Class Result

crates/c-api/include/wasmtime/error.hh:70–116

 * C++ standard when it exists.
 */
template <typename T, typename E = Error> class [[nodiscard]] Result {
  std::variant<T, E> data;

public:
  /// \brief Creates a `Result` from its successful value.
  Result(T t) : data(std::move(t)) {}
  /// \brief Creates a `Result` from an error value.
  Result(E e) : data(std::move(e)) {}

  /// \brief Returns `true` if this result is a success, `false` if it's an
  /// error
  explicit operator bool() const { return data.index() == 0; }

  /// \brief Returns the error, if present, aborts if this is not an error.
  E &&err() { return std::get<E>(std::move(data)); }
  /// \brief Returns the error, if present, aborts if this is not an error.
  const E &&err() const { return std::get<E>(std::move(data)); }

  /// \brief Returns the success, if present, aborts if this is an error.
  T &&ok() { return std::get<T>(std::move(data)); }
  /// \brief Returns the success, if present, aborts if this is an error.
  const T &&ok() const { return std::get<T>(std::move(data)); }

  /// \brief Returns the success, if present, aborts if this is an error.
  T &ok_ref() { return std::get<T>(data); }
  /// \brief Returns the success, if present, aborts if this is an error.
  const T &ok_ref() const { return std::get<T>(data); }

  /// \brief Returns the error, if present, aborts if this is not an error.
  E &err_ref() { return std::get<E>(data); }
  /// \brief Returns the error, if present, aborts if this is not an error.
  const E &err_ref() const { return std::get<E>(data); }

  /// \brief Returns the success, if present, aborts if this is an error.
  T unwrap() {
    if (!*this) {
      unwrap_failed();
    }
    return this->ok();
  }

private:
  [[noreturn]] void unwrap_failed() {
    fprintf(stderr, "error: %s\n", this->err().message().c_str()); // NOLINT
    std::abort();
  }
};

} // namespace wasmtime