math_opt: add solvers info

ortools/math_opt/samples/mathopt_info.cc

@@ -0,0 +1,50 @@
+// Copyright 2010-2022 Google LLC
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Check MathOpt available solvers.
+#include <iostream>
+
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_join.h"
+#include "ortools/base/init_google.h"
+
+#include "ortools/math_opt/cpp/math_opt.h"
+#include "ortools/math_opt/parameters.pb.h"
+#include "ortools/math_opt/core/solver_interface.h"
+//#include "ortools/math_opt/cpp/enums.h"
+
+namespace {
+
+struct SolverTypeProtoFormatter {
+  void operator()(
+      std::string* const out,
+      const operations_research::math_opt::SolverTypeProto solver_type) {
+    out->append(EnumToString(EnumFromProto(solver_type).value()));
+  }
+};
+
+}  // namespace
+
+int main(int argc, char* argv[]) {
+  InitGoogle(argv[0], &argc, &argv, /*remove_flags=*/true);
+
+  std::cout <<
+    absl::StrCat(
+        "the solver to use, possible values: ",
+        absl::StrJoin(
+          operations_research::math_opt::AllSolversRegistry::Instance()->RegisteredSolvers(),
+          ", ",
+          SolverTypeProtoFormatter())) << std::endl;
+
+  return 0;
+}