onek_eval.py

from globalconst import BLACK, WHITE, KING
from goalevaluator import GoalEvaluator
from onekingattack import GoalOneKingAttack
from onekingflee import GoalOneKingFlee


class OneKingAttackOneKingEvaluator(GoalEvaluator):
    def __init__(self, bias):
        GoalEvaluator.__init__(self, bias)

    def calculate_desirability(self, board):
        plr_color = board.to_move
        enemy_color = board.enemy
        # if we don't have one man on each side or the player
        # doesn't have the opposition, then goal is undesirable.
        if board.count(BLACK) != 1 or board.count(WHITE) != 1 or not board.has_opposition(plr_color):
            return 0.0
        player = board.get_pieces(plr_color)[0]
        p_idx, p_val = player
        p_row, p_col = board.row_col_for_index(p_idx)
        enemy = board.get_pieces(enemy_color)[0]
        e_idx, e_val = enemy
        e_row, e_col = board.row_col_for_index(e_idx)
        # must be two kings against each other and the distance
        # between them at least three rows or cols away
        if (p_val & KING) and (e_val & KING) and (abs(p_row - e_row) > 2 or abs(p_col - e_col) > 2):
            return 1.0
        return 0.0

    def set_goal(self, board):
        player = board.to_move
        board.remove_all_subgoals()
        goal_set = board.add_white_subgoal if player == WHITE else board.add_black_subgoal
        goal_set(GoalOneKingAttack(board))


class OneKingFleeOneKingEvaluator(GoalEvaluator):
    def __init__(self, bias):
        GoalEvaluator.__init__(self, bias)

    def calculate_desirability(self, board):
        plr_color = board.to_move
        enemy_color = board.enemy
        # if we don't have one man on each side or the player
        # has the opposition (meaning we should attack instead),
        # then goal is not applicable.
        if board.count(BLACK) != 1 or board.count(WHITE) != 1 or board.has_opposition(plr_color):
            return 0.0
        player = board.get_pieces(plr_color)[0]
        p_idx, p_val = player
        enemy = board.get_pieces(enemy_color)[0]
        e_idx, e_val = enemy
        # must be two kings against each other; otherwise it's
        # not applicable.
        if not ((p_val & KING) and (e_val & KING)):
            return 0.0
        return 1.0

    def set_goal(self, board):
        player = board.to_move
        board.remove_all_subgoals()
        goal_set = board.add_white_subgoal if player == WHITE else board.add_black_subgoal
        goal_set(GoalOneKingFlee(board))