1 files changed, 52 insertions, 0 deletions
diff --git a/srv.go b/srv.go
new file mode 100644
index 0000000..48cc3d3
--- /dev/null
+++ b/srv.go
@@ -0,0 +1,52 @@
+package gui
+
+// server is a concurrent interface that stores a value and serves it to clients.
+// The stored value can be changed by sending the new value via update. server blocks
+// until the first value is received.
+//
+// A client can read the stored value by sending a channel via request. The server
+// responds by sending the value back via the channel. The client is responsible for
+// closing the channel.
+//
+// A server should be closed after use.
+type server[T any] struct {
+	request chan<- chan T
+	update  chan<- T
+}
+
+func newServer[T any]() server[T] {
+	request := make(chan chan T)
+	update := make(chan T)
+	go func() {
+		val := <-update // wait for initial value
+		for {
+			select {
+			case v, ok := <-update:
+				if !ok { // closed
+					return
+				}
+				val = v
+			case req, ok := <-request:
+				if !ok { // closed
+					return
+				}
+				go func() { // don't wait for client to receive
+					req <- val
+				}()
+			}
+		}
+	}()
+	return server[T]{request, update}
+}
+
+// get makes a synchronous request to the server and returns the stored value.
+func (srv server[T]) get() T {
+	c := make(chan T)
+	srv.request <- c
+	return <-c
+}
+
+func (srv server[T]) close() {
+	close(srv.request)
+	close(srv.update)
+}