switch to iterators and client polling

pkg/types/readsb/filter.go

@@ -1,6 +1,8 @@
 package readsb
 
 import (
+	"iter"
+	"slices"
 	"strings"
 	"time"
 )
@@ -9,19 +11,26 @@ import (
 // an aircraft is kept only if every filter passes (logical AND).
 type AircraftFilter func(*Aircraft) bool
 
-// Filter returns the aircraft that satisfy all of the supplied filters. With no
-// filters it returns every aircraft. The receiver report is never mutated.
+// All yields each aircraft that satisfies every supplied filter, lazily and in
+// order. With no filters it yields every aircraft. Ranging may break early; the
+// receiver report is never mutated.
+func (r *AircraftReport) All(filters ...AircraftFilter) iter.Seq[Aircraft] {
+	return func(yield func(Aircraft) bool) {
+		for i := range r.Aircraft {
+			if keep(&r.Aircraft[i], filters) && !yield(r.Aircraft[i]) {
+				return
+			}
+		}
+	}
+}
+
+// Filter is the eager form of All: it collects the matching aircraft into a
+// slice. With no filters it returns the report's own slice without copying.
 func (r *AircraftReport) Filter(filters ...AircraftFilter) []Aircraft {
 	if len(filters) == 0 {
 		return r.Aircraft
 	}
-	out := make([]Aircraft, 0, len(r.Aircraft))
-	for i := range r.Aircraft {
-		if keep(&r.Aircraft[i], filters) {
-			out = append(out, r.Aircraft[i])
-		}
-	}
-	return out
+	return slices.Collect(r.All(filters...))
 }
 
 func keep(a *Aircraft, filters []AircraftFilter) bool {