[ONNX] Tool to serialize ONNX models (#1793)

* [ONNX] Tool to serialize ONNX models

* Review fix.

* Add back dependencies to onnx_import_interface target.

* Review fix pt. 2

* Check also for errors when opening file stream.

src/tools/CMakeLists.txt

@@ -16,3 +16,6 @@
 
 add_subdirectory(nbench)
 add_subdirectory(reserialize)
+if (NGRAPH_ONNX_IMPORT_ENABLE)
+    add_subdirectory(serialize_onnx)
+endif()

src/tools/serialize_onnx/CMakeLists.txt

+# ******************************************************************************
+# Copyright 2017-2018 Intel Corporation
+#
+# 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.
+# ******************************************************************************
+
+add_executable(serialize_onnx serialize_onnx.cpp)
+add_dependencies(serialize_onnx ngraph)
+target_link_libraries(serialize_onnx ngraph)

src/tools/serialize_onnx/serialize_onnx.cpp

+//*****************************************************************************
+// Copyright 2017-2018 Intel Corporation
+//
+// 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.
+//*****************************************************************************
+
+// tool to serialize an ONNX model to an ngraph json graph
+
+#include <fstream>
+#include <iostream>
+#include <string>
+
+#include "ngraph/frontend/onnx_import/onnx.hpp"
+#include "ngraph/serializer.hpp"
+#include "ngraph/util.hpp"
+
+using namespace std;
+
+void help()
+{
+    cout << R"###(
+DESCRIPTION
+    Serialize an ONNX model
+
+SYNOPSIS
+        serialize_onnx [-i|--input <input file>] [-o|--output <output file>]
+
+OPTIONS
+        -i or --input  input ONNX file
+        -o or --output output serialized model
+)###";
+}
+
+int main(int argc, char** argv)
+{
+    string input;
+    string output;
+    for (size_t i = 1; i < argc; i++)
+    {
+        string arg = argv[i];
+        if (arg == "-o" || arg == "--output")
+        {
+            output = argv[++i];
+        }
+        else if (arg == "-i" || arg == "--input")
+        {
+            input = argv[++i];
+        }
+        else if (arg == "-h" || arg == "--help")
+        {
+            help();
+            return 0;
+        }
+    }
+
+    ifstream f(input);
+    if (f)
+    {
+        shared_ptr<ngraph::Function> function = ngraph::onnx_import::import_onnx_function(input);
+
+        ngraph::stopwatch timer;
+        timer.start();
+        ngraph::serialize(output, function, 2);
+        timer.stop();
+        cout << "serialize took   " << timer.get_milliseconds() << "ms\n";
+    }
+    else
+    {
+        cout << "failed to open '" << input << "' for input\n";
+        return 2;
+    }
+
+    return 0;
+}