tactics/selfatari.h

   1 #ifndef PACHI_TACTICS_SELFATARI_H
   2 #define PACHI_TACTICS_SELFATARI_H
   3
   4 /* A fairly reliable elf-atari detector. */
   5
   6 #include "board.h"
   7 #include "debug.h"
   8
   9 /* Check if this move is undesirable self-atari (resulting group would have
  10  * only single liberty and not capture anything; ko is allowed); we mostly
  11  * want to avoid these moves. The function actually does a rather elaborate
  12  * tactical check, allowing self-atari moves that are nakade, eye falsification
  13  * or throw-ins. */
  14 static bool is_bad_selfatari(struct board *b, enum stone color, coord_t to);
  15
  16 /* Move (color, coord) is a selfatari; this means that it puts a group of
  17  * ours in atari; i.e., the group has two liberties now. Return the other
  18  * liberty of such a troublesome group (optionally stored at *bygroup)
  19  * if that one is not a self-atari.
  20  * (In case (color, coord) is a multi-selfatari, consider a randomly chosen
  21  * candidate.) */
  22 coord_t selfatari_cousin(struct board *b, enum stone color, coord_t coord, group_t *bygroup);
  23
  24
  25 bool is_bad_selfatari_slow(struct board *b, enum stone color, coord_t to);
  26 static inline bool
  27 is_bad_selfatari(struct board *b, enum stone color, coord_t to)
  28 {
  29         /* Ko threats fear no self atari! */
  30         if (board_playing_ko_threat(b))
  31                 return false;
  32         /* More than one immediate liberty, thumbs up! */
  33         if (immediate_liberty_count(b, to) > 1)
  34                 return false;
  35
  36         return is_bad_selfatari_slow(b, color, to);
  37 }
  38
  39 #endif