Add libbox wrapper

experimental/libbox/iterator.go

@@ -0,0 +1,31 @@
+package libbox
+
+import "github.com/sagernet/sing/common"
+
+type StringIterator interface {
+	Next() string
+	HasNext() bool
+}
+
+var _ StringIterator = (*iterator[string])(nil)
+
+type iterator[T any] struct {
+	values []T
+}
+
+func newIterator[T any](values []T) *iterator[T] {
+	return &iterator[T]{values}
+}
+
+func (i *iterator[T]) Next() T {
+	if len(i.values) == 0 {
+		return common.DefaultValue[T]()
+	}
+	nextValue := i.values[0]
+	i.values = i.values[1:]
+	return nextValue
+}
+
+func (i *iterator[T]) HasNext() bool {
+	return len(i.values) > 0
+}