optimize rewrite visitor

src/graph/validator/GroupByValidator.cpp

@@ -49,7 +49,7 @@ Status GroupByValidator::validateYield(const YieldClause* yieldClause) {
         needGenProject_ = true;
       }
       if (!aggs.empty()) {
-        auto* colRewrited = ExpressionUtils::rewriteAgg2VarProp(colExpr);
+        auto* colRewrited = ExpressionUtils::rewriteAgg2VarProp(colExpr->clone());
         projCols_->addColumn(new YieldColumn(colRewrited, colOldName));
         continue;
       }

src/graph/validator/MatchValidator.cpp

@@ -718,7 +718,7 @@ Status MatchValidator::validateGroup(YieldClauseContext &yieldCtx) const {
         yieldCtx.aggOutputColumnNames_.emplace_back(agg->toString());
       }
       if (!aggs.empty()) {
-        auto *rewritedExpr = ExpressionUtils::rewriteAgg2VarProp(colExpr);
+        auto *rewritedExpr = ExpressionUtils::rewriteAgg2VarProp(colExpr->clone());
         yieldCtx.projCols_->addColumn(new YieldColumn(rewritedExpr, colOldName));
         yieldCtx.projOutputColumnNames_.emplace_back(colOldName);
         continue;

src/graph/visitor/RewriteVisitor.cpp

@@ -324,9 +324,9 @@ Expression *RewriteVisitor::transform(const Expression *expr, Matcher matcher, R
     return rewriter(expr);
   } else {
     RewriteVisitor visitor(std::move(matcher), std::move(rewriter));
-    auto exprCopy = expr->clone();
-    exprCopy->accept(&visitor);
-    return exprCopy;
+    auto *e = const_cast<Expression *>(expr);
+    e->accept(&visitor);
+    return e;
   }
 }
 
@@ -339,9 +339,9 @@ Expression *RewriteVisitor::transform(
     return rewriter(expr);
   } else {
     RewriteVisitor visitor(std::move(matcher), std::move(rewriter), std::move(needVisitedTypes));
-    auto exprCopy = expr->clone();
-    exprCopy->accept(&visitor);
-    return exprCopy;
+    auto *e = const_cast<Expression *>(expr);
+    e->accept(&visitor);
+    return e;
   }
 }
 }  // namespace graph