argpar.h: argpar_iter_create(): add iterator lifetime details
[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 don't accept `-` or `--` as arguments. The latter
71 * means "end of options" for many command-line tools, but this library
72 * is all about keeping the order of the arguments, so it doesn't mean
73 * much to put them at the end. This has the side effect that a
74 * non-option argument cannot have the form of an option, for example if
75 * you need to pass the exact relative path `--component`. In that case,
76 * you would need to pass `./--component`. There's no generic way to
77 * escape `-` as of this version.
78 *
79 * Both argpar_iter_create() and argpar_parse() accept duplicate options
80 * (they produce one item for each instance).
81 *
82 * A returned parsing item has the type `const struct argpar_item *`.
83 * Get the type (option or non-option) of an item with
84 * argpar_item_type(). Each item type has its set of dedicated methods
85 * (`argpar_item_opt_` and `argpar_item_non_opt_` prefixes).
86 *
87 * Both argpar_iter_create() and argpar_parse() produce the items in
88 * the same order that the arguments were parsed, including non-option
89 * arguments. This means, for example, that for:
90 *
91 * --hello --count=23 /path/to/file -ab --type file magie
92 *
93 * The produced items are, in this order:
94 *
95 * 1. Option item (`--hello`).
96 * 2. Option item (`--count` with argument `23`).
97 * 3. Non-option item (`/path/to/file`).
98 * 4. Option item (`-a`).
99 * 5. Option item (`-b`).
100 * 6. Option item (`--type` with argument `file`).
101 * 7. Non-option item (`magie`).
102 */
103
104 /* Sentinel for an option descriptor array */
105 #define ARGPAR_OPT_DESCR_SENTINEL { -1, '\0', NULL, false }
106
107 /*
108 * If argpar is used in some shared library, we don't want said library
109 * to export its symbols, so mark them as "hidden".
110 *
111 * On Windows, symbols are local unless explicitly exported; see
112 * <https://gcc.gnu.org/wiki/Visibility>.
113 */
114 #if defined(_WIN32) || defined(__CYGWIN__)
115 # define ARGPAR_HIDDEN
116 #else
117 # define ARGPAR_HIDDEN __attribute__((visibility("hidden")))
118 #endif
119
120 /* Forward-declaration for the opaque type */
121 struct argpar_iter;
122
123 /* Option descriptor */
124 struct argpar_opt_descr {
125 /* Numeric ID for this option */
126 const int id;
127
128 /* Short option character, or `\0` */
129 const char short_name;
130
131 /* Long option name (without `--`), or `NULL` */
132 const char * const long_name;
133
134 /* True if this option has an argument */
135 const bool with_arg;
136 };
137
138 /* Item type */
139 enum argpar_item_type {
140 /* Option */
141 ARGPAR_ITEM_TYPE_OPT,
142
143 /* Non-option */
144 ARGPAR_ITEM_TYPE_NON_OPT,
145 };
146
147 /* Parsing item, as created by argpar_parse() and argpar_iter_next() */
148 struct argpar_item;
149
150 /*
151 * Returns the type of the parsing item `item`.
152 */
153 ARGPAR_HIDDEN
154 enum argpar_item_type argpar_item_type(const struct argpar_item *item);
155
156 /*
157 * Returns the option descriptor of the option parsing item `item`.
158 */
159 ARGPAR_HIDDEN
160 const struct argpar_opt_descr *argpar_item_opt_descr(
161 const struct argpar_item *item);
162
163 /*
164 * Returns the argument of the option parsing item `item`, or `NULL` if
165 * none.
166 */
167 ARGPAR_HIDDEN
168 const char *argpar_item_opt_arg(const struct argpar_item *item);
169
170 /*
171 * Returns the complete argument, pointing to one of the entries of the
172 * original arguments (`argv`), of the non-option parsing item `item`.
173 */
174 ARGPAR_HIDDEN
175 const char *argpar_item_non_opt_arg(const struct argpar_item *item);
176
177 /*
178 * Returns the original index, within ALL the original arguments
179 * (`argv`), of the non-option parsing item `item`.
180 */
181 ARGPAR_HIDDEN
182 unsigned int argpar_item_non_opt_orig_index(const struct argpar_item *item);
183
184 /*
185 * Returns the index, within the non-option arguments, of the non-option
186 * parsing item `item`.
187 */
188 ARGPAR_HIDDEN
189 unsigned int argpar_item_non_opt_non_opt_index(const struct argpar_item *item);
190
191 /*
192 * Destroys `item`, as created by argpar_iter_next().
193 */
194 ARGPAR_HIDDEN
195 void argpar_item_destroy(const struct argpar_item *item);
196
197 struct argpar_item_array {
198 const struct argpar_item **items;
199
200 /* Number of used slots in `items` */
201 unsigned int n_items;
202
203 /* Number of allocated slots in `items` */
204 unsigned int n_alloc;
205 };
206
207 /* What is returned by argpar_parse() */
208 struct argpar_parse_ret {
209 /*
210 * Array of parsing items, or `NULL` on error.
211 *
212 * Do NOT destroy those items manually with
213 * argpar_iter_destroy(): call argpar_parse_ret_fini() to
214 * finalize the whole structure.
215 */
216 struct argpar_item_array *items;
217
218 /* Error string, or `NULL` if none */
219 char *error;
220
221 /* Number of original arguments (`argv`) ingested */
222 unsigned int ingested_orig_args;
223 };
224
225 /*
226 * Parses arguments in `argv` until the end is reached or an error is
227 * encountered.
228 *
229 * On success, this function returns an array of items (field `items` of
230 * `struct argpar_parse_ret`).
231 *
232 * In the returned structure, `ingested_orig_args` is the number of
233 * ingested arguments within `argv` to produce the resulting array of
234 * items.
235 *
236 * If `fail_on_unknown_opt` is true, then on success
237 * `ingested_orig_args` is equal to `argc`. Otherwise,
238 * `ingested_orig_args` contains the number of original arguments until
239 * an unknown _option_ occurs. For example, with
240 *
241 * --great --white contact nuance --shark nuclear
242 *
243 * if `--shark` is not described within `descrs` and
244 * `fail_on_unknown_opt` is false, then `ingested_orig_args` is 4 (two
245 * options, two non-options), whereas `argc` is 6.
246 *
247 * This makes it possible to know where a command name is, for example.
248 * With those arguments:
249 *
250 * --verbose --stuff=23 do-something --specific-opt -f -b
251 *
252 * and the descriptors for `--verbose` and `--stuff` only, the function
253 * returns the `--verbose` and `--stuff` option items, the
254 * `do-something` non-option item, and that three original arguments
255 * were ingested. This means you can start the next argument parsing
256 * stage, with option descriptors depending on the command name, at
257 * `&argv[3]`.
258 *
259 * Note that `ingested_orig_args` is not always equal to the number of
260 * returned items, as
261 *
262 * --hello -fdw
263 *
264 * for example contains two ingested original arguments, but four
265 * resulting items.
266 *
267 * On failure, the `items` member of the returned structure is `NULL`,
268 * and the `error` string member contains details about the error.
269 *
270 * Finalize the returned structure with argpar_parse_ret_fini().
271 */
272 ARGPAR_HIDDEN
273 struct argpar_parse_ret argpar_parse(unsigned int argc,
274 const char * const *argv,
275 const struct argpar_opt_descr *descrs,
276 bool fail_on_unknown_opt);
277
278 /*
279 * Finalizes what argpar_parse() returns.
280 *
281 * You may call argpar_parse() multiple times with the same structure.
282 */
283 ARGPAR_HIDDEN
284 void argpar_parse_ret_fini(struct argpar_parse_ret *ret);
285
286 /*
287 * Creates an argument parsing iterator.
288 *
289 * This function initializes the returned structure, but doesn't
290 * actually start parsing the arguments.
291 *
292 * `*argv` and `*descrs` must NOT change for the lifetime of the
293 * returned iterator (until you call argpar_iter_destroy()) and for the
294 * lifetime of any parsing item (until you call argpar_item_destroy())
295 * argpar_iter_next() creates for the returned iterator.
296 *
297 * Call argpar_iter_next() with the returned iterator to obtain the next
298 * parsing result (item).
299 */
300 ARGPAR_HIDDEN
301 struct argpar_iter *argpar_iter_create(unsigned int argc,
302 const char * const *argv,
303 const struct argpar_opt_descr *descrs);
304
305 /*
306 * Destroys `iter`, as returned by argpar_iter_create().
307 */
308 ARGPAR_HIDDEN
309 void argpar_iter_destroy(struct argpar_iter *iter);
310
311 /*
312 * Return type of argpar_iter_next().
313 */
314 enum argpar_iter_next_status {
315 ARGPAR_ITER_NEXT_STATUS_OK,
316 ARGPAR_ITER_NEXT_STATUS_END,
317 ARGPAR_ITER_NEXT_STATUS_ERROR_UNKNOWN_OPT,
318 ARGPAR_ITER_NEXT_STATUS_ERROR_MISSING_OPT_ARG,
319 ARGPAR_ITER_NEXT_STATUS_ERROR_INVALID_ARG,
320 ARGPAR_ITER_NEXT_STATUS_ERROR_UNEXPECTED_OPT_ARG,
321 ARGPAR_ITER_NEXT_STATUS_ERROR_MEMORY,
322 };
323
324 /*
325 * Parses and returns the next item from `iter`.
326 *
327 * On success, this function:
328 *
329 * * Sets `*item` to a parsing item which describes the next option
330 * or non-option argument.
331 *
332 * Destroy `*item` with argpar_item_destroy().
333 *
334 * * Returns `ARGPAR_ITER_NEXT_STATUS_OK`.
335 *
336 * If there are no more items to return, this function returns
337 * `ARGPAR_ITER_NEXT_STATUS_END`.
338 *
339 * On failure, this function:
340 *
341 * * Returns one of:
342 *
343 * `ARGPAR_ITER_NEXT_STATUS_ERROR_UNKNOWN_OPT`:
344 * Unknown option (not found in `descrs` as passed to
345 * argpar_iter_create() to create `iter`).
346 *
347 * `ARGPAR_ITER_NEXT_STATUS_ERROR_MISSING_OPT_ARG`:
348 * Missing option argument.
349 *
350 * `ARGPAR_ITER_NEXT_STATUS_ERROR_INVALID_ARG`:
351 * Invalid argument.
352 *
353 * `ARGPAR_ITER_NEXT_STATUS_ERROR_UNEXPECTED_OPT_ARG`:
354 * Unexpected option argument.
355 *
356 * `ARGPAR_ITER_NEXT_STATUS_ERROR_MEMORY`:
357 * Memory error.
358 *
359 * * Except for the `ARGPAR_ITER_NEXT_STATUS_ERROR_MEMORY` status,
360 * sets `*error`, if not `NULL`, to a descriptive error string.
361 * Free `*error` with free().
362 */
363 enum argpar_iter_next_status argpar_iter_next(
364 struct argpar_iter *iter, const struct argpar_item **item,
365 char **error);
366
367 /*
368 * Returns the number of ingested elements from `argv`, as passed to
369 * argpar_iter_create() to create `*iter`, that were required to produce
370 * the previously returned items.
371 */
372 ARGPAR_HIDDEN
373 unsigned int argpar_iter_ingested_orig_args(const struct argpar_iter *iter);
374
375 /*
376 * Destroys `_item` (`const struct argpar_item *`) and sets it to
377 * `NULL`.
378 */
379 #define ARGPAR_ITEM_DESTROY_AND_RESET(_item) \
380 { \
381 argpar_item_destroy(_item); \
382 _item = NULL; \
383 }
384
385 #endif /* ARGPAR_ARGPAR_H */
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