[GENERAL] How to restore a Plan from a stored plan text?

[sunpeng]

I've used the following codes to translate the PlannedStmt node to a char
string:
PlannedStmt * pltl = (PlannedStmt *) linitial(plantree_list);
Plan *pl = pltl->planTree;
char       *s;
s = nodeToString(pl);
 How to restore from this s to Plan?
  I noticed using func parseNodeString() in /backends/nodes/readfuncs.c
can't work, for example there is no codes translating into Agg node, should
I write my code to parse this string back into PlannedStmt node?
  Thanks!