diff options
| -rw-r--r-- | board.cpp | 79 | ||||
| -rw-r--r-- | board.h | 8 |
2 files changed, 80 insertions, 7 deletions
@@ -293,18 +293,76 @@ void Board::apply(const Move &mv) { lastTarget = mv.to; } -bool Board::isValid(const Move &mv) { +bool Board::isValid(const Move &mv) const { assert(mv.castle == 0); if (colour(at(mv.from)) != onTurn) return false; Board B(*this); B.apply(mv); - // cerr << "after applying:" << endl << B << endl; - // cerr << subsequents()[27] << endl; - // cerr << (B == subsequents()[27]) << endl; + bool found = false; for (const Board &B2 : subsequents()) { - if (B == B2) return true; + if (B == B2) { + found = true; + break; + } + } + if (!found) return false; + switch (B.checkCheck(onTurn)) { + case CheckResult::check: + case CheckResult::checkmate: + return false; + default: + return true; + } +} + +CheckResult Board::checkCheck(int player) const { + // First check 'check' (p), then check if we have 'check' after any move (q). + // p | q | Result + // 0 | 0 | safe + // 0 | 1 | stalemate + // 1 | 0 | check + // 1 | 1 | checkmate + + + // Check 'check' by switching onTurn and seeing if the king can be taken + bool haveP = false; + Board B1(*this); + B1.onTurn = !player; + for (const Board &B2 : B1.subsequents()) { + if (B2.pieceScore[B1.onTurn] >= worth(KING)) { + haveP = true; + break; + } + } + + // Then check if we have 'check' after any move + bool haveQ = true; + B1.onTurn = player; + for (const Board &B2 : subsequents()) { + bool checkNow = false; + for (const Board &B3 : B2.subsequents()) { + if (B3.pieceScore[B2.onTurn] >= worth(KING)) { + checkNow = true; + break; + } + } + if (!checkNow) { + haveQ = false; + break; + } + } + + if (haveP) { + if (haveQ) return CheckResult::checkmate; + else return CheckResult::check; + } else { + if (haveQ) return CheckResult::stalemate; + else return CheckResult::safe; } - return false; +} + +static const char* playerName(int player) { + return &"WHITE\0BLACK"[player * 6]; } ostream& operator<<(ostream &os, const Board &B) { @@ -320,9 +378,16 @@ ostream& operator<<(ostream &os, const Board &B) { } if (y == 0) { os << " ps[W] = " << B.pieceScore[WHITE]; - os << " onTurn = " << (&"WHITE\0BLACK"[B.onTurn * 6]); + os << " onTurn = " << playerName(B.onTurn); } else if (y == 1) { os << " ps[B] = " << B.pieceScore[BLACK]; + } else if (y == 2) { + switch (B.checkCheck(B.onTurn)) { + case CheckResult::safe: break; + case CheckResult::check: os << " " << playerName(B.onTurn) << " IN CHECK"; break; + case CheckResult::checkmate: os << " " << playerName(B.onTurn) << " CHECKMATED."; break; + case CheckResult::stalemate: os << " " << playerName(B.onTurn) << " STALEMATED."; break; + } } os << '\n'; } @@ -17,6 +17,10 @@ const int EMPTY = 0, PAWN = 1, ROOK = 2, KNIGHT = 3, BISHOP = 4, KING = 5, QUEEN // ... // WHITE WHITE WHITE y = 7 +enum class CheckResult { + safe, check, checkmate, stalemate +}; + #define IDX(x_, y_) (8 * (y_) + (x_)) @@ -59,6 +63,10 @@ public: bool isValid(const Move &mv) const; // SLOW + // SLOW; Only detects anything for the given player. + // Assumes no king has been taken yet. + CheckResult checkCheck(int player) const; + friend bool operator==(const Board &B1, const Board &B2); }; |