iterator.hpp

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#pragma once
 
/// @file userver/formats/json/iterator.hpp
/// @brief @copybrief formats::json::Iterator
 
#include <iterator>
#include <optional>
#include <string>
 
#include <userver/formats/common/iterator_direction.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace formats::json {
 
/// @brief Iterator for `formats::json::Value`
template <typename Traits, common::IteratorDirection Direction =
                               common::IteratorDirection::kForward>
class Iterator final {
 public:
  using iterator_category = std::forward_iterator_tag;
  using difference_type = std::ptrdiff_t;
  using value_type = typename Traits::ValueType;
  using reference = typename Traits::Reference;
  using pointer = typename Traits::Pointer;
 
  using ContainerType = typename Traits::ContainerType;
 
  Iterator(ContainerType container, int pos);
 
  Iterator(const Iterator& other);
  Iterator(Iterator&& other) noexcept;
  Iterator& operator=(const Iterator& other);
  Iterator& operator=(Iterator&& other) noexcept;
 
  ~Iterator();
 
  Iterator operator++(int);
  Iterator& operator++();
  reference operator*() const;
  pointer operator->() const;
 
  bool operator==(const Iterator& other) const;
  bool operator!=(const Iterator& other) const;
 
  /// @brief Returns name of the referenced field
  /// @throws `TypeMismatchException` if iterated value is not an object
  template <typename T = void>
  std::string GetName() const {
    static_assert(Direction == common::IteratorDirection::kForward,
                  "Reverse iterator should be used only on arrays or null, "
                  "they do not have GetName()");
    return GetNameImpl();
  }
 
  /// @brief Returns index of the referenced field
  /// @throws `TypeMismatchException` if iterated value is not an array
  size_t GetIndex() const;
 
 private:
  std::string GetNameImpl() const;
  Iterator(ContainerType&& container, int type, int pos) noexcept;
 
  void UpdateValue() const;
 
  /// Container being iterated
  ContainerType container_;
  /// Internal container type
  int type_;
  /// Position inside container being iterated
  int pos_;
  // Temporary object replaced on every value access.
  mutable std::optional<value_type> current_;
};
 
}  // namespace formats::json
 
USERVER_NAMESPACE_END