/* emacs-module.h - GNU Emacs module API.

Copyright (C) 2015-2021 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */

/*
This file defines the Emacs module API.  Please see the chapter
`Dynamic Modules' in the GNU Emacs Lisp Reference Manual for
information how to write modules and use this header file.
*/

#ifndef EMACS_MODULE_H
#define EMACS_MODULE_H

#include <stddef.h>
#include <stdint.h>
#include <time.h>

#ifndef __cplusplus
#include <stdbool.h>
#endif

#define EMACS_MAJOR_VERSION @emacs_major_version@

#if defined __cplusplus && __cplusplus >= 201103L
# define EMACS_NOEXCEPT noexcept
#else
# define EMACS_NOEXCEPT
#endif

#if defined __cplusplus && __cplusplus >= 201703L
# define EMACS_NOEXCEPT_TYPEDEF noexcept
#else
# define EMACS_NOEXCEPT_TYPEDEF
#endif

#if 3 < __GNUC__ + (3 <= __GNUC_MINOR__)
# define EMACS_ATTRIBUTE_NONNULL(...) \
   __attribute__ ((__nonnull__ (__VA_ARGS__)))
#elif (defined __has_attribute \
       && (!defined __clang_minor__ \
	   || 3 < __clang_major__ + (5 <= __clang_minor__)))
# if __has_attribute (__nonnull__)
#  define EMACS_ATTRIBUTE_NONNULL(...) \
    __attribute__ ((__nonnull__ (__VA_ARGS__)))
# endif
#endif
#ifndef EMACS_ATTRIBUTE_NONNULL
# define EMACS_ATTRIBUTE_NONNULL(...)
#endif

#ifdef __cplusplus
extern "C" {
#endif

/* Current environment.  */
typedef struct emacs_env_@emacs_major_version@ emacs_env;

/* Opaque pointer representing an Emacs Lisp value.
   BEWARE: Do not assume NULL is a valid value!  */
typedef struct emacs_value_tag *emacs_value;

enum { emacs_variadic_function = -2 };

/* Struct passed to a module init function (emacs_module_init).  */
struct emacs_runtime
{
  /* Structure size (for version checking).  */
  ptrdiff_t size;

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

  /* Return an environment pointer.  */
  emacs_env *(*get_environment) (struct emacs_runtime *runtime)
    EMACS_ATTRIBUTE_NONNULL (1);
};

/* Type aliases for function pointer types used in the module API.
   Note that we don't use these aliases directly in the API to be able
   to mark the function arguments as 'noexcept' before C++20.
   However, users can use them if they want.  */

/* Function prototype for the module Lisp functions.  These must not
   throw C++ exceptions.  */
typedef emacs_value (*emacs_function) (emacs_env *env, ptrdiff_t nargs,
                                       emacs_value *args,
                                       void *data)
  EMACS_NOEXCEPT_TYPEDEF EMACS_ATTRIBUTE_NONNULL (1);

/* Function prototype for module user-pointer and function finalizers.
   These must not throw C++ exceptions.  */
typedef void (*emacs_finalizer) (void *data) EMACS_NOEXCEPT_TYPEDEF;

/* Possible Emacs function call outcomes.  */
enum emacs_funcall_exit
{
  /* Function has returned normally.  */
  emacs_funcall_exit_return = 0,

  /* Function has signaled an error using `signal'.  */
  emacs_funcall_exit_signal = 1,

  /* Function has exit using `throw'.  */
  emacs_funcall_exit_throw = 2
};

/* Possible return values for emacs_env.process_input.  */
enum emacs_process_input_result
{
  /* Module code may continue  */
  emacs_process_input_continue = 0,

  /* Module code should return control to Emacs as soon as possible.  */
  emacs_process_input_quit = 1
};

/* Define emacs_limb_t so that it is likely to match GMP's mp_limb_t.
   This micro-optimization can help modules that use mpz_export and
   mpz_import, which operate more efficiently on mp_limb_t.  It's OK
   (if perhaps a bit slower) if the two types do not match, and
   modules shouldn't rely on the two types matching.  */
typedef size_t emacs_limb_t;
#define EMACS_LIMB_MAX SIZE_MAX

struct emacs_env_25
{
@module_env_snippet_25@
};

struct emacs_env_26
{
@module_env_snippet_25@

@module_env_snippet_26@
};

struct emacs_env_27
{
@module_env_snippet_25@

@module_env_snippet_26@

@module_env_snippet_27@
};

struct emacs_env_28
{
@module_env_snippet_25@

@module_env_snippet_26@

@module_env_snippet_27@

@module_env_snippet_28@
};

struct emacs_env_29
{
@module_env_snippet_25@

@module_env_snippet_26@

@module_env_snippet_27@

@module_env_snippet_28@

@module_env_snippet_29@
};

/* Every module should define a function as follows.  */
extern int emacs_module_init (struct emacs_runtime *runtime)
  EMACS_NOEXCEPT
  EMACS_ATTRIBUTE_NONNULL (1);

#ifdef __cplusplus
}
#endif

#endif /* EMACS_MODULE_H */