argpar/argpar.h

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright 2019 Philippe Proulx <pproulx@efficios.com>
   5  */
   6
   7 #ifndef BABELTRACE_ARGPAR_H
   8 #define BABELTRACE_ARGPAR_H
   9
  10 #include <stdbool.h>
  11
  12 /* Sentinel for an option descriptor array */
  13 #define ARGPAR_OPT_DESCR_SENTINEL       { -1, '\0', NULL, false }
  14
  15 /*
  16  * ARGPAR_HIDDEN: if argpar is used in some shared library, we don't want them
  17  * to be exported by that library, so mark them as "hidden".
  18  *
  19  * On Windows, symbols are local unless explicitly exported,
  20  * see https://gcc.gnu.org/wiki/Visibility
  21  */
  22 #if defined(_WIN32) || defined(__CYGWIN__)
  23 #define ARGPAR_HIDDEN
  24 #else
  25 #define ARGPAR_HIDDEN __attribute__((visibility("hidden")))
  26 #endif
  27
  28 /* Option descriptor */
  29 struct argpar_opt_descr {
  30         /* Numeric ID for this option */
  31         const int id;
  32
  33         /* Short option character, or `\0` */
  34         const char short_name;
  35
  36         /* Long option name (without `--`), or `NULL` */
  37         const char * const long_name;
  38
  39         /* True if this option has an argument */
  40         const bool with_arg;
  41 };
  42
  43 /* Item type */
  44 enum argpar_item_type {
  45         /* Option */
  46         ARGPAR_ITEM_TYPE_OPT,
  47
  48         /* Non-option */
  49         ARGPAR_ITEM_TYPE_NON_OPT,
  50 };
  51
  52 /* Base item */
  53 struct argpar_item {
  54         enum argpar_item_type type;
  55 };
  56
  57 /* Option item */
  58 struct argpar_item_opt {
  59         struct argpar_item base;
  60
  61         /* Corresponding descriptor */
  62         const struct argpar_opt_descr *descr;
  63
  64         /* Argument, or `NULL` if none */
  65         const char *arg;
  66 };
  67
  68 /* Non-option item */
  69 struct argpar_item_non_opt {
  70         struct argpar_item base;
  71
  72         /*
  73          * Complete argument, pointing to one of the entries of the
  74          * original arguments (`argv`).
  75          */
  76         const char *arg;
  77
  78         /* Index of this argument amongst all original arguments (`argv`) */
  79         unsigned int orig_index;
  80
  81         /* Index of this argument amongst other non-option arguments */
  82         unsigned int non_opt_index;
  83 };
  84
  85 struct argpar_item_array {
  86         /* Array of `struct argpar_item *`, or `NULL` on error */
  87         struct argpar_item **items;
  88
  89         /* Number of used slots in `items`. */
  90         unsigned int n_items;
  91
  92         /* Number of allocated slots in `items`. */
  93         unsigned int n_alloc;
  94 };
  95
  96 /* What is returned by argpar_parse() */
  97 struct argpar_parse_ret {
  98         /* Array of `struct argpar_item *`, or `NULL` on error */
  99         struct argpar_item_array *items;
 100
 101         /* Error string, or `NULL` if none */
 102         char *error;
 103
 104         /* Number of original arguments (`argv`) ingested */
 105         unsigned int ingested_orig_args;
 106 };
 107
 108 /*
 109  * Parses the arguments `argv` of which the count is `argc` using the
 110  * sentinel-terminated (use `ARGPAR_OPT_DESCR_SENTINEL`) option
 111  * descriptor array `descrs`.
 112  *
 113  * This function considers ALL the elements of `argv`, including the
 114  * first one, so that you would typically pass `argc - 1` and
 115  * `&argv[1]` from what main() receives.
 116  *
 117  * This argument parser supports:
 118  *
 119  * * Short options without an argument, possibly tied together:
 120  *
 121  *       -f -auf -n
 122  *
 123  * * Short options with argument:
 124  *
 125  *       -b 45 -f/mein/file -xyzhello
 126  *
 127  * * Long options without an argument:
 128  *
 129  *       --five-guys --burger-king --pizza-hut --subway
 130  *
 131  * * Long options with arguments:
 132  *
 133  *       --security enable --time=18.56
 134  *
 135  * * Non-option arguments (anything else).
 136  *
 137  * This function does not accept `-` or `--` as arguments. The latter
 138  * means "end of options" for many command-line tools, but this function
 139  * is all about keeping the order of the arguments, so it does not mean
 140  * much to put them at the end. This has the side effect that a
 141  * non-option argument cannot have the form of an option, for example if
 142  * you need to pass the exact relative path `--component`. In that case,
 143  * you would need to pass `./--component`. There's no generic way to
 144  * escape `-` for the moment.
 145  *
 146  * This function accepts duplicate options (the resulting array of items
 147  * contains one entry for each instance).
 148  *
 149  * On success, this function returns an array of items
 150  * (`struct argpar_item *`). Each item is to be casted to the
 151  * appropriate type (`struct argpar_item_opt *` or
 152  * `struct argpar_item_non_opt *`) depending on its type.
 153  *
 154  * The returned array contains the items in the same order that the
 155  * arguments were parsed, including non-option arguments. This means,
 156  * for example, that for
 157  *
 158  *     --hello --meow=23 /path/to/file -b
 159  *
 160  * the function returns an array of four items: two options, one
 161  * non-option, and one option.
 162  *
 163  * In the returned structure, `ingested_orig_args` is the number of
 164  * ingested arguments within `argv` to produce the resulting array of
 165  * items. If `fail_on_unknown_opt` is true, then on success
 166  * `ingested_orig_args` is equal to `argc`. Otherwise,
 167  * `ingested_orig_args` contains the number of original arguments until
 168  * an unknown _option_ occurs. For example, with
 169  *
 170  *     --great --white contact nuance --shark nuclear
 171  *
 172  * if `--shark` is not described within `descrs` and
 173  * `fail_on_unknown_opt` is false, then `ingested_orig_args` is 4 (two
 174  * options, two non-options), whereas `argc` is 6.
 175  *
 176  * This makes it possible to know where a command name is, for example.
 177  * With those arguments:
 178  *
 179  *     --verbose --stuff=23 do-something --specific-opt -f -b
 180  *
 181  * and the descriptors for `--verbose` and `--stuff` only, the function
 182  * returns the `--verbose` and `--stuff` option items, the
 183  * `do-something` non-option item, and that three original arguments
 184  * were ingested. This means you can start the next argument parsing
 185  * stage, with option descriptors depending on the command name, at
 186  * `&argv[3]`.
 187  *
 188  * Note that `ingested_orig_args` is not always equal to the number of
 189  * returned items, as
 190  *
 191  *     --hello -fdw
 192  *
 193  * for example contains two ingested original arguments, but four
 194  * resulting items.
 195  *
 196  * On failure, the returned structure's `items` member is `NULL`, and
 197  * the `error` string member contains details about the error.
 198  *
 199  * You can finalize the returned structure with
 200  * argpar_parse_ret_fini().
 201  */
 202 ARGPAR_HIDDEN
 203 struct argpar_parse_ret argpar_parse(unsigned int argc,
 204                 const char * const *argv,
 205                 const struct argpar_opt_descr *descrs,
 206                 bool fail_on_unknown_opt);
 207
 208 /*
 209  * Finalizes what is returned by argpar_parse().
 210  *
 211  * It is safe to call argpar_parse() multiple times with the same
 212  * structure.
 213  */
 214 ARGPAR_HIDDEN
 215 void argpar_parse_ret_fini(struct argpar_parse_ret *ret);
 216
 217 #endif /* BABELTRACE_ARGPAR_H */