From e1d83825b7e646ac623ea0131cb0a6a8eed02c40 Mon Sep 17 00:00:00 2001
From: Simon Gardling <titaniumtown@proton.me>
Date: Thu, 20 Feb 2025 16:40:11 -0500
Subject: [PATCH] initial BVM usage (halfs performance :( )

---
 src/logic/board_value.rs | 29 +++++++++++++++++++++--------
 src/logic/move.rs        | 21 +++++++++------------
 src/repr/board.rs        | 27 ++++++++++++++++++++++++---
 3 files changed, 54 insertions(+), 23 deletions(-)

diff --git a/src/logic/board_value.rs b/src/logic/board_value.rs
index 62d9ae5..b837990 100644
--- a/src/logic/board_value.rs
+++ b/src/logic/board_value.rs
@@ -1,20 +1,33 @@
 use crate::repr::{Board, Piece, PosMap};
 
-pub struct BoardValueMap(PosMap<f32>);
+pub struct BoardValueMap(PosMap<i8>);
 
 impl BoardValueMap {
-    pub fn board_value(&self, board: &Board, color: Piece) -> f32 {
-        let mut board_value: f32 = 0.0;
-        for (i, j) in Board::all_positions() {
-            if let Some(pos_p) = board.get(i, j) {
+    pub fn board_value(&self, board: &Board, color: Piece) -> i8 {
+        Board::all_positions()
+            .filter_map(|(i, j)| board.get(i, j).map(|p| (i, j, p)))
+            .map(|(i, j, pos_p)| {
                 let mut value = *self.0.get(i, j);
                 if pos_p != color {
                     // enemy has position
                     value = -value;
                 }
-                board_value += value;
-            }
+                value
+            })
+            .sum()
+    }
+
+    pub fn new() -> Self {
+        let mut map = PosMap::new();
+
+        for (i, j) in Board::all_positions() {
+            map.set(i, j, 1);
         }
-        board_value
+
+        for (i, j) in Board::sides() {
+            map.set(i, j, 4);
+        }
+
+        Self(map)
     }
 }
diff --git a/src/logic/move.rs b/src/logic/move.rs
index 2ae9e26..0794ad3 100644
--- a/src/logic/move.rs
+++ b/src/logic/move.rs
@@ -1,5 +1,9 @@
+use lazy_static::lazy_static;
+
 use crate::repr::{Board, Piece, Winner};
 
+use super::board_value::BoardValueMap;
+
 #[derive(Clone, Debug)]
 pub struct Move {
     /// `i` position of move
@@ -28,6 +32,10 @@ pub struct Move {
     pub lazy_children: bool,
 }
 
+lazy_static! {
+    static ref BVM: BoardValueMap = BoardValueMap::new();
+}
+
 impl Move {
     pub const fn coords(&self) -> (usize, usize) {
         (self.i, self.j)
@@ -47,17 +55,6 @@ impl Move {
             return 0;
         }
 
-        let mut self_value = self.board.net_score(agent_color) as i64;
-        let corner_v_agent = Board::sides()
-            .filter(|&(i, j)| self.board.get_piece(i, j, agent_color))
-            .count() as i64;
-        let corner_v_not_agent = Board::sides()
-            .filter(|&(i, j)| self.board.get_piece(i, j, !agent_color))
-            .count() as i64;
-
-        // make net-corner capture important
-        self_value += (corner_v_agent - corner_v_not_agent) * 4;
-
-        self_value
+        BVM.board_value(&self.board, agent_color) as i64
     }
 }
diff --git a/src/repr/board.rs b/src/repr/board.rs
index 85d95a2..a368ae1 100644
--- a/src/repr/board.rs
+++ b/src/repr/board.rs
@@ -26,11 +26,21 @@ type ChainCollection = ArrayVec<Chain, 8>;
 /// Map of all points on the board against some type T
 /// Used to index like so: example[i][j]
 /// with each coordinate
-pub struct PosMap<T>(ArrayVec<T, BOARD_AREA>);
+pub struct PosMap<T: Default>(ArrayVec<T, BOARD_AREA>);
+
+impl<T: Default> PosMap<T> {
+    const fn index(row: usize, col: usize) -> usize {
+        row * BOARD_SIZE + col
+    }
+
+    pub fn new() -> Self {
+        Self(ArrayVec::from_iter(
+            (0..BOARD_AREA).map(|_| Default::default()),
+        ))
+    }
 
-impl<T> PosMap<T> {
     pub fn get(&self, row: usize, col: usize) -> &T {
-        let index = row * BOARD_SIZE + col;
+        let index = Self::index(row, col);
 
         debug_assert!(
             BOARD_AREA + 1 >= index,
@@ -40,6 +50,17 @@ impl<T> PosMap<T> {
 
         unsafe { self.0.get_unchecked(index) }
     }
+
+    pub fn set(&mut self, row: usize, col: usize, value: T) {
+        let index = Self::index(row, col);
+        debug_assert!(
+            BOARD_AREA + 1 >= index,
+            "index out of range, was: {}",
+            index
+        );
+
+        self.0[index] = value;
+    }
 }
 
 /// Creates a lookup map for adjacencies and chains from each position on the board