From 30476757dac89ed3b9525766e6a9455801bd3058 Mon Sep 17 00:00:00 2001
From: Simon Gardling <titaniumtown@proton.me>
Date: Tue, 1 Apr 2025 15:49:18 -0400
Subject: [PATCH] Board: make starting_pos a const variable instead

---
 benches/future_children.rs |  2 +-
 src/allocs.rs              |  2 +-
 src/game.rs                |  2 +-
 src/logic/future_moves.rs  |  8 ++++----
 src/repr/board.rs          | 21 +++++++++++----------
 5 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/benches/future_children.rs b/benches/future_children.rs
index 217ca3e..9c76387 100644
--- a/benches/future_children.rs
+++ b/benches/future_children.rs
@@ -16,7 +16,7 @@ fn extend_layers_no_pruning(depth: usize) -> usize {
         children_eval_method: ChildrenEvalMethod::AverageDivDepth,
     };
     let mut fut = FutureMoves::new(Piece::Black, config);
-    fut.update_from_board(&Board::new().starting_pos());
+    fut.update_from_board(&Board::STARTING_POSITION);
     fut.extend_layers();
     fut.arena_len()
 }
diff --git a/src/allocs.rs b/src/allocs.rs
index 8d80c84..0d7105c 100644
--- a/src/allocs.rs
+++ b/src/allocs.rs
@@ -22,7 +22,7 @@ pub fn run() {
         },
     );
 
-    let mut board = Board::new().starting_pos();
+    let mut board = Board::STARTING_POSITION;
     let mut rng = rand::rng();
     let mut i = 0;
     while board.game_winner() == Winner::None && i < 2 {
diff --git a/src/game.rs b/src/game.rs
index 056c293..a86a214 100644
--- a/src/game.rs
+++ b/src/game.rs
@@ -8,7 +8,7 @@ pub struct Game {
 impl Game {
     pub fn new(player1: Box<dyn Agent>, player2: Box<dyn Agent>) -> Self {
         Self {
-            inner: GameInner::new(player1, player2, true, Board::new().starting_pos()),
+            inner: GameInner::new(player1, player2, true, Board::STARTING_POSITION),
         }
     }
 
diff --git a/src/logic/future_moves.rs b/src/logic/future_moves.rs
index d323fbf..0b784e3 100644
--- a/src/logic/future_moves.rs
+++ b/src/logic/future_moves.rs
@@ -629,7 +629,7 @@ mod tests {
         let mut futm = FutureMoves::new(Piece::Black, FUTURE_MOVES_CONFIG);
         futm.config.max_depth = 1;
 
-        futm.update_from_board(&Board::new().starting_pos());
+        futm.update_from_board(&Board::STARTING_POSITION);
 
         futm.extend_layers();
         assert_eq!(futm.arena_len(), 5);
@@ -710,7 +710,7 @@ mod tests {
     #[test]
     fn skip_move_recovery() {
         let mut futm = FutureMoves::new(Piece::Black, FUTURE_MOVES_CONFIG);
-        let mut board = Board::new().starting_pos();
+        let mut board = Board::STARTING_POSITION;
 
         // replay of a test I did
         // TODO! make this as small of a test as possible
@@ -774,8 +774,8 @@ mod tests {
     fn derive_board() {
         let mut futm = FutureMoves::new(Piece::White, FUTURE_MOVES_CONFIG);
 
-        let mut b = Board::new().starting_pos();
-        futm.update_from_board(&Board::new().starting_pos());
+        let mut b = Board::STARTING_POSITION;
+        futm.update_from_board(&b);
 
         b.place((4, 2).into(), Piece::White).unwrap();
 
diff --git a/src/repr/board.rs b/src/repr/board.rs
index bfebb15..d2cd99b 100644
--- a/src/repr/board.rs
+++ b/src/repr/board.rs
@@ -123,7 +123,7 @@ impl Board {
     }
 
     pub fn random(steps: usize) -> Self {
-        let mut new = Self::new().starting_pos();
+        let mut new = Self::STARTING_POSITION;
         let mut p = Piece::Black;
         let mut rng = rand::rng();
         for _ in 0..steps {
@@ -137,16 +137,17 @@ impl Board {
         new
     }
 
-    /// Starting position
-    pub const fn starting_pos(mut self) -> Self {
+    pub const STARTING_POSITION: Self = {
+        let mut new = Self::new();
         let hf = Self::SIZE / 2;
-        self.place_unchecked(CoordPair::from_axes(hf - 1, hf - 1), Piece::White);
-        self.place_unchecked(CoordPair::from_axes(hf, hf - 1), Piece::Black);
 
-        self.place_unchecked(CoordPair::from_axes(hf - 1, hf), Piece::Black);
-        self.place_unchecked(CoordPair::from_axes(hf, hf), Piece::White);
-        self
-    }
+        new.place_unchecked(CoordPair::from_axes(hf - 1, hf - 1), Piece::White);
+        new.place_unchecked(CoordPair::from_axes(hf, hf - 1), Piece::Black);
+
+        new.place_unchecked(CoordPair::from_axes(hf - 1, hf), Piece::Black);
+        new.place_unchecked(CoordPair::from_axes(hf, hf), Piece::White);
+        new
+    };
 
     /// Provides an iterator of all possible positions on the board
     pub fn all_positions() -> impl Iterator<Item = CoordPair> {
@@ -499,7 +500,7 @@ mod test {
     #[test]
     fn format_test() {
         assert_eq!(
-            Board::new().starting_pos().to_string().as_str(),
+            Board::STARTING_POSITION.to_string().as_str(),
             "  7 6 5 4 3 2 1 0
  -----------------
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