loopgen.h

   1 /*
   2  * loopgen.h: interface file for loop generation functions for grid.[ch].
   3  */
   4
   5 #ifndef _LOOPGEN_H
   6 #define _LOOPGEN_H
   7
   8 #include "puzzles.h"
   9 #include "grid.h"
  10
  11 enum face_colour { FACE_WHITE, FACE_GREY, FACE_BLACK };
  12
  13 /* face should be of type grid_face* here. */
  14 #define FACE_COLOUR(face) \
  15     ( (face) == NULL ? FACE_BLACK : \
  16           board[(face) - g->faces] )
  17
  18 typedef int (*loopgen_bias_fn_t)(void *ctx, char *board, int face);
  19
  20 /* 'board' should be a char array whose length is the same as
  21  * g->num_faces: this will be filled in with FACE_WHITE or FACE_BLACK
  22  * after loop generation.
  23  *
  24  * If 'bias' is non-null, it should be a user-provided function which
  25  * rates a half-finished board (i.e. may include some FACE_GREYs) for
  26  * desirability; this will cause the loop generator to bias in favour
  27  * of loops with a high return value from that function. The 'face'
  28  * parameter to the bias function indicates which face of the grid has
  29  * been modified since the last call; it is guaranteed that only one
  30  * will have been (so that bias functions can work incrementally
  31  * rather than re-scanning the whole grid on every call). */
  32 extern void generate_loop(grid *g, char *board, random_state *rs,
  33                           loopgen_bias_fn_t bias, void *biasctx);
  34
  35 #endif