void Factor(out Graph g)
{
string name; int kind; Position pos; bool weak = false;
g = null;
switch (la.kind)
{
case 1:
case 3:
case 5:
case 29: {
if (la.kind == 29)
{
Get();
weak = true;
}
Sym(out name, out kind);
Symbol sym = tab.FindSym(name);
if (sym == null && kind == str)
{
sym = tab.literals[name] as Symbol;
}
bool undef = sym == null;
if (undef)
{
if (kind == id)
{
sym = tab.NewSym(Node.nt, name, 0); // forward nt
}
else if (genScanner)
{
sym = tab.NewSym(Node.t, name, t.line);
dfa.MatchLiteral(sym.name, sym);
}
else // undefined string in production
{
SemErr("undefined string in production");
sym = tab.eofSy; // dummy
}
}
int typ = sym.typ;
if (typ != Node.t && typ != Node.nt)
{
SemErr("this symbol kind is not allowed in a production");
}
if (weak)
{
if (typ == Node.t)
{
typ = Node.wt;
}
else
{
SemErr("only terminals may be weak");
}
}
Node p = tab.NewNode(typ, sym, t.line);
g = new Graph(p);
if (la.kind == 24 || la.kind == 26)
{
Attribs(p);
if (kind != id)
{
SemErr("a literal must not have attributes");
}
}
if (undef)
{
sym.attrPos = p.pos; // dummy
}
else if ((p.pos == null) != (sym.attrPos == null))
{
SemErr("attribute mismatch between declaration and use of this symbol");
}
break;
}
case 30: {
Get();
Expression(out g);
Expect(31);
break;
}
case 32: {
Get();
Expression(out g);
Expect(33);
tab.MakeOption(g);
break;
}
case 34: {
Get();
Expression(out g);
Expect(35);
tab.MakeIteration(g);
break;
}
case 39: {
SemText(out pos);
Node p = tab.NewNode(Node.sem, null, 0);
p.pos = pos;
g = new Graph(p);
break;
}
case 23: {
Get();
Node p = tab.NewNode(Node.any, null, 0); // p.set is set in tab.SetupAnys
g = new Graph(p);
break;
}
case 36: {
Get();
Node p = tab.NewNode(Node.sync, null, 0);
g = new Graph(p);
break;
}
default: SynErr(49); break;
}
if (g == null) // invalid start of Factor
{
g = new Graph(tab.NewNode(Node.eps, null, 0));
}
}