text: // Copyright (C) 2018-2021 Intel Corporation
  // SPDX-License-Identifier: Apache-2.0
  //
  
  #pragma once
  
  #include <string>
  #include <unordered_map>
  #include <utility>
  
  #include "openvino/core/partial_shape.hpp"
  #include "openvino/core/type.hpp"
  #include "openvino/core/type/element_type.hpp"
  
  namespace ov {
  class Node;
  class Function;
  template <typename T>
  class ValueAccessor;
  template <typename T>
  class AttributeAdapter;
  class VisitorAdapter;
  
  /// \brief Visits the attributes of a node, primarily for serialization-like tasks.
  ///
  /// Attributes are the node parameters that are always compile-time constants.
  /// Values computed from the graph topology and attributes during compilation are not
  /// attributes.
  ///
  /// Attributes have a wide variety of types, but serialization formats are more restricted.
  /// We asume serialation easily supports scalar types of bool 64-bit signed, string, and double,
  /// and has specialized ways to support numeric arrays and raw data+size. The visitor and
  /// adapter convert between the limited serialization types and the unlimited attribute types.
  ///
  /// A visitor is passed to an op's visit_attributes method. The visit_attributes method calls
  /// the template method visitor.on_attribute<AT>(const std::string& name, AT& value) on each
  /// attribute. The visitor can read or write the attribute's value. The on_attribute
  /// method creates an AttributeAdapter<AT> for the value and passes it to one of the visitors
  /// on_adapter methods. The on_adapter methods expect a reference to a ValueAccessor<VAT> or a
  /// VisitorAdapter. A ValueAccessor<VAT> has get/set methods that can be used to read/write the
  /// attribute value as type VAT. These methods are triggered by deriving AttributeAdapter<AT>
  /// from ValueAccessor<VAT>. For more complex cases, such as structs, the on_adapter method for
  /// VisitorAdapter passes the name and visitor to the adapter, so that the adapter can perform
  /// additional work such as visiting struct members or sequence values.
  ///
  /// When a node visits an attribute with structure, the node's on_attribute passes a name for
  /// the entire attribute, but the struct will have its own methods to be visited. Similarly, a
  /// vector will have a sequence of members to be visited. The adapter may use the visitor
  /// methods start_struct/finish_struct and start_vector/next_vector/finish_vector to inidicate
  /// nexted members.
  ///
  /// The visitor method get_name_with_context creates a generic nested version of the name.
  /// Visitors can override according to their serialization requirements.
  ///
  /// Attributes that are shared_ptr<Node> are special. They must have been already been
  /// registered with the visitor using register_node, which needs a shared pointer to a node and
  /// a string ID. The ID string will be used to serialize the node or find the node during
  /// deserialization.
  class OPENVINO_API AttributeVisitor {
  public:
      virtual ~AttributeVisitor() = default;
      // Must implement these methods
      /// \brief handles all specialized on_adapter methods implemented by the visitor.
      ///
      /// The adapter implements get_type_info(), which can be used to determine the adapter
      /// directly
      /// or via is_type and as_type on any platform
      virtual void on_adapter(const std::string& name, ValueAccessor<void>& adapter) = 0;
      // The remaining adapter methods fall back on the void adapter if not implemented
      virtual void on_adapter(const std::string& name, ValueAccessor<void*>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<std::string>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<bool>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<int8_t>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<int16_t>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<int32_t>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<int64_t>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<uint8_t>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<uint16_t>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<uint32_t>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<uint64_t>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<float>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<double>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<std::vector<int8_t>>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<std::vector<int16_t>>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<std::vector<int32_t>>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<std::vector<int64_t>>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<std::vector<uint8_t>>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<std::vector<uint16_t>>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<std::vector<uint32_t>>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<std::vector<uint64_t>>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<std::vector<float>>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<std::vector<double>>& adapter);
      virtual void on_adapter(const std::string& name, ValueAccessor<std::vector<std::string>>& adapter);
      /// \brief Hook for adapters that need visitor access
      virtual void on_adapter(const std::string& name, VisitorAdapter& adapter);
  
      /// \brief Provides API to handle openvino Function attribute type, accessed as ValueAccessor
      /// \param name attribute name
      /// \param adapter reference to a Function ValueAccessor<VAT>
      virtual void on_adapter(const std::string& name, ValueAccessor<std::shared_ptr<ov::Function>>& adapter);
  
      /// The generic visitor. There must be a definition of AttributeAdapter<T> that can convert
      /// to a ValueAccessor<U> for one of the on_adpater methods.
      template <typename AT>
      void on_attribute(const std::string& name, AT& value) {
          AttributeAdapter<AT> adapter(value);
          start_structure(name);
          on_adapter(get_name_with_context(), adapter);
          finish_structure();
      }
      /// \returns The nested context of visits
      const std::vector<std::string>& get_context() const {
          return m_context;
      }
      /// \returns context prepended to names
      virtual std::string get_name_with_context();
      /// \brief Start visiting a nested structure
      virtual void start_structure(const std::string& name);
      /// \brief Finish visiting a nested structure
      virtual std::string finish_structure();
      using node_id_t = std::string;
      static constexpr char invalid_node_id[] = "";
      /// \brief Associate a node with an id.
      ///
      /// No node may be used as an attribute unless it has already been registered with an ID.
      /// References to nodes are visited with a ValueAccessor of their ID.
      virtual void register_node(const std::shared_ptr<Node>& node, node_id_t id = invalid_node_id);
      /// Returns the node with the given id, or nullptr if there is no registered node
      virtual std::shared_ptr<Node> get_registered_node(node_id_t id);
      /// Returns the id for the node, or -1 if the node is not registered
      virtual node_id_t get_registered_node_id(const std::shared_ptr<Node>& node);
  
  protected:
      std::vector<std::string> m_context;
      std::unordered_map<std::shared_ptr<Node>, node_id_t> m_node_id_map;
      std::unordered_map<node_id_t, std::shared_ptr<Node>> m_id_node_map;
  };
  }  // namespace ov
  