Implement fog_fen() (#840)

setup.py

@@ -39,7 +39,7 @@
     sources=sources,
     extra_compile_args=args)
 
-setup(name="pyffish", version="0.0.84",
+setup(name="pyffish", version="0.0.85",
       description="Fairy-Stockfish Python wrapper",
       long_description=long_description,
       long_description_content_type="text/markdown",

src/position.cpp

@@ -681,7 +681,7 @@ Position& Position::set(const string& code, Color c, StateInfo* si) {
 /// Position::fen() returns a FEN representation of the position. In case of
 /// Chess960 the Shredder-FEN notation is used. This is mainly a debugging function.
 
-string Position::fen(bool sfen, bool showPromoted, int countStarted, std::string holdings) const {
+string Position::fen(bool sfen, bool showPromoted, int countStarted, std::string holdings, Bitboard fogArea) const {
 
   int emptyCnt;
   std::ostringstream ss;
@@ -690,15 +690,15 @@ string Position::fen(bool sfen, bool showPromoted, int countStarted, std::string
   {
       for (File f = FILE_A; f <= max_file(); ++f)
       {
-          for (emptyCnt = 0; f <= max_file() && !(pieces() & make_square(f, r)); ++f)
+          for (emptyCnt = 0; f <= max_file() && !(pieces() & make_square(f, r)) && !(fogArea & make_square(f, r)); ++f)
               ++emptyCnt;
 
           if (emptyCnt)
               ss << emptyCnt;
 
           if (f <= max_file())
           {
-              if (empty(make_square(f, r)))
+              if (empty(make_square(f, r)) || fogArea & make_square(f, r))
                   // Wall square
                   ss << "*";
               else if (unpromoted_piece_on(make_square(f, r)))

src/position.h

@@ -114,7 +114,7 @@ class Position {
   // FEN string input/output
   Position& set(const Variant* v, const std::string& fenStr, bool isChess960, StateInfo* si, Thread* th, bool sfen = false);
   Position& set(const std::string& code, Color c, StateInfo* si);
-  std::string fen(bool sfen = false, bool showPromoted = false, int countStarted = 0, std::string holdings = "-") const;
+  std::string fen(bool sfen = false, bool showPromoted = false, int countStarted = 0, std::string holdings = "-", Bitboard fogArea = 0) const;
 
   // Variant rule properties
   const Variant* variant() const;
@@ -328,6 +328,7 @@ class Position {
   Score psq_score() const;
   Value non_pawn_material(Color c) const;
   Value non_pawn_material() const;
+  Bitboard fog_area() const;
 
   // Position consistency check, for debugging
   bool pos_is_ok() const;
@@ -1407,6 +1408,20 @@ inline Piece Position::captured_piece() const {
   return st->capturedPiece;
 }
 
+inline Bitboard Position::fog_area() const {
+  Bitboard b = board_bb();
+  // Our own pieces are visible
+  Bitboard visible = pieces(sideToMove);
+  // Squares where we can move to are visible as well
+  for (const auto& m : MoveList<LEGAL>(*this))
+  {
+    Square to = to_sq(m);
+    visible |= to;
+  }
+  // Everything else is invisible
+  return ~visible & b;
+}
+
 inline const std::string Position::piece_to_partner() const {
   if (!st->capturedPiece) return std::string();
   Color color = color_of(st->capturedPiece);

src/pyffish.cpp

@@ -54,7 +54,7 @@ void buildPosition(Position& pos, StateListPtr& states, const char *variant, con
 }
 
 extern "C" PyObject* pyffish_version(PyObject* self) {
-    return Py_BuildValue("(iii)", 0, 0, 84);
+    return Py_BuildValue("(iii)", 0, 0, 85);
 }
 
 extern "C" PyObject* pyffish_info(PyObject* self) {
@@ -383,6 +383,22 @@ extern "C" PyObject* pyffish_validateFen(PyObject* self, PyObject *args) {
     return Py_BuildValue("i", FEN::validate_fen(std::string(fen), variants.find(std::string(variant))->second, chess960));
 }
 
+// INPUT variant, fen
+extern "C" PyObject* pyffish_getFogFEN(PyObject* self, PyObject *args) {
+    PyObject* moveList = PyList_New(0);
+    Position pos;
+    const char *fen, *variant;
+
+    int chess960 = false, sfen = false, showPromoted = false, countStarted = 0;
+    if (!PyArg_ParseTuple(args, "ss|p", &fen, &variant, &chess960)) {
+        return NULL;
+    }
+    StateListPtr states(new std::deque<StateInfo>(1));
+    buildPosition(pos, states, variant, fen, moveList, chess960);
+
+    Py_XDECREF(moveList);
+    return Py_BuildValue("s", pos.fen(sfen, showPromoted, countStarted, "-", pos.fog_area()).c_str());
+}
 
 static PyMethodDef PyFFishMethods[] = {
     {"version", (PyCFunction)pyffish_version, METH_NOARGS, "Get package version."},
@@ -405,6 +421,7 @@ static PyMethodDef PyFFishMethods[] = {
     {"is_optional_game_end", (PyCFunction)pyffish_isOptionalGameEnd, METH_VARARGS, "Get result from given FEN it rules enable game end by player."},
     {"has_insufficient_material", (PyCFunction)pyffish_hasInsufficientMaterial, METH_VARARGS, "Checks for insufficient material."},
     {"validate_fen", (PyCFunction)pyffish_validateFen, METH_VARARGS, "Validate an input FEN."},
+    {"get_fog_fen", (PyCFunction)pyffish_getFogFEN, METH_VARARGS, "Get Fog of War FEN from given FEN."},
     {NULL, NULL, 0, NULL},  // sentinel
 };
 

test.py

@@ -113,6 +113,13 @@
 customPiece5 = f:mBpBmWpR2
 promotedPieceType = u:w a:w c:f i:f
 startFen = lnsgkgsnl/1rci1uab1/p1p1p1p1p/9/9/9/P1P1P1P1P/1BAU1ICR1/LNSGKGSNL[-] w 0 1
+
+[fogofwar:chess]
+king = -
+commoner = k
+castlingKingPiece = k
+extinctionValue = loss
+extinctionPieceTypes = k
 """
 
 sf.load_variant_config(ini_text)
@@ -1156,5 +1163,15 @@ def test_validate_fen(self):
                 fen = sf.start_fen(variant)
                 self.assertEqual(sf.validate_fen(fen, variant), sf.FEN_OK)
 
+    def test_get_fog_fen(self):
+        fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"  # startpos
+        result = sf.get_fog_fen(fen, "fogofwar")
+        self.assertEqual(result, "********/********/********/********/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1")
+
+        fen = "rnbqkbnr/p1p2ppp/8/Pp1pp3/4P3/8/1PPP1PPP/RNBQKBNR w KQkq b6 0 1"
+        result = sf.get_fog_fen(fen, "fogofwar")
+        self.assertEqual(result, "********/********/2******/Pp*p***1/4P3/4*3/1PPP1PPP/RNBQKBNR w KQkq b6 0 1")
+
+
 if __name__ == '__main__':
     unittest.main(verbosity=2)