static Symbol curSy; // current symbol in computation of sets
//---------------------------------------------------------------------
// Symbol set computations
//---------------------------------------------------------------------
/* Computes the first set for the given Node. */
static BitArray First0(Node p, BitArray mark) {
BitArray fs = new BitArray(Symbol.terminals.Count);
while (p != null && !mark[p.n]) {
mark[p.n] = true;
switch (p.typ) {
case Node.nt: {
if (p.sym.firstReady) fs.Or(p.sym.first);
else fs.Or(First0(p.sym.graph, mark));
break;
}
case Node.t: case Node.wt: {
fs[p.sym.n] = true; break;
}
case Node.any: {
fs.Or(p.set); break;
}
case Node.alt: {
fs.Or(First0(p.sub, mark));
fs.Or(First0(p.down, mark));
break;
}
case Node.iter: case Node.opt: {
fs.Or(First0(p.sub, mark));
break;
}
}
if (!Node.DelNode(p)) break;
p = p.next;
}
return fs;
}
static void GetSingles(Node p, ArrayList singles) {
if (p == null) return; // end of graph
if (p.typ == Node.nt) {
if (p.up || Node.DelGraph(p.next)) singles.Add(p.sym);
} else if (p.typ == Node.alt || p.typ == Node.iter || p.typ == Node.opt) {
if (p.up || Node.DelGraph(p.next)) {
GetSingles(p.sub, singles);
if (p.typ == Node.alt) GetSingles(p.down, singles);
}
}
if (!p.up && Node.DelNode(p)) GetSingles(p.next, singles);
}
static Node LeadingAny(Node p) {
if (p == null) return null;
Node a = null;
if (p.typ == Node.any) a = p;
else if (p.typ == Node.alt) {
a = LeadingAny(p.sub);
if (a == null) a = LeadingAny(p.down);
}
else if (p.typ == Node.opt || p.typ == Node.iter) a = LeadingAny(p.sub);
else if (Node.DelNode(p) && !p.up) a = LeadingAny(p.next);
return a;
}
