . '\');" value="' .
        get_string('removeselected', 'quiz') . '"  ' . $disabled . ' /></div>';

    $a = '<input name="moveselectedonpagetop" type="text" size="2" ' .
        $pagingdisabled . ' />';
    $b = '<input name="moveselectedonpagebottom" type="text" size="2" ' .
        $pagingdisabled . ' />';

    $reordercontrols2top = '<div class="moveselectedonpage">' .
        get_string('moveselectedonpage', 'quiz', $a) .
        '<input type="submit" name="savechanges" value="' .
        $strmove . '"  ' . $pagingdisabled . ' />' . '
        <br /><input type="submit" name="savechanges" value="' .
        $strreorderquestions . '" /></div>';
    $reordercontrols2bottom = '<div class="moveselectedonpage">' .
        '<input type="submit" name="savechanges" value="' .
        $strreorderquestions . '" /><br />' .
        get_string('moveselectedonpage', 'quiz', $b) .
        '<input type="submit" name="savechanges" value="' .
        $strmove . '"  ' . $pagingdisabled . ' /> ' . '</div>';

    $reordercontrols3 = '<a href="javascript:select_all_in(\'FORM\', null, ' .
            '\'quizquestions\');">' .
            $strselectall . '</a> /';
    $reordercontrols3.=    ' <a href="javascript:deselect_all_in(\'FORM\', ' .
            'null, \'quizquestions\');">' .
            $strselectnone . '</a>';
//.........这里部分代码省略.........

$viewobj->editurl = new moodle_url('/mod/quiz/edit.php', array('cmid' => $cm->id));
$viewobj->backtocourseurl = new moodle_url('/course/view.php', array('id' => $course->id));
$viewobj->startattempturl = $quizobj->start_attempt_url();
$viewobj->startattemptwarning = $quizobj->confirm_start_attempt_message($unfinished);
$viewobj->popuprequired = $accessmanager->attempt_must_be_in_popup();
$viewobj->popupoptions = $accessmanager->get_popup_options();

// Display information about this quiz.
$viewobj->infomessages = $viewobj->accessmanager->describe_rules();
if ($quiz->attempts != 1) {
    $viewobj->infomessages[] = get_string('gradingmethod', 'quiz',
            quiz_get_grading_option_name($quiz->grademethod));
}

// Determine wheter a start attempt button should be displayed.
$viewobj->quizhasquestions = (bool) quiz_clean_layout($quiz->questions, true);
$viewobj->preventmessages = array();
if (!$viewobj->quizhasquestions) {
    $viewobj->buttontext = '';

} else {
    if ($unfinished) {
        if ($canattempt) {
            $viewobj->buttontext = get_string('continueattemptquiz', 'quiz');
        } else if ($canpreview) {
            $viewobj->buttontext = get_string('continuepreview', 'quiz');
        }

    } else {
        if ($canattempt) {
            $viewobj->preventmessages = $viewobj->accessmanager->prevent_new_attempt(

/**
 * Prints a list of quiz questions for the edit.php main view for edit
 * ($reordertool = false) and order and paging ($reordertool = true) tabs
 *
 * @return int sum of maximum grades
 * @param object $quiz This is not the standard quiz object used elsewhere but
 *     it contains the quiz layout in $quiz->questions and the grades in
 *     $quiz->grades
 * @param object $pageurl The url of the current page with the parameters required
 *     for links returning to the current page, as a moodle_url object
 * @param boolean $allowdelete Indicates whether the delete icons should be displayed
 * @param boolean $reordertool  Indicates whether the reorder tool should be displayed
 * @param boolean $quiz_qbanktool  Indicates whether the question bank should be displayed
 * @param boolean $hasattempts  Indicates whether the quiz has attempts
 */
function quiz_print_question_list($quiz, $pageurl, $allowdelete = true, $reordertool = false, $quiz_qbanktool = false, $hasattempts = false)
{
    global $USER, $CFG, $QTYPES, $DB;
    $strorder = get_string('order');
    $strquestionname = get_string('questionname', 'quiz');
    $strgrade = get_string('grade');
    $strremove = get_string('remove', 'quiz');
    $stredit = get_string('edit');
    $strview = get_string('view');
    $straction = get_string('action');
    $strmove = get_string('move');
    $strmoveup = get_string('moveup');
    $strmovedown = get_string('movedown');
    $strsave = get_string('save', 'quiz');
    $strreorderquestions = get_string('reorderquestions', 'quiz');
    $strselectall = get_string('selectall', 'quiz');
    $strselectnone = get_string('selectnone', 'quiz');
    $strtype = get_string('type', 'quiz');
    $strpreview = get_string('preview', 'quiz');
    if ($quiz->questions) {
        list($usql, $params) = $DB->get_in_or_equal(explode(',', $quiz->questions));
        $questions = $DB->get_records_sql("SELECT q.*,c.contextid\n                              FROM {question} q,\n                                   {question_categories} c\n                             WHERE q.id {$usql}\n                               AND q.category = c.id", $params);
    } else {
        $questions = array();
    }
    $layout = quiz_clean_layout($quiz->questions);
    $order = explode(',', $layout);
    $lastindex = count($order) - 1;
    $disabled = '';
    $pagingdisabled = '';
    if ($hasattempts) {
        $disabled = 'disabled="disabled"';
    }
    if ($hasattempts || $quiz->shufflequestions) {
        $pagingdisabled = 'disabled="disabled"';
    }
    $reordercontrolssetdefaultsubmit = '<div style="display:none;">' . '<input type="submit" name="savechanges" value="' . $strreorderquestions . '" ' . $pagingdisabled . ' /></div>';
    $reordercontrols1 = '<div class="addnewpagesafterselected">' . '<input type="submit" name="addnewpagesafterselected" value="' . get_string('addnewpagesafterselected', 'quiz') . '"  ' . $pagingdisabled . ' /></div>';
    $reordercontrols1 .= '<div class="quizdeleteselected">' . '<input type="submit" name="quizdeleteselected" ' . 'onclick="return confirm(\'' . get_string('areyousureremoveselected', 'quiz') . '\');" value="' . get_string('removeselected', 'quiz') . '"  ' . $disabled . ' /></div>';
    $a = '<input name="moveselectedonpagetop" type="text" size="2" ' . $pagingdisabled . ' />';
    $reordercontrols2top = '<div class="moveselectedonpage">' . get_string('moveselectedonpage', 'quiz', $a) . '<input type="submit" name="savechanges" value="' . $strmove . '"  ' . $pagingdisabled . ' />' . '
        <br /><input type="submit" name="savechanges" value="' . $strreorderquestions . '" /></div>';
    $reordercontrols2bottom = '<div class="moveselectedonpage">' . '<input type="submit" name="savechanges" value="' . $strreorderquestions . '" /><br />' . get_string('moveselectedonpage', 'quiz', $a) . '<input type="submit" name="savechanges" value="' . $strmove . '"  ' . $pagingdisabled . ' /> ' . '</div>';
    $reordercontrols3 = '<a href="javascript:select_all_in(\'FORM\', null, ' . '\'quizquestions\');">' . $strselectall . '</a> /';
    $reordercontrols3 .= ' <a href="javascript:deselect_all_in(\'FORM\', ' . 'null, \'quizquestions\');">' . $strselectnone . '</a>';
    $reordercontrolstop = '<div class="reordercontrols">' . $reordercontrolssetdefaultsubmit . $reordercontrols1 . $reordercontrols2top . $reordercontrols3 . "</div>";
    $reordercontrolsbottom = '<div class="reordercontrols">' . $reordercontrolssetdefaultsubmit . $reordercontrols2bottom . $reordercontrols1 . $reordercontrols3 . "</div>";
    if ($reordertool) {
        echo '<form method="post" action="edit.php" id="quizquestions"><div>';
        echo $pageurl->hidden_params_out();
        echo '<input type="hidden" name="sesskey" value="' . sesskey() . '" />';
        echo $reordercontrolstop;
    }
    //the current question ordinal (no descriptions)
    $qno = 1;
    //the current question (includes questions and descriptions)
    $questioncount = 0;
    //the ordinal of current element in the layout
    //(includes page breaks, questions and descriptions)
    $count = 0;
    //the current page number in iteration
    $pagecount = 0;
    $sumgrade = 0;
    $pageopen = false;
    $returnurl = $pageurl->out();
    $questiontotalcount = count($order);
    foreach ($order as $i => $qnum) {
        $reordercheckbox = '';
        $reordercheckboxlabel = '';
        $reordercheckboxlabelclose = '';
        if ($qnum && empty($questions[$qnum])) {
            continue;
        }
        // If the questiontype is missing change the question type
        if ($qnum && !array_key_exists($questions[$qnum]->qtype, $QTYPES)) {
            $questions[$qnum]->qtype = 'missingtype';
        }
        $deletex = "delete.gif";
        if ($qnum != 0 || $qnum == 0 && !$pageopen) {
            //this is either a question or a page break after another
            //        (no page is currently open)
            if (!$pageopen) {
                //if no page is open, start display of a page
                $pagecount++;
                echo '<div class="quizpage"><span class="pagetitle">' . get_string('page') . '&nbsp;' . $pagecount . '</span><div class="pagecontent">';
//.........这里部分代码省略.........

 private function determine_layout()
 {
     $this->pagelayout = array();
     // Break up the layout string into pages.
     $pagelayouts = explode(',0', quiz_clean_layout($this->attempt->layout, true));
     // Strip off any empty last page (normally there is one).
     if (end($pagelayouts) == '') {
         array_pop($pagelayouts);
     }
     // File the ids into the arrays.
     $this->pagelayout = array();
     foreach ($pagelayouts as $page => $pagelayout) {
         $pagelayout = trim($pagelayout, ',');
         if ($pagelayout == '') {
             continue;
         }
         $this->pagelayout[$page] = explode(',', $pagelayout);
     }
 }

/**
 * Returns the number of questions in the quiz layout
 *
 * @param string $layout the string representing the quiz layout.
 * @return int The number of questions in the quiz.
 */
function quiz_number_of_questions_in_quiz($layout) {
    $layout = quiz_questions_in_quiz(quiz_clean_layout($layout));
    $count = substr_count($layout, ',');
    if ($layout !== '') {
        $count++;
    }
    return $count;
}

        $resultinfo .= '<p class="quizteacherfeedback">' . $gradebookfeedback . "</p>\n";
    }
    if ($feedbackcolumn) {
        $resultinfo .= $OUTPUT->heading(get_string('overallfeedback', 'quiz'), 3, 'main');
        $resultinfo .= '<p class="quizgradefeedback">' . quiz_feedback_for_grade($mygrade, $quiz, $context, $cm) . "</p>\n";
    }
    if ($resultinfo) {
        echo $OUTPUT->box($resultinfo, 'generalbox', 'feedback');
    }
}
/// Determine if we should be showing a start/continue attempt button,
/// or a button to go back to the course page.
echo $OUTPUT->box_start('quizattempt');
$buttontext = '';
// This will be set something if as start/continue attempt button should appear.
if (!quiz_clean_layout($quiz->questions, true)) {
    echo $OUTPUT->heading(get_string("noquestions", "quiz"));
} else {
    if ($unfinished) {
        if ($canpreview) {
            $buttontext = get_string('continuepreview', 'quiz');
        } else {
            if ($canattempt) {
                $buttontext = get_string('continueattemptquiz', 'quiz');
            }
        }
    } else {
        if ($canpreview) {
            $buttontext = get_string('previewquiznow', 'quiz');
        } else {
            if ($canattempt) {

/**
 * Given an object containing all the necessary data,
 * (defined by the form in mod_form.php) this function
 * will update an existing instance with new data.
 *
 * @param object $quiz the data that came from the form.
 * @return mixed true on success, false or a string error message on failure.
 */
function quiz_update_instance($quiz, $mform) {
    global $CFG, $DB;

    // Process the options from the form.
    $result = quiz_process_options($quiz);
    if ($result && is_string($result)) {
        return $result;
    }

    $oldquiz = $DB->get_record('quiz', array('id' => $quiz->instance));

    // Repaginate, if asked to.
    if (!$quiz->shufflequestions && !empty($quiz->repaginatenow)) {
        require_once($CFG->dirroot . '/mod/quiz/locallib.php');
        $quiz->questions = quiz_repaginate(quiz_clean_layout($oldquiz->questions, true),
                $quiz->questionsperpage);
    }
    unset($quiz->repaginatenow);

    // Update the database.
    $quiz->id = $quiz->instance;
    $DB->update_record('quiz', $quiz);

    // Do the processing required after an add or an update.
    quiz_after_add_or_update($quiz);

    if ($oldquiz->grademethod != $quiz->grademethod) {
        require_once($CFG->dirroot . '/mod/quiz/locallib.php');
        $quiz->sumgrades = $oldquiz->sumgrades;
        $quiz->grade = $oldquiz->grade;
        quiz_update_all_final_grades($quiz);
        quiz_update_grades($quiz);
    }

    // Delete any previous preview attempts.
    quiz_delete_previews($quiz);

    return true;
}

/**
 * Given an object containing all the necessary data,
 * (defined by the form in mod_form.php) this function
 * will update an existing instance with new data.
 *
 * @param object $quiz the data that came from the form.
 * @return mixed true on success, false or a string error message on failure.
 */
function quiz_update_instance($quiz, $mform)
{
    global $CFG, $DB;
    require_once $CFG->dirroot . '/mod/quiz/locallib.php';
    // Process the options from the form.
    $result = quiz_process_options($quiz);
    if ($result && is_string($result)) {
        return $result;
    }
    // Get the current value, so we can see what changed.
    $oldquiz = $DB->get_record('quiz', array('id' => $quiz->instance));
    // We need two values from the existing DB record that are not in the form,
    // in some of the function calls below.
    $quiz->sumgrades = $oldquiz->sumgrades;
    $quiz->grade = $oldquiz->grade;
    // Repaginate, if asked to.
    if (!$quiz->shufflequestions && !empty($quiz->repaginatenow)) {
        $quiz->questions = quiz_repaginate(quiz_clean_layout($oldquiz->questions, true), $quiz->questionsperpage);
    }
    unset($quiz->repaginatenow);
    // Update the database.
    $quiz->id = $quiz->instance;
    $DB->update_record('quiz', $quiz);
    // Do the processing required after an add or an update.
    quiz_after_add_or_update($quiz);
    if ($oldquiz->grademethod != $quiz->grademethod) {
        quiz_update_all_final_grades($quiz);
        quiz_update_grades($quiz);
    }
    $quizdateschanged = $oldquiz->timelimit != $quiz->timelimit || $oldquiz->timeclose != $quiz->timeclose || $oldquiz->graceperiod != $quiz->graceperiod;
    if ($quizdateschanged) {
        quiz_update_open_attempts(array('quizid' => $quiz->id));
    }
    // Delete any previous preview attempts.
    quiz_delete_previews($quiz);
    return true;
}

/**
 * Update the sumgrades field of the quiz. This needs to be called whenever
 * the grading structure of the quiz is changed. For example if a question is
 * added or removed, or a question weight is changed.
 *
 * @param object $quiz a quiz.
 */
function quiz_update_sumgrades($quiz) {
    global $DB;
    $sql = 'UPDATE {quiz}
            SET sumgrades = COALESCE((
                SELECT SUM(grade)
                FROM {quiz_question_instances}
                WHERE quiz = {quiz}.id
            ), 0)
            WHERE id = ?';
    $DB->execute($sql, array($quiz->id));
    $quiz->sumgrades = $DB->get_field('quiz', 'sumgrades', array('id' => $quiz->id));
    if ($quiz->sumgrades < 0.000005 && quiz_clean_layout($quiz->questions, true)) {
        // If there is at least one question in the quiz, and the sumgrades has been
        // set to 0, then also set the maximum possible grade to 0.
        quiz_set_grade(0, $quiz);
    }
}

/**
 * Creates an object to represent a new attempt at a quiz
 *
 * Creates an attempt object to represent an attempt at the quiz by the current
 * user starting at the current time. The ->id field is not set. The object is
 * NOT written to the database.
 *
 * @param object $quiz the quiz to create an attempt for.
 * @param integer $attemptnumber the sequence number for the attempt.
 * @param object $lastattempt the previous attempt by this user, if any. Only needed
 *         if $attemptnumber > 1 and $quiz->attemptonlast is true.
 * @param integer $timenow the time the attempt was started at.
 * @param boolean $ispreview whether this new attempt is a preview.
 *
 * @return object the newly created attempt object.
 */
function quiz_create_attempt($quiz, $attemptnumber, $lastattempt, $timenow, $ispreview = false)
{
    global $USER;
    if ($attemptnumber == 1 || !$quiz->attemptonlast) {
        /// We are not building on last attempt so create a new attempt.
        $attempt = new stdClass();
        $attempt->quiz = $quiz->id;
        $attempt->userid = $USER->id;
        $attempt->preview = 0;
        if ($quiz->shufflequestions) {
            $attempt->layout = quiz_clean_layout(quiz_repaginate($quiz->questions, $quiz->questionsperpage, true), true);
        } else {
            $attempt->layout = quiz_clean_layout($quiz->questions, true);
        }
    } else {
        /// Build on last attempt.
        if (empty($lastattempt)) {
            print_error('cannotfindprevattempt', 'quiz');
        }
        $attempt = $lastattempt;
    }
    $attempt->attempt = $attemptnumber;
    $attempt->sumgrades = 0.0;
    $attempt->timestart = $timenow;
    $attempt->timefinish = 0;
    $attempt->timemodified = $timenow;
    $attempt->uniqueid = question_new_attempt_uniqueid();
    /// If this is a preview, mark it as such.
    if ($ispreview) {
        $attempt->preview = 1;
    }
    return $attempt;
}

 /**
  * Populate {@link $questionids} and {@link $pagequestionids} from the layout.
  */
 protected function determine_layout()
 {
     $this->questionids = array();
     $this->pagequestionids = array();
     // Get the appropriate layout string (from quiz or attempt).
     $layout = $this->get_layout_string();
     if (empty($layout)) {
         // Nothing to do.
         return;
     }
     // Break up the layout string into pages.
     $pagelayouts = explode(',0', quiz_clean_layout($layout, true));
     // Strip off any empty last page (normally there is one).
     if (end($pagelayouts) == '') {
         array_pop($pagelayouts);
     }
     // File the ids into the arrays.
     $this->questionids = array();
     $this->pagequestionids = array();
     foreach ($pagelayouts as $page => $pagelayout) {
         $pagelayout = trim($pagelayout, ',');
         if ($pagelayout == '') {
             continue;
         }
         $this->pagequestionids[$page] = explode(',', $pagelayout);
         foreach ($this->pagequestionids[$page] as $id) {
             $this->questionids[] = $id;
         }
     }
 }