Ejemplo n.º 1
0
  /**
   * From {@code (A)?} build either:
   *
   * <pre>
   *  o--A-&gt;o
   *  |     ^
   *  o----&gt;|
   * </pre>
   *
   * or, if {@code A} is a block, just add an empty alt to the end of the block
   */
  @Override
  public Handle optional(GrammarAST optAST, Handle blk) {
    BlockStartState blkStart = (BlockStartState) blk.left;
    ATNState blkEnd = blk.right;
    preventEpsilonOptionalBlocks.add(
        new Triple<Rule, ATNState, ATNState>(currentRule, blkStart, blkEnd));

    boolean greedy = ((QuantifierAST) optAST).isGreedy();
    blkStart.nonGreedy = !greedy;
    epsilon(blkStart, blk.right, !greedy);

    optAST.atnState = blk.left;
    return blk;
  }
Ejemplo n.º 2
0
 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;
 }