Tidy up SGF loading code

cc/gtp_player.cc

@@ -161,6 +161,19 @@ void GtpClient::Ponder() {
   ponder_read_count_ += player_->root()->N() - n;
 }
 
+GtpClient::Response GtpClient::ReplaySgf(
+    const std::vector<std::unique_ptr<sgf::Node>>& trees) {
+  if (!trees.empty()) {
+    for (const auto& move : trees[0]->ExtractMainLine()) {
+      if (!player_->PlayMove(move.c)) {
+        MG_LOG(ERROR) << "couldn't play move " << move.c;
+        return Response::Error("cannot load file");
+      }
+    }
+  }
+  return Response::Ok();
+}
+
 GtpClient::Response GtpClient::HandleCmd(const std::string& line) {
   std::vector<absl::string_view> args =
       absl::StrSplit(line, absl::ByAnyChar(" \t\r\n"), absl::SkipWhitespace());
@@ -379,16 +392,7 @@ GtpClient::Response GtpClient::HandleLoadsgf(CmdArgs args) {
 
   NewGame();
 
-  if (!trees.empty()) {
-    for (const auto& move : trees[0]->ExtractMainLine()) {
-      if (!player_->PlayMove(move.c)) {
-        MG_LOG(ERROR) << "couldn't play move " << move.c;
-        return Response::Error("cannot load file");
-      }
-    }
-  }
-
-  return Response::Ok();
+  return ReplaySgf(trees);
 }
 
 GtpClient::Response GtpClient::HandleName(CmdArgs args) {

cc/gtp_player.h

@@ -126,14 +126,20 @@ class GtpClient {
         std::bind(handler, static_cast<T*>(this), std::placeholders::_1);
   }
 
+  // Begin pondering again if requested.
+  void MaybeStartPondering();
+
   // If waiting for the opponent to play, consider thinking for a bit.
   // Returns true if we pondered.
   bool MaybePonder();
 
   virtual void Ponder();
 
-  // Begin pondering again if requested.
-  void MaybeStartPondering();
+  // Replay a loaded SGF game.
+  // Called by HandleLoadSgf after the SGF file has been loaded and parsed, and
+  // a new has been started.
+  virtual Response ReplaySgf(
+      const std::vector<std::unique_ptr<sgf::Node>>& trees);
 
   // Handles a GTP command specified by `line`.
   // Returns a (bool, string) pair containing whether the GtpPlayer should

cc/minigui_player.cc

@@ -37,7 +37,6 @@ MiniguiGtpClient::MiniguiGtpClient(std::unique_ptr<MctsPlayer> player,
     : GtpClient(std::move(player), options) {
   RegisterCmd("echo", &MiniguiGtpClient::HandleEcho);
   RegisterCmd("genmove", &MiniguiGtpClient::HandleGenmove);
-  RegisterCmd("loadsgf", &MiniguiGtpClient::HandleLoadsgf);
   RegisterCmd("play", &MiniguiGtpClient::HandlePlay);
   RegisterCmd("prune_nodes", &MiniguiGtpClient::HandlePruneNodes);
   RegisterCmd("report_search_interval",
@@ -147,26 +146,6 @@ GtpClient::Response MiniguiGtpClient::HandleGenmove(CmdArgs args) {
   return response;
 }
 
-GtpClient::Response MiniguiGtpClient::HandleLoadsgf(CmdArgs args) {
-  auto response = CheckArgsExact(1, args);
-  if (!response.ok) {
-    return response;
-  }
-
-  std::string contents;
-  if (!file::ReadFile(std::string(args[0]), &contents)) {
-    return Response::Error("cannot load file");
-  }
-
-  std::vector<std::unique_ptr<sgf::Node>> trees;
-  response = ParseSgf(contents, &trees);
-  if (!response.ok) {
-    return response;
-  }
-
-  return ProcessSgf(trees);
-}
-
 GtpClient::Response MiniguiGtpClient::HandlePlay(CmdArgs args) {
   auto response = GtpClient::HandlePlay(args);
   if (response.ok) {
@@ -254,11 +233,8 @@ GtpClient::Response MiniguiGtpClient::HandleWinrateEvals(CmdArgs args) {
   return Response::Ok();
 }
 
-GtpClient::Response MiniguiGtpClient::ProcessSgf(
+GtpClient::Response MiniguiGtpClient::ReplaySgf(
     const std::vector<std::unique_ptr<sgf::Node>>& trees) {
-  // Clear the board before replaying sgf.
-  NewGame();
-
   // Traverse the SGF's game trees, loading them into the backend & running
   // inference on the positions in batches.
   std::function<Response(const sgf::Node&)> traverse =

cc/minigui_player.h

@@ -75,24 +75,20 @@ class MiniguiGtpClient : public GtpClient {
     std::string comment;
   };
 
-  // If waiting for the opponent to play, consider thinking for a bit.
-  // Returns true if we pondered.
   void Ponder() override;
 
   Response HandleCmd(const std::string& line) override;
   Response HandleGenmove(CmdArgs args) override;
-  Response HandleLoadsgf(CmdArgs args) override;
   Response HandlePlay(CmdArgs args) override;
+  Response ReplaySgf(
+      const std::vector<std::unique_ptr<sgf::Node>>& trees) override;
 
   Response HandleEcho(CmdArgs args);
   Response HandlePruneNodes(CmdArgs args);
   Response HandleReportSearchInterval(CmdArgs args);
   Response HandleSelectPosition(CmdArgs args);
   Response HandleWinrateEvals(CmdArgs args);
 
-  // Shared implementation used by HandleLoadsgf and HandlePlaysgf.
-  Response ProcessSgf(const std::vector<std::unique_ptr<sgf::Node>>& trees);
-
   // Writes the search data for the tree search being performed at the given
   // root to stderr. If leaf is non-null, the search path from root to leaf
   // is also written.