feat: 置换表 — Zobrist 索引 + depth 优先替换 + 5 测试

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

core/src/ai/mod.rs

@@ -10,4 +10,6 @@ pub trait AiEngine: Send + Sync {
 pub mod evaluate;
 pub mod killer;
 pub mod search;
+pub mod trans_table;
 pub mod vcf;
+pub mod opening;

core/src/ai/trans_table.rs

@@ -0,0 +1,120 @@
+use crate::types::{Position, ZobristHash};
+
+const TT_SIZE: usize = 1 << 20; // ~100 万条目
+const TT_MASK: usize = TT_SIZE - 1;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum BoundType {
+    Exact,
+    LowerBound,
+    UpperBound,
+}
+
+#[derive(Debug, Clone)]
+pub struct TTEntry {
+    pub hash: ZobristHash,
+    pub depth: u8,
+    pub score: i32,
+    pub bound: BoundType,
+    pub best_move: Option<Position>,
+}
+
+pub struct TransTable {
+    entries: Box<[Option<TTEntry>]>,
+}
+
+impl TransTable {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn probe(&self, hash: ZobristHash, depth: u8) -> Option<&TTEntry> {
+        let idx = (hash as usize) & TT_MASK;
+        self.entries[idx]
+            .as_ref()
+            .filter(|e| e.hash == hash && e.depth >= depth)
+    }
+
+    pub fn store(
+        &mut self,
+        hash: ZobristHash,
+        depth: u8,
+        score: i32,
+        bound: BoundType,
+        best_move: Option<Position>,
+    ) {
+        let idx = (hash as usize) & TT_MASK;
+        let should_replace = match &self.entries[idx] {
+            None => true,
+            Some(old) => depth >= old.depth,
+        };
+        if should_replace {
+            self.entries[idx] = Some(TTEntry {
+                hash,
+                depth,
+                score,
+                bound,
+                best_move,
+            });
+        }
+    }
+
+    pub fn clear(&mut self) {
+        for entry in self.entries.iter_mut() {
+            *entry = None;
+        }
+    }
+}
+
+impl Default for TransTable {
+    fn default() -> Self {
+        Self {
+            entries: vec![None; TT_SIZE].into_boxed_slice(),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_store_and_probe() {
+        let mut tt = TransTable::new();
+        tt.store(12345, 3, 100, BoundType::Exact, Some(Position::new(7, 7)));
+        let entry = tt.probe(12345, 2).unwrap();
+        assert_eq!(entry.score, 100);
+        assert_eq!(entry.best_move, Some(Position::new(7, 7)));
+    }
+
+    #[test]
+    fn test_depth_requirement() {
+        let mut tt = TransTable::new();
+        tt.store(42, 5, 200, BoundType::Exact, None);
+        assert!(tt.probe(42, 4).is_some());
+        assert!(tt.probe(42, 6).is_none());
+    }
+
+    #[test]
+    fn test_hash_collision_prevention() {
+        let mut tt = TransTable::new();
+        tt.store(100, 3, 50, BoundType::Exact, None);
+        assert!(tt.probe(200, 1).is_none());
+    }
+
+    #[test]
+    fn test_depth_priority_replacement() {
+        let mut tt = TransTable::new();
+        tt.store(999, 2, 10, BoundType::Exact, None);
+        tt.store(999, 5, 99, BoundType::Exact, None);
+        assert_eq!(tt.probe(999, 3).unwrap().score, 99);
+    }
+
+    #[test]
+    fn test_clear() {
+        let mut tt = TransTable::new();
+        tt.store(1, 1, 1, BoundType::Exact, None);
+        tt.clear();
+        assert!(tt.probe(1, 0).is_none());
+    }
+}