Parse `-` and `--` as non-option arguments
[argpar.git] / argpar / argpar.h
1 /*
2 * SPDX-License-Identifier: MIT
3 *
4 * Copyright (c) 2019-2021 Philippe Proulx <pproulx@efficios.com>
5 * Copyright (c) 2020-2021 Simon Marchi <simon.marchi@efficios.com>
6 */
7
8 #ifndef ARGPAR_ARGPAR_H
9 #define ARGPAR_ARGPAR_H
10
11 #include <stdbool.h>
12
13 /*
14 * argpar is a library which provides facilities for command-line
15 * argument parsing.
16 *
17 * Two APIs are available:
18 *
19 * Iterator API:
20 * Create a parsing iterator with argpar_iter_create(), then
21 * repeatedly call argpar_iter_next() to access the parsing results,
22 * until one of:
23 *
24 * * There are no more arguments.
25 *
26 * * The argument parser encounters an error (for example, an
27 * unknown option).
28 *
29 * * You need to stop.
30 *
31 * This API provides more parsing control than the next one.
32 *
33 * Single call API:
34 * Call argpar_parse(), which parses the arguments until one of:
35 *
36 * * There are no more arguments.
37 *
38 * * It encounters an argument parsing error.
39 *
40 * argpar_parse() returns a single array of parsing results.
41 *
42 * Both methods parse the arguments `argv` of which the count is `argc`
43 * using the sentinel-terminated (use `ARGPAR_OPT_DESCR_SENTINEL`)
44 * option descriptor array `descrs`.
45 *
46 * argpar considers ALL the elements of `argv`, including the first one,
47 * so that you would typically pass `argc - 1` and `&argv[1]` from what
48 * main() receives.
49 *
50 * The argpar parsers support:
51 *
52 * * Short options without an argument, possibly tied together:
53 *
54 * -f -auf -n
55 *
56 * * Short options with argument:
57 *
58 * -b 45 -f/mein/file -xyzhello
59 *
60 * * Long options without an argument:
61 *
62 * --five-guys --burger-king --pizza-hut --subway
63 *
64 * * Long options with arguments:
65 *
66 * --security enable --time=18.56
67 *
68 * * Non-option arguments (anything else).
69 *
70 * The argpar parsers parse `-` and `--` as non-option arguments. A
71 * non-option argument cannot have the form of an option, for example if
72 * you need to pass the exact relative path `--component`. In that case,
73 * you would need to pass `./--component`. There's no generic way to
74 * escape `-` as of this version.
75 *
76 * Both argpar_iter_create() and argpar_parse() accept duplicate options
77 * (they produce one item for each instance).
78 *
79 * A returned parsing item has the type `const struct argpar_item *`.
80 * Get the type (option or non-option) of an item with
81 * argpar_item_type(). Each item type has its set of dedicated methods
82 * (`argpar_item_opt_` and `argpar_item_non_opt_` prefixes).
83 *
84 * Both argpar_iter_create() and argpar_parse() produce the items in
85 * the same order that the arguments were parsed, including non-option
86 * arguments. This means, for example, that for:
87 *
88 * --hello --count=23 /path/to/file -ab --type file magie
89 *
90 * The produced items are, in this order:
91 *
92 * 1. Option item (`--hello`).
93 * 2. Option item (`--count` with argument `23`).
94 * 3. Non-option item (`/path/to/file`).
95 * 4. Option item (`-a`).
96 * 5. Option item (`-b`).
97 * 6. Option item (`--type` with argument `file`).
98 * 7. Non-option item (`magie`).
99 */
100
101 /* Sentinel for an option descriptor array */
102 #define ARGPAR_OPT_DESCR_SENTINEL { -1, '\0', NULL, false }
103
104 /*
105 * If argpar is used in some shared library, we don't want said library
106 * to export its symbols, so mark them as "hidden".
107 *
108 * On Windows, symbols are local unless explicitly exported; see
109 * <https://gcc.gnu.org/wiki/Visibility>.
110 */
111 #if defined(_WIN32) || defined(__CYGWIN__)
112 # define ARGPAR_HIDDEN
113 #else
114 # define ARGPAR_HIDDEN __attribute__((visibility("hidden")))
115 #endif
116
117 /* Forward-declaration for the opaque type */
118 struct argpar_iter;
119
120 /* Option descriptor */
121 struct argpar_opt_descr {
122 /* Numeric ID for this option */
123 const int id;
124
125 /* Short option character, or `\0` */
126 const char short_name;
127
128 /* Long option name (without the `--` prefix), or `NULL` */
129 const char * const long_name;
130
131 /* True if this option has an argument */
132 const bool with_arg;
133 };
134
135 /* Item type */
136 enum argpar_item_type {
137 /* Option */
138 ARGPAR_ITEM_TYPE_OPT,
139
140 /* Non-option */
141 ARGPAR_ITEM_TYPE_NON_OPT,
142 };
143
144 /* Parsing item, as created by argpar_parse() and argpar_iter_next() */
145 struct argpar_item;
146
147 /*
148 * Returns the type of the parsing item `item`.
149 */
150 ARGPAR_HIDDEN
151 enum argpar_item_type argpar_item_type(const struct argpar_item *item);
152
153 /*
154 * Returns the option descriptor of the option parsing item `item`.
155 */
156 ARGPAR_HIDDEN
157 const struct argpar_opt_descr *argpar_item_opt_descr(
158 const struct argpar_item *item);
159
160 /*
161 * Returns the argument of the option parsing item `item`, or `NULL` if
162 * none.
163 */
164 ARGPAR_HIDDEN
165 const char *argpar_item_opt_arg(const struct argpar_item *item);
166
167 /*
168 * Returns the complete argument, pointing to one of the entries of the
169 * original arguments (`argv`), of the non-option parsing item `item`.
170 */
171 ARGPAR_HIDDEN
172 const char *argpar_item_non_opt_arg(const struct argpar_item *item);
173
174 /*
175 * Returns the original index, within ALL the original arguments
176 * (`argv`), of the non-option parsing item `item`.
177 */
178 ARGPAR_HIDDEN
179 unsigned int argpar_item_non_opt_orig_index(const struct argpar_item *item);
180
181 /*
182 * Returns the index, within the non-option arguments, of the non-option
183 * parsing item `item`.
184 */
185 ARGPAR_HIDDEN
186 unsigned int argpar_item_non_opt_non_opt_index(const struct argpar_item *item);
187
188 /*
189 * Destroys `item`, as created by argpar_iter_next().
190 */
191 ARGPAR_HIDDEN
192 void argpar_item_destroy(const struct argpar_item *item);
193
194 struct argpar_item_array {
195 const struct argpar_item **items;
196
197 /* Number of used slots in `items` */
198 unsigned int n_items;
199
200 /* Number of allocated slots in `items` */
201 unsigned int n_alloc;
202 };
203
204 /* What is returned by argpar_parse() */
205 struct argpar_parse_ret {
206 /*
207 * Array of parsing items, or `NULL` on error.
208 *
209 * Do NOT destroy those items manually with
210 * argpar_iter_destroy(): call argpar_parse_ret_fini() to
211 * finalize the whole structure.
212 */
213 struct argpar_item_array *items;
214
215 /* Error string, or `NULL` if none */
216 char *error;
217
218 /* Number of original arguments (`argv`) ingested */
219 unsigned int ingested_orig_args;
220 };
221
222 /*
223 * Parses arguments in `argv` until the end is reached or an error is
224 * encountered.
225 *
226 * On success, this function returns an array of items (field `items` of
227 * `struct argpar_parse_ret`).
228 *
229 * In the returned structure, `ingested_orig_args` is the number of
230 * ingested arguments within `argv` to produce the resulting array of
231 * items.
232 *
233 * If `fail_on_unknown_opt` is true, then on success
234 * `ingested_orig_args` is equal to `argc`. Otherwise,
235 * `ingested_orig_args` contains the number of original arguments until
236 * an unknown _option_ occurs. For example, with
237 *
238 * --great --white contact nuance --shark nuclear
239 *
240 * if `--shark` is not described within `descrs` and
241 * `fail_on_unknown_opt` is false, then `ingested_orig_args` is 4 (two
242 * options, two non-options), whereas `argc` is 6.
243 *
244 * This makes it possible to know where a command name is, for example.
245 * With those arguments:
246 *
247 * --verbose --stuff=23 do-something --specific-opt -f -b
248 *
249 * and the descriptors for `--verbose` and `--stuff` only, the function
250 * returns the `--verbose` and `--stuff` option items, the
251 * `do-something` non-option item, and that three original arguments
252 * were ingested. This means you can start the next argument parsing
253 * stage, with option descriptors depending on the command name, at
254 * `&argv[3]`.
255 *
256 * Note that `ingested_orig_args` is not always equal to the number of
257 * returned items, as
258 *
259 * --hello -fdw
260 *
261 * for example contains two ingested original arguments, but four
262 * resulting items.
263 *
264 * On failure, the `items` member of the returned structure is `NULL`,
265 * and the `error` string member contains details about the error.
266 *
267 * Finalize the returned structure with argpar_parse_ret_fini().
268 */
269 ARGPAR_HIDDEN
270 struct argpar_parse_ret argpar_parse(unsigned int argc,
271 const char * const *argv,
272 const struct argpar_opt_descr *descrs,
273 bool fail_on_unknown_opt);
274
275 /*
276 * Finalizes what argpar_parse() returns.
277 *
278 * You may call argpar_parse() multiple times with the same structure.
279 */
280 ARGPAR_HIDDEN
281 void argpar_parse_ret_fini(struct argpar_parse_ret *ret);
282
283 /*
284 * Creates an argument parsing iterator.
285 *
286 * This function initializes the returned structure, but doesn't
287 * actually start parsing the arguments.
288 *
289 * `*argv` and `*descrs` must NOT change for the lifetime of the
290 * returned iterator (until you call argpar_iter_destroy()) and for the
291 * lifetime of any parsing item (until you call argpar_item_destroy())
292 * argpar_iter_next() creates for the returned iterator.
293 *
294 * Call argpar_iter_next() with the returned iterator to obtain the next
295 * parsing result (item).
296 */
297 ARGPAR_HIDDEN
298 struct argpar_iter *argpar_iter_create(unsigned int argc,
299 const char * const *argv,
300 const struct argpar_opt_descr *descrs);
301
302 /*
303 * Destroys `iter`, as returned by argpar_iter_create().
304 */
305 ARGPAR_HIDDEN
306 void argpar_iter_destroy(struct argpar_iter *iter);
307
308 /*
309 * Return type of argpar_iter_next().
310 */
311 enum argpar_iter_next_status {
312 ARGPAR_ITER_NEXT_STATUS_OK,
313 ARGPAR_ITER_NEXT_STATUS_END,
314 ARGPAR_ITER_NEXT_STATUS_ERROR_UNKNOWN_OPT,
315 ARGPAR_ITER_NEXT_STATUS_ERROR_MISSING_OPT_ARG,
316 ARGPAR_ITER_NEXT_STATUS_ERROR_INVALID_ARG,
317 ARGPAR_ITER_NEXT_STATUS_ERROR_UNEXPECTED_OPT_ARG,
318 ARGPAR_ITER_NEXT_STATUS_ERROR_MEMORY,
319 };
320
321 /*
322 * Parses and returns the next item from `iter`.
323 *
324 * On success, this function:
325 *
326 * * Sets `*item` to a parsing item which describes the next option
327 * or non-option argument.
328 *
329 * Destroy `*item` with argpar_item_destroy().
330 *
331 * * Returns `ARGPAR_ITER_NEXT_STATUS_OK`.
332 *
333 * If there are no more items to return, this function returns
334 * `ARGPAR_ITER_NEXT_STATUS_END`.
335 *
336 * On failure, this function:
337 *
338 * * Returns one of:
339 *
340 * `ARGPAR_ITER_NEXT_STATUS_ERROR_UNKNOWN_OPT`:
341 * Unknown option (not found in `descrs` as passed to
342 * argpar_iter_create() to create `iter`).
343 *
344 * `ARGPAR_ITER_NEXT_STATUS_ERROR_MISSING_OPT_ARG`:
345 * Missing option argument.
346 *
347 * `ARGPAR_ITER_NEXT_STATUS_ERROR_INVALID_ARG`:
348 * Invalid argument.
349 *
350 * `ARGPAR_ITER_NEXT_STATUS_ERROR_UNEXPECTED_OPT_ARG`:
351 * Unexpected option argument.
352 *
353 * `ARGPAR_ITER_NEXT_STATUS_ERROR_MEMORY`:
354 * Memory error.
355 *
356 * * Except for the `ARGPAR_ITER_NEXT_STATUS_ERROR_MEMORY` status,
357 * sets `*error`, if not `NULL`, to a descriptive error string.
358 * Free `*error` with free().
359 */
360 enum argpar_iter_next_status argpar_iter_next(
361 struct argpar_iter *iter, const struct argpar_item **item,
362 char **error);
363
364 /*
365 * Returns the number of ingested elements from `argv`, as passed to
366 * argpar_iter_create() to create `*iter`, that were required to produce
367 * the previously returned items.
368 */
369 ARGPAR_HIDDEN
370 unsigned int argpar_iter_ingested_orig_args(const struct argpar_iter *iter);
371
372 /*
373 * Destroys `_item` (`const struct argpar_item *`) and sets it to
374 * `NULL`.
375 */
376 #define ARGPAR_ITEM_DESTROY_AND_RESET(_item) \
377 { \
378 argpar_item_destroy(_item); \
379 _item = NULL; \
380 }
381
382 #endif /* ARGPAR_ARGPAR_H */
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