public static TypeCheckProcFactory<RexNode>.DefaultExprProcessor getExprNodeDefaultExprProcessor(RexBuilder rexBuilder) {
    TypeCheckProcFactory<RexNode> factory =
        new TypeCheckProcFactory<>(new RexNodeExprFactory(rexBuilder));
    return factory.getDefaultExprProcessor();
  }
Returns the default processor to generate Calcite RexNode from AST nodes.
ql/src/java/org/apache/hadoop/hive/ql/parse/type/RexNodeTypeCheck.java