chore: upgrade coredns version (#550)

vendor/github.com/expr-lang/expr/ast/visitor.go

@@ -0,0 +1,78 @@
+package ast
+
+import "fmt"
+
+type Visitor interface {
+	Visit(node *Node)
+}
+
+func Walk(node *Node, v Visitor) {
+	if *node == nil {
+		return
+	}
+	switch n := (*node).(type) {
+	case *NilNode:
+	case *IdentifierNode:
+	case *IntegerNode:
+	case *FloatNode:
+	case *BoolNode:
+	case *StringNode:
+	case *ConstantNode:
+	case *UnaryNode:
+		Walk(&n.Node, v)
+	case *BinaryNode:
+		Walk(&n.Left, v)
+		Walk(&n.Right, v)
+	case *ChainNode:
+		Walk(&n.Node, v)
+	case *MemberNode:
+		Walk(&n.Node, v)
+		Walk(&n.Property, v)
+	case *SliceNode:
+		Walk(&n.Node, v)
+		if n.From != nil {
+			Walk(&n.From, v)
+		}
+		if n.To != nil {
+			Walk(&n.To, v)
+		}
+	case *CallNode:
+		Walk(&n.Callee, v)
+		for i := range n.Arguments {
+			Walk(&n.Arguments[i], v)
+		}
+	case *BuiltinNode:
+		for i := range n.Arguments {
+			Walk(&n.Arguments[i], v)
+		}
+	case *PredicateNode:
+		Walk(&n.Node, v)
+	case *PointerNode:
+	case *VariableDeclaratorNode:
+		Walk(&n.Value, v)
+		Walk(&n.Expr, v)
+	case *SequenceNode:
+		for i := range n.Nodes {
+			Walk(&n.Nodes[i], v)
+		}
+	case *ConditionalNode:
+		Walk(&n.Cond, v)
+		Walk(&n.Exp1, v)
+		Walk(&n.Exp2, v)
+	case *ArrayNode:
+		for i := range n.Nodes {
+			Walk(&n.Nodes[i], v)
+		}
+	case *MapNode:
+		for i := range n.Pairs {
+			Walk(&n.Pairs[i], v)
+		}
+	case *PairNode:
+		Walk(&n.Key, v)
+		Walk(&n.Value, v)
+	default:
+		panic(fmt.Sprintf("undefined node type (%T)", node))
+	}
+
+	v.Visit(node)
+}