コード例 #1
0
 // traversing origin, find ExprNodeDesc in sources and replaces it with ExprNodeDesc
 // in targets having same index.
 // return null if failed to find
 public static ExprNodeDesc replace(
     ExprNodeDesc origin, List<ExprNodeDesc> sources, List<ExprNodeDesc> targets) {
   int index = indexOf(origin, sources);
   if (index >= 0) {
     return targets.get(index);
   }
   // encountered column or field which cannot be found in sources
   if (origin instanceof ExprNodeColumnDesc || origin instanceof ExprNodeFieldDesc) {
     return null;
   }
   // for ExprNodeGenericFuncDesc, it should be deterministic and stateless
   if (origin instanceof ExprNodeGenericFuncDesc) {
     ExprNodeGenericFuncDesc func = (ExprNodeGenericFuncDesc) origin;
     if (!FunctionRegistry.isDeterministic(func.getGenericUDF())
         || FunctionRegistry.isStateful(func.getGenericUDF())) {
       return null;
     }
     List<ExprNodeDesc> children = new ArrayList<ExprNodeDesc>();
     for (int i = 0; i < origin.getChildren().size(); i++) {
       ExprNodeDesc child = replace(origin.getChildren().get(i), sources, targets);
       if (child == null) {
         return null;
       }
       children.add(child);
     }
     // duplicate function with possibly replaced children
     ExprNodeGenericFuncDesc clone = (ExprNodeGenericFuncDesc) func.clone();
     clone.setChildren(children);
     return clone;
   }
   // constant or null, just return it
   return origin;
 }