Java 类org.antlr.v4.runtime.atn.StarLoopbackState 实例源码

protected String getStateLabel(ATNState s) {
    if ( s==null ) return "null";
    String stateLabel = "";

    if (s instanceof BlockStartState) {
        stateLabel += "→\\n";
    }
    else if (s instanceof BlockEndState) {
        stateLabel += "←\\n";
    }

    stateLabel += String.valueOf(s.stateNumber);

    if (s instanceof PlusBlockStartState || s instanceof PlusLoopbackState) {
        stateLabel += "+";
    }
    else if (s instanceof StarBlockStartState || s instanceof StarLoopEntryState || s instanceof StarLoopbackState) {
        stateLabel += "*";
    }

    if ( s instanceof DecisionState && ((DecisionState)s).decision>=0 ) {
        stateLabel = stateLabel+"\\nd="+((DecisionState)s).decision;
    }

    return stateLabel;
}

String getStateString(ATNState s) {
    int n = s.stateNumber;
    String stateStr = "s"+n;
    if ( s instanceof StarBlockStartState ) stateStr = "StarBlockStart_"+n;
    else if ( s instanceof PlusBlockStartState ) stateStr = "PlusBlockStart_"+n;
    else if ( s instanceof BlockStartState) stateStr = "BlockStart_"+n;
    else if ( s instanceof BlockEndState ) stateStr = "BlockEnd_"+n;
    else if ( s instanceof RuleStartState) stateStr = "RuleStart_"+g.getRule(s.ruleIndex).name+"_"+n;
    else if ( s instanceof RuleStopState ) stateStr = "RuleStop_"+g.getRule(s.ruleIndex).name+"_"+n;
    else if ( s instanceof PlusLoopbackState) stateStr = "PlusLoopBack_"+n;
    else if ( s instanceof StarLoopbackState) stateStr = "StarLoopBack_"+n;
    else if ( s instanceof StarLoopEntryState) stateStr = "StarLoopEntry_"+n;
    return stateStr;
}

@Override
public void visitState(ATNState p) {
    if (p.getStateType() == ATNState.BASIC && p.getNumberOfTransitions() == 1) {
        ATNState q = p.transition(0).target;
        if (p.transition(0) instanceof RuleTransition) {
            q = ((RuleTransition) p.transition(0)).followState;
        }
        if (q.getStateType() == ATNState.BASIC) {
            // 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 instanceof EpsilonTransition) {
                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);
                }
            }
        }
    }
}

/**
 * From {@code (blk)*} build {@code ( blk+ )?} with *two* decisions, one for
 * entry and one for choosing alts of {@code blk}.
 *
 * <pre>
 *   |-------------|
 *   v             |
 *   o--[o-blk-o]-&gt;o  o
 *   |                ^
 *   -----------------|
 * </pre>
 *
 * Note that the optional bypass must jump outside the loop as
 * {@code (A|B)*} is not the same thing as {@code (A|B|)+}.
 */

@Override
public Handle star(GrammarAST starAST, Handle elem) {
    StarBlockStartState blkStart = (StarBlockStartState)elem.left;
    BlockEndState blkEnd = (BlockEndState)elem.right;
    preventEpsilonClosureBlocks.add(new Triple<Rule, ATNState, ATNState>(currentRule, blkStart, blkEnd));

    StarLoopEntryState entry = newState(StarLoopEntryState.class, starAST);
    entry.nonGreedy = !((QuantifierAST)starAST).isGreedy();
    atn.defineDecisionState(entry);
    LoopEndState end = newState(LoopEndState.class, starAST);
    StarLoopbackState loop = newState(StarLoopbackState.class, starAST);
    entry.loopBackState = loop;
    end.loopBackState = loop;

    BlockAST blkAST = (BlockAST)starAST.getChild(0);
    if ( ((QuantifierAST)starAST).isGreedy() ) {
        if (expectNonGreedy(blkAST)) {
            g.tool.errMgr.grammarError(ErrorType.EXPECTED_NON_GREEDY_WILDCARD_BLOCK, g.fileName, starAST.getToken(), starAST.getToken().getText());
        }

        epsilon(entry, blkStart);   // loop enter edge (alt 1)
        epsilon(entry, end);        // bypass loop edge (alt 2)
    }
    else {
        // 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);
}