dev: Continue to write the chess logic, working through it bit by bit

Piece.cpp

@@ -7,9 +7,57 @@
 
 #include "Piece.hpp"
 
-std::vector<std::pair<int, int>> King::getLegalMoves(int x, int y, const Board& board) const {
-    std::vector<std::pair<int, int>> moveList;
-    
+Piece::~Piece() {
+    return;
+}
+
+// because the Piece class is instantiated in another class using
+// unique_ptr, non-pure virtual functions apparently *must*
+// have definitions, or the linker freaks out
+// so this is just a stub that does nothing. it doesn't matter
+// because only the derived class versions should be called.
+
+std::vector<Move> Piece::getLegalMoves(const Square &from, const Board &board) const {
+    std::vector<Move> moveList;
+    return moveList;
+}
+
+std::vector<Move> King::getLegalMoves(const Square &from, const Board &board) const {
+    std::vector<Move> moveList;
+
+}
+
+std::vector<Move> Rook::getLegalMoves(const Square &from, const Board &board) const {
+    std::vector<Move> moveList;
+    const int directions[8][2] = {
+        {-1, 0}, // Up
+        {1, 0}, // Down
+        {0, -1}, // Left
+        {0, 1} // Right
+    };
+    for (auto& dir : directions) {
+        int r = from.rank + dir[0];
+        int f = from.file + dir[1];
+
+        while (r >= 0 && r < 8 && f >= 0 && f < 8) {
+            const auto& target = board[r][f];
+
+            if (!target) {
+                moves.push_back({from,
+                    {r, f}});
+            } else if (target->color != this->color) {
+                moves.push_back({from,
+                    {r, f}});
+                break;
+            } else {
+                break;
+            }
+
+            r += dir[0];
+            f += dir[1];
+        }
+    }
+
     // calculate legal moves somehow
     return moveList;
 }