Add serialiable and flatbufferable representations of World and Tank

schema/world.fbs

@@ -17,4 +17,3 @@ table WorldState {
   player: Tank;
   others: [Tank];
 }
-

server/src/main.rs

@@ -10,7 +10,13 @@ use log::{debug, info, warn};
 use tungstenite::Message;
 
 use schema::actions_generated::get_root_as_action_root;
-use schema::{messages_generated, world_generated};
+
+mod math;
+mod serialization;
+mod world;
+use math::Position;
+use serialization::{Config, SerializableAsMessage};
+use world::{Tank, World};
 
 type Peers = Arc<Mutex<HashSet<SocketAddr>>>;
 type Buffer = Vec<u8>;
@@ -130,22 +136,13 @@ async fn run() -> anyhow::Result<()> {
     });
 
     let mut builder = flatbuffers::FlatBufferBuilder::new_with_capacity(1024);
-    let world = world_generated::WorldState::create(
-        &mut builder,
-        &world_generated::WorldStateArgs {
-            player: None,
-            others: None,
-        },
-    );
-    let message = messages_generated::MessageRoot::create(
-        &mut builder,
-        &messages_generated::MessageRootArgs {
-            message_type: messages_generated::Message::WorldState,
-            message: Some(world.as_union_value()),
-        },
-    );
-    builder.finish(message, None);
-    let world = Arc::new(builder.finished_data().to_vec());
+    let mut world = World::new();
+
+    world.add_tank(Tank::new(0, Position { x: 69.0, y: 420.0 }));
+    world.add_tank(Tank::new(1, Position { x: 23.0, y: 54.0 }));
+    world.add_tank(Tank::new(2, Position { x: 84.0, y: 34.0 }));
+
+    let world = Arc::new(world.serialize(&mut builder, &Config::new(0)).unwrap());
 
     // Listen for new WebSocket connections.
     while let Ok((stream, address)) = tcp_listener.accept().await {

server/src/math.rs

@@ -0,0 +1,5 @@
+#[derive(Clone, Copy, Debug)]
+pub struct Position {
+    pub x: f32,
+    pub y: f32,
+}

server/src/serialization.rs

@@ -0,0 +1,166 @@
+use anyhow::{anyhow, Result};
+use flatbuffers::{FlatBufferBuilder, ForwardsUOffset, Vector, WIPOffset};
+
+use schema::math_generated;
+use schema::messages_generated;
+use schema::world_generated;
+
+use crate::world::{Tank, World};
+
+pub trait SerializableAsMessage {
+    fn serialize(&self, builder: &mut FlatBufferBuilder, config: &Config) -> Result<Vec<u8>>;
+}
+
+trait Flatbufferable<'a> {
+    type Buffer;
+    fn add_to_fb(
+        &self,
+        builder: &mut FlatBufferBuilder<'a>,
+        config: &Config,
+    ) -> WIPOffset<Self::Buffer>;
+}
+
+pub struct Config {
+    pub player_id: u16,
+}
+
+impl Config {
+    pub fn new(player_id: u16) -> Config {
+        Config { player_id }
+    }
+}
+
+impl<'a> Flatbufferable<'a> for Tank {
+    type Buffer = world_generated::Tank<'a>;
+    #[allow(unused_variables)]
+    fn add_to_fb(
+        &self,
+        builder: &mut FlatBufferBuilder<'a>,
+        config: &Config,
+    ) -> WIPOffset<world_generated::Tank<'a>> {
+        world_generated::Tank::create(
+            builder,
+            &world_generated::TankArgs {
+                pos: Some(&math_generated::Vec2::new(self.pos().x, self.pos().y)),
+            },
+        )
+    }
+}
+
+// TODO: 1) see if it's possible to add a test for this. Currently it's hard because you can't
+// get_root for an array. Perhaps make a testing schema that just has the [Tank] field.
+// 2) See if we can simplify for all Vec<&T> where T is Flatbufferable. Currently difficult because
+//    each T has its own associated Buffer type.
+impl<'a> Flatbufferable<'a> for Vec<&Tank> {
+    type Buffer = Vector<'a, ForwardsUOffset<world_generated::Tank<'a>>>;
+    fn add_to_fb(
+        &self,
+        builder: &mut FlatBufferBuilder<'a>,
+        config: &Config,
+    ) -> WIPOffset<Vector<'a, ForwardsUOffset<world_generated::Tank<'a>>>> {
+        let mut vec = Vec::new();
+
+        for tank in self.iter() {
+            vec.push(tank.add_to_fb(builder, config));
+        }
+
+        builder.create_vector(vec.as_slice())
+    }
+}
+
+impl SerializableAsMessage for World {
+    fn serialize(&self, builder: &mut FlatBufferBuilder, config: &Config) -> Result<Vec<u8>> {
+        builder.reset();
+
+        let (player, other_tanks): (Vec<&Tank>, Vec<&Tank>) = self
+            .tanks()
+            .iter()
+            .partition(|tank| tank.player() == config.player_id);
+
+        if player.len() != 1 {
+            return Err(anyhow!(
+                "Config does not specify unique player; can't serialize for schema."
+            ));
+        }
+
+        let player = player
+            .first()
+            .ok_or_else(|| anyhow!("Player doesn't exist."))?
+            .add_to_fb(builder, config);
+        let other_tanks = other_tanks.add_to_fb(builder, config);
+
+        let world = world_generated::WorldState::create(
+            builder,
+            &world_generated::WorldStateArgs {
+                player: Some(player),
+                others: Some(other_tanks),
+            },
+        );
+
+        let message = messages_generated::MessageRoot::create(
+            builder,
+            &messages_generated::MessageRootArgs {
+                message_type: messages_generated::Message::WorldState,
+                message: Some(world.as_union_value()),
+            },
+        );
+
+        builder.finish(message, None);
+        Ok(builder.finished_data().to_vec())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::math::Position;
+    use flatbuffers::get_root;
+
+    #[test]
+    fn tank_can_be_flatbuffered() {
+        let config = Config::new(0);
+        let mut builder = flatbuffers::FlatBufferBuilder::new_with_capacity(1024);
+        let tank = Tank::new(0, Position { x: 69.0, y: 420.0 });
+        let tank_buf = tank.add_to_fb(&mut builder, &config);
+        builder.finish(tank_buf, None);
+
+        let recovered_tank = get_root::<world_generated::Tank>(builder.finished_data());
+
+        assert_eq!(recovered_tank.pos().unwrap().x(), tank.pos().x);
+        assert_eq!(recovered_tank.pos().unwrap().y(), tank.pos().y);
+    }
+
+    #[test]
+    fn world_can_be_serialized() {
+        let config = Config::new(0);
+        let mut builder = flatbuffers::FlatBufferBuilder::new_with_capacity(1024);
+
+        let mut world = World::new();
+
+        world.add_tank(Tank::new(0, Position { x: 69.0, y: 420.0 }));
+        world.add_tank(Tank::new(1, Position { x: 23.0, y: 54.0 }));
+        world.add_tank(Tank::new(2, Position { x: 84.0, y: 34.0 }));
+
+        let world_as_bytes = world.serialize(&mut builder, &config).unwrap();
+
+        let message = get_root::<messages_generated::MessageRoot>(world_as_bytes.as_ref());
+        assert_eq!(
+            message.message_type(),
+            messages_generated::Message::WorldState
+        );
+        let recovered_world = message.message_as_world_state().unwrap();
+
+        let player = recovered_world.player().unwrap();
+        let others = recovered_world.others().unwrap();
+        let tanks = world.tanks();
+
+        assert_eq!(player.pos().unwrap().x(), tanks[0].pos().x);
+        assert_eq!(player.pos().unwrap().y(), tanks[0].pos().y);
+
+        assert_eq!(others.len(), 2);
+        assert_eq!(others.get(0).pos().unwrap().x(), tanks[1].pos().x);
+        assert_eq!(others.get(0).pos().unwrap().y(), tanks[1].pos().y);
+        assert_eq!(others.get(1).pos().unwrap().x(), tanks[2].pos().x);
+        assert_eq!(others.get(1).pos().unwrap().y(), tanks[2].pos().y);
+    }
+}

server/src/world.rs

@@ -0,0 +1,40 @@
+use crate::math::Position;
+
+pub struct World {
+    tanks: Vec<Tank>,
+}
+
+pub struct Tank {
+    // TODO: discuss what player would look like and replace.
+    player: u16,
+    pos: Position,
+}
+
+impl Tank {
+    pub fn player(&self) -> u16 {
+        self.player
+    }
+
+    pub fn pos(&self) -> Position {
+        self.pos
+    }
+
+    pub fn new(player: u16, pos: Position) -> Tank {
+        Tank { player, pos }
+    }
+}
+
+impl World {
+    pub fn new() -> World {
+        World { tanks: Vec::new() }
+    }
+
+    // TODO: replace with add_player after discussion on representing player.
+    pub fn add_tank(&mut self, tank: Tank) {
+        self.tanks.push(tank);
+    }
+
+    pub fn tanks(&self) -> &Vec<Tank> {
+        &self.tanks
+    }
+}