/** parse <tt>input</tt> for a exactly one unique result, throwing <tt>Ambiguous</tt> if not unique or <tt>Failed</tt> if none */
- public Tree<R> parse1(Token.Stream<T> input) throws IOException, Failed, Ambiguous { return parse(input).expand1(); }
+ public Tree<R> parse1(Token.Stream<T> input) throws IOException, Failed, Ambiguous {
+ Forest<R> ret = parse(input);
+ try { return ret.expand1(); }
+ catch (Ambiguous a) {
+ System.out.println("while expanding:");
+ System.out.println(ret);
+ throw a;
+ }
+ }
/** parse <tt>input</tt>, using the table <tt>pt</tt> to drive the parser */
public Forest<R> parse(Token.Stream<T> input) throws IOException, Failed {
/** a single state in the LR table and the transitions possible from it */
public class State implements Comparable<Table.State>, Iterable<Position> {
+ /*
+ public boolean isResolvable(Token t) {
+ boolean found = false;
+ for(Reduction r : getReductions(t)) {
+ Position p = r.position;
+ if (!p.isRightNullable(cache)) continue;
+ if (p.owner().firstp()==p) continue;
+ if (found) {
+ // found two items meeting criteria #1
+ return false;
+ } else {
+ found = true;
+ continue;
+ }
+ if (p.element()==null) continue;
+ Topology first = new Walk.First(top(), cache).walk(p.element());
+ if (first.contains(t))
+ }
+ }
+ */
+
public final int idx = master_state_idx++;
private final HashSet<Position> hs;
public class Reduction {
// FIXME: cleanup; almost everything in here could go in either Sequence.Position.getRewrite() or else in GSS.Reduct
public final int numPop;
- private final Position position;
+ /*private*/ final Position position;
private final Forest[] holder; // to avoid constant reallocation
public int hashCode() { return position.hashCode(); }
public boolean equals(Object o) {
return reduce(parent, numPop-1, rex, onlychild, target);
}
+ private Forest zero = null;
+ public Forest zero() {
+ if (zero != null) return zero;
+ if (numPop > 0) throw new Error();
+ return zero = position.rewrite(null);
+ }
+
// FIXME: this could be more elegant and/or cleaner and/or somewhere else
private Forest reduce(GSS.Phase.Node parent, int pos, Forest rex, GSS.Phase.Node onlychild, GSS.Phase target) {
if (pos>=0) holder[pos] = parent.pending();