types/views: add Slice.All iterator

And convert a few callers as an example, but nowhere near all.

Updates #12912

Change-Id: I5eaa12a29a6cd03b58d6f1072bd27bc0467852f2
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

types/views/views.go

@@ -10,6 +10,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"iter"
 	"maps"
 	"reflect"
 	"slices"
@@ -208,6 +209,17 @@ type Slice[T any] struct {
 	ж []T
 }
 
+// All returns an iterator over v.
+func (v Slice[T]) All() iter.Seq2[int, T] {
+	return func(yield func(int, T) bool) {
+		for i, v := range v.ж {
+			if !yield(i, v) {
+				return
+			}
+		}
+	}
+}
+
 // MapKey returns a unique key for a slice, based on its address and length.
 func (v Slice[T]) MapKey() SliceMapKey[T] { return mapKey(v.ж) }
 

types/views/views_test.go

@@ -6,8 +6,10 @@ package views
 import (
 	"bytes"
 	"encoding/json"
+	"fmt"
 	"net/netip"
 	"reflect"
+	"slices"
 	"strings"
 	"testing"
 	"unsafe"
@@ -412,3 +414,15 @@ func TestContainsPointers(t *testing.T) {
 		})
 	}
 }
+
+func TestSliceRange(t *testing.T) {
+	sv := SliceOf([]string{"foo", "bar"})
+	var got []string
+	for i, v := range sv.All() {
+		got = append(got, fmt.Sprintf("%d-%s", i, v))
+	}
+	want := []string{"0-foo", "1-bar"}
+	if !slices.Equal(got, want) {
+		t.Errorf("got %q; want %q", got, want)
+	}
+}