tactics.h

   1 #ifndef ZZGO_TACTICS_H
   2 #define ZZGO_TACTICS_H
   3
   4 /* Advanced tactical checks non-essential to the board implementation. */
   5
   6 #include "board.h"
   7
   8 /* Check if this move is undesirable self-atari (resulting group would have
   9  * only single liberty and not capture anything; ko is allowed); we mostly
  10  * want to avoid these moves. The function actually does a rather elaborate
  11  * tactical check, allowing self-atari moves that are nakade, eye falsification
  12  * or throw-ins. */
  13 static bool is_bad_selfatari(struct board *b, enum stone color, coord_t to);
  14
  15 /* Checks if there are any stones in n-vincinity of coord. */
  16 bool board_stone_radar(struct board *b, coord_t coord, int distance);
  17
  18 /* Construct a "common fate graph" from given coordinate; that is, a weighted
  19  * graph of intersections where edges between all neighbors have weight 1,
  20  * but edges between neighbors of same color have weight 0. Thus, this is
  21  * "stone chain" metric in a sense. */
  22 /* The output are distanes from start stored in given [board_size2()] array;
  23  * intersections further away than maxdist have all distance maxdist+1 set. */
  24 void cfg_distances(struct board *b, coord_t start, int *distances, int maxdist);
  25
  26
  27 bool is_bad_selfatari_slow(struct board *b, enum stone color, coord_t to);
  28 static inline bool
  29 is_bad_selfatari(struct board *b, enum stone color, coord_t to)
  30 {
  31         /* More than one immediate liberty, thumbs up! */
  32         if (immediate_liberty_count(b, to) > 1)
  33                 return false;
  34
  35         return is_bad_selfatari_slow(b, color, to);
  36 }
  37
  38 #endif