Allow RngDeck to be passed between threads

board-shared/src/deck.rs

@@ -1,6 +1,6 @@
 use crate::tile::Operator;
 use enum_map::EnumMap;
-use rand::Rng;
+use rand::{thread_rng, Rng};
 
 type DeckSize = u16;
 type DigitDeck = [DeckSize; 19];
@@ -63,40 +63,37 @@ impl Deck {
 #[derive(Debug, Clone, Default)]
 pub struct RngDeck {
     deck: Deck,
-    rng: rand::rngs::ThreadRng,
 }
 
 impl RngDeck {
     pub fn new_complete() -> Self {
         Self {
             deck: Deck::new_complete(),
-            rng: rand::thread_rng(),
         }
     }
 
     /// Gets a random tile from the deck and remove it from the deck.
     pub fn rand_digit(&mut self) -> Option<i8> {
         let sum = self.deck.digits.iter().sum();
-        Self::select_rng(&mut self.rng, sum, self.deck.digits.iter_mut().enumerate())
-            .map(|n| n as i8 - 9)
+        Self::select_rng(sum, self.deck.digits.iter_mut().enumerate()).map(|n| n as i8 - 9)
     }
 
     /// Gets a random operator from the deck and remove it from the deck.
     pub fn rand_operator(&mut self) -> Option<Operator> {
         let sum = self.deck.operators.values().sum();
-        Self::select_rng(&mut self.rng, sum, self.deck.operators.iter_mut())
+        Self::select_rng(sum, self.deck.operators.iter_mut())
     }
 
     /// Selects a random item from an iterator of (item, count) pairs.
     /// The count is decremented by one if the item is selected.
     fn select_rng<'a, T>(
-        rng: &mut rand::rngs::ThreadRng,
         sum: DeckSize,
         it: impl Iterator<Item = (T, &'a mut DeckSize)>,
     ) -> Option<T> {
         if sum == 0 {
             return None;
         }
+        let mut rng = thread_rng();
         let mut threshold = rng.gen_range(1..=sum);
         for (item, count) in it {
             threshold = threshold.saturating_sub(*count);