chore: upgrade coredns version (#550)

vendor/github.com/expr-lang/expr/optimizer/sum_array.go

@@ -0,0 +1,37 @@
+package optimizer
+
+import (
+	"fmt"
+
+	. "github.com/expr-lang/expr/ast"
+)
+
+type sumArray struct{}
+
+func (*sumArray) Visit(node *Node) {
+	if sumBuiltin, ok := (*node).(*BuiltinNode); ok &&
+		sumBuiltin.Name == "sum" &&
+		len(sumBuiltin.Arguments) == 1 {
+		if array, ok := sumBuiltin.Arguments[0].(*ArrayNode); ok &&
+			len(array.Nodes) >= 2 {
+			patchCopyType(node, sumArrayFold(array))
+		}
+	}
+}
+
+func sumArrayFold(array *ArrayNode) *BinaryNode {
+	if len(array.Nodes) > 2 {
+		return &BinaryNode{
+			Operator: "+",
+			Left:     array.Nodes[0],
+			Right:    sumArrayFold(&ArrayNode{Nodes: array.Nodes[1:]}),
+		}
+	} else if len(array.Nodes) == 2 {
+		return &BinaryNode{
+			Operator: "+",
+			Left:     array.Nodes[0],
+			Right:    array.Nodes[1],
+		}
+	}
+	panic(fmt.Errorf("sumArrayFold: invalid array length %d", len(array.Nodes)))
+}