/**
* Tests the changed params
*/
function test__changing_params() {
$formula = new calc_formula('=a+b+c', array('a'=>10,'b'=>20,'c'=>30));
$res = $formula->evaluate();
$this->assertEqual($res, 60, '10+20+30 is: %s');
$formula->set_params(array('a'=>1,'b'=>2,'c'=>3));
$res = $formula->evaluate();
$this->assertEqual($res, 6, 'changed params 1+2+3 is: %s');
}
/**
* Validate the formula.
* @param string $formula
* @return boolean true if calculation possible, false otherwise
*/
function validate_formula($formulastr)
{
global $CFG;
require_once $CFG->libdir . '/mathslib.php';
$formulastr = grade_item::normalize_formula($formulastr, $this->courseid);
if (empty($formulastr)) {
return true;
}
if (strpos($formulastr, '=') !== 0) {
return get_string('errorcalculationnoequal', 'grades');
}
// get used items
if (preg_match_all('/##gi(\\d+)##/', $formulastr, $matches)) {
$useditems = array_unique($matches[1]);
// remove duplicates
} else {
$useditems = array();
}
// MDL-11902
// unset the value if formula is trying to reference to itself
// but array keys does not match itemid
if (!empty($this->id)) {
$useditems = array_diff($useditems, array($this->id));
//unset($useditems[$this->id]);
}
// prepare formula and init maths library
$formula = preg_replace('/##(gi\\d+)##/', '\\1', $formulastr);
$formula = new calc_formula($formula);
if (empty($useditems)) {
$grade_items = array();
} else {
$gis = implode(',', $useditems);
$sql = "SELECT gi.*\n FROM {$CFG->prefix}grade_items gi\n WHERE gi.id IN ({$gis}) and gi.courseid={$this->courseid}";
// from the same course only!
if (!($grade_items = get_records_sql($sql))) {
$grade_items = array();
}
}
$params = array();
foreach ($useditems as $itemid) {
// make sure all grade items exist in this course
if (!array_key_exists($itemid, $grade_items)) {
return false;
}
// use max grade when testing formula, this should be ok in 99.9%
// division by 0 is one of possible problems
$params['gi' . $grade_items[$itemid]->id] = $grade_items[$itemid]->grademax;
}
// do the calculation
$formula->set_params($params);
$result = $formula->evaluate();
// false as result indicates some problem
if ($result === false) {
// TODO: add more error hints
return get_string('errorcalculationunknown', 'grades');
} else {
return true;
}
}