/**
* From (blk)* build ( blk+ )? with *two* decisions, one for entry and one for choosing alts of
* blk.
*
* <p>|-------------| v | o--[o-blk-o]->o o | ^ -----------------|
*
* <p>Note that the optional bypass must jump outside the loop as (A|B)* is not the same thing as
* (A|B|)+.
*/
@NotNull
public Handle star(@NotNull GrammarAST starAST, @NotNull Handle elem) {
StarBlockStartState blkStart = (StarBlockStartState) elem.left;
BlockEndState blkEnd = (BlockEndState) elem.right;
StarLoopEntryState entry = newState(StarLoopEntryState.class, starAST);
atn.defineDecisionState(entry);
LoopEndState end = newState(LoopEndState.class, starAST);
StarLoopbackState loop = newState(StarLoopbackState.class, starAST);
entry.loopBackState = loop;
end.loopBackStateNumber = loop.stateNumber;
BlockAST blkAST = (BlockAST) starAST.getChild(0);
entry.isGreedy = isGreedy(blkAST);
if (!g.isLexer() || entry.isGreedy) {
epsilon(entry, blkStart); // loop enter edge (alt 1)
epsilon(entry, end); // bypass loop edge (alt 2)
} else { // only lexers flip entry/exit branches for nongreedy
// if not greedy, priority to exit branch; make it first
epsilon(entry, end); // bypass loop edge (alt 1)
epsilon(entry, blkStart); // loop enter edge (alt 2)
}
epsilon(blkEnd, loop); // block end hits loop back
epsilon(loop, entry); // loop back to entry/exit decision
starAST.atnState = entry; // decision is to enter/exit; blk is its own decision
return new Handle(entry, end);
}
/** From an empty alternative build o-e->o */
public Handle epsilon(GrammarAST node) {
ATNState left = newState(node);
ATNState right = newState(node);
epsilon(left, right);
node.atnState = left;
return new Handle(left, right);
}
/**
* From (blk)+ build
*
* <p>|---------| v | [o-blk-o]->o->o
*
* <p>We add a decision for loop back node to the existing one at blk start.
*/
@NotNull
public Handle plus(@NotNull GrammarAST plusAST, @NotNull Handle blk) {
PlusBlockStartState blkStart = (PlusBlockStartState) blk.left;
BlockEndState blkEnd = (BlockEndState) blk.right;
PlusLoopbackState loop = newState(PlusLoopbackState.class, plusAST);
atn.defineDecisionState(loop);
LoopEndState end = newState(LoopEndState.class, plusAST);
blkStart.loopBackState = loop;
end.loopBackStateNumber = loop.stateNumber;
plusAST.atnState = blkStart;
epsilon(blkEnd, loop); // blk can see loop back
BlockAST blkAST = (BlockAST) plusAST.getChild(0);
loop.isGreedy = isGreedy(blkAST);
if (!g.isLexer() || loop.isGreedy) {
epsilon(loop, blkStart); // loop back to start
epsilon(loop, end); // or exit
} else { // only lexers flip entry/exit branches for nongreedy
// if not greedy, priority to exit branch; make it first
epsilon(loop, end); // exit
epsilon(loop, blkStart); // loop back to start
}
return new Handle(blkStart, end);
}
/** Build an atom with all possible values in its label */
@NotNull
public Handle wildcard(GrammarAST node) {
ATNState left = newState(node);
ATNState right = newState(node);
left.addTransition(new WildcardTransition(right));
node.atnState = left;
return new Handle(left, right);
}
/**
* From (A)? build either:
*
* <p>o--A->o | ^ o---->|
*
* <p>or, if A is a block, just add an empty alt to the end of the block
*/
@NotNull
public Handle optional(@NotNull GrammarAST optAST, @NotNull Handle blk) {
// TODO: no such thing as nongreedy ()? so give error
BlockStartState blkStart = (BlockStartState) blk.left;
epsilon(blkStart, blk.right);
optAST.atnState = blk.left;
return blk;
}
/* start->ruleblock->end */
public Handle rule(GrammarAST ruleAST, String name, Handle blk) {
Rule r = g.getRule(name);
RuleStartState start = atn.ruleToStartState[r.index];
epsilon(start, blk.left);
RuleStopState stop = atn.ruleToStopState[r.index];
epsilon(blk.right, stop);
Handle h = new Handle(start, stop);
// ATNPrinter ser = new ATNPrinter(g, h.left);
// System.out.println(ruleAST.toStringTree()+":\n"+ser.asString());
ruleAST.atnState = start;
return h;
}
public Handle _ruleRef(GrammarAST node) {
Rule r = g.getRule(node.getText());
if (r == null) {
g.tool.errMgr.toolError(ErrorType.INTERNAL_ERROR, "Rule " + node.getText() + " undefined");
return null;
}
RuleStartState start = atn.ruleToStartState[r.index];
ATNState left = newState(node);
ATNState right = newState(node);
RuleTransition call = new RuleTransition(start, r.index, right);
left.addTransition(call);
node.atnState = left;
return new Handle(left, right);
}
/**
* From set build single edge graph o->o-set->o. To conform to what an alt block looks like, must
* have extra state on left. This handles ~A also, converted to ~{A} set.
*/
public Handle set(GrammarAST associatedAST, List<GrammarAST> terminals, boolean invert) {
ATNState left = newState(associatedAST);
ATNState right = newState(associatedAST);
IntervalSet set = new IntervalSet();
for (GrammarAST t : terminals) {
int ttype = g.getTokenType(t.getText());
set.add(ttype);
}
if (invert) {
IntervalSet notSet = set.complement(Token.MIN_TOKEN_TYPE, g.getMaxTokenType());
left.addTransition(new NotSetTransition(right, set, notSet));
} else {
left.addTransition(new SetTransition(right, set));
}
associatedAST.atnState = left;
return new Handle(left, right);
}
protected Handle makeBlock(BlockStartState start, GrammarAST blkAST, List<Handle> alts) {
BlockEndState end = newState(BlockEndState.class, blkAST);
start.endState = end;
for (Handle alt : alts) {
// hook alts up to decision block
epsilon(start, alt.left);
epsilon(alt.right, end);
// no back link in ATN so must walk entire alt to see if we can
// strip out the epsilon to 'end' state
TailEpsilonRemover opt = new TailEpsilonRemover();
opt.visit(alt.left);
}
Handle h = new Handle(start, end);
// FASerializer ser = new FASerializer(g, h.left);
// System.out.println(blkAST.toStringTree()+":\n"+ser);
blkAST.atnState = start;
return h;
}