public function adapt_to_model_answer($teacheranswer)
{
// Work out how big the matrix should be from the INSTANTIATED VALUE of the teacher's answer.
$cs = new stack_cas_casstring('ta:matrix_size(' . $teacheranswer . ')');
$cs->get_valid('t');
$at1 = new stack_cas_session(array($cs), null, 0);
$at1->instantiate();
if ('' != $at1->get_errors()) {
$this->errors = $at1->get_errors();
return;
}
$size = $at1->get_value_key('ta');
$dimensions = explode(',', $size);
$this->height = trim($dimensions[0], '[]');
$this->width = trim($dimensions[1], '[]');
}
private function validate()
{
if (empty($this->raw) or '' == trim($this->raw)) {
$this->valid = true;
return true;
}
// CAS keyval may not contain @ or $.
if (strpos($this->raw, '@') !== false || strpos($this->raw, '$') !== false) {
$this->errors = stack_string('illegalcaschars');
$this->valid = false;
return false;
}
// Subtle one: must protect things inside strings before we explode.
$str = $this->raw;
$strings = stack_utils::all_substring_strings($str);
foreach ($strings as $key => $string) {
$str = str_replace('"' . $string . '"', '[STR:' . $key . ']', $str);
}
$str = str_replace("\n", ';', $str);
$str = stack_utils::remove_comments($str);
$str = str_replace(';', "\n", $str);
$kvarray = explode("\n", $str);
foreach ($strings as $key => $string) {
foreach ($kvarray as $kkey => $kstr) {
$kvarray[$kkey] = str_replace('[STR:' . $key . ']', '"' . $string . '"', $kstr);
}
}
// 23/4/12 - significant changes to the way keyvals are interpreted. Use Maxima assignmentsm i.e. x:2.
$errors = '';
$valid = true;
$vars = array();
foreach ($kvarray as $kvs) {
$kvs = trim($kvs);
if ('' != $kvs) {
$cs = new stack_cas_casstring($kvs);
$cs->get_valid($this->security, $this->syntax, $this->insertstars);
$vars[] = $cs;
}
}
$this->session->add_vars($vars);
$this->valid = $this->session->get_valid();
$this->errors = $this->session->get_errors();
}
