/*
* Function: machine
* Description: Recursive descent regular expression parser.
*/
private static Nfa machine()
{
Nfa start;
Nfa p;
BitSet states;
#if DESCENT_DEBUG
Utility.enter("machine", spec.lexeme, spec.current_token);
#endif
start = Alloc.NewNfa(spec);
p = start;
states = gen.GetStates();
/* Begin: Added for states. */
spec.current_token = Gen.EOS;
gen.Advance();
/* End: Added for states. */
if (Gen.END_OF_INPUT != spec.current_token)
{
p.SetNext(rule());
ProcessStates(states, p.GetNext());
}
while (Gen.END_OF_INPUT != spec.current_token)
{
/* Make state changes HERE. */
states = gen.GetStates();
/* Begin: Added for states. */
gen.Advance();
if (Gen.END_OF_INPUT == spec.current_token)
{
break;
}
/* End: Added for states. */
p.SetSib(Alloc.NewNfa(spec));
p = p.GetSib();
p.SetNext(rule());
ProcessStates(states, p.GetNext());
}
/*
* add pseudo-rules for BOL and EOF
*/
p.SetSib(Alloc.NewNfa(spec));
p = p.GetSib();
p.SetNext(Alloc.NewNfa(spec));
Nfa pnext = p.GetNext();
pnext.SetEdge(Nfa.CCL);
pnext.SetNext(Alloc.NewNfa(spec));
pnext.SetCharSet(new CharSet());
pnext.GetCharSet().add(spec.BOL);
pnext.GetCharSet().add(spec.EOF);
// do-nothing accept rule
pnext.GetNext().SetAccept(new Accept(null, input.line_number + 1));
/* add the pseudo rules */
for (int i = 0; i < spec.states.Count; i++)
{
ArrayList srule = spec.state_rules[i];
srule.Add(pnext);
}
#if DESCENT_DEBUG
Utility.leave("machine", spec.lexeme, spec.current_token);
#endif
return(start);
}