streamdata: optionally reuse buffer

This enables use of stdlib iterator helpers.

Signed-off-by: Yonah <contrib@gensokyo.uk>

cmd/streamdata/main.go

@@ -221,7 +221,7 @@ func main() {
 				return errors.New("list requires a channel selected")
 			}
 
-			for ident := range channel.All(&err) {
+			for ident := range channel.All(&err, true) {
 				fmt.Println(ident)
 			}
 			return

streamdata.go

@@ -276,7 +276,10 @@ func (c *Channel) Path(ident *Ident) string {
 // All returns an iterator over all known [Ident] in the on-disk representation.
 // Iteration stops when encountering the first non-nil error, and its value is
 // saved to the value pointed to by errP.
-func (c *Channel) All(errP *error) iter.Seq[*Ident] {
+//
+// If reuse is true, the same value is updated every iteration and the same
+// address is yileded as a result.
+func (c *Channel) All(errP *error, reuse bool) iter.Seq[*Ident] {
 	return func(yield func(*Ident) bool) {
 		dents, err := c.root.FS().(fs.ReadDirFS).ReadDir(channelPathVOD)
 		if err != nil {
@@ -298,7 +301,11 @@ func (c *Channel) All(errP *error) iter.Seq[*Ident] {
 				return
 			}
 
-			if !yield(&ident) {
+			p := &ident
+			if !reuse {
+				p = new(ident)
+			}
+			if !yield(p) {
 				return
 			}
 		}

streamdata_test.go

@@ -303,7 +303,7 @@ func TestChannel(t *testing.T) {
 	}
 
 	var iterErr error
-	idents := slices.Collect(c.All(&iterErr))
+	idents := slices.Collect(c.All(&iterErr, false))
 	if iterErr != nil {
 		t.Fatalf("All: error = %#v", iterErr)
 	}