/**
* Validate a CAS string field to make sure that: 1. it fits in the DB, and
* 2. that it is syntactically valid.
* @param array $errors the errors array that validation is assembling.
* @param string $value the submitted value validate.
* @param string $fieldname the name of the field add any errors to.
* @param string $savesession the array key to save the string to in $this->validationcasstrings.
* @param bool|string $notblank false means do nothing (default). A string
* will validate that the field is not blank, and if it is, display that error.
* @param int $maxlength the maximum allowable length. Defaults to 255.
* @return array updated $errors array.
*/
protected function validate_cas_string($errors, $value, $fieldname, $savesession, $notblank = true, $maxlength = 255)
{
if ($notblank && '' === trim($value)) {
$errors[$fieldname][] = stack_string('nonempty');
} else {
if (strlen($value) > $maxlength) {
$errors[$fieldname][] = stack_string('strlengtherror');
} else {
$casstring = new stack_cas_casstring($value);
if (!$casstring->get_valid('t')) {
$errors[$fieldname][] = $casstring->get_errors();
}
}
}
return $errors;
}
/**
* Validates the options, when needed.
*
* @return (bool, string)
* @access public
*/
public function validate_atoptions($opt)
{
if ($this->processcasoptions) {
$cs = new stack_cas_casstring($opt);
return array($cs->get_valid('t'), $cs->get_errors());
}
return array(true, '');
}
public function do_test()
{
$this->atmark = 1;
$anotes = array();
// Note that in casting to an integer we are lucky here.
// Non-integer strings get cast to zero, which is invalid anyway....
$atestops = (int) $this->atoption;
if (!is_int($atestops) or $atestops <= 0) {
$this->aterror = 'TEST_FAILED';
$this->atfeedback = stack_string('TEST_FAILED', array('errors' => ''));
$this->atfeedback .= stack_string('ATNumDecPlaces_OptNotInt', array('opt' => $this->atoption));
$this->atansnote = 'ATNumDecPlaces_STACKERROR_Option.';
$this->atmark = 0;
$this->atvalid = false;
return null;
}
$commands = array($this->sanskey, $this->tanskey, (string) $this->atoption);
foreach ($commands as $com) {
$cs = new stack_cas_casstring($com);
if (!$cs->get_valid('t', true, 0)) {
$this->aterror = 'TEST_FAILED';
$this->atfeedback = stack_string('TEST_FAILED', array('errors' => ''));
$this->atfeedback .= stack_string('AT_InvalidOptions', array('errors' => $cs->get_errors()));
$this->atansnote = 'ATNumDecPlaces_STACKERROR_Option.';
$this->atmark = 0;
$this->atvalid = false;
return null;
}
}
// Check that the first expression is a floating point number,
// with the right number of decimal places.
$sans = explode('.', $this->sanskey);
if (2 === count($sans)) {
if ($atestops != strlen($sans[1])) {
$this->atfeedback .= stack_string('ATNumDecPlaces_Wrong_DPs');
$anotes[] = 'ATNumDecPlaces_Wrong_DPs (' . strlen($sans[1]) . ' <> ' . $atestops . ')';
$this->atmark = 0;
} else {
$anotes[] = 'ATNumDecPlaces_Correct';
}
} else {
// No '.' found.
$this->atfeedback .= stack_string('ATNumDecPlaces_NoDP');
$anotes[] = 'ATNumDecPlaces_NoDP';
$this->atmark = 0;
}
// Check that the two numbers evaluate to the same value.
$cascommands = array();
$cascommands[] = "caschat2:ev({$this->atoption},simp)";
$cascommands[] = "caschat0:ev(float(round(10^caschat2*{$this->sanskey})/10^caschat2),simp)";
$cascommands[] = "caschat1:ev(float(round(10^caschat2*{$this->tanskey})/10^caschat2),simp)";
$cascommands[] = "caschat3:ev(second(ATAlgEquiv(caschat0,caschat1)),simp)";
$cts = array();
foreach ($cascommands as $com) {
$cs = new stack_cas_casstring($com);
$cs->get_valid('t', true, 0);
$cts[] = $cs;
}
$session = new stack_cas_session($cts, null, 0);
$session->instantiate();
if ('' != $session->get_errors_key('caschat0')) {
$this->aterror = 'TEST_FAILED';
$this->atfeedback = stack_string('TEST_FAILED', array('errors' => $session->get_errors_key('caschat0')));
$anotes[] = 'ATNumDecPlaces_STACKERROR_SAns';
$this->atansnote = implode('. ', $anotes) . '.';
$this->atmark = 0;
$this->atvalid = false;
return null;
}
if ('' != $session->get_errors_key('caschat1')) {
$this->aterror = 'TEST_FAILED';
$this->atfeedback = stack_string('TEST_FAILED', array('errors' => $session->get_errors_key('caschat1')));
$anotes[] = 'ATNumDecPlaces_STACKERROR_TAns';
$this->atansnote = implode('. ', $anotes) . '.';
$this->atmark = 0;
$this->atvalid = false;
return null;
}
if ('' != $session->get_errors_key('caschat2')) {
$this->aterror = 'TEST_FAILED';
$this->atfeedback = stack_string('TEST_FAILED', array('errors' => ''));
$this->atfeedback .= stack_string('AT_InvalidOptions', array('errors' => $session->get_errors_key('caschat2')));
$anotes[] = 'ATNumDecPlaces_STACKERROR_Options.';
$this->atansnote = implode('. ', $anotes) . '.';
$this->atmark = 0;
$this->atvalid = false;
return null;
}
if ($session->get_value_key('caschat3') == 'true') {
// Note, we only want the mark to *stay* at 1.
$this->atmark *= 1;
$anotes[] = 'ATNumDecPlaces_Equiv';
} else {
$this->atmark = 0;
$anotes[] = 'ATNumDecPlaces_Not_equiv';
}
$this->atansnote = implode('. ', $anotes) . '.';
if ($this->atmark) {
return true;
}
return false;
}
public function test_strings_4()
{
$s = 'a:["system(\'rm *\')",3*x]';
$at1 = new stack_cas_casstring($s);
$this->assertFalse($at1->get_valid('t'));
$this->assertEquals('The expression <span class="stacksyntaxexample">system</span> is forbidden.', $at1->get_errors());
}
/**
* This is the basic validation of the student's "answer".
* This method is only called if the input is not blank.
*
* Only a few input methods need to modify this method.
* For example, Matrix types have two dimensional contents arrays to loop over.
*
* @param array $contents the content array of the student's input.
* @return array of the validity, errors strings and modified contents.
*/
protected function validate_contents($contents, $forbiddenkeys)
{
$errors = $this->extra_validation($contents);
$valid = !$errors;
// Now validate the input as CAS code.
$modifiedcontents = array();
$allowwords = $this->get_parameter('allowWords', '');
foreach ($contents as $val) {
$answer = new stack_cas_casstring($val);
$answer->get_valid('s', $this->get_parameter('strictSyntax', true), $this->get_parameter('insertStars', 0), $allowwords);
// Ensure student hasn't used a variable name used by the teacher.
if ($forbiddenkeys) {
$answer->check_external_forbidden_words($forbiddenkeys);
}
$forbiddenwords = $this->get_parameter('forbidWords', '');
if ($forbiddenwords) {
$answer->check_external_forbidden_words_literal($forbiddenwords);
}
$modifiedcontents[] = $answer->get_casstring();
$valid = $valid && $answer->get_valid();
$errors .= $answer->get_errors();
}
return array($valid, $errors, $modifiedcontents);
}
public static function run_test($test)
{
// Note: What we would really like to do is the following.
// $el = stack_input_factory::make('algebraic', 'sans1', 'x');
// $el->set_parameter('insertStars', 1);
// $el->set_parameter('strictSyntax', false);
// $el->set_parameter('sameType', false);
// $cs = $el->validate_student_response($test->rawstring);
// However, we want to pull apart the bits to expose where the various errors occur.
$cs = new stack_cas_casstring($test->rawstring);
$cs->get_valid('s', false, 1);
$cs->set_cas_validation_casstring('sans1', true, true, false, null);
$phpvalid = $cs->get_valid();
if ($phpvalid) {
// Trim off stack_validate_typeless([..], true, true).
$phpcasstring = $cs->get_casstring();
$phpcasstring = substr($phpcasstring, 25);
$phpcasstring = substr($phpcasstring, 0, strlen($phpcasstring) - 12);
$outputphpcasstring = $phpcasstring;
} else {
$phpcasstring = '';
$outputphpcasstring = 'N/A...';
}
$errors = $cs->get_errors();
$passed = true;
if ('php_true' === $test->phpvalid) {
$expected = true;
} else {
$expected = false;
}
if ($phpvalid != $expected) {
$passed = false;
$errors .= ' ' . stack_string('phpvalidatemismatch');
}
if ($phpvalid && $phpcasstring != $test->phpcasstring) {
$passed = false;
$errors .= ' ' . stack_maxima_format_casstring($phpcasstring) . ' \\(\\neq \\) ' . stack_maxima_format_casstring($test->phpcasstring);
}
$casvalid = '';
$caserrors = '';
$casvalue = '';
$casdisplay = '';
if ($cs->get_valid()) {
$options = new stack_options();
$options->set_option('simplify', false);
$session = new stack_cas_session(array($cs), $options, 0);
$session->instantiate();
$session = $session->get_session();
$cs = $session[0];
$caserrors = stack_maxima_translate($cs->get_errors());
$casvalue = stack_maxima_format_casstring($cs->get_value());
if ('cas_true' == $test->casvalid) {
$casexpected = true;
} else {
$casexpected = false;
}
if ('' == $cs->get_value()) {
$casvalid = false;
} else {
$casvalid = true;
}
if ($casexpected != $casvalid) {
$passed = false;
$caserrors .= ' ' . stack_string('casvalidatemismatch');
}
$casdisplay = $cs->get_display();
}
$answernote = $cs->get_answernote();
if ($answernote != $test->ansnotes) {
$passed = false;
$errors .= ' ' . stack_string('ansnotemismatch');
}
return array($passed, $phpvalid, $phpcasstring, $errors, $casvalid, $caserrors, $casdisplay, $casvalue, $answernote);
}
/**
* Extract the CAS commands from the string
*
* @access public
* @return bool false if no commands to extract, true if succeeds.
*/
private function extract_cas_commands()
{
// First check contains @s.
$count = preg_match_all('~(?<!@)@(?!@)~', $this->trimmedcastext, $notused);
if ($count == 0) {
// Nothing to do.
return null;
} else {
// Extract the CAS commands.
$temp = stack_utils::all_substring_between($this->trimmedcastext, '@', '@', true);
// Create array of commands matching with their labels.
$i = 0;
$valid = true;
$errors = '';
$cmdarray = array();
$labels = array();
$sessionkeys = array();
if (is_a($this->session, 'stack_cas_session')) {
$sessionkeys = $this->session->get_all_keys();
}
foreach ($temp as $cmd) {
// Trim of surrounding white space and CAS commands.
$cmd = stack_utils::trim_commands($cmd);
$cs = new stack_cas_casstring($cmd);
$cs->get_valid($this->security, $this->syntax, $this->insertstars);
do {
// ... make sure names are not already in use.
$key = 'caschat' . $i;
$i++;
} while (in_array($key, $sessionkeys));
$sesionkeys[] = $key;
$labels[] = $key;
$cs->set_key($key, true);
$cmdarray[] = $cs;
$valid = $valid && $cs->get_valid();
$errors .= $cs->get_errors();
}
if (!$valid) {
$this->valid = false;
$this->errors .= stack_string('stackCas_invalidCommand') . '</br>' . $errors;
}
if (!empty($cmdarray)) {
$newsession = $this->session;
if (null === $newsession) {
$newsession = new stack_cas_session($cmdarray, null, $this->seed);
} else {
$newsession->add_vars($cmdarray);
}
$this->session = $newsession;
// Now replace the commannds with their labels in the text.
$this->trimmedcastext = stack_utils::replace_between($this->trimmedcastext, '@', '@', $labels, true);
}
}
}