argparse.h

#ifndef ARGPARSE_H
#define ARGPARSE_H

/* For c++ compatibility */
#ifdef __cplusplus
extern "C" {
#endif

#include <stdint.h>

struct argparse;
struct argparse_option;

typedef int argparse_callback(struct argparse *self,
                              const struct argparse_option *option);

enum argparse_flag {
  ARGPARSE_STOP_AT_NON_OPTION = 1 << 0,
  ARGPARSE_IGNORE_UNKNOWN_ARGS = 1 << 1,
};

enum argparse_option_type {
  /* special */
  ARGPARSE_OPT_END,
  ARGPARSE_OPT_GROUP,
  /* options with no arguments */
  ARGPARSE_OPT_BOOLEAN,
  ARGPARSE_OPT_BIT,
  /* options with arguments (optional or required) */
  ARGPARSE_OPT_INTEGER,
  ARGPARSE_OPT_FLOAT,
  ARGPARSE_OPT_STRING,
};

enum argparse_option_flags {
  OPT_NONEG = 1, /* disable negation */
};

/**
 *  argparse option
 *
 *  `type`:
 *    holds the type of the option, you must have an ARGPARSE_OPT_END last in
 * your array.
 *
 *  `short_name`:
 *    the character to use as a short option name, '\0' if none.
 *
 *  `long_name`:
 *    the long option name, without the leading dash, NULL if none.
 *
 *  `value`:
 *    stores pointer to the value to be filled.
 *
 *  `help`:
 *    the short help message associated to what the option does.
 *    Must never be NULL (except for ARGPARSE_OPT_END).
 *
 *  `callback`:
 *    function is called when corresponding argument is parsed.
 *
 *  `data`:
 *    associated data. Callbacks can use it like they want.
 *
 *  `flags`:
 *    option flags.
 */
struct argparse_option {
  enum argparse_option_type type;
  const char short_name;
  const char *long_name;
  void *value;
  const char *help;
  argparse_callback *callback;
  intptr_t data;
  int flags;
};

/**
 * argpparse
 */
struct argparse {
  // user supplied
  const struct argparse_option *options;
  const char *const *usages;
  int flags;
  const char *description; // a description after usage
  const char *epilog;      // a description at the end
  // internal context
  int argc;
  const char **argv;
  const char **out;
  int cpidx;
  const char *optvalue; // current option value
};

// built-in callbacks
int argparse_help_cb(struct argparse *self,
                     const struct argparse_option *option);
int argparse_help_cb_no_exit(struct argparse *self,
                             const struct argparse_option *option);

// built-in option macros
#define OPT_END()                                                              \
  { ARGPARSE_OPT_END, 0, NULL, NULL, 0, NULL, 0, 0 }
#define OPT_BOOLEAN(...)                                                       \
  { ARGPARSE_OPT_BOOLEAN, __VA_ARGS__ }
#define OPT_BIT(...)                                                           \
  { ARGPARSE_OPT_BIT, __VA_ARGS__ }
#define OPT_INTEGER(...)                                                       \
  { ARGPARSE_OPT_INTEGER, __VA_ARGS__ }
#define OPT_FLOAT(...)                                                         \
  { ARGPARSE_OPT_FLOAT, __VA_ARGS__ }
#define OPT_STRING(...)                                                        \
  { ARGPARSE_OPT_STRING, __VA_ARGS__ }
#define OPT_GROUP(h)                                                           \
  { ARGPARSE_OPT_GROUP, 0, NULL, NULL, h, NULL, 0, 0 }
#define OPT_HELP()                                                             \
  OPT_BOOLEAN('h', "help", NULL, "show this help message and exit",            \
              argparse_help_cb, 0, OPT_NONEG)

int argparse_init(struct argparse *self, struct argparse_option *options,
                  const char *const *usages, int flags);
void argparse_describe(struct argparse *self, const char *description,
                       const char *epilog);
int argparse_parse(struct argparse *self, int argc, const char **argv);
void argparse_usage(struct argparse *self);

#ifdef __cplusplus
}
#endif

#endif