ANTLR duplicate a tree

Question

I use ANTLR to build a tree (CommonTree) like follwing (language: JAVA):

  Parser.prog_return r = parser.prog();
  CommonTree t = (CommonTree) r.getTree();
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Answer 1

I had the same issue stumbling over dupTree(), which seemed to be deprecated and then Bart's posting, which steered me into the right direction. I finally ended up with the following, which is using the constructor of CommonTree accepting a CommonTree - abstracting it from the need to copy the individual fields.

  private static CommonTree copyTreeRecursive(CommonTree original) {

    CommonTree copy = new CommonTree(original); // Leverage constructor

    if(original.getChildren() != null) {
      for(Object o : original.getChildren()) {
        CommonTree childCopy  = copyTreeRecursive((CommonTree)o);
        childCopy.setParent(copy);
        copy.addChild(childCopy);
      }
    };
    return copy;
  }

NB: I stuck with Bart's naming convention.