Initial

1 files changed, 78 insertions, 0 deletions

diff --git a/board.h b/board.h
new file mode 100644
index 0000000..1ab0646
--- /dev/null
+++ b/board.h
@@ -0,0 +1,78 @@
+#pragma once
+
+#include <iostream>
+#include <optional>
+#include <string_view>
+#include <cstdint>
+
+using namespace std;
+
+const int N = 9;
+const int BOARDMID = N * (N/2) + N/2;
+
+const uint8_t EMPTY = 0, WHITE = 1, KING = 2, BLACK = 4;
+
+
+struct Move {
+	int from, to;
+
+	Move() = default;
+	Move(int from, int to);
+
+	static optional<Move> parse(string_view str);
+};
+
+struct Board {
+	uint8_t cells[N * N];
+
+	static Board makeInitial();
+
+	void apply(Move mv);
+	int applyCW(Move mv);
+	int checkWin() const;  // 1=win white, -1=win black, 0=none yet
+
+	bool isValid(Move mv, int player) const;
+
+	// Calls the callback for each valid move of the specified player.
+	// F should have a signature compatible with bool F(Move mv).
+	// If the callback returns true, iteration is stopped.
+	// Callback should not modify this Board instance.
+	template <typename F>
+	void forEachMove(int player, F callback) const;
+
+private:
+	Board();
+
+	bool isValid(Move mv) const;
+	bool stoneFlankedH(int pos, uint8_t by) const;
+	bool stoneFlankedV(int pos, uint8_t by) const;
+	bool kingEncircled(int pos) const;
+};
+
+ostream& operator<<(ostream &os, const Move &mv);
+ostream& operator<<(ostream &os, const Board &bd);
+
+
+template <typename F>
+void Board::forEachMove(int player, F callback) const {
+	static const int deltas[4][2] = {{-1, 0}, {0, -1}, {1, 0}, {0, 1}};
+
+	for (int y = 0; y < N; y++)
+	for (int x = 0; x < N; x++) {
+		uint8_t v = cells[N * y + x];
+		if (player == 1 ? v != WHITE && v != KING : v != BLACK) continue;
+
+		for (int i = 0; i < 4; i++) {
+			int x2 = x + deltas[i][0], y2 = y + deltas[i][1];
+			while (x2 >= 0 && x2 < N && y2 >= 0 && y2 < N) {
+				if (cells[N * y2 + x2] != EMPTY) break;
+				if (N * y2 + x2 != BOARDMID) {
+					callback(Move(N * y + x, N * y2 + x2));
+				}
+
+				x2 += deltas[i][0];
+				y2 += deltas[i][1];
+			}
+		}
+	}
+}