/* module.h - GNU Emacs module API.

Copyright (C) 2015 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 <http://www.gnu.org/licenses/>.  */

#ifndef EMACS_MODULE_H
#define EMACS_MODULE_H

#include <stdint.h>
#include <stdlib.h>
#include <stdbool.h>

#ifdef __cplusplus
#define EMACS_EXTERN_C_BEGIN extern "C" {
#define EMACS_EXTERN_C_END }
#else
#define EMACS_EXTERN_C_BEGIN
#define EMACS_EXTERN_C_END
#endif

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

EMACS_EXTERN_C_BEGIN

/* Current environement */
typedef struct emacs_env_25 emacs_env;

/* Opaque structure pointer representing an Emacs Lisp value */
typedef struct emacs_value_tag* emacs_value;

enum emacs_arity {
  emacs_variadic_function = -2
};

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

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

  /* Returns an environment pointer. */
  emacs_env* (*get_environment)(struct emacs_runtime *ert);
};


/* Function prototype for the module init function */
typedef int (*emacs_init_function)(struct emacs_runtime *ert);

/* Function prototype for the module Lisp functions */
typedef emacs_value (*emacs_subr)(emacs_env *env,
                                  int nargs,
                                  emacs_value args[],
                                  void *data);

/* Function prototype for module user-pointer finalizers */
typedef void (*emacs_finalizer_function)(void*);

/* 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,
};

struct emacs_env_25 {
  /*
   * Structure size (for version checking)
   */

  size_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 any_reference);

  void (*free_global_ref)(emacs_env *env,
                          emacs_value global_reference);

  /*
   * Non-local exit handling
   */

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

  void (*non_local_exit_clear)(emacs_env *env);

  enum emacs_funcall_exit (*non_local_exit_get)(emacs_env *env,
                                       emacs_value *non_local_exit_symbol_out,
                                       emacs_value *non_local_exit_data_out);

  void (*non_local_exit_signal)(emacs_env *env,
                       emacs_value non_local_exit_symbol,
                       emacs_value non_local_exit_data);

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

  /*
   * Function registration
   */

  emacs_value (*make_function)(emacs_env *env,
                               int min_arity,
                               int max_arity,
                               emacs_value (*function)(emacs_env*, int, emacs_value*, void*) EMACS_NOEXCEPT,
                               const char *documentation,
                               void *data);

  emacs_value (*funcall)(emacs_env *env,
                         emacs_value function,
                         int nargs,
                         emacs_value args[]);

  emacs_value (*intern)(emacs_env *env,
                        const char *symbol_name);

  /*
   * Type conversion
   */

  emacs_value (*type_of)(emacs_env *env,
                         emacs_value value);

  bool (*is_not_nil)(emacs_env *env, emacs_value value);

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

  int64_t (*extract_integer)(emacs_env *env,
                             emacs_value value);

  emacs_value (*make_integer)(emacs_env *env,
                              int64_t value);

  double (*extract_float)(emacs_env *env,
                          emacs_value value);

  emacs_value (*make_float)(emacs_env *env,
                            double value);

  /*
   * 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 false.
   *
   * Note that SIZE must include the last null byte (e.g. "abc" needs
   * a buffer of size 4).
   *
   * Returns true if the string was successfully copied.
   */

  bool (*copy_string_contents)(emacs_env *env,
                               emacs_value value,
                               char *buffer,
                               size_t *size_inout);

  /*
   * Create a lisp string from a utf8 encoded string.
   */
  emacs_value (*make_string)(emacs_env *env,
                             const char *contents, size_t length);

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

  void* (*get_user_ptr)(emacs_env *env, emacs_value uptr);
  void (*set_user_ptr)(emacs_env *env, emacs_value uptr, void *ptr);

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

  /*
   * Vector functions
   */
  emacs_value (*vec_get) (emacs_env *env,
			  emacs_value vec,
			  size_t i);

  void (*vec_set) (emacs_env *env,
		   emacs_value vec,
		   size_t i,
		   emacs_value val);

  size_t (*vec_size) (emacs_env *env,
		      emacs_value vec);
};

EMACS_EXTERN_C_END

#endif /* EMACS_MODULE_H */