💹 Remove unnecessary `Rc` in `FullTile`

stackline/src/context.rs

@@ -1,5 +1,4 @@
 use std::marker::PhantomData;
-use std::rc::Rc;
 use super::*;
 
 /** An `UpdateContext` is created for every tile update during the "update" phase,
@@ -48,7 +47,7 @@ impl Tile for MyTile {
         ctx.next_state(); // Become dormant
     }
 #
-#    fn transmit<'b>(&'b self, signal: std::rc::Rc<Signal>, ctx: TransmitContext<'b>) {}
+#    fn transmit<'b>(&'b self, signal: Signal, ctx: TransmitContext<'b>) {}
 }
 ```
 
@@ -90,7 +89,7 @@ impl<'a> UpdateContext<'a> {
 
     /// Returns the [signal](crate::FullTile::signal) of the currently updated tile.
     #[inline]
-    pub fn signal<'b>(&'b self) -> Option<&'b Rc<Signal>> where 'a: 'b {
+    pub fn signal<'b>(&'b self) -> Option<&'b Signal> where 'a: 'b {
         let pane = unsafe { self.pane() };
 
         // SAFETY: `pane[position].signal` is not borrowed mutably
@@ -170,7 +169,7 @@ pub struct TransmitContext<'a> {
 }
 
 impl<'a> TransmitContext<'a> {
-    pub(crate) fn new(pane: &'a mut Pane, position: (usize, usize)) -> Option<(Self, &'a AnyTile, Rc<Signal>)> {
+    pub(crate) fn new(pane: &'a mut Pane, position: (usize, usize)) -> Option<(Self, &'a AnyTile, Signal)> {
         let ptr: *mut Pane = &mut *pane;
         // SAFETY: no mutable accesses to `∀x, pane[x].cell` are made by `TransmitContext`
         let tile: &AnyTile = unsafe {
@@ -240,22 +239,18 @@ impl<'a> TransmitContext<'a> {
     /// Returns true if the signal was stored in a cell, false otherwise.
     /// The target cell's state will be set to `Active` if it received the signal.
     /// The signal's `position` will be set to `pos`.
-    pub fn send<'b>(&'b mut self, pos: (usize, usize), mut signal: Signal) -> Option<Weak<Signal>> where 'a: 'b {
+    pub fn send<'b>(&'b mut self, pos: (usize, usize), mut signal: Signal) -> Option<()> where 'a: 'b {
         // SAFETY: we do not return any reference to any data borrowed in this function
         // SAFETY: we only access `pane[pos].signal`, `pane[pos].state` and `pane.signals`
         let pane = unsafe { self.pane_mut() };
 
         signal.set_position(pos);
 
-        match pane.set_signal(pos, signal) {
-            Some(signal) => {
+        pane.set_signal(pos, signal)?;
         // SAFETY: we only access `pane[pos].state`
         pane.get_mut(pos).unwrap_or_else(|| unreachable!()).set_state(State::Active);
 
-                Some(signal)
-            }
-            None => None
-        }
+        Some(())
     }
 
     /// Returns `Some((position.x + Δx, position.y + Δy))` iff `(x + Δx, y + Δy)` is inside the pane

stackline/src/lib.rs

@@ -1,5 +1,4 @@
 use std::num::NonZeroUsize;
-use std::rc::Weak;
 
 mod signal;
 pub use signal::*;

stackline/src/pane.rs

@@ -6,7 +6,7 @@ pub struct Pane {
     width: NonZeroUsize,
     height: NonZeroUsize,
 
-    signals: Vec<Weak<Signal>>,
+    signals: Vec<(usize, usize)>,
 }
 
 impl Pane {
@@ -71,10 +71,11 @@ impl Pane {
     /// - the tile accepts a signal (ie. it isn't empty)
     // SAFETY: may only access `self[pos].signal` and `self.signals`
     #[inline]
-    pub fn set_signal(&mut self, position: (usize, usize), signal: Signal) -> Option<Weak<Signal>> {
-        let signal = self.get_mut(position)?.set_signal(signal)?;
-        self.signals.push(signal.clone());
-        Some(signal)
+    pub fn set_signal(&mut self, position: (usize, usize), mut signal: Signal) -> Option<()> {
+        signal.set_position(position);
+        self.get_mut(position)?.set_signal(signal)?;
+        self.signals.push(position);
+        Some(())
     }
 
     #[inline]
@@ -116,13 +117,10 @@ impl Pane {
     /// Calls [`Pane::transmit`] on all tiles with a signal
     fn transmit_all(&mut self) {
         // TODO: store a second buffer and perform swap reads
-        for signal in std::mem::replace(&mut self.signals, vec![]) {
-            if let Some(upgraded) = signal.upgrade() {
-                let position = upgraded.position();
+        for position in std::mem::replace(&mut self.signals, vec![]) {
             let _ = self.transmit(position); // May return None if the signal was aliased
         }
     }
-    }
 
     /// Runs a single simulation step, which consists of:
     /// - an update phase, which mutates the inner state of [active](State::Active)] cells by calling [`Tile::update`]

stackline/src/tile/mod.rs

@@ -1,6 +1,5 @@
 use super::*;
 use dyn_clone::{clone_box, DynClone};
-use std::rc::Rc;
 
 mod wire;
 pub use wire::*;
@@ -17,7 +16,7 @@ Cloning a `FullTile` results in a `FullTile` that does not have any signal.
 #[derive(Clone, Debug)]
 pub struct FullTile {
     cell: Option<AnyTile>,
-    signal: Option<Rc<Signal>>,
+    signal: Option<Signal>,
     state: State,
 }
 
@@ -40,12 +39,10 @@ impl FullTile {
     }
 
     /// Returns Some(signal) iff self.cell.is_some()
-    pub(crate) fn set_signal(&mut self, signal: Signal) -> Option<Weak<Signal>> {
+    pub(crate) fn set_signal(&mut self, signal: Signal) -> Option<()> {
         if self.cell.is_some() {
-            let rc = Rc::new(signal);
-            let weak = Rc::downgrade(&rc);
-            self.signal = Some(rc);
-            Some(weak)
+            self.signal = Some(signal);
+            Some(())
         } else {
             None
         }
@@ -65,12 +62,12 @@ impl FullTile {
 
     /// Returns the signal of this tile
     #[inline]
-    pub fn signal<'b>(&'b self) -> Option<&'b Rc<Signal>> {
+    pub fn signal<'b>(&'b self) -> Option<&'b Signal> {
         self.signal.as_ref()
     }
 
     #[inline]
-    pub fn take_signal(&mut self) -> Option<Rc<Signal>> {
+    pub fn take_signal(&mut self) -> Option<Signal> {
         std::mem::take(&mut self.signal)
     }
 
@@ -91,7 +88,7 @@ impl FullTile {
         self.state = self.state.next();
     }
 
-    pub fn into_raw_mut<'b>(&'b mut self) -> (&'b mut Option<AnyTile>, &'b mut Option<Rc<Signal>>, &'b mut State) {
+    pub fn into_raw_mut<'b>(&'b mut self) -> (&'b mut Option<AnyTile>, &'b mut Option<Signal>, &'b mut State) {
         (&mut self.cell, &mut self.signal, &mut self.state)
     }
 }
@@ -126,7 +123,7 @@ pub trait Tile: DynClone + std::fmt::Debug {
     }
 
     /// Function that will be called if the tile has a signal.
-    fn transmit<'b>(&'b self, signal: Rc<Signal>, context: TransmitContext<'b>);
+    fn transmit<'b>(&'b self, signal: Signal, context: TransmitContext<'b>);
 
     /// Should return true iff the tile accepts a signal travelling in `Direction`
     #[inline]
@@ -151,7 +148,7 @@ impl AnyTile {
     }
 
     #[inline]
-    pub fn transmit<'b>(&'b self, signal: Rc<Signal>, context: TransmitContext<'b>) {
+    pub fn transmit<'b>(&'b self, signal: Signal, context: TransmitContext<'b>) {
         self.0.transmit(signal, context)
     }
 

stackline/src/tile/wire.rs

@@ -12,7 +12,7 @@ impl Wire {
 }
 
 impl Tile for Wire {
-    fn transmit<'b>(&'b self, signal: Rc<Signal>, mut context: TransmitContext<'b>) {
+    fn transmit<'b>(&'b self, signal: Signal, mut context: TransmitContext<'b>) {
         for &direction in self.0.into_directions() {
             if direction == signal.direction().opposite() {
                 continue;
@@ -41,7 +41,7 @@ impl Diode {
 }
 
 impl Tile for Diode {
-    fn transmit<'b>(&'b self, signal: Rc<Signal>, mut context: TransmitContext<'b>) {
+    fn transmit<'b>(&'b self, signal: Signal, mut context: TransmitContext<'b>) {
         // Block signals coming from where the diode is looking
         if signal.direction().opposite() == self.0 {
             return;