streamdata: optionally reuse buffer

This enables use of stdlib iterator helpers.

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

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
 			}
 		}