Fixed captures - everything works correctly now

lib/goban.py

@@ -67,7 +67,7 @@ class Goban:
         # Who are we capturing
         who = self._other_color(self.to_move)
 
-        for p in [pos + 1, pos - 1, pos + self.board_size, pos - self.board_size]:
+        for p in self._neighbors(pos):
             if not self._on_board(p):
                 continue
                 
@@ -94,7 +94,7 @@ class Goban:
         opponent = self._other_color(self.to_move)
 
         kills_group = False
-        for d in [pos + 1, pos - 1, pos + self.board_size, pos - self.board_size]:
+        for d in self._neighbors(pos):
             if not self._on_board(d):
                 continue
             
@@ -112,14 +112,17 @@ class Goban:
     # Recursively find whether there are liberties for the group
     # at pos. Positive numbers are not necessarily accurate - 
     # treat this as a boolean
-    def _has_liberties(self, pos, who, checked=None):
+    def _has_liberties(self, pos, who):
-        if not self._on_board(pos):
+        if not self._on_board(pos) or self.board[pos] != who:
-            return 0
+            return -1
 
-        if checked is None:
         bs = self.board_size * self.board_size
         checked = [False] * bs
 
+        return self._has_liberties_r(pos, who, checked)
+
+
+    def _has_liberties_r(self, pos, who, checked=None):
         if checked[pos]:
             return 0
         else:
@@ -133,18 +136,8 @@ class Goban:
             return 0
         else:
             liberties = 0
-            neighbors = []
+            for d in self._neighbors(pos):
-            if pos >= self.board_size:
+                liberties += self._has_liberties_r(d, who, checked)
-                neighbors.append(pos - self.board_size)
-            if pos <= self.board_size * self.board_size - self.board_size - 1:
-                neighbors.append(pos + self.board_size)
-            if pos % self.board_size != 0:
-                neighbors.append(pos - 1)
-            if (pos + 1) % self.board_size != 0:
-                neighbors.append(pos + 1)
-
-            for d in neighbors:
-                liberties += self._has_liberties(d, who, checked)
 
             return liberties
 
@@ -289,3 +282,17 @@ class Goban:
             return Goban.WHITE
         elif color == Goban.WHITE:
             return Goban.BLACK
+
+
+    def _neighbors(self, pos):
+        neighbors = []
+        if pos >= self.board_size:
+            neighbors.append(pos - self.board_size)
+        if pos <= self.board_size * self.board_size - self.board_size - 1:
+            neighbors.append(pos + self.board_size)
+        if pos % self.board_size != 0:
+            neighbors.append(pos - 1)
+        if (pos + 1) % self.board_size != 0:
+            neighbors.append(pos + 1)
+
+        return neighbors