wayland: implement tablet-v2

src/utils/pending_serial.rs

@@ -0,0 +1,19 @@
+use crate::client::Client;
+
+pub struct PendingSerial<'a> {
+    serial: Option<u32>,
+    client: &'a Client,
+}
+
+impl<'a> PendingSerial<'a> {
+    pub fn new(client: &'a Client) -> Self {
+        Self {
+            serial: None,
+            client,
+        }
+    }
+
+    pub fn get(&mut self) -> u32 {
+        *self.serial.get_or_insert_with(|| self.client.next_serial())
+    }
+}