wip

vendor/github.com/antonmedv/expr/ast/visitor.go

@@ -0,0 +1,108 @@
+package ast
+
+import "fmt"
+
+type Visitor interface {
+	Enter(node *Node)
+	Exit(node *Node)
+}
+
+type walker struct {
+	visitor Visitor
+}
+
+func Walk(node *Node, visitor Visitor) {
+	w := walker{
+		visitor: visitor,
+	}
+	w.walk(node)
+}
+
+func (w *walker) walk(node *Node) {
+	w.visitor.Enter(node)
+
+	switch n := (*node).(type) {
+	case *NilNode:
+		w.visitor.Exit(node)
+	case *IdentifierNode:
+		w.visitor.Exit(node)
+	case *IntegerNode:
+		w.visitor.Exit(node)
+	case *FloatNode:
+		w.visitor.Exit(node)
+	case *BoolNode:
+		w.visitor.Exit(node)
+	case *StringNode:
+		w.visitor.Exit(node)
+	case *ConstantNode:
+		w.visitor.Exit(node)
+	case *UnaryNode:
+		w.walk(&n.Node)
+		w.visitor.Exit(node)
+	case *BinaryNode:
+		w.walk(&n.Left)
+		w.walk(&n.Right)
+		w.visitor.Exit(node)
+	case *MatchesNode:
+		w.walk(&n.Left)
+		w.walk(&n.Right)
+		w.visitor.Exit(node)
+	case *PropertyNode:
+		w.walk(&n.Node)
+		w.visitor.Exit(node)
+	case *IndexNode:
+		w.walk(&n.Node)
+		w.walk(&n.Index)
+		w.visitor.Exit(node)
+	case *SliceNode:
+		if n.From != nil {
+			w.walk(&n.From)
+		}
+		if n.To != nil {
+			w.walk(&n.To)
+		}
+		w.visitor.Exit(node)
+	case *MethodNode:
+		w.walk(&n.Node)
+		for i := range n.Arguments {
+			w.walk(&n.Arguments[i])
+		}
+		w.visitor.Exit(node)
+	case *FunctionNode:
+		for i := range n.Arguments {
+			w.walk(&n.Arguments[i])
+		}
+		w.visitor.Exit(node)
+	case *BuiltinNode:
+		for i := range n.Arguments {
+			w.walk(&n.Arguments[i])
+		}
+		w.visitor.Exit(node)
+	case *ClosureNode:
+		w.walk(&n.Node)
+		w.visitor.Exit(node)
+	case *PointerNode:
+		w.visitor.Exit(node)
+	case *ConditionalNode:
+		w.walk(&n.Cond)
+		w.walk(&n.Exp1)
+		w.walk(&n.Exp2)
+		w.visitor.Exit(node)
+	case *ArrayNode:
+		for i := range n.Nodes {
+			w.walk(&n.Nodes[i])
+		}
+		w.visitor.Exit(node)
+	case *MapNode:
+		for i := range n.Pairs {
+			w.walk(&n.Pairs[i])
+		}
+		w.visitor.Exit(node)
+	case *PairNode:
+		w.walk(&n.Key)
+		w.walk(&n.Value)
+		w.visitor.Exit(node)
+	default:
+		panic(fmt.Sprintf("undefined node type (%T)", node))
+	}
+}