math_opt: Add update_result

ortools/math_opt/cpp/BUILD.bazel

@@ -336,6 +336,7 @@ cc_library(
         ":solve_arguments",
         ":solve_result",
         ":solver_init_arguments",
+        ":update_result",
         "//ortools/base",
         "//ortools/base:status_macros",
         "//ortools/math_opt:callback_cc_proto",
@@ -409,3 +410,9 @@ cc_library(
     hdrs = ["formatters.h"],
     deps = ["//ortools/util:fp_roundtrip_conv"],
 )
+
+cc_library(
+    name = "update_result",
+    hdrs = ["update_result.h"],
+    deps = ["//ortools/math_opt:model_update_cc_proto"],
+)

ortools/math_opt/cpp/update_result.h

@@ -0,0 +1,41 @@
+// 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.
+
+#ifndef OR_TOOLS_MATH_OPT_CPP_UPDATE_RESULT_H_
+#define OR_TOOLS_MATH_OPT_CPP_UPDATE_RESULT_H_
+
+#include <optional>
+#include <utility>
+
+#include "ortools/math_opt/model_update.pb.h"
+
+namespace operations_research::math_opt {
+
+// Result of the Update() on an incremental solver.
+struct UpdateResult {
+  UpdateResult(const bool did_update, std::optional<ModelUpdateProto> update)
+      : did_update(did_update), update(std::move(update)) {}
+
+  // True if the solver has been successfully updated or if no update was
+  // necessary (in which case `update` will be nullopt). False if the solver
+  // had to be recreated.
+  bool did_update;
+
+  // The update that was attempted on the solver. Can be nullopt when no
+  // update was needed (the model was not changed).
+  std::optional<ModelUpdateProto> update;
+};
+
+}  // namespace operations_research::math_opt
+
+#endif  // OR_TOOLS_MATH_OPT_CPP_UPDATE_RESULT_H_