Example #1
0
  /**
   * 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);
  }