Class BuilderPtr

cpp/src/arrow/json/parser.cc:137–165

\brief packed pointer to a RawArrayBuilder RawArrayBuilders are stored in HandlerBase, which allows storage of their indices (uint32_t) instead of a full pointer. BuilderPtr is also tagged with the json kind and nullable properties so those can be accessed before dereferencing the builder.

/// BuilderPtr is also tagged with the json kind and nullable properties
/// so those can be accessed before dereferencing the builder.
struct BuilderPtr {
  BuilderPtr() : BuilderPtr(BuilderPtr::null) {}
  BuilderPtr(Kind::type k, uint32_t i, bool n) : index(i), kind(k), nullable(n) {}

  BuilderPtr(const BuilderPtr&) = default;
  BuilderPtr& operator=(const BuilderPtr&) = default;
  BuilderPtr(BuilderPtr&&) = default;
  BuilderPtr& operator=(BuilderPtr&&) = default;

  // index of builder in its arena
  // OR the length of that builder if kind == Kind::kNull
  // (we don't allocate an arena for nulls since they're trivial)
  uint32_t index;
  Kind::type kind;
  bool nullable;

  bool operator==(BuilderPtr other) const {
    return kind == other.kind && index == other.index;
  }

  bool operator!=(BuilderPtr other) const { return !(other == *this); }

  operator bool() const { return *this != null; }

  bool operator!() const { return *this == null; }

  // The static BuilderPtr for null type data
  static const BuilderPtr null;
};

const BuilderPtr BuilderPtr::null(Kind::kNull, 0, true);