@Override
public void visitState(ATNState p) {
if (p.getClass() == ATNState.class && p.getNumberOfTransitions() == 1) {
ATNState q = p.transition(0).target;
if (p.transition(0) instanceof RuleTransition) {
q = ((RuleTransition) p.transition(0)).followState;
}
if (q.getClass() == ATNState.class) {
// we have p-x->q for x in {rule, action, pred, token, ...}
// if edge out of q is single epsilon to block end
// we can strip epsilon p-x->q-eps->r
Transition trans = q.transition(0);
if (q.getNumberOfTransitions() == 1
&& trans.isEpsilon()
&& !(trans instanceof ActionTransition)) {
ATNState r = trans.target;
if (r instanceof BlockEndState
|| r instanceof PlusLoopbackState
|| r instanceof StarLoopbackState) {
// skip over q
if (p.transition(0) instanceof RuleTransition) {
((RuleTransition) p.transition(0)).followState = r;
} else {
p.transition(0).target = r;
}
atn.removeState(q);
}
}
}
}
}
@NotNull
public Handle elemList(@NotNull List<Handle> els) {
int n = els.size();
for (int i = 0; i < n - 1; i++) { // hook up elements (visit all but last)
Handle el = els.get(i);
// if el is of form o-x->o for x in {rule, action, pred, token, ...}
// and not last in alt
Transition tr = null;
if (el.left.getNumberOfTransitions() == 1) tr = el.left.transition(0);
boolean isRuleTrans = tr instanceof RuleTransition;
if (el.left.getClass() == ATNState.class
&& el.right.getClass() == ATNState.class
&& tr != null
&& (isRuleTrans || tr.target == el.right)) {
// we can avoid epsilon edge to next el
if (isRuleTrans) ((RuleTransition) tr).followState = els.get(i + 1).left;
else tr.target = els.get(i + 1).left;
atn.removeState(el.right); // we skipped over this state
} else { // need epsilon if previous block's right end node is complicated
epsilon(el.right, els.get(i + 1).left);
}
}
Handle first = els.get(0);
Handle last = els.get(n - 1);
if (first == null || last == null) {
g.tool.errMgr.toolError(ErrorType.INTERNAL_ERROR, "element list has first|last == null");
}
return new Handle(first.left, last.right);
}