Rewrite benchmark

First step in improving bench to handle
arbitrary UCI commands so to test many
more code paths.

This first patch just set the new code
structure.

No functional change.

src/uci.cpp

@@ -35,7 +35,7 @@
 
 using namespace std;
 
-extern void benchmark(const Position& pos, istream& is);
+extern std::vector<string> setup_bench(const Position&, istream&);
 
 namespace {
 
@@ -134,6 +134,48 @@ namespace {
     Threads.start_thinking(pos, states, limits, ponderMode);
   }
 
+
+  // bench() is called when engine receives the "bench" command. Firstly
+  // a list of UCI commands is setup according to bench parameters, then
+  // it is run one by one printing summaries at the end.
+
+  void bench(Position& pos, istream& args, StateListPtr& states) {
+
+    string token;
+    uint64_t num, nodes = 0, cnt = 1;
+
+    vector<string> list = setup_bench(pos, args);
+    num = count_if (list.begin(), list.end(), [](string s) { return s.find("go ") == 0; });
+
+    TimePoint elapsed = now();
+
+    for (const auto& cmd : list)
+    {
+        istringstream is(cmd);
+        is >> skipws >> token;
+
+        if (token == "go")
+        {
+            cerr << "\nPosition: " << cnt++ << '/' << num << endl;
+            go(pos, is, states);
+            Threads.main()->wait_for_search_finished();
+            nodes += Threads.nodes_searched();
+        }
+        else if (token == "setoption")  setoption(is);
+        else if (token == "position")   position(pos, is, states);
+        else if (token == "ucinewgame") Search::clear();
+    }
+
+    elapsed = now() - elapsed + 1; // Ensure positivity to avoid a 'divide by zero'
+
+    dbg_print(); // Just before exiting
+
+    cerr << "\n==========================="
+         << "\nTotal time (ms) : " << elapsed
+         << "\nNodes searched  : " << nodes
+         << "\nNodes/second    : " << 1000 * nodes / elapsed << endl;
+  }
+
 } // namespace
 
 
@@ -190,7 +232,7 @@ void UCI::loop(int argc, char* argv[]) {
 
       // Additional custom non-UCI commands, mainly for debugging
       else if (token == "flip")  pos.flip();
-      else if (token == "bench") benchmark(pos, is);
+      else if (token == "bench") bench(pos, is, states);
       else if (token == "d")     sync_cout << pos << sync_endl;
       else if (token == "eval")  sync_cout << Eval::trace(pos) << sync_endl;
       else if (token == "perft")
@@ -202,7 +244,7 @@ void UCI::loop(int argc, char* argv[]) {
           ss << Options["Hash"] << " " << Options["Threads"]
              << " " << depth << " current perft";
 
-          benchmark(pos, ss);
+          // TODO benchmark(pos, ss);
       }
       else
           sync_cout << "Unknown command: " << cmd << sync_endl;