2006-01-14 Carl Worth <cworth@cworth.org>

[ttt] / src / ttt-board.c

diff --git a/src/ttt-board.c b/src/ttt-board.c
index c6d36f0b42ba161c6070b01a8c7ef5f8e16826c0..bafa0fd56fae79a0873daee57cf06152b4f93f2a 100644 (file)
--- a/src/ttt-board.c
+++ b/src/ttt-board.c
@@ -44,9 +44,21 @@ void
 ttt_board_init_from_string (ttt_board_t *board,
                            const char  *s)
 {
-    /* XXX: NYI */
+    int i, j;
+    j = 0;
+    for (i = 0; i < strlen (s); i++)
+    {
+       if ((s[i] == 'X') |
+           (s[i] == 'O') |
+           (s[i] == '_'))
+       {
+           board->cells[j] = s[i];
+           j++;
+       }
+    }
 }
 
+
 /* Return the string representation of a board.
  *
  * The return value is a malloc()ed string that should be free()ed
@@ -94,32 +106,74 @@ ttt_board_write (ttt_board_t *board, FILE *file)
  *  3|4|5
  *  6|7|8
  *
- * Returns: TTT_ERROR_NONE if a move is made succesfully. TTT_ERROR_NOT_VALID_MOVE
- * if a move is invalid (the given cell is not empty).
+ * Returns: TTT_ERROR_NONE if a move is made
+ * succesfully. TTT_ERROR_NOT_VALID_MOVE if a move is invalid (the
+ * given cell is not empty). TTT_ERROR_NOT_GRID if the move is
+ * impossible (user input 'a' or '9' etc.)
  */
 
 ttt_error_t ttt_board_make_move (ttt_board_t *board, int move)
 {  
+    if (move < 0 || move > 8)
+       return TTT_ERROR_NOT_GRID;
+    
     if (board->cells[move] != TTT_CELL_EMPTY)
        return TTT_ERROR_NOT_VALID_MOVE;
-
+    
     board->cells[move] = board->current_player;
-
+    
     if (board->current_player == TTT_CELL_X)
-    {
-       ttt_board_is_won (board);
        board->current_player = TTT_CELL_O;     
-    }
     else
-    {
-       ttt_board_is_won (board);
        board->current_player = TTT_CELL_X;
-    }
     return TTT_ERROR_NONE;
 }
 
+/* Checks to see if a player has won the game and should be called
+ * after every move.
+ * 
+ * Returns: TTT_CELL_X if X's win. TTT_CELL_O if O's
+ * win. TTT_CELL_EMPTY if no win.  The game can then check the value
+ * of the return and declare the winner.
+ */
 
+ttt_cell_t ttt_board_is_won (ttt_board_t *board)
+{
+    int i;
 
+    /* Loop over rows and columns looking for a win. */
+    for (i = 0; i < 3; i++)
+    {
+       /* Check the current column */
+       if (board->cells[i] != TTT_CELL_EMPTY &&
+           board->cells[i] == board->cells[i + 3] &&
+           board->cells[i] == board->cells[i + 6])
+       {
+           return board->cells[i];
+       }
+       
+       /* Check the current row */
+       if (board->cells[i * 3] != TTT_CELL_EMPTY &&
+           board->cells[i * 3] == board->cells[(i * 3) + 1] &&
+           board->cells[i * 3] == board->cells[(i * 3) + 2])
+       {
+           return board->cells[i * 3];
+       }
+    }
 
+    if (board->cells[0] != TTT_CELL_EMPTY &&
+       board->cells[0] == board->cells[4] &&
+       board->cells[0] == board->cells[8])
+    {
+       return board->cells[0];
+    }
 
+    if (board->cells[2] != TTT_CELL_EMPTY &&
+       board->cells[2] == board->cells[4] &&
+       board->cells[2] == board->cells[6])
+    {
+       return board->cells[2];
+    }
 
+    return TTT_CELL_EMPTY;
+}