compressed.py

class Position(namedtuple('Position', 'board score')):
    def gen_moves(self):
        for i, p in enumerate(self.board):
            if p == 'K':
                for scanpos in range(i - 16,A9,-16):
                    if self.board[scanpos] == 'k':
                        yield (i,scanpos)
                    elif self.board[scanpos] != '.':
                        break
            if not p.isupper(): continue
            if p == 'C':
                for d in directions[p]:
                    cfoot = 0
                    for j in count(i+d, d):
                        q = self.board[j]
                        if q.isspace():break
                        if cfoot == 0 and q == '.':yield (i,j)
                        elif cfoot == 0 and q != '.':cfoot += 1
                        elif cfoot == 1 and q.islower(): yield (i,j);break
                        elif cfoot == 1 and q.isupper(): break;
                continue
            for d in directions[p]:
                for j in count(i+d, d):
                    q = self.board[j]
                    if q.isspace() or q.isupper(): break
                    if p == 'P' and d in (E, W) and i > 128: break
                    elif p in ('Q','K') and (j < 160 or j & 15 > 8 or j & 15 < 6): break
                    elif p == 'B' and j < 128: break
                    elif p == 'N':
                        n_diff_x = (j - i) & 15
                        if n_diff_x == 14 or n_diff_x == 2:
                            if self.board[i + (1 if n_diff_x == 2 else -1)] != '.': break
                        else:
                            if j > i and self.board[i + 16] != '.': break
                            elif j < i and self.board[i - 16] != '.': break
                    elif p == 'B' and self.board[i + d / 2] != '.':break
                    yield (i, j)
                    if p in 'PNBQK' or q.islower(): break
    def rotate(self):
        return Position(
            self.board[-2::-1].swapcase() + " ", -self.score)
    def nullmove(self):
        return self.rotate()
    def move(self, move):
        i, j = move
        p, q = self.board[i], self.board[j]
        put = lambda board, i, p: board[:i] + p + board[i+1:]
        board = self.board
        score = self.score + self.value(move)
        board = put(board, j, board[i])
        board = put(board, i, '.')
        return Position(board, score).rotate()
    def value(self, move):
        i, j = move
        p, q = self.board[i], self.board[j]
        score = pst[p][j] - pst[p][i]
        if q.islower():
            score += pst[q.upper()][255-j-1]
        return score
Entry = namedtuple('Entry', 'lower upper')
class Searcher:
    def __init__(self):
        self.tp_score = {}
        self.tp_move = {}
        self.history = set()
        self.nodes = 0
    def bound(self, pos, gamma, depth, root=True):
        self.nodes += 1
        depth = max(depth, 0)
        if pos.score <= -MATE_LOWER:
            return -MATE_UPPER
        if DRAW_TEST:
            if not root and pos in self.history:
                return 0
        entry = self.tp_score.get((pos, depth, root), Entry(-MATE_UPPER, MATE_UPPER))
        if entry.lower >= gamma and (not root or self.tp_move.get(pos) is not None):
            return entry.lower
        if entry.upper < gamma:
            return entry.upper
        def moves():
            if depth > 0 and not root and any(c in pos.board for c in 'RNC'):
                yield None, -self.bound(pos.nullmove(), 1-gamma, depth-3, root=False)
            if depth == 0:
                yield None, pos.score
            killer = self.tp_move.get(pos)
            if killer and (depth > 0 or pos.value(killer) >= QS_LIMIT):
                yield killer, -self.bound(pos.move(killer), 1-gamma, depth-1, root=False)
            for move in sorted(pos.gen_moves(), key=pos.value, reverse=True):
                if depth > 0 or pos.value(move) >= QS_LIMIT:
                    yield move, -self.bound(pos.move(move), 1-gamma, depth-1, root=False)
        best = -MATE_UPPER
        for move, score in moves():
            best = max(best, score)
            if best >= gamma:
                if len(self.tp_move) > TABLE_SIZE: self.tp_move.clear()
                self.tp_move[pos] = move
                break
        if best < gamma and best < 0 and depth > 0:
            is_dead = lambda pos: any(pos.value(m) >= MATE_LOWER for m in pos.gen_moves())
            if all(is_dead(pos.move(m)) for m in pos.gen_moves()):
                in_check = is_dead(pos.nullmove())
                best = -MATE_UPPER if in_check else 0
        if len(self.tp_score) > TABLE_SIZE: self.tp_score.clear()
        if best >= gamma:
            self.tp_score[pos, depth, root] = Entry(best, entry.upper)
        if best < gamma:
            self.tp_score[pos, depth, root] = Entry(entry.lower, best)
        return best
    def search(self, pos, history=()):
        self.nodes = 0
        if DRAW_TEST:
            self.history = set(history)
            self.tp_score.clear()
        for depth in range(1, 1000):
            lower, upper = -MATE_UPPER, MATE_UPPER
            while lower < upper - EVAL_ROUGHNESS:
                gamma = (lower+upper+1)//2
                score = self.bound(pos, gamma, depth)
                if score >= gamma:
                    lower = score
                if score < gamma:
                    upper = score
            self.bound(pos, lower, depth)
            yield depth, self.tp_move.get(pos), self.tp_score.get((pos, depth, True)).lower