Refactor loading of Go games & states from SGF file to use new general SGF reader. This separates the Go-specific logic of rebuilding the states to games/go and the parsing of the SGF strings to utils/sgf_reader.cc.

PiperOrigin-RevId: 883275313
Change-Id: Ia44aa1ba4844dfb140b6176422cdb47131f62279

Author: lanctot

open_spiel/games/CMakeLists.txt

@@ -96,8 +96,8 @@ set(GAME_SOURCES
   go/go.h
   go/go_board.cc
   go/go_board.h
-  go/sgf_reader.cc
-  go/sgf_reader.h
+  go/sgf_game_loader.cc
+  go/sgf_game_loader.h
   gomoku/gomoku.cc
   gomoku/gomoku.h
   gomoku/gomoku_grid.h
@@ -497,9 +497,9 @@ add_executable(go_test go/go_test.cc ${OPEN_SPIEL_OBJECTS}
                $<TARGET_OBJECTS:tests>)
 add_test(go_test go_test)
 
-add_executable(sgf_reader_test go/sgf_reader_test.cc ${OPEN_SPIEL_OBJECTS}
+add_executable(sgf_game_loader_test go/sgf_game_loader_test.cc ${OPEN_SPIEL_OBJECTS}
                $<TARGET_OBJECTS:tests>)
-add_test(sgf_reader_test sgf_reader_test)
+add_test(sgf_game_loader_test sgf_game_loader_test)
 
 add_executable(phantom_go_test phantom_go/phantom_go_test.cc ${OPEN_SPIEL_OBJECTS}
                $<TARGET_OBJECTS:tests>)

open_spiel/games/go/go.cc

@@ -16,18 +16,17 @@
 
 #include <algorithm>
 #include <array>
+#include <iostream>
 #include <memory>
 #include <sstream>
 #include <string>
 #include <utility>
 #include <vector>
 
-#include "open_spiel/abseil-cpp/absl/strings/ascii.h"
 #include "open_spiel/abseil-cpp/absl/strings/str_cat.h"
 #include "open_spiel/abseil-cpp/absl/types/span.h"
 #include "open_spiel/game_parameters.h"
 #include "open_spiel/games/go/go_board.h"
-#include "open_spiel/games/go/sgf_reader.h"
 #include "open_spiel/observer.h"
 #include "open_spiel/spiel.h"
 #include "open_spiel/spiel_globals.h"
@@ -120,8 +119,7 @@ GoState::GoState(std::shared_ptr<const Game> game, int board_size, float komi,
       komi_(komi),
       handicap_(handicap),
       max_game_length_(game_->MaxGameLength()),
-      to_play_(GoColor::kBlack),
-      initial_sgf_string_("") {
+      to_play_(GoColor::kBlack) {
   ResetBoard();
 }
 
@@ -302,16 +300,6 @@ void GoState::ResetBoard() {
   superko_ = false;
 }
 
-std::string GoState::Serialize() const {
-  std::string ser_str = State::Serialize();
-  if (!initial_sgf_string_.empty()) {
-    return absl::StrCat(kSerializeStartingState, initial_sgf_string_, "\n",
-                        ser_str);
-  } else {
-    return ser_str;
-  }
-}
-
 GoGame::GoGame(const GameParameters& params)
     : Game(kGameType, params),
       komi_(ParameterValue<double>("komi")),
@@ -320,51 +308,5 @@ GoGame::GoGame(const GameParameters& params)
       max_game_length_(ParameterValue<int>(
           "max_game_length", DefaultMaxGameLength(board_size_))) {}
 
-std::unique_ptr<State> GoGame::NewInitialState(
-    const std::string& sgf_string) const {
-  VectorOfGamesAndStates games_and_states = LoadGamesFromSGFString(sgf_string);
-  const GameAndState& game_and_state = games_and_states.back();
-
-  // First check that the game parameters are the same.
-  const GoGame* other_game =
-      down_cast<const GoGame*>(game_and_state.first.get());
-  SPIEL_CHECK_EQ(board_size_, other_game->board_size_);
-  SPIEL_CHECK_EQ(komi_, other_game->komi_);
-  SPIEL_CHECK_EQ(handicap_, other_game->handicap_);
-
-  const auto* other_state =
-      static_cast<const GoState*>(game_and_state.second.get());
-  auto state = std::unique_ptr<State>(
-      new GoState(shared_from_this(), board_size_, komi_, handicap_));
-
-  // if there's a history, just play back the moves
-  if (!other_state->History().empty()) {
-    for (const auto& action : other_state->History()) {
-      state->ApplyAction(action);
-    }
-    // Do not save the SGF string in this case because it is already included
-    // in the state.
-    static_cast<GoState*>(state.get())->initial_sgf_string_ = "";
-  } else {
-    // if there isn't, then just copy the boards
-    GoBoard* my_board = static_cast<GoState*>(state.get())->mutable_board();
-    *my_board = other_state->board();
-
-    // Change all the whitespace in the SGF string so that there are no
-    // newlines.
-    std::string sgf_string_copy = sgf_string;
-    for (int i = 0; i < sgf_string_copy.length(); ++i) {
-      if (absl::ascii_isspace(sgf_string_copy[i])) {
-        sgf_string_copy[i] = ' ';
-      }
-    }
-    static_cast<GoState*>(state.get())->initial_sgf_string_ = sgf_string_copy;
-  }
-
-  SPIEL_CHECK_EQ(state->ToString(), other_state->ToString());
-
-  return state;
-}
-
 }  // namespace go
 }  // namespace open_spiel

open_spiel/games/go/go.h

@@ -103,8 +103,7 @@ struct GoStateStruct : StateStruct {
 // The pass action is board_size * board_size.
 class GoState : public State {
  public:
-  friend class SGFReader;  // for mutable_board().
-  friend class GoGame;     // also for mutable_board(), constructing by SGF.
+  friend class GoGame;
 
   // Constructs a Go state for the empty board.
   GoState(std::shared_ptr<const Game> game, int board_size, float komi,
@@ -132,12 +131,14 @@ class GoState : public State {
   std::unique_ptr<State> Clone() const override;
   void UndoAction(Player player, Action action) override;
 
-  // Custom serialize only necessary when starting from an SGF string.
-  // Uses standard serialization otherwise.
-  virtual std::string Serialize() const override;
-
   const GoBoard& board() const { return board_; }
 
+  // Use with care. Modifying the board directly can lead to undefined behavior.
+  // The history is not maintained properly when using this method. This method
+  // is mainly used by the SGF game loader to create arbitrary boards from SGF
+  // files via the AB[] and AW[] properties.
+  GoBoard* mutable_board() { return &board_; }
+
  protected:
   void DoApplyAction(Action action) override;
 
@@ -146,12 +147,6 @@ class GoState : public State {
 
   GoBoard board_;
 
-  // Use with care. Modifying the board directly can lead to undefined behavior.
-  // The history is not maintained properly when using this method. This method
-  // is mainly used by the SGF reader to create arbitrary boards from SGF files
-  // via the AB[] and AW[] properties.
-  GoBoard* mutable_board() { return &board_; }
-
   // RepetitionTable records which positions we have already encountered.
   // We are already indexing by board hash, so there is no need to hash that
   // hash again, so we use a custom passthrough hasher.
@@ -169,10 +164,6 @@ class GoState : public State {
   const int max_game_length_;
   GoColor to_play_;
   bool superko_;
-
-  // Only used when calling NewInitialState(sgf_string). The SGF string is
-  // saved here to ensure that the state is properly serialized.
-  std::string initial_sgf_string_;
 };
 
 // Game object.
@@ -189,11 +180,6 @@ class GoGame : public Game {
         new GoState(shared_from_this(), board_size_, komi_, handicap_));
   }
 
-  // Starts a go game from the given SGF string. If there are multiple games in
-  // the SGF string, only the last one is used.
-  std::unique_ptr<State> NewInitialState(
-      const std::string& sgf_string) const override;
-
   std::vector<int> ObservationTensorShape() const override {
     // Planes: black, white, empty, and a bias plane indicating komi (whether
     // white is to play).

open_spiel/games/go/go_board.cc

@@ -557,7 +557,7 @@ VirtualPoint GoBoard::Chain::single_liberty() const {
   return static_cast<VirtualPoint>(liberty_vertex_sum / num_pseudo_liberties);
 }
 
-std::string GoBoard::ToString() {
+std::string GoBoard::ToString() const {
   std::ostringstream stream;
   stream << *this;
   return stream.str();

open_spiel/games/go/go_board.h

@@ -175,7 +175,7 @@ class GoBoard {
   // Number of stones in a chain.
   inline int ChainSize(VirtualPoint p) const { return chain(p).num_stones; }
 
-  std::string ToString();
+  std::string ToString() const;
 
   class GroupIter {
    public: