/**
* 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);
}
/**
* From {@code (blk)+} build
*
* <pre>
* |---------|
* v |
* [o-blk-o]->o->o
* </pre>
*
* We add a decision for loop back node to the existing one at {@code blk} start.
*/
@NotNull
@Override
public Handle plus(@NotNull GrammarAST plusAST, @NotNull Handle blk) {
PlusBlockStartState blkStart = (PlusBlockStartState) blk.left;
BlockEndState blkEnd = (BlockEndState) blk.right;
preventEpsilonClosureBlocks.add(
new Triple<Rule, ATNState, ATNState>(currentRule, blkStart, blkEnd));
PlusLoopbackState loop = newState(PlusLoopbackState.class, plusAST);
loop.nonGreedy = !((QuantifierAST) plusAST).isGreedy();
atn.defineDecisionState(loop);
LoopEndState end = newState(LoopEndState.class, plusAST);
blkStart.loopBackState = loop;
end.loopBackState = loop;
plusAST.atnState = blkStart;
epsilon(blkEnd, loop); // blk can see loop back
BlockAST blkAST = (BlockAST) plusAST.getChild(0);
if (((QuantifierAST) plusAST).isGreedy()) {
if (expectNonGreedy(blkAST)) {
g.tool.errMgr.grammarError(
ErrorType.EXPECTED_NON_GREEDY_WILDCARD_BLOCK,
g.fileName,
plusAST.getToken(),
plusAST.getToken().getText());
}
epsilon(loop, blkStart); // loop back to start
epsilon(loop, end); // or exit
} else {
// 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);
}