onnx [2]: add core wrappers (#1169)

* onnx: add core wrappers
Signed-off-by: Artur Wojcik <artur.wojcik@intel.com>

* onnx: add '\n' at end of files
Signed-off-by: Artur Wojcik <artur.wojcik@intel.com>

* onnx: fix compilation with clang
Signed-off-by: Artur Wojcik <artur.wojcik@intel.com>

* onnx: fix code style
Signed-off-by: Artur Wojcik <artur.wojcik@intel.com>

src/ngraph/frontend/onnx_import/CMakeLists.txt

@@ -31,7 +31,18 @@ add_library(onnx_import_interface OBJECT
     onnx.proto)
 
 add_library(onnx_import STATIC
-    onnx.pb.cc)
+    onnx.pb.cc
+    attribute.cpp
+    attribute.hpp
+    graph.cpp
+    graph.hpp
+    model.hpp
+    node.cpp
+    node.hpp
+    ops_bridge.cpp
+    ops_bridge.hpp
+    tensor.hpp
+    value_info.hpp)
 
 add_dependencies(onnx_import onnx_import_interface)
 
@@ -46,5 +57,8 @@ if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "^(Apple)?Clang$")
     target_compile_options(onnx_import PRIVATE -Wno-undef -Wno-reserved-id-macro -Wno-switch-enum
         -Wno-extended-offsetof -Wno-zero-as-null-pointer-constant -Wno-shorten-64-to-32 -Wno-unused-macros
         -Wno-missing-variable-declarations -Wno-unused-private-field)
+    target_compile_options(onnx_import_interface PRIVATE -Wno-undef -Wno-reserved-id-macro -Wno-switch-enum
+        -Wno-extended-offsetof -Wno-zero-as-null-pointer-constant -Wno-shorten-64-to-32 -Wno-unused-macros
+        -Wno-missing-variable-declarations -Wno-unused-private-field)
 endif()
 

src/ngraph/frontend/onnx_import/attribute.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.
+ *******************************************************************************/
+
+#include "attribute.hpp"
+#include "graph.hpp"
+
+namespace ngraph
+{
+    namespace onnx_import
+    {
+        std::vector<Graph> Attribute::get_graph_array() const
+        {
+            return {std::begin(m_attribute_proto.graphs()), std::end(m_attribute_proto.graphs())};
+        }
+
+        Graph Attribute::get_graph() const { return Graph{m_attribute_proto.g()}; }
+    } // namespace onnx_import
+
+} // namespace ngraph

src/ngraph/frontend/onnx_import/attribute.hpp

+/*******************************************************************************
+ * 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.
+ *******************************************************************************/
+
+#pragma once
+
+#include "ngraph/except.hpp"
+#include "onnx.pb.h"
+#include "tensor.hpp"
+
+namespace ngraph
+{
+    namespace onnx_import
+    {
+        // forward declaration
+        class Graph;
+
+        namespace error
+        {
+            namespace attribute
+            {
+                namespace detail
+                {
+                    struct attribute : ngraph_error
+                    {
+                        attribute(std::string msg, onnx::AttributeProto_AttributeType type)
+                            : ngraph_error{std::move(msg) + ": " +
+                                           onnx::AttributeProto_AttributeType_Name(type)}
+                        {
+                        }
+                    };
+
+                } // namespace detail
+
+                struct invalid_data : detail::attribute
+                {
+                    explicit invalid_data(onnx::AttributeProto_AttributeType type)
+                        : attribute{"invalid attribute type", type}
+                    {
+                    }
+                };
+
+                struct unsupported_type : detail::attribute
+                {
+                    explicit unsupported_type(onnx::AttributeProto_AttributeType type)
+                        : attribute("unsupported attribute type", type)
+                    {
+                    }
+                };
+
+            } // namespace attribute
+
+        } // namespace error
+
+        class Attribute
+        {
+        public:
+            enum class Type
+            {
+                undefined = onnx::AttributeProto_AttributeType_UNDEFINED,
+                float_point = onnx::AttributeProto_AttributeType_FLOAT,
+                integer = onnx::AttributeProto_AttributeType_INT,
+                string = onnx::AttributeProto_AttributeType_STRING,
+                tensor = onnx::AttributeProto_AttributeType_TENSOR,
+                graph = onnx::AttributeProto_AttributeType_GRAPH,
+                float_point_array = onnx::AttributeProto_AttributeType_FLOATS,
+                integer_array = onnx::AttributeProto_AttributeType_INTS,
+                string_array = onnx::AttributeProto_AttributeType_STRINGS,
+                tensor_array = onnx::AttributeProto_AttributeType_TENSORS,
+                graph_array = onnx::AttributeProto_AttributeType_GRAPHS
+            };
+
+            Attribute() = delete;
+            explicit Attribute(const onnx::AttributeProto& attribute_proto)
+                : m_attribute_proto{attribute_proto}
+            {
+            }
+
+            Attribute(Attribute&&) noexcept = default;
+            Attribute(const Attribute&) = default;
+
+            Attribute& operator=(Attribute&&) noexcept = delete;
+            Attribute& operator=(const Attribute&) = delete;
+
+            const std::string& get_name() const { return m_attribute_proto.name(); }
+            Type get_type() const { return static_cast<Type>(m_attribute_proto.type()); }
+            bool is_tensor() const { return get_type() == Type::tensor; }
+            bool is_tensor_array() const { return get_type() == Type::tensor_array; }
+            bool is_float() const { return get_type() == Type::float_point; }
+            bool is_float_array() const { return get_type() == Type::float_point_array; }
+            bool is_integer() const { return get_type() == Type::integer; }
+            bool is_integer_array() const { return get_type() == Type::integer_array; }
+            bool is_string() const { return get_type() == Type::string; }
+            bool is_string_array() const { return get_type() == Type::string_array; }
+            bool is_graph() const { return get_type() == Type::graph; }
+            bool is_graph_array() const { return get_type() == Type::graph_array; }
+            Tensor get_tensor() const { return Tensor{m_attribute_proto.t()}; }
+            float get_float() const { return m_attribute_proto.f(); }
+            int64_t get_integer() const { return m_attribute_proto.i(); }
+            const std::string& get_string() const { return m_attribute_proto.s(); }
+            Graph get_graph() const;
+
+            std::vector<Tensor> get_tensor_array() const
+            {
+                return {std::begin(m_attribute_proto.tensors()),
+                        std::end(m_attribute_proto.tensors())};
+            }
+
+            std::vector<float> get_float_array() const
+            {
+                return {std::begin(m_attribute_proto.floats()),
+                        std::end(m_attribute_proto.floats())};
+            }
+
+            std::vector<int64_t> get_integer_array() const
+            {
+                return {std::begin(m_attribute_proto.ints()), std::end(m_attribute_proto.ints())};
+            }
+
+            std::vector<std::string> get_string_array() const
+            {
+                return {std::begin(m_attribute_proto.strings()),
+                        std::end(m_attribute_proto.strings())};
+            }
+
+            std::vector<Graph> get_graph_array() const;
+
+            /* explicit */ operator onnx::AttributeProto_AttributeType() const
+            {
+                return m_attribute_proto.type();
+            }
+
+        private:
+            const onnx::AttributeProto& m_attribute_proto;
+        };
+
+    } // namespace onnx_import
+
+} // namespace ngraph

src/ngraph/frontend/onnx_import/graph.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.
+ *******************************************************************************/
+
+#include "graph.hpp"
+#include "node.hpp"
+
+namespace ngraph
+{
+    namespace onnx_import
+    {
+        Graph::Graph(const onnx::GraphProto& graph_proto)
+            : m_graph_proto(graph_proto)
+        {
+            for (const auto& tensor : m_graph_proto.initializer())
+            {
+                if (tensor.has_name())
+                {
+                    m_initializers.emplace(tensor.name(), Tensor{tensor});
+                }
+            }
+
+            // Process all ONNX graph inputs, convert them to nGraph nodes and store in cache
+            for (const auto& input : m_graph_proto.input())
+            {
+                m_inputs.emplace_back(input);
+                m_ng_node_cache[input.name()] =
+                    m_inputs.back().get_ng_node(m_parameters, m_initializers);
+            }
+
+            for (const auto& output : m_graph_proto.output())
+                m_outputs.emplace_back(output);
+
+            // Process ONNX graph nodes, convert to nGraph nodes
+            for (const auto& node_proto : m_graph_proto.node())
+            {
+                m_nodes.emplace_back(node_proto, this);
+                const Node& node{m_nodes.back()};
+                const auto& ng_nodes{node.get_ng_nodes()};
+                for (int i = 0; i < ng_nodes.size(); i++)
+                {
+                    m_ng_node_cache[node.output(i)] = ng_nodes[i];
+                }
+            }
+        }
+
+    } // namespace onnx_import
+
+} // namespace ngraph

src/ngraph/frontend/onnx_import/graph.hpp

+/*******************************************************************************
+ * 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.
+ *******************************************************************************/
+
+#pragma once
+
+#include <map>
+#include <ostream>
+#include <string>
+#include <vector>
+
+#include "ngraph/op/parameter_vector.hpp"
+
+#include "onnx.pb.h"
+#include "value_info.hpp"
+
+namespace ngraph
+{
+    namespace onnx_import
+    {
+        class Graph
+        {
+        public:
+            explicit Graph(const onnx::GraphProto& proto);
+
+            const std::vector<Node>& get_nodes() const { return m_nodes; }
+            const std::vector<ValueInfo>& get_inputs() const { return m_inputs; }
+            const std::vector<ValueInfo>& get_outputs() const { return m_outputs; }
+            const op::ParameterVector& get_ng_parameters() const { return m_parameters; }
+            std::shared_ptr<ngraph::Node> get_ng_node_from_cache(const std::string& name) const
+            {
+                return m_ng_node_cache.at(name);
+            }
+
+            const std::string& get_name() const { return m_graph_proto.name(); }
+        private:
+            const onnx::GraphProto& m_graph_proto;
+            std::vector<Node> m_nodes;
+            std::vector<ValueInfo> m_inputs;
+            std::vector<ValueInfo> m_outputs;
+            op::ParameterVector m_parameters;
+            std::map<std::string, std::shared_ptr<ngraph::Node>> m_ng_node_cache;
+            std::map<std::string, Tensor> m_initializers;
+        };
+
+        inline std::ostream& operator<<(std::ostream& outs, const Graph& graph)
+        {
+            return (outs << "<Graph: " << graph.get_name() << ">");
+        }
+
+    } // namespace onnx_import
+
+} // namespace ngraph

src/ngraph/frontend/onnx_import/model.hpp

+/*******************************************************************************
+ * 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.
+ *******************************************************************************/
+
+#pragma once
+
+#include <ostream>
+#include "onnx.pb.h"
+
+namespace ngraph
+{
+    namespace onnx_import
+    {
+        class Model
+        {
+        public:
+            Model() = delete;
+            explicit Model(const onnx::ModelProto& model_proto)
+                : m_model_proto{model_proto}
+            {
+            }
+
+            Model(Model&&) noexcept = default;
+            Model(const Model&) = default;
+
+            Model& operator=(Model&&) noexcept = delete;
+            Model& operator=(const Model&) = delete;
+
+            const std::string& get_producer_name() const { return m_model_proto.producer_name(); }
+            const onnx::GraphProto& get_graph() const { return m_model_proto.graph(); }
+            std::int64_t get_model_version() const { return m_model_proto.model_version(); }
+            const std::string& get_producer_version() const
+            {
+                return m_model_proto.producer_version();
+            }
+
+        private:
+            const onnx::ModelProto& m_model_proto;
+        };
+
+        inline std::ostream& operator<<(std::ostream& outs, const Model& model)
+        {
+            return (outs << "<Model: " << model.get_producer_name() << ">");
+        }
+
+    } // namespace onnx_import
+
+} // namespace ngraph

src/ngraph/frontend/onnx_import/node.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.
+ *******************************************************************************/
+
+#include "node.hpp"
+#include "graph.hpp"
+#include "ops_bridge.hpp"
+
+namespace ngraph
+{
+    namespace onnx_import
+    {
+        NodeVector Node::get_ng_nodes() const { return ops_bridge::make_ng_nodes(*this); }
+        NodeVector Node::get_ng_inputs() const
+        {
+            NodeVector result;
+            for (const auto& name : m_node_proto.input())
+            {
+                result.push_back(m_graph->get_ng_node_from_cache(name));
+            }
+            return result;
+        }
+
+    } // namespace onnx_import
+
+} // namespace ngraph

src/ngraph/frontend/onnx_import/node.hpp

+/*******************************************************************************
+ * 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.
+ *******************************************************************************/
+
+#pragma once
+
+#include <ostream>
+#include <string>
+
+#include "ngraph/node_vector.hpp"
+
+#include "onnx.pb.h"
+
+#include "attribute.hpp"
+#include "tensor.hpp"
+
+namespace ngraph
+{
+    namespace onnx_import
+    {
+        class Graph;
+
+        class Node
+        {
+        public:
+            Node() = delete;
+            Node(const onnx::NodeProto& node_proto, const Graph* graph)
+                : m_node_proto{node_proto}
+                , m_graph{graph}
+                , m_attributes{std::begin(node_proto.attribute()), std::end(node_proto.attribute())}
+            {
+            }
+
+            Node(Node&&) noexcept = default;
+            Node(const Node&) = default;
+
+            Node& operator=(Node&&) noexcept = delete;
+            Node& operator=(const Node&) = delete;
+
+            const std::vector<Attribute>& attributes() const { return m_attributes; }
+            NodeVector get_ng_nodes() const;
+            NodeVector get_ng_inputs() const;
+
+            const std::string& op_type() const { return m_node_proto.op_type(); }
+            const std::string& get_name() const { return m_node_proto.name(); }
+            const std::string& output(int index) const { return m_node_proto.output(index); }
+        private:
+            const onnx::NodeProto& m_node_proto;
+            const Graph* m_graph;
+            std::vector<Attribute> m_attributes;
+        };
+
+        inline std::ostream& operator<<(std::ostream& outs, const Node& node)
+        {
+            return (outs << "<Node(" << node.op_type() << "): " << node.get_name() << ">");
+        }
+
+    } // namespace onnx_import
+
+} // namespace ngraph

src/ngraph/frontend/onnx_import/ops_bridge.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.
+ *******************************************************************************/
+
+#include <algorithm>
+#include <functional>
+
+#include "ops_bridge.hpp"
+
+namespace ngraph
+{
+    namespace onnx_import
+    {
+        namespace detail
+        {
+            namespace error
+            {
+                struct unknown_operation : ngraph_error
+                {
+                    explicit unknown_operation(const std::string& op_type)
+                        : ngraph_error{"unknown operation: " + op_type}
+                    {
+                    }
+                };
+
+            } // namespace error
+
+            class ops_bridge
+            {
+            public:
+                ops_bridge(const ops_bridge&) = delete;
+                ops_bridge& operator=(const ops_bridge&) = delete;
+                ops_bridge(ops_bridge&&) = delete;
+                ops_bridge& operator=(ops_bridge&&) = delete;
+
+                static NodeVector make_ng_nodes(const Node& node)
+                {
+                    return ops_bridge::get()(node);
+                }
+
+            private:
+                std::map<std::string, std::function<NodeVector(const Node&)>> m_map;
+
+                static const ops_bridge& get()
+                {
+                    static ops_bridge instance;
+                    return instance;
+                }
+
+                ops_bridge() {}
+                NodeVector operator()(const Node& node) const
+                {
+                    try
+                    {
+                        return m_map.at(node.op_type())(node);
+                    }
+                    catch (const std::exception&)
+                    {
+                        throw detail::error::unknown_operation{node.op_type()};
+                    }
+                }
+            };
+
+        } // namespace detail
+
+        namespace ops_bridge
+        {
+            NodeVector make_ng_nodes(const Node& node)
+            {
+                return detail::ops_bridge::make_ng_nodes(node);
+            }
+
+        } // namespace ops_bridge
+
+    } // namespace onnx_import
+
+} // namespace ngraph

src/ngraph/frontend/onnx_import/ops_bridge.hpp

+/*******************************************************************************
+ * 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.
+ *******************************************************************************/
+
+#pragma once
+
+#include "ngraph/node_vector.hpp"
+#include "node.hpp"
+
+namespace ngraph
+{
+    namespace onnx_import
+    {
+        namespace ops_bridge
+        {
+            NodeVector make_ng_nodes(const onnx_import::Node&);
+        }
+
+    } // namespace onnx_import
+
+} // namespace ngraph

src/ngraph/frontend/onnx_import/value_info.hpp

+/*******************************************************************************
+ * 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.
+ *******************************************************************************/
+
+#pragma once
+
+#include <ostream>
+
+#include "ngraph/op/constant.hpp"
+#include "ngraph/op/parameter_vector.hpp"
+#include "ngraph/shape.hpp"
+#include "ngraph/type/element_type.hpp"
+
+#include "onnx.pb.h"
+
+#include "node.hpp"
+#include "tensor.hpp"
+
+namespace ngraph
+{
+    namespace onnx_import
+    {
+        namespace error
+        {
+            namespace value_info
+            {
+                struct unspecified_element_type : ngraph_error
+                {
+                    unspecified_element_type()
+                        : ngraph_error{"value info has not element type specified"}
+                    {
+                    }
+                };
+                struct unsupported_element_type : ngraph_error
+                {
+                    explicit unsupported_element_type(onnx::TensorProto_DataType type)
+                        : ngraph_error{"unsupported value info element type: " +
+                                       onnx::TensorProto_DataType_Name(type)}
+                    {
+                    }
+                };
+            }
+        }
+
+        class ValueInfo
+        {
+        public:
+            ValueInfo(ValueInfo&&) = default;
+            ValueInfo(const ValueInfo&) = default;
+
+            ValueInfo() = delete;
+            explicit ValueInfo(const onnx::ValueInfoProto& value_info_proto)
+                : m_value_info_proto{value_info_proto}
+            {
+                if (value_info_proto.type().has_tensor_type())
+                {
+                    for (const auto& dim : value_info_proto.type().tensor_type().shape().dim())
+                    {
+                        m_shape.emplace_back(static_cast<Shape::value_type>(dim.dim_value()));
+                    }
+                }
+            }
+
+            ValueInfo& operator=(const ValueInfo&) = delete;
+            ValueInfo& operator=(ValueInfo&&) = delete;
+
+            const std::string& get_name() const { return m_value_info_proto.name(); }
+            const Shape& get_shape() const { return m_shape; }
+            const element::Type& get_element_type() const
+            {
+                if (!m_value_info_proto.type().tensor_type().has_elem_type())
+                {
+                    throw error::value_info::unspecified_element_type{};
+                }
+                switch (m_value_info_proto.type().tensor_type().elem_type())
+                {
+                case onnx::TensorProto_DataType::TensorProto_DataType_BOOL: return element::boolean;
+                case onnx::TensorProto_DataType::TensorProto_DataType_FLOAT:
+                case onnx::TensorProto_DataType::TensorProto_DataType_FLOAT16: return element::f32;
+                case onnx::TensorProto_DataType::TensorProto_DataType_DOUBLE: return element::f64;
+                case onnx::TensorProto_DataType::TensorProto_DataType_INT8: return element::i8;
+                case onnx::TensorProto_DataType::TensorProto_DataType_INT16: return element::i16;
+                case onnx::TensorProto_DataType::TensorProto_DataType_INT32: return element::i32;
+                case onnx::TensorProto_DataType::TensorProto_DataType_INT64: return element::i64;
+                case onnx::TensorProto_DataType::TensorProto_DataType_UINT8: return element::u8;
+                case onnx::TensorProto_DataType::TensorProto_DataType_UINT16: return element::u16;
+                case onnx::TensorProto_DataType::TensorProto_DataType_UINT32: return element::u32;
+                case onnx::TensorProto_DataType::TensorProto_DataType_UINT64: return element::u64;
+                default:
+                    throw error::value_info::unsupported_element_type{
+                        m_value_info_proto.type().tensor_type().elem_type()};
+                }
+            }
+
+            std::shared_ptr<ngraph::Node>
+                get_ng_node(op::ParameterVector& parameters,
+                            const std::map<std::string, Tensor>& initializers) const
+            {
+                const auto it{initializers.find(get_name())};
+                if (it != std::end(initializers))
+                {
+                    return get_ng_constant(it->second);
+                }
+                else
+                {
+                    parameters.push_back(get_ng_parameter());
+                    return parameters.back();
+                }
+            }
+
+        protected:
+            std::shared_ptr<op::Parameter> get_ng_parameter() const
+            {
+                return std::make_shared<op::Parameter>(get_element_type(), get_shape());
+            }
+
+            std::shared_ptr<op::Constant> get_ng_constant(const Tensor& tensor) const
+            {
+                switch (m_value_info_proto.type().tensor_type().elem_type())
+                {
+                case onnx::TensorProto_DataType::TensorProto_DataType_BOOL:
+                    return make_ng_constant<bool>(element::boolean, tensor);
+                case onnx::TensorProto_DataType::TensorProto_DataType_FLOAT:
+                case onnx::TensorProto_DataType::TensorProto_DataType_FLOAT16:
+                    return make_ng_constant<float>(element::f32, tensor);
+                case onnx::TensorProto_DataType::TensorProto_DataType_DOUBLE:
+                    return make_ng_constant<double>(element::f64, tensor);
+                case onnx::TensorProto_DataType::TensorProto_DataType_INT8:
+                    return make_ng_constant<int8_t>(element::i8, tensor);
+                case onnx::TensorProto_DataType::TensorProto_DataType_INT16:
+                    return make_ng_constant<int16_t>(element::i16, tensor);
+                case onnx::TensorProto_DataType::TensorProto_DataType_INT32:
+                    return make_ng_constant<int32_t>(element::i32, tensor);
+                case onnx::TensorProto_DataType::TensorProto_DataType_INT64:
+                    return make_ng_constant<int64_t>(element::i64, tensor);
+                case onnx::TensorProto_DataType::TensorProto_DataType_UINT8:
+                    return make_ng_constant<uint8_t>(element::u8, tensor);
+                case onnx::TensorProto_DataType::TensorProto_DataType_UINT16:
+                    return make_ng_constant<uint16_t>(element::u16, tensor);
+                case onnx::TensorProto_DataType::TensorProto_DataType_UINT32:
+                    return make_ng_constant<uint32_t>(element::u32, tensor);
+                case onnx::TensorProto_DataType::TensorProto_DataType_UINT64:
+                    return make_ng_constant<uint64_t>(element::u64, tensor);
+                default:
+                    throw error::value_info::unsupported_element_type{
+                        m_value_info_proto.type().tensor_type().elem_type()};
+                }
+            }
+
+            template <typename T>
+            std::shared_ptr<op::Constant> make_ng_constant(const element::Type& type,
+                                                           const Tensor& tensor) const
+            {
+                return std::make_shared<op::Constant>(type, m_shape, tensor.get_data<T>());
+            }
+
+        private:
+            const onnx::ValueInfoProto& m_value_info_proto;
+            Shape m_shape;
+        };
+
+        inline std::ostream& operator<<(std::ostream& outs, const ValueInfo& info)
+        {
+            return (outs << "<ValueInfo: " << info.get_name() << ">");
+        }
+
+    } // namespace onnx_import
+
+} // namespace ngraph