From 04ce5366c8b450d9e764bb216daea116f4798452 Mon Sep 17 00:00:00 2001
From: Ryan <ryanj00a@gmail.com>
Date: Sun, 3 Jul 2022 18:02:00 -0700
Subject: [PATCH] Add a null state to some IDs

---
 src/client.rs  | 19 ++++++++++++-------
 src/entity.rs  |  4 +++-
 src/slotmap.rs | 16 ++++++++++++++++
 src/world.rs   |  6 +++++-
 4 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/src/client.rs b/src/client.rs
index 1bfd312..722f546 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -86,8 +86,13 @@ impl Clients {
     }
 }
 
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default, Debug)]
 pub struct ClientId(Key);
 
+impl ClientId {
+    pub const NULL: Self = Self(Key::NULL);
+}
+
 /// Represents a client connected to the server after logging in.
 pub struct Client {
     /// Setting this to `None` disconnects the client.
@@ -98,8 +103,8 @@ pub struct Client {
     uuid: Uuid,
     username: String,
     textures: Option<SignedPlayerTextures>,
-    new_world: Option<WorldId>,
-    old_world: Option<WorldId>,
+    new_world: WorldId,
+    old_world: WorldId,
     on_ground: bool,
     new_position: Vec3<f64>,
     old_position: Vec3<f64>,
@@ -157,8 +162,8 @@ impl Client {
             uuid: ncd.uuid,
             username: ncd.username,
             textures: ncd.textures,
-            new_world: None,
-            old_world: None,
+            new_world: WorldId::default(),
+            old_world: WorldId::default(),
             on_ground: false,
             new_position: Vec3::default(),
             old_position: Vec3::default(),
@@ -203,12 +208,12 @@ impl Client {
         self.textures.as_ref()
     }
 
-    pub fn world(&self) -> Option<WorldId> {
+    pub fn world(&self) -> WorldId {
         self.new_world
     }
 
     pub fn set_world(&mut self, world: WorldId) {
-        self.new_world = Some(world);
+        self.new_world = world;
     }
 
     /// Sends a system message to the player.
@@ -573,7 +578,7 @@ impl Client {
             return;
         }
 
-        let world = match self.new_world.and_then(|id| worlds.get(id)) {
+        let world = match worlds.get(self.new_world) {
             Some(world) => world,
             None => {
                 log::warn!(
diff --git a/src/entity.rs b/src/entity.rs
index 2841dce..82b89c1 100644
--- a/src/entity.rs
+++ b/src/entity.rs
@@ -164,10 +164,12 @@ impl Entities {
     }
 }
 
-#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default, Debug)]
 pub struct EntityId(Key);
 
 impl EntityId {
+    pub const NULL: Self = Self(Key::NULL);
+
     pub(crate) fn to_network_id(self) -> i32 {
         self.0.version().get() as i32
     }
diff --git a/src/slotmap.rs b/src/slotmap.rs
index e5384bb..35f861f 100644
--- a/src/slotmap.rs
+++ b/src/slotmap.rs
@@ -23,6 +23,22 @@ pub struct Key {
     version: NonZeroU32,
 }
 
+impl Key {
+    pub const NULL: Self = Self {
+        index: u32::MAX,
+        version: match NonZeroU32::new(u32::MAX) {
+            Some(n) => n,
+            None => unreachable!(),
+        },
+    };
+}
+
+impl Default for Key {
+    fn default() -> Self {
+        Self::NULL
+    }
+}
+
 impl Key {
     pub fn new(index: u32, version: NonZeroU32) -> Self {
         Self { index, version }
diff --git a/src/world.rs b/src/world.rs
index fa09b23..958684f 100644
--- a/src/world.rs
+++ b/src/world.rs
@@ -11,9 +11,13 @@ pub struct Worlds {
     server: SharedServer,
 }
 
-#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default, Debug)]
 pub struct WorldId(Key);
 
+impl WorldId {
+    pub const NULL: Self = Self(Key::NULL);
+}
+
 impl Worlds {
     pub(crate) fn new(server: SharedServer) -> Self {
         Self {