/**
* Create the actual response data. The response data in the test case may
* include expressions in terms of the question variables.
* @param qtype_stack_question $question the question - with $question->session initialised.
* @return array the respones to send to $quba->process_action.
*/
public static function compute_response(qtype_stack_question $question, $inputs)
{
// If the question has simp:false, then the local options should reflect this.
// In this case, test constructors (question authors) will need to explicitly simplify their test case constructions.
$localoptions = clone $question->options;
// Start with the question variables (note that order matters here).
$cascontext = new stack_cas_session(null, $localoptions, $question->seed);
$question->add_question_vars_to_session($cascontext);
// Turn off simplification - we *always* need test cases to be unsimplified, even if the question option is true.
$vars = array();
$cs = new stack_cas_casstring('false');
$cs->set_key('simp');
$vars[] = $cs;
// Now add the expressions we want evaluated.
foreach ($inputs as $name => $value) {
if ('' !== $value) {
$cs = new stack_cas_casstring($value);
if ($cs->get_valid('t')) {
$cs->set_key('testresponse_' . $name);
$vars[] = $cs;
}
}
}
$cascontext->add_vars($vars);
$cascontext->instantiate();
$response = array();
foreach ($inputs as $name => $notused) {
$computedinput = $cascontext->get_value_key('testresponse_' . $name);
// In the case we start with an invalid input, and hence don't send it to the CAS
// We want the response to constitute the raw invalid input.
// This permits invalid expressions in the inputs, and to compute with valid expressions.
if ('' == $computedinput) {
$computedinput = $inputs[$name];
}
if (array_key_exists($name, $question->inputs)) {
$response = array_merge($response, $question->inputs[$name]->maxima_to_response_array($computedinput));
}
}
return $response;
}
/**
* Display and appropriate piece of standard PRT feedback given the overall
* state of the question.
* @param question_attempt $qa
* @param qtype_stack_question $question the question being displayed.
* @param array $response the current response.
* @return string HTML fragment.
*/
protected function overall_standard_prt_feedback(question_attempt $qa, qtype_stack_question $question, $response)
{
$fraction = null;
foreach ($question->prts as $name => $prt) {
$relevantresponse = $this->get_applicable_response_for_prt($name, $response, $qa);
if (is_null($relevantresponse)) {
continue;
}
$result = $question->get_prt_result($name, $relevantresponse, $qa->get_state()->is_finished());
if (is_null($result->valid)) {
continue;
}
$fraction += $result->fraction;
}
if (is_null($fraction)) {
return '';
}
$result = new stack_potentialresponse_tree_state(1, true, $fraction);
return $this->standard_prt_feedback($qa, $qa->get_question(), $result);
}
