/**
* Resolve non-deterministic automaton into a deterministic state tree
* @return LRStateSet
*/
function resolve()
{
LRState::clear_index();
LRStation::clear_index();
// create Root Set
// we SHOULD have a single etransition to an intial state
return LRStateSet::init($this->etransitions[0], $this->Grammar);
}
/**
* Start recursive collection of e-transtions to states
* @param Grammar
* @param int number of symbols to look ahead, currently only 0 or 1
* @return void
*/
function collect_non_deterministic(Grammar $Grammar, $k)
{
// avoid recursion by testing if already collected
if (isset($this->etransitions)) {
return;
}
$this->etransitions = array();
// get all rules with our non-terminal as left had side
foreach ($Grammar->get_rules($this->nt) as $r => $rule) {
// create single Item for new state with pointer at start of rule
$Item = LRItem::make($r, $rule, 0);
if (isset($this->la) && $k === 1) {
$Item->lookahead($this->la);
}
// create e-transition to state with single item
$State = LRState::make($Item);
$State->collect_non_deterministic($Grammar, $k);
$this->etransitions[] = $State;
}
}
/**
* Clear registered states
* @return void
*/
static function clear_index()
{
self::$uindex = array();
self::$incid = 0;
}
