-/** a node in the GSS */
-final class Node
- implements Invokable<Pos, Result>,
- IntegerMappable,
- GraphViz.ToGraphViz,
- Iterable<Result> {
-
- /** which GSS.Phase this Node belongs to */
- public GSS.Phase phase() { return phase; }
- public Iterator<Result> iterator() { return results.iterator(); }
- public Parser.Table.State state() { return state; }
-
- public int toInt() { return idx; }
-
- boolean destroyed = false;
-
- public void check() {
- if (destroyed) return;
- boolean dead = true;
- // - all nodes must have a parent
- // - non-doomed nodes must either:
- // - be on the frontier or
- // - have a non-doomed node closer to the frontier than themself
- if (phase.isFrontier()) dead = false;
- else for(Result r : children)
- if (state.doomed) { if (r.usedByAnyNode()) { dead = false; break; } }
- else { if (r.usedByNonDoomedNode()) { dead = false; break; } }
- dead |= results.size()==0;
- if (!dead) return;
- destroyed = true;
- while(children.size()>0)
- for(Result r : children) {
- children.remove(r);
- r.destroy();
- break;
- }
- while(results.size()>0)
- for(Result r : results) {
- results.remove(r);
- r.removeChild(this);
- break;
- }
- results = null;
- children = null;
- }
-
- //////////////////////////////////////////////////////////////////////
-
- private static int node_idx = 0;
- private final int idx = node_idx++;
-
- private final GSS.Phase phase;
- private final Parser.Table.State state;
- private final boolean fromEmptyReduction;
- //private FastSet<Result> results = new FastSet<Result>();
- private HashSet<Result> results = new HashSet<Result>();
- private HashSet<Result> children = new HashSet<Result>();
-
- public final void invoke(Pos r, Result only) {
- boolean emptyProductions = only==null;
- if (emptyProductions != (r.numPops()==0)) return;
- if (r.numPops()!=0) reduce(r, r.numPops()-1, phase(), only);
- else {
- Input.Region region = phase().getLocation().createRegion(phase().getLocation());
- new Result(r.rewrite(region, phase().parser().cache()), this, r, phase());
- }
- }
-
- private void reduce(Pos r, int pos, GSS.Phase target, Result only) {
- Forest[] holder = r.holder;
- Forest old = holder[pos];
- if (results==null) return; // FIXME: this should not happen
- for(Result res : results)
- if (only == null || res == only) {
- Node child = res.parent();
- holder[pos] = res.getForest();
- if (pos>0) child.reduce(r, pos-1, target, null);
- else {
- Input.Region region = child.phase().getLocation().createRegion(target.getLocation());
- new Reduction(child, r, r.rewrite(region, phase().parser().cache()), target);
- }
- }
- holder[pos] = old;
- }
-
- Node(GSS.Phase phase, Result result, State state, boolean fromEmptyReduction) {
- this.phase = phase;
- this.state = state;
- this.fromEmptyReduction = fromEmptyReduction;
- if (phase.hash.get(state, result.phase()) != null) throw new Error("severe problem!");
- phase.hash.put(state, result.phase(), this);
- addResult(result);
- state.invokeEpsilonReductions(phase().token, this);
- }
-
- // Add/Remove Children/Results //////////////////////////////////////////////////////////////////////////////
-
- public void removeChild(Result child) {
- if (children==null) return;
- children.remove(child);
- check();
- }
- public void removeResult(Result result) {
- if (results==null) return;
- results.remove(result);
- check();
- }
- public void addChild(Result child) {
- if (children==null) return; // FIXME: this should not happen
- children.add(child);
- }
- public void addResult(Result r) {
- if (results.contains(r)) return;
- results.add(r);
- r.addChild(this);
- if (!fromEmptyReduction) state.invokeReductions(phase().getToken(), this, r);
- }