Initial revision

[become] / src / mdwopt.h

/* -*-c-*-
 *
 * $Id: mdwopt.h,v 1.1 1997/07/21 13:47:47 mdw Exp $
 *
 * Options parsing, similar to GNU @getopt_long@
 *
 * (c) 1996 Mark Wooding
 */

/*----- Licencing notice --------------------------------------------------*
 *
 * This file is part of many programs.
 *
 * `mdwopt' 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 2 of the License, or
 * (at your option) any later version.
 *
 * `mdwopt' 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 `mdwopt'; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*----- Revision history --------------------------------------------------*
 *
 * $Log: mdwopt.h,v $
 * Revision 1.1  1997/07/21 13:47:47  mdw
 * Initial revision
 *
 * Revision 1.4  1997/02/26 00:39:55  mdw
 * Added GPL notice to the top.  Slight formatting changes.  Commented out
 * arguments to functions.
 *
 * Revision 1.3  1996/12/31 19:41:33  mdw
 * Formatting changes.
 *
 * Revision 1.2  1996/11/23 00:47:25  mdw
 * Added `MdwOpt' object from the `anagram' source code.
 *
 * Revision 1.1  1996/09/24 18:01:43  mdw
 * Initial revision
 *
 */

#ifndef MDWOPT_H
#define MDWOPT_H

/*----- Options handling structures ---------------------------------------*/

#ifdef __cplusplus
  extern "C" {
#endif

/* --- @mdwopt_data@ --- *
 *
 * Contains all the information needed by the @mdwopt@ routine to do its
 * work.
 */

typedef struct {
  /* --- Public variables --- */

  char *arg;                            /* Arg of current option, or 0 */
  int opt;                              /* Value of current option */
  int ind;                              /* 0 for init, index when done */
  int err;                              /* Set nonzero for error messages */
  char *prog;                           /* Program name (from @argv[0]@) */

  /* --- Private variables --- *
   *
   * Don't play with these, please.
   */

  char *list;                           /* Current short options pointer */
  int next;                             /* Next argument, unpermuted */
  int order;                            /* Ordering of options, flags */
  char *env;                            /* Where we are in the env var */
  char *estart;                         /* Pointer to env var buffer */
}
mdwopt_data;

/*----- Global variables --------------------------------------------------*/

extern mdwopt_data mdwopt_global;       /* The default global data */

/* --- For compatibility with older programs (and prettiness) --- *
 *
 * The macros here access the global structure defined above.  I consider it
 * to be perfectly acceptable to use these macros in new code, because it
 * looks nicer than playing with @mdwopt_global@.
 */

#define optarg (mdwopt_global.arg)      /* Argument of current option */
#define optopt (mdwopt_global.opt)      /* Code of current option */
#define opterr (mdwopt_global.err)      /* Zero to report error messages */
#define optind (mdwopt_global.ind)      /* Index of first non-option */
#define optprog (mdwopt_global.prog)    /* Pointer to program name */

/*----- Type definitions --------------------------------------------------*/

/* --- Long options definition table --- */

struct option {
  const char *name;                     /* Name of the long option */
  int has_arg;                          /* Does it have an argument? */
  int *flag;                            /* Address of flag variable */
  int val;                              /* Value to store/return */
};

/* --- Old-style names for argument flags in long options table --- */

enum {
  no_argument,                          /* No argument required */
  required_argument,                    /* User must specify argument */
  optional_argument                     /* Argument is optional */
};

/* --- New style flag names --- */

enum {
  gFlag_argReq = 1,                     /* Required argument */
  gFlag_argOpt = 2,                     /* Optional argument */
  gFlag_switch = 4,                     /* OR val into flag, don't store */
  gFlag_negate = 8,                     /* Allow long option to be negated */
  gFlag__last_long_opt_flag = 0         /* Dummy value */
};

enum {
  gFlag_noLongs = 1,                    /* Don't read long options */
  gFlag_noShorts = 2,                   /* Don't read short options */
  gFlag_numbers = 4,                    /* Read numeric options */
  gFlag_negation = 8,                   /* Allow `%|+|%' for negations */
  gFlag_envVar = 16,                    /* Parse options from env var */
  gFlag_noProgName = 32,                /* Don't set @optprog@  */
  gFlag_negNumber = 64,                 /* Allow negated number options */
  gFlag__last_mdwopt_flag = 0           /* Dummy value */
};

enum {
  gFlag_negated = 256,                  /* Option flag was negated by user */
  gFlag__last_return_flag = 0           /* Dummy value */
};

/*----- Main code ---------------------------------------------------------*/

/* --- @mdwopt@ --- *
 *
 * Arguments:   @int argc@ = number of command line arguments
 *              @char * const *argv@ = pointer to command line arguments
 *              @const char *shortopt@ = pointer to short options information
 *              @const struct option *longopts@ = pointer to long opts info
 *              @int *longind@ = where to store matched longopt
 *              @mdwopt_data *data@ = persistent state for the parser
 *              @int flags@ = various useful flags
 *
 * Returns:     Value of option found next, or an error character, or
 *              @EOF@ for the last thing.
 *
 * Use:         Reads options.  The routine should be more-or-less compatible
 *              with standard getopts, although it provides many more
 *              features even than the standard GNU implementation.
 *
 *              The precise manner of options parsing is determined by
 *              various flag settings, which are described below.  By setting
 *              flag values appropriately, you can achieve behaviour very
 *              similar to most other getopt routines.
 *
 *
 *          How options parsing appears to users
 *
 *              A command line consists of a number of `words' (which may
 *              contain spaces, according to various shell quoting
 *              conventions).  A word may be an option, an argument to an
 *              option, or a non-option.  An option begins with a special
 *              character, usually `%|-|%', although `%|+|%' is also used
 *              sometimes.  As special exceptions, the word containing only a
 *              `%|-|%' is considered to be a non-option, since it usually
 *              represents standard input or output as a filename, and the
 *              word containing a double-dash `%|--|%' is used to mark all
 *              following words as being non-options regardless of their
 *              initial character.
 *
 *              Traditionally, all words after the first non-option have been
 *              considered to be non-options automatically, so that options
 *              must be specified before filenames.  However, this
 *              implementation can extract all the options from the command
 *              line regardless of their position.  This can usually be
 *              disabled by setting one of the environment variables
 *              `%|POSIXLY_CORRECT|%' or `%|_POSIX_OPTION_ORDER|%'.
 *
 *              There are two different styles of options: `short' and
 *              `long'.
 *
 *              Short options are the sort which Unix has known for ages: an
 *              option is a single letter, preceded by a `%|-|%'.  Short
 *              options can be joined together to save space (and possibly to
 *              make silly words): e.g., instead of giving options
 *              `%|-x.-y|%', a user could write `%|-xy|%'.  Some short
 *              options can have arguments, which appear after the option
 *              letter, either immediately following, or in the next `word'
 *              (so an option with an argument could be written as
 *              `%|-o foo|%' or as `%|-ofoo|%').  Note that options with
 *              optional arguments must be written in the second style.
 *
 *              When a short option controls a flag setting, it is sometimes
 *              possible to explicitly turn the flag off, as well as turning
 *              it on, (usually to override default options).  This is
 *              usually done by using a `%|+|%' instead of a `%|-|%' to
 *              introduce the option.
 *
 *              Long options, as popularised by the GNU utilities, are given
 *              long-ish memorable names, preceded by a double-dash `%|--|%'.
 *              Since their names are more than a single character, long
 *              options can't be combined in the same way as short options.
 *              Arguments to long options may be given either in the same
 *              `word', separated from the option name by an equals sign, or
 *              in the following `word'.
 *
 *              Long option names can be abbreviated if necessary, as long
 *              as the abbreviation is unique.  This means that options can
 *              have sensible and memorable names but still not require much
 *              typing from an experienced user.
 *
 *              Like short options, long options can control flag settings.
 *              The options to manipulate these settings come in pairs: an
 *              option of the form `%|--set-flag|%' might set the flag, while
 *              an option of the form `%|--no-set-flag|%' might clear it.
 *
 *              It is usual for applications to provide both short and long
 *              options with identical behaviour.  Some applications with
 *              lots of options may only provide long options (although they
 *              will often be only two or three characters long).  In this
 *              case, long options can be preceded with a single `%|-|%'
 *              character, and negated by a `%|+|%' character.
 *
 *              Finally, some (older) programs accept arguments of the form
 *              `%%@.{"-"<number>}%%', to set some numerical parameter,
 *              typically a line count of some kind.
 *
 *
 *          How programs parse options
 *
 *              An application parses its options by calling mdwopt
 *              repeatedly.  Each time it is called, mdwopt returns a value
 *              describing the option just read, and stores information about
 *              the option in a data block.  The value %$-1$% is returned
 *              when there are no more options to be read.  The `%|?|%'
 *              character is returned when an error is encountered.
 *
 *              Before starting to parse options, the value @data->ind@ must
 *              be set to 0 or 1. The value of @data->err@ can also be set,
 *              to choose whether errors are reported by mdwopt.
 *
 *              The program's `@argc@' and `@argv@' arguments are passed to
 *              the options parser, so that it can read the command line.  A
 *              flags word is also passed, allowing the program fine control
 *              over parsing.  The flags are described above.
 *
 *              Short options are described by a string, which once upon a
 *              time just contained the permitted option characters.  Now the
 *              options string begins with a collection of flag characters,
 *              and various flag characters can be put after options
 *              characters to change their properties.
 *
 *              If the first character of the short options string is
 *              `%|+|%', `%|-|%' or `%|!|%', the order in which options are
 *              read is modified, as follows:
 *
 *              `%|+|%' forces the POSIX order to be used. As soon as a non-
 *                      option is found, mdwopt returns %$-1$%.
 *
 *              `%|-|%' makes mdwopt treat non-options as being `special'
 *                      sorts of option. When a non-option word is found, the
 *                      value 0 is returned, and the actual text of the word
 *                      is stored as being the option's argument.
 *
 *              `%|!|%' forces the default order to be used.  The entire
 *                      command line is scanned for options, which are
 *                      returned in order.  However, during this process,
 *                      the options are moved in the @argv@ array, so that
 *                      they appear before the non- options.
 *
 *              A `%|:|%' character may be placed after the ordering flag (or
 *              at the very beginning if no ordering flag is given) which
 *              indicates that the character `%|:|%', rather than `%|?|%',
 *              should be returned if a missing argument error is detected.
 *
 *              Each option in the string can be followed by a `%|+|%' sign,
 *              indicating that it can be negated, a `%|:|%' sign indicating
 *              that it requires an argument, or a `%|::|%' string,
 *              indicating an optional argument.  Both `%|+|%' and `%|:|%' or
 *              `%|::|%' may be given, although the `%|+|%' must come first.
 *
 *              If an option is found, the option character is returned to
 *              the caller.  A pointer to an argument is stored in
 *              @data->arg@, or @NULL@ is stored if there was no argument.
 *              If a negated option was found, the option character is
 *              returned ORred with @gFlag_negated@ (bit 8 set).
 *
 *              Long options are described in a table.  Each entry in the
 *              table is of type @struct option@, and the table is terminated
 *              by an entry whose @name@ field is null.  Each option has
 *              a flags word which, due to historical reasons, is called
 *              @has_arg@.  This describes various properties of the option,
 *              such as what sort of argument it takes, and whether it can
 *              be negated.
 *
 *              When mdwopt finds a long option, it looks the name up in the
 *              table. The index of the matching entry is stored in the
 *              @longind@ variable, passed to mdwopt (unless @longind@ is 0):
 *              a value of %$-1$% indicates that no long option was
 *              found. The behaviour is then dependent on the values in the
 *              table entry.  If @flag@ is nonzero, it points to an integer
 *              to be modified by mdwopt.  Usually the value in the @val@
 *              field is simply stored in the @flag@ variable. If the flag
 *              @gFlag_switch@ is set, however, the value is combined with
 *              the existing value of the flags using a bitwise OR.  If
 *              @gFlag_negate@ is set, then the flag bit will be cleared if a
 *              matching negated long option is found.  The value 0 is
 *              returned.
 *
 *              If @flag@ is zero, the value in @val@ is returned by mdwopt,
 *              possibly with bit 8 set if the option was negated.
 *
 *              Arguments for long options are stored in @data->arg@, as
 *              before.
 *
 *              Numeric options, if enabled, cause the value `%|#|%' to be
 *              returned, and the numeric value to be stored in @data->opt@.
 *
 *              If the flag @gFlag_envVar@ is set on entry, options will be
 *              extracted from an environment variable whose name is built by
 *              capitalising all the letters of the program's name.  (This
 *              allows a user to have different default settings for a
 *              program, by calling it through different symbolic links.)  */

extern int mdwopt(int /*argc*/, char *const */*argv*/,
                  const char */*shortopt*/,
                  const struct option */*longopts*/, int */*longind*/,
                  mdwopt_data */*data*/, int /*flags*/);

/* --- Macros for more commonly used routines --- */

#define getopt(c, v, o) mdwopt(c, v, o, 0, 0, 0, gFlag_noLongs)
#define getopt_long(c, v, o, l, li) mdwopt(c, v, o, l, li, 0, 0)
#define getopt_long_only(c, v, o, l, li)                                \
  mdwopt(c, v, o, l, li, 0, gFlag_noShorts)

#ifdef __cplusplus
}
#endif

/*----- C++ wrapper class -------------------------------------------------*/

#ifdef __cplusplus

/* --- Class: @MdwOpt@ --- *
 *
 * Parent:      ---
 *
 * Methods:     @MdwOpt@ -- construct a new mdwopt object with the given
 *                      arguments.  These are remembered for later use.
 *              @arg@ -- return the argument of the current option
 *                      arguments.  These are remembered for later use.
 *              @arg@ -- return the argument of the current option
 *              @opt@ -- return the value of the current option
 *              @ind@ -- return the index of the next unread argument
 *              @longind@ -- return index of current long option in table
 *              @errors@ -- return or set whether we report errors to the
 *                      user
 *              @prog@ -- return program name from @argv[0]@
 *              @next@ -- return next option read from the table
 *
 * Use:         A simple C++ class for encapsulating the options parser.
 *              The methods are all nice and simple, and extremely similar
 *              to the normal C interface described above.
 */

class MdwOpt {
  protected:
    int argc;
    char * const *argv;
    const char *shortopts;
    const struct option *longopts;
    int long_ind;
    int flags;

    mdwopt_data data;

  public:
    MdwOpt(int c, char * const *v, const char *so,
           const struct option *lo, int f=0) :
      argc(c), argv(v), shortopts(so), longopts(lo), flags(f) {
        data.ind = 0;
        data.err = 1;
    }

    const char *arg(void) const { return (data.arg); }
    int opt(void) const { return (data.opt); }
    int errors(void) const { return (data.err); }
    int errors(int e) { int oe = data.err; data.err = e; return (oe); }
    int ind(void) const { return (data.ind); }
    int longind(void) const { return (long_ind); }
    const char *prog(void) const { return (data.prog); }

    int next(void) {
      return (mdwopt(argc, argv, shortopts,
                     longopts, &long_ind, &data, flags));
    }
};

#endif

/*----- That's all, folks -------------------------------------------------*/

#endif