public static Dependency getExprDependency(LineageCtx lctx,
      Operator<? extends OperatorDesc> inpOp, ExprNodeDesc expr)
      throws SemanticException {
    return getExprDependency(lctx, inpOp, expr, new HashMap<Node, Object>());
  }
Gets the expression dependencies for the expression.

@param lctx
         The lineage context containing the input operators dependencies.
@param inpOp
         The input operator to the current operator.
@param expr
         The expression that is being processed.
@throws SemanticException
ql/src/java/org/apache/hadoop/hive/ql/optimizer/lineage/ExprProcFactory.java