/* Structure size (for version checking).  */
  ptrdiff_t size;

  /* Private data; users should not touch this.  */
  struct emacs_env_private *private_members;

  /* Memory management.  */

  emacs_value (*make_global_ref) (emacs_env *env, emacs_value value)
    EMACS_ATTRIBUTE_NONNULL(1);

  void (*free_global_ref) (emacs_env *env, emacs_value global_value)
    EMACS_ATTRIBUTE_NONNULL(1);

  /* Non-local exit handling.  */

  enum emacs_funcall_exit (*non_local_exit_check) (emacs_env *env)
    EMACS_ATTRIBUTE_NONNULL(1);

  void (*non_local_exit_clear) (emacs_env *env)
    EMACS_ATTRIBUTE_NONNULL(1);

  enum emacs_funcall_exit (*non_local_exit_get)
    (emacs_env *env, emacs_value *symbol, emacs_value *data)
    EMACS_ATTRIBUTE_NONNULL(1, 2, 3);

  void (*non_local_exit_signal) (emacs_env *env,
				 emacs_value symbol, emacs_value data)
    EMACS_ATTRIBUTE_NONNULL(1);

  void (*non_local_exit_throw) (emacs_env *env,
				emacs_value tag, emacs_value value)
    EMACS_ATTRIBUTE_NONNULL(1);

  /* Function registration.  */

  emacs_value (*make_function) (emacs_env *env,
				ptrdiff_t min_arity,
				ptrdiff_t max_arity,
				emacs_value (*func) (emacs_env *env,
                                                     ptrdiff_t nargs,
                                                     emacs_value* args,
                                                     void *data)
				  EMACS_NOEXCEPT
                                  EMACS_ATTRIBUTE_NONNULL(1),
				const char *docstring,
				void *data)
    EMACS_ATTRIBUTE_NONNULL(1, 4);

  emacs_value (*funcall) (emacs_env *env,
                          emacs_value func,
                          ptrdiff_t nargs,
                          emacs_value* args)
    EMACS_ATTRIBUTE_NONNULL(1);

  emacs_value (*intern) (emacs_env *env, const char *name)
    EMACS_ATTRIBUTE_NONNULL(1, 2);

  /* Type conversion.  */

  emacs_value (*type_of) (emacs_env *env, emacs_value arg)
    EMACS_ATTRIBUTE_NONNULL(1);

  bool (*is_not_nil) (emacs_env *env, emacs_value arg)
    EMACS_ATTRIBUTE_NONNULL(1);

  bool (*eq) (emacs_env *env, emacs_value a, emacs_value b)
    EMACS_ATTRIBUTE_NONNULL(1);

  intmax_t (*extract_integer) (emacs_env *env, emacs_value arg)
    EMACS_ATTRIBUTE_NONNULL(1);

  emacs_value (*make_integer) (emacs_env *env, intmax_t n)
    EMACS_ATTRIBUTE_NONNULL(1);

  double (*extract_float) (emacs_env *env, emacs_value arg)
    EMACS_ATTRIBUTE_NONNULL(1);

  emacs_value (*make_float) (emacs_env *env, double d)
    EMACS_ATTRIBUTE_NONNULL(1);

  /* Copy the content of the Lisp string VALUE to BUFFER as an utf8
     null-terminated string.

     SIZE must point to the total size of the buffer.  If BUFFER is
     NULL or if SIZE is not big enough, write the required buffer size
     to SIZE and return true.

     Note that SIZE must include the last null byte (e.g. "abc" needs
     a buffer of size 4).

     Return true if the string was successfully copied.  */

  bool (*copy_string_contents) (emacs_env *env,
                                emacs_value value,
                                char *buf,
                                ptrdiff_t *len)
    EMACS_ATTRIBUTE_NONNULL(1, 4);

  /* Create a Lisp string from a utf8 encoded string.  */
  emacs_value (*make_string) (emacs_env *env,
			      const char *str, ptrdiff_t len)
    EMACS_ATTRIBUTE_NONNULL(1, 2);

  /* Embedded pointer type.  */
  emacs_value (*make_user_ptr) (emacs_env *env,
				void (*fin) (void *) EMACS_NOEXCEPT,
				void *ptr)
    EMACS_ATTRIBUTE_NONNULL(1);

  void *(*get_user_ptr) (emacs_env *env, emacs_value arg)
    EMACS_ATTRIBUTE_NONNULL(1);
  void (*set_user_ptr) (emacs_env *env, emacs_value arg, void *ptr)
    EMACS_ATTRIBUTE_NONNULL(1);

  void (*(*get_user_finalizer) (emacs_env *env, emacs_value uptr))
    (void *) EMACS_NOEXCEPT EMACS_ATTRIBUTE_NONNULL(1);
  void (*set_user_finalizer) (emacs_env *env, emacs_value arg,
			      void (*fin) (void *) EMACS_NOEXCEPT)
    EMACS_ATTRIBUTE_NONNULL(1);

  /* Vector functions.  */
  emacs_value (*vec_get) (emacs_env *env, emacs_value vector, ptrdiff_t index)
    EMACS_ATTRIBUTE_NONNULL(1);

  void (*vec_set) (emacs_env *env, emacs_value vector, ptrdiff_t index,
		   emacs_value value)
    EMACS_ATTRIBUTE_NONNULL(1);

  ptrdiff_t (*vec_size) (emacs_env *env, emacs_value vector)
    EMACS_ATTRIBUTE_NONNULL(1);