/**
* Traverse this node, updating the results array that is used by
* {@link stack_potentialresponse_tree::evaluate_response()}.
*
* @param stack_potentialresponse_tree_state $results to be updated.
* @param int $key the index of this node.
* @param stack_cas_session $cascontext the CAS context that holds all the relevant variables.
* @param stack_options $options
* @return array with two elements, the updated $results and the index of the next node.
*/
public function traverse($results, $key, $cascontext, $options)
{
$errorfree = true;
if ($cascontext->get_errors_key('PRSANS' . $key)) {
$results->_errors .= $cascontext->get_errors_key('PRSANS' . $key);
$results->add_feedback(' ' . stack_string('prtruntimeerror', array('node' => 'PRSANS' . ($key + 1), 'error' => $cascontext->get_errors_key('PRSANS' . $key))));
$errorfree = false;
}
if ($cascontext->get_errors_key('PRTANS' . $key)) {
$results->_errors .= $cascontext->get_errors_key('PRTANS' . $key);
$results->add_feedback(' ' . stack_string('prtruntimeerror', array('node' => 'PRTANS' . ($key + 1), 'error' => $cascontext->get_errors_key('PRTANS' . $key))));
$errorfree = false;
}
if ($cascontext->get_errors_key('PRATOPT' . $key)) {
$results->_errors .= $cascontext->get_errors_key('PRATOPT' . $key);
$results->add_feedback(' ' . stack_string('prtruntimeerror', array('node' => 'PRATOPT' . ($key + 1), 'error' => $cascontext->get_errors_key('PRATOPT' . $key))));
$errorfree = false;
}
if (!$errorfree) {
return -1;
}
$sans = $cascontext->get_value_key('PRSANS' . $key);
$tans = $cascontext->get_value_key('PRTANS' . $key);
$atopts = $cascontext->get_value_key('PRATOPT' . $key);
// If we can't find atopts then they were not processed by the CAS.
// They might still be some in the potential response which do not
// need to be processed.
if (false === $atopts) {
$atopts = null;
}
$nextnode = $this->do_test($sans, $tans, $atopts, $options, $results);
return $nextnode;
}
/**
* This function actually traverses the tree and generates outcomes.
*
* @param stack_cas_session $questionvars the question varaibles.
* @param stack_options $options
* @param array $answers name => value the student response.
* @param int $seed the random number seed.
* @return stack_potentialresponse_tree_state the result.
*/
public function evaluate_response(stack_cas_session $questionvars, $options, $answers, $seed)
{
if (empty($this->nodes)) {
throw new stack_exception('stack_potentialresponse_tree: evaluate_response ' . 'attempting to traverse an empty tree. Something is wrong here.');
}
$localoptions = clone $options;
$localoptions->set_option('simplify', $this->simplify);
$cascontext = $this->create_cas_context_for_evaluation($questionvars, $localoptions, $answers, $seed);
$results = new stack_potentialresponse_tree_state($this->value, true, 0, 0);
// Traverse the tree.
$nodekey = $this->firstnode;
$visitednodes = array();
while ($nodekey != -1) {
if (!array_key_exists($nodekey, $this->nodes)) {
throw new stack_exception('stack_potentialresponse_tree: ' . 'evaluate_response: attempted to jump to a potential response ' . 'which does not exist in this question. This is a question ' . 'authoring/validation problem.');
}
if (array_key_exists($nodekey, $visitednodes)) {
$results->add_answernote('[PRT-CIRCULARITY]=' . $nodekey);
break;
}
$visitednodes[$nodekey] = true;
$nodekey = $this->nodes[$nodekey]->traverse($results, $nodekey, $cascontext, $localoptions);
if ($results->_errors) {
break;
}
}
// Make sure these are PHP numbers.
$results->_score = $results->_score + 0;
$results->_penalty = $results->_penalty + 0;
// Restrict score to be between 0 and 1.
$results->_score = min(max($results->_score, 0), 1);
// From a strictly logical point of view the 'score' and the 'penalty' are independent.
// Hence, this clause belongs in the question behaviour.
// From a practical point of view, it is confusing/off-putting when testing to see "score=1, penalty=0.1".
// Why does this correct attempt attract a penalty? So, this is a unilateral decision:
// If the score is 1 there is never a penalty.
if ($results->_score > 0.99999995) {
$results->_penalty = 0;
}
if ($results->errors) {
$results->_score = null;
$results->_penalty = null;
}
$results->set_cas_context($cascontext, $seed);
return $results;
}
/**
* Actually generate the display of the PRT feedback.
* @param string $name the PRT name.
* @param question_attempt $qa the question attempt to display.
* @param question_definition $question the question being displayed.
* @param stack_potentialresponse_tree_state $result the results to display.
* @param question_display_options $options controls what should and should not be displayed.
* @return string nicely formatted feedback, for display.
*/
protected function prt_feedback_display($name, question_attempt $qa, question_definition $question, stack_potentialresponse_tree_state $result, question_display_options $options, $includestandardfeedback)
{
$err = '';
if ($result->errors) {
$err = $result->errors;
}
$feedback = '';
$feedbackbits = $result->get_feedback();
if ($feedbackbits) {
$feedback = array();
$format = null;
foreach ($feedbackbits as $bit) {
$feedback[] = $qa->rewrite_pluginfile_urls($bit->feedback, 'qtype_stack', $bit->filearea, $bit->itemid);
if (!is_null($bit->format)) {
if (is_null($format)) {
$format = $bit->format;
}
if ($bit->format != $format) {
throw new coding_exception('Inconsistent feedback formats found in PRT ' . $name);
}
}
}
if (is_null($format)) {
$format = FORMAT_HTML;
}
$feedback = $result->substitue_variables_in_feedback(implode(' ', $feedback));
$feedback = format_text(stack_maths::process_display_castext($feedback, $this), $format, array('noclean' => true, 'para' => false));
}
$gradingdetails = '';
if (!$result->errors && $qa->get_behaviour_name() == 'adaptivemultipart') {
// This is rather a hack, but it will probably work.
$renderer = $this->page->get_renderer('qbehaviour_adaptivemultipart');
$gradingdetails = $renderer->render_adaptive_marks($qa->get_behaviour()->get_part_mark_details($name), $options);
}
if ($includestandardfeedback) {
$standardfeedback = $this->standard_prt_feedback($qa, $question, $result);
} else {
$standardfeedback = '';
}
return html_writer::nonempty_tag('div', $standardfeedback . $err . $feedback . $gradingdetails, array('class' => 'stackprtfeedback stackprtfeedback-' . $name));
}
