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import copy
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from tugo.gotypes import Player, Point
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from tugo.scoring import compute_game_result
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from tugo import zobrist
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from tugo.utils import MoveAge
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__all__ = [
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'Board',
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'GameState',
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'Move',
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]
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neighbor_tables = {}
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corner_tables = {}
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def init_neighbor_table(dim):
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rows, cols = dim
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new_table = {}
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for r in range(1, rows + 1):
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for c in range(1, cols + 1):
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p = Point(row=r, col=c)
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full_neighbors = p.neighbors()
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true_neighbors = [
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n for n in full_neighbors
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if 1 <= n.row <= rows and 1 <= n.col <= cols]
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new_table[p] = true_neighbors
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neighbor_tables[dim] = new_table
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def init_corner_table(dim):
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rows, cols = dim
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new_table = {}
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for r in range(1, rows + 1):
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for c in range(1, cols + 1):
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p = Point(row=r, col=c)
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full_corners = [
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Point(row=p.row - 1, col=p.col - 1),
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Point(row=p.row - 1, col=p.col + 1),
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Point(row=p.row + 1, col=p.col - 1),
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Point(row=p.row + 1, col=p.col + 1),
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]
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true_corners = [
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n for n in full_corners
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if 1 <= n.row <= rows and 1 <= n.col <= cols]
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new_table[p] = true_corners
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corner_tables[dim] = new_table
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class IllegalMoveError(Exception):
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pass
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class GoString():
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"""Stones that are linked by a chain of connected stones of the
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same color.
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"""
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def __init__(self, color, stones, liberties):
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self.color = color
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self.stones = frozenset(stones)
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self.liberties = frozenset(liberties)
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def without_liberty(self, point):
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new_liberties = self.liberties - set([point])
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return GoString(self.color, self.stones, new_liberties)
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def with_liberty(self, point):
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new_liberties = self.liberties | set([point])
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return GoString(self.color, self.stones, new_liberties)
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def merged_with(self, string):
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"""Return a new string containing all stones in both strings."""
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assert string.color == self.color
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combined_stones = self.stones | string.stones
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return GoString(
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self.color,
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combined_stones,
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(self.liberties | string.liberties) - combined_stones)
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@property
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def num_liberties(self):
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return len(self.liberties)
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def __eq__(self, other):
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return isinstance(other, GoString) and \
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self.color == other.color and \
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self.stones == other.stones and \
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self.liberties == other.liberties
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def __deepcopy__(self, memodict={}):
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return GoString(self.color, self.stones, copy.deepcopy(self.liberties))
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class Board():
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def __init__(self, num_rows, num_cols):
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self.num_rows = num_rows
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self.num_cols = num_cols
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self._grid = {}
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self._hash = zobrist.EMPTY_BOARD
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global neighbor_tables
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dim = (num_rows, num_cols)
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if dim not in neighbor_tables:
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init_neighbor_table(dim)
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if dim not in corner_tables:
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init_corner_table(dim)
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self.neighbor_table = neighbor_tables[dim]
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self.corner_table = corner_tables[dim]
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self.move_ages = MoveAge(self)
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def neighbors(self, point):
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return self.neighbor_table[point]
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def corners(self, point):
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return self.corner_table[point]
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def place_stone(self, player, point):
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assert self.is_on_grid(point)
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if self._grid.get(point) is not None:
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print('Illegal play on %s' % str(point))
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assert self._grid.get(point) is None
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# 0. Examine the adjacent points.
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adjacent_same_color = []
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adjacent_opposite_color = []
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liberties = []
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self.move_ages.increment_all()
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self.move_ages.add(point)
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for neighbor in self.neighbor_table[point]:
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neighbor_string = self._grid.get(neighbor)
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if neighbor_string is None:
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liberties.append(neighbor)
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elif neighbor_string.color == player:
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if neighbor_string not in adjacent_same_color:
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adjacent_same_color.append(neighbor_string)
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else:
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if neighbor_string not in adjacent_opposite_color:
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adjacent_opposite_color.append(neighbor_string)
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new_string = GoString(player, [point], liberties)
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# tag::apply_zobrist[]
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# 1. Merge any adjacent strings of the same color.
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for same_color_string in adjacent_same_color:
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new_string = new_string.merged_with(same_color_string)
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for new_string_point in new_string.stones:
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self._grid[new_string_point] = new_string
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# Remove empty-point hash code.
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self._hash ^= zobrist.HASH_CODE[point, None]
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# Add filled point hash code.
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self._hash ^= zobrist.HASH_CODE[point, player]
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# end::apply_zobrist[]
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# 2. Reduce liberties of any adjacent strings of the opposite
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# color.
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# 3. If any opposite color strings now have zero liberties,
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# remove them.
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for other_color_string in adjacent_opposite_color:
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replacement = other_color_string.without_liberty(point)
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if replacement.num_liberties:
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self._replace_string(other_color_string.without_liberty(point))
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else:
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self._remove_string(other_color_string)
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def _replace_string(self, new_string):
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for point in new_string.stones:
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self._grid[point] = new_string
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def _remove_string(self, string):
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for point in string.stones:
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self.move_ages.reset_age(point)
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# Removing a string can create liberties for other strings.
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for neighbor in self.neighbor_table[point]:
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neighbor_string = self._grid.get(neighbor)
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if neighbor_string is None:
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continue
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if neighbor_string is not string:
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self._replace_string(neighbor_string.with_liberty(point))
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self._grid[point] = None
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# Remove filled point hash code.
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self._hash ^= zobrist.HASH_CODE[point, string.color]
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# Add empty point hash code.
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self._hash ^= zobrist.HASH_CODE[point, None]
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def is_self_capture(self, player, point):
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friendly_strings = []
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for neighbor in self.neighbor_table[point]:
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neighbor_string = self._grid.get(neighbor)
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if neighbor_string is None:
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# This point has a liberty. Can't be self capture.
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return False
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elif neighbor_string.color == player:
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# Gather for later analysis.
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friendly_strings.append(neighbor_string)
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else:
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if neighbor_string.num_liberties == 1:
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# This move is real capture, not a self capture.
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return False
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if all(neighbor.num_liberties == 1 for neighbor in friendly_strings):
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return True
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return False
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def will_capture(self, player, point):
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for neighbor in self.neighbor_table[point]:
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neighbor_string = self._grid.get(neighbor)
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if neighbor_string is None:
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continue
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elif neighbor_string.color == player:
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continue
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else:
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if neighbor_string.num_liberties == 1:
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# This move would capture.
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return True
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return False
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def is_on_grid(self, point):
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return 1 <= point.row <= self.num_rows and \
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1 <= point.col <= self.num_cols
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def get(self, point):
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"""Return the content of a point on the board.
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Returns None if the point is empty, or a Player if there is a
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stone on that point.
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"""
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string = self._grid.get(point)
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if string is None:
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return None
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return string.color
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def get_go_string(self, point):
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"""Return the entire string of stones at a point.
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Returns None if the point is empty, or a GoString if there is
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a stone on that point.
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"""
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string = self._grid.get(point)
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if string is None:
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return None
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return string
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def __eq__(self, other):
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return isinstance(other, Board) and \
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self.num_rows == other.num_rows and \
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self.num_cols == other.num_cols and \
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self._hash() == other._hash()
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def __deepcopy__(self, memodict={}):
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copied = Board(self.num_rows, self.num_cols)
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# Can do a shallow copy b/c the dictionary maps tuples
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# (immutable) to GoStrings (also immutable)
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copied._grid = copy.copy(self._grid)
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copied._hash = self._hash
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return copied
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# tag::return_zobrist[]
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def zobrist_hash(self):
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return self._hash
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# end::return_zobrist[]
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class Move():
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"""Any action a player can play on a turn.
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Exactly one of is_play, is_pass, is_resign will be set.
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"""
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def __init__(self, point=None, is_pass=False, is_resign=False):
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assert (point is not None) ^ is_pass ^ is_resign
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self.point = point
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self.is_play = (self.point is not None)
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self.is_pass = is_pass
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self.is_resign = is_resign
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@classmethod
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def play(cls, point):
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"""A move that places a stone on the board."""
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return Move(point=point)
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@classmethod
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def pass_turn(cls):
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return Move(is_pass=True)
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@classmethod
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def resign(cls):
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return Move(is_resign=True)
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def __str__(self):
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if self.is_pass:
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return 'pass'
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if self.is_resign:
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return 'resign'
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return '(r %d, c %d)' % (self.point.row, self.point.col)
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def __hash__(self):
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return hash((
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self.is_play,
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self.is_pass,
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self.is_resign,
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self.point))
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def __eq__(self, other):
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return (
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self.is_play,
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self.is_pass,
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self.is_resign,
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self.point) == (
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other.is_play,
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other.is_pass,
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other.is_resign,
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other.point)
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class GameState():
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def __init__(self, board, next_player, previous, move):
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self.board = board
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self.next_player = next_player
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self.previous_state = previous
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if previous is None:
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self.previous_states = frozenset()
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else:
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self.previous_states = frozenset(
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previous.previous_states |
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{(previous.next_player, previous.board.zobrist_hash())})
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self.last_move = move
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def apply_move(self, move):
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"""Return the new GameState after applying the move."""
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if move.is_play:
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next_board = copy.deepcopy(self.board)
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next_board.place_stone(self.next_player, move.point)
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else:
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next_board = self.board
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return GameState(next_board, self.next_player.other, self, move)
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@classmethod
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def new_game(cls, board_size):
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if isinstance(board_size, int):
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board_size = (board_size, board_size)
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board = Board(*board_size)
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return GameState(board, Player.black, None, None)
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def is_move_self_capture(self, player, move):
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if not move.is_play:
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return False
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return self.board.is_self_capture(player, move.point)
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@property
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def situation(self):
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return (self.next_player, self.board)
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def does_move_violate_ko(self, player, move):
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if not move.is_play:
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return False
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if not self.board.will_capture(player, move.point):
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return False
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next_board = copy.deepcopy(self.board)
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next_board.place_stone(player, move.point)
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next_situation = (player.other, next_board.zobrist_hash())
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return next_situation in self.previous_states
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def is_valid_move(self, move):
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if self.is_over():
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return False
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if move.is_pass or move.is_resign:
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return True
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return (
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self.board.get(move.point) is None and
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not self.is_move_self_capture(self.next_player, move) and
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not self.does_move_violate_ko(self.next_player, move))
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def is_over(self):
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if self.last_move is None:
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return False
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if self.last_move.is_resign:
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return True
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if self.previous_state is None:
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return False
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second_last_move = self.previous_state.last_move
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if second_last_move is None:
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return False
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return self.last_move.is_pass and second_last_move.is_pass
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def legal_moves(self):
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moves = []
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for row in range(1, self.board.num_rows + 1):
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for col in range(1, self.board.num_cols + 1):
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move = Move.play(Point(row, col))
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if self.is_valid_move(move):
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moves.append(move)
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# These two moves are always legal.
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moves.append(Move.pass_turn())
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moves.append(Move.resign())
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return moves
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def winner(self):
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if not self.is_over():
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return None
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if self.last_move.is_resign:
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return self.next_player
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game_result = compute_game_result(self)
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return game_result.winner
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