Add basic parts of the Transposition Table

src/board/mod.rs

@@ -6,4 +6,5 @@ pub mod history;
 pub mod mailbox;
 pub mod square;
 pub mod state;
+pub mod transposition_table;
 pub mod zobrist;

src/board/transposition_table.rs

@@ -0,0 +1,81 @@
+use crate::movegen::r#move::Move;
+
+use super::zobrist::ZobristHash;
+
+#[derive(Clone)]
+pub struct TranspositionTable {
+    positions: Vec<Option<TranspositionTableEntry>>,
+    size: u64,
+}
+
+impl TranspositionTable {
+    pub fn new(size: u64) -> Self {
+        Self {
+            positions: (0..size).map(|_| None).collect(),
+            size,
+        }
+    }
+
+    pub fn lookup(&self, zobrist_hash: ZobristHash) -> &TranspositionTableEntry {
+        self.positions
+            .get((zobrist_hash.hash % self.size) as usize)
+            .unwrap()
+            .as_ref()
+            .unwrap()
+    }
+
+    pub fn insert(&mut self, tt_entry: TranspositionTableEntry, hash: ZobristHash) {
+        let index = hash.hash % self.size;
+        self.positions.insert(index as usize, Some(tt_entry));
+    }
+}
+
+#[derive(Clone)]
+pub struct TranspositionTableEntry {
+    hash: ZobristHash,
+    depth: u8,
+    alpha: i32,
+    beta: i32,
+    mv: Move,
+    node_type: NodeType,
+}
+
+impl TranspositionTableEntry {
+    pub const fn new(
+        hash: ZobristHash,
+        depth: u8,
+        alpha: i32,
+        beta: i32,
+        mv: Move,
+        node_type: NodeType,
+    ) -> Self {
+        Self {
+            hash,
+            depth,
+            alpha,
+            beta,
+            mv,
+            node_type,
+        }
+    }
+}
+
+#[derive(Clone)]
+pub enum NodeType {
+    Exact,
+    LowerBound,
+    UpperBound,
+}
+
+#[cfg(test)]
+mod tests {
+
+    #[test]
+    fn test_transpotisition() -> Result<(), String> {
+        // TODO:
+        // >have specific board state
+        // >run a deep search for this board state
+        // >test some expected outcomes that should have been stored in the TT
+        Ok(())
+    }
+}

src/board/zobrist.rs

@@ -106,7 +106,7 @@ impl Default for ZobristKeys {
 
 #[derive(Debug, Clone, PartialEq, Eq, Copy)]
 pub struct ZobristHash {
-    hash: u64,
+    pub hash: u64,
 }
 
 impl ZobristHash {