Lasker Morris: Allow pieces to move before they have all been placed

.gitignore

@@ -438,6 +438,7 @@ cov-int
 flutter_export_environment.sh
 .autogit
 build/
+out/
 
 # Snapcraft
 *.snap

src/mills.cpp

@@ -461,6 +461,7 @@ bool is_star_squares_full(Position *pos)
     return ret;
 }
 
+// TODO: For Lasker Morris
 Depth get_search_depth(const Position *pos)
 {
     Depth d = 0;

src/movegen.cpp

@@ -61,8 +61,13 @@ ExtMove *generate<MOVE>(Position &pos, ExtMove *moveList)
 template <>
 ExtMove *generate<PLACE>(Position &pos, ExtMove *moveList)
 {
+    const Color us = pos.side_to_move();
     ExtMove *cur = moveList;
 
+    if (pos.piece_in_hand_count(us) == 0) {
+        return cur;
+    }
+
     for (auto s : MoveList<LEGAL>::movePriorityList) {
         if (!pos.get_board()[s]) {
             *cur++ = static_cast<Move>(s);
@@ -129,11 +134,14 @@ ExtMove *generate<LEGAL>(Position &pos, ExtMove *moveList)
     switch (pos.get_action()) {
     case Action::select:
     case Action::place:
+        // Generate both PLACE and MOVE actions if the phase is placing
         if (pos.get_phase() == Phase::placing ||
             pos.get_phase() == Phase::ready) {
-            return generate<PLACE>(pos, moveList);
+            cur = generate<PLACE>(pos, moveList);
+            return generate<MOVE>(pos, cur);
         }
 
+        // Generate MOVE actions if the phase is moving
         if (pos.get_phase() == Phase::moving) {
             return generate<MOVE>(pos, moveList);
         }

src/movepick.cpp

@@ -69,7 +69,8 @@ void MovePicker::score()
             to, pos.side_to_move(), from);
 
 #ifndef SORT_MOVE_WITHOUT_HUMAN_KNOWLEDGE
-        // TODO(calcitem): rule.mayRemoveMultiple adapt other rules
+        // TODO(calcitem): rule.mayRemoveMultiple adapt other rules such as
+        // Lasker Morris
         if (type_of(m) != MOVETYPE_REMOVE) {
             // all phrase, check if place sq can close mill
             if (ourMillsCount > 0) {

src/position.cpp

@@ -690,8 +690,7 @@ bool Position::put_piece(Square s, bool updateRecord)
 {
     const Color us = sideToMove;
 
-    if (phase == Phase::gameOver || action != Action::place ||
-        !(SQ_BEGIN <= s && s < SQ_END) || board[s]) {
+    if (phase == Phase::gameOver || !(SQ_BEGIN <= s && s < SQ_END)) {
         return false;
     }
 
@@ -701,7 +700,17 @@ bool Position::put_piece(Square s, bool updateRecord)
         start();
     }
 
-    if (phase == Phase::placing) {
+    // Emanuel Lasker Morris: Allow moving pieces during the placing phase
+    if (phase == Phase::placing && can_move_during_placing_phase()) {
+        // Allow moving if the piece is already on the board
+        if (board[s] & make_piece(us)) {
+            currentSquare = s;
+            action = Action::place;
+            return true;
+        }
+    }
+
+    if (phase == Phase::placing && action == Action::place) {
         const auto piece = static_cast<Piece>((0x01 | make_piece(sideToMove)) +
                                               rule.pieceCount -
                                               pieceInHandCount[us]);
@@ -995,7 +1004,9 @@ bool Position::remove_piece(Square s, bool updateRecord)
 
 bool Position::select_piece(Square s)
 {
-    if (phase != Phase::moving)
+    // Allow selecting pieces during placing phase if allowed
+    if (phase != Phase::moving &&
+        !(phase == Phase::placing && can_move_during_placing_phase()))
         return false;
 
     if (action != Action::select && action != Action::place)
@@ -1046,6 +1057,11 @@ bool Position::handle_placing_phase_end()
     return true;
 }
 
+inline bool Position::can_move_during_placing_phase() const
+{
+    return rule.mayMoveInPlacingPhase; // TODO: piece in hand
+}
+
 bool Position::resign(Color loser)
 {
     if (phase == Phase::ready || phase == Phase::gameOver ||
@@ -1257,7 +1273,7 @@ inline void Position::set_side_to_move(Color c)
 
     them = ~sideToMove;
 
-    if (pieceInHandCount[sideToMove] == 0) {
+    if (pieceInHandCount[sideToMove] == 0 || can_move_during_placing_phase()) {
         phase = Phase::moving;
         action = Action::select;
     } else {

src/position.h

@@ -191,6 +191,8 @@ class Position
 
     bool handle_placing_phase_end();
 
+    bool can_move_during_placing_phase() const;
+
     // Data members
     Piece board[SQUARE_EXT_NB];
     Bitboard byTypeBB[PIECE_TYPE_NB];

src/search.cpp

@@ -103,7 +103,9 @@ int Thread::search()
     std::chrono::steady_clock::time_point cycleEnd;
 #endif
 
-    if (rootPos->get_phase() == Phase::moving) {
+    if (rootPos->get_phase() == Phase::moving ||
+        (rootPos->get_phase() == Phase::placing &&
+         rule.mayMoveInPlacingPhase)) {
 #ifdef RULE_50
         if (posKeyHistory.size() >= rule.nMoveRule) {
             return 50;
@@ -123,10 +125,12 @@ int Thread::search()
         assert(posKeyHistory.size() < 256);
     }
 
-    if (rootPos->get_phase() == Phase::placing) {
+    if (rootPos->get_phase() == Phase::placing && !rule.mayMoveInPlacingPhase) {
         posKeyHistory.clear();
         rootPos->st.rule50 = 0;
-    } else if (rootPos->get_phase() == Phase::moving) {
+    } else if (rootPos->get_phase() == Phase::moving ||
+               (rootPos->get_phase() == Phase::placing &&
+                rule.mayMoveInPlacingPhase)) {
         rootPos->st.rule50 = static_cast<unsigned>(posKeyHistory.size());
     }
 

src/ui/qt/game_interaction.cpp

@@ -62,7 +62,7 @@ bool Game::validateClick(QPointF p, File &f, Rank &r)
 
 bool Game::performAction(File f, Rank r, QPointF p)
 {
-    // Judge whether to select, place or remove the piece
+    // Judge whether to select, place, move, or remove the piece
     bool result = false;
     PieceItem *piece;
     QGraphicsItem *item = scene.itemAt(p, QTransform());
@@ -87,8 +87,8 @@ bool Game::performAction(File f, Rank r, QPointF p)
             break;
         }
 
-        // If the moving is not successful, try to reselect. There is no break
-        // here
+        // If placing is not successful, try to reselect or move. There is no
+        // break here
         [[fallthrough]];
 
     case Action::select:

src/ui/qt/game_ui.cpp

@@ -287,6 +287,11 @@ void Game::setTips()
             tips = turnStr + " to remove a piece. " +
                    std::to_string(p.pieceToRemoveCount[p.sideToMove]) +
                    " pieces can be removed.";
+        } else if (rule.mayMoveInPlacingPhase &&
+                   (p.action == Action::select || p.action == Action::place)) {
+            tips = turnStr + " to place or move a piece. " +
+                   std::to_string(p.pieceInHandCount[p.sideToMove]) +
+                   " pieces remain unplaced.";
         }
         break;