cristy | 3ed852e | 2009-09-05 21:47:34 +0000 | [diff] [blame] | 1 | /* slist.c -- generalised singly linked lists |
| 2 | |
cristy | 98dddb5 | 2010-11-04 00:30:15 +0000 | [diff] [blame] | 3 | Copyright (C) 2000, 2004, 2007, 2008, 2009 Free Software Foundation, Inc. |
cristy | 3ed852e | 2009-09-05 21:47:34 +0000 | [diff] [blame] | 4 | Written by Gary V. Vaughan, 2000 |
| 5 | |
| 6 | NOTE: The canonical source of this file is maintained with the |
| 7 | GNU Libtool package. Report bugs to bug-libtool@gnu.org. |
| 8 | |
| 9 | GNU Libltdl is free software; you can redistribute it and/or |
| 10 | modify it under the terms of the GNU Lesser General Public |
| 11 | License as published by the Free Software Foundation; either |
| 12 | version 2 of the License, or (at your option) any later version. |
| 13 | |
| 14 | As a special exception to the GNU Lesser General Public License, |
| 15 | if you distribute this file as part of a program or library that |
| 16 | is built using GNU Libtool, you may include this file under the |
| 17 | same distribution terms that you use for the rest of that program. |
| 18 | |
| 19 | GNU Libltdl is distributed in the hope that it will be useful, |
| 20 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 21 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 22 | GNU Lesser General Public License for more details. |
| 23 | |
| 24 | You should have received a copy of the GNU Lesser General Public |
cristy | cee9711 | 2010-05-28 00:44:52 +0000 | [diff] [blame] | 25 | License along with GNU Libltdl; see the file COPYING.LIB. If not, a |
cristy | 3ed852e | 2009-09-05 21:47:34 +0000 | [diff] [blame] | 26 | copy can be downloaded from http://www.gnu.org/licenses/lgpl.html, |
| 27 | or obtained by writing to the Free Software Foundation, Inc., |
| 28 | 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
| 29 | */ |
| 30 | |
| 31 | #include <assert.h> |
| 32 | |
| 33 | #include "slist.h" |
| 34 | #include <stddef.h> |
cristy | 98dddb5 | 2010-11-04 00:30:15 +0000 | [diff] [blame] | 35 | #include <stdlib.h> |
cristy | 3ed852e | 2009-09-05 21:47:34 +0000 | [diff] [blame] | 36 | |
| 37 | static SList * slist_sort_merge (SList *left, SList *right, |
| 38 | SListCompare *compare, void *userdata); |
| 39 | |
| 40 | |
| 41 | /* Call DELETE repeatedly on each element of HEAD. |
| 42 | |
| 43 | CAVEAT: If you call this when HEAD is the start of a list of boxed |
| 44 | items, you must remember that each item passed back to your |
| 45 | DELETE function will be a boxed item that must be slist_unbox()ed |
| 46 | before operating on its contents. |
| 47 | |
| 48 | e.g. void boxed_delete (void *item) { item_free (slist_unbox (item)); } |
| 49 | ... |
| 50 | slist = slist_delete (slist, boxed_delete); |
| 51 | ... |
| 52 | */ |
| 53 | SList * |
| 54 | slist_delete (SList *head, void (*delete_fct) (void *item)) |
| 55 | { |
| 56 | assert (delete_fct); |
| 57 | |
| 58 | while (head) |
| 59 | { |
| 60 | SList *next = head->next; |
| 61 | (*delete_fct) (head); |
| 62 | head = next; |
| 63 | } |
| 64 | |
| 65 | return 0; |
| 66 | } |
| 67 | |
| 68 | /* Call FIND repeatedly with MATCHDATA and each item of *PHEAD, until |
| 69 | FIND returns non-NULL, or the list is exhausted. If a match is found |
| 70 | the matching item is destructively removed from *PHEAD, and the value |
| 71 | returned by the matching call to FIND is returned. |
| 72 | |
| 73 | CAVEAT: To avoid memory leaks, unless you already have the address of |
| 74 | the stale item, you should probably return that from FIND if |
| 75 | it makes a successful match. Don't forget to slist_unbox() |
| 76 | every item in a boxed list before operating on its contents. */ |
cristy | 98dddb5 | 2010-11-04 00:30:15 +0000 | [diff] [blame] | 77 | SList * |
cristy | 3ed852e | 2009-09-05 21:47:34 +0000 | [diff] [blame] | 78 | slist_remove (SList **phead, SListCallback *find, void *matchdata) |
| 79 | { |
| 80 | SList *stale = 0; |
| 81 | void *result = 0; |
| 82 | |
| 83 | assert (find); |
| 84 | |
| 85 | if (!phead || !*phead) |
| 86 | return 0; |
| 87 | |
| 88 | /* Does the head of the passed list match? */ |
| 89 | result = (*find) (*phead, matchdata); |
| 90 | if (result) |
| 91 | { |
| 92 | stale = *phead; |
| 93 | *phead = stale->next; |
| 94 | } |
| 95 | /* what about the rest of the elements? */ |
| 96 | else |
| 97 | { |
| 98 | SList *head; |
| 99 | for (head = *phead; head->next; head = head->next) |
| 100 | { |
| 101 | result = (*find) (head->next, matchdata); |
| 102 | if (result) |
| 103 | { |
| 104 | stale = head->next; |
| 105 | head->next = stale->next; |
| 106 | break; |
| 107 | } |
| 108 | } |
| 109 | } |
| 110 | |
cristy | 98dddb5 | 2010-11-04 00:30:15 +0000 | [diff] [blame] | 111 | return (SList *) result; |
cristy | 3ed852e | 2009-09-05 21:47:34 +0000 | [diff] [blame] | 112 | } |
| 113 | |
| 114 | /* Call FIND repeatedly with each element of SLIST and MATCHDATA, until |
| 115 | FIND returns non-NULL, or the list is exhausted. If a match is found |
| 116 | the value returned by the matching call to FIND is returned. */ |
| 117 | void * |
| 118 | slist_find (SList *slist, SListCallback *find, void *matchdata) |
| 119 | { |
| 120 | void *result = 0; |
| 121 | |
| 122 | assert (find); |
| 123 | |
| 124 | for (; slist; slist = slist->next) |
| 125 | { |
| 126 | result = (*find) (slist, matchdata); |
| 127 | if (result) |
| 128 | break; |
| 129 | } |
| 130 | |
| 131 | return result; |
| 132 | } |
| 133 | |
| 134 | /* Return a single list, composed by destructively concatenating the |
| 135 | items in HEAD and TAIL. The values of HEAD and TAIL are undefined |
| 136 | after calling this function. |
| 137 | |
| 138 | CAVEAT: Don't mix boxed and unboxed items in a single list. |
| 139 | |
| 140 | e.g. slist1 = slist_concat (slist1, slist2); */ |
| 141 | SList * |
| 142 | slist_concat (SList *head, SList *tail) |
| 143 | { |
| 144 | SList *last; |
| 145 | |
| 146 | if (!head) |
| 147 | { |
| 148 | return tail; |
| 149 | } |
| 150 | |
| 151 | last = head; |
| 152 | while (last->next) |
| 153 | last = last->next; |
| 154 | |
| 155 | last->next = tail; |
| 156 | |
| 157 | return head; |
| 158 | } |
| 159 | |
| 160 | /* Return a single list, composed by destructively appending all of |
| 161 | the items in SLIST to ITEM. The values of ITEM and SLIST are undefined |
| 162 | after calling this function. |
| 163 | |
| 164 | CAVEAT: Don't mix boxed and unboxed items in a single list. |
| 165 | |
| 166 | e.g. slist1 = slist_cons (slist_box (data), slist1); */ |
| 167 | SList * |
| 168 | slist_cons (SList *item, SList *slist) |
| 169 | { |
| 170 | if (!item) |
| 171 | { |
| 172 | return slist; |
| 173 | } |
| 174 | |
| 175 | assert (!item->next); |
| 176 | |
| 177 | item->next = slist; |
| 178 | return item; |
| 179 | } |
| 180 | |
| 181 | /* Return a list starting at the second item of SLIST. */ |
| 182 | SList * |
| 183 | slist_tail (SList *slist) |
| 184 | { |
| 185 | return slist ? slist->next : NULL; |
| 186 | } |
| 187 | |
| 188 | /* Return a list starting at the Nth item of SLIST. If SLIST is less |
cristy | 85278ed | 2010-05-31 15:10:05 +0000 | [diff] [blame] | 189 | than N items long, NULL is returned. Just to be confusing, list items |
cristy | 3ed852e | 2009-09-05 21:47:34 +0000 | [diff] [blame] | 190 | are counted from 1, to get the 2nd element of slist: |
| 191 | |
| 192 | e.g. shared_list = slist_nth (slist, 2); */ |
| 193 | SList * |
| 194 | slist_nth (SList *slist, size_t n) |
| 195 | { |
| 196 | for (;n > 1 && slist; n--) |
| 197 | slist = slist->next; |
| 198 | |
| 199 | return slist; |
| 200 | } |
| 201 | |
| 202 | /* Return the number of items in SLIST. We start counting from 1, so |
| 203 | the length of a list with no items is 0, and so on. */ |
| 204 | size_t |
| 205 | slist_length (SList *slist) |
| 206 | { |
| 207 | size_t n; |
| 208 | |
| 209 | for (n = 0; slist; ++n) |
| 210 | slist = slist->next; |
| 211 | |
| 212 | return n; |
| 213 | } |
| 214 | |
| 215 | /* Destructively reverse the order of items in SLIST. The value of SLIST |
| 216 | is undefined after calling this function. |
| 217 | |
| 218 | CAVEAT: You must store the result of this function, or you might not |
| 219 | be able to get all the items except the first one back again. |
| 220 | |
| 221 | e.g. slist = slist_reverse (slist); */ |
| 222 | SList * |
| 223 | slist_reverse (SList *slist) |
| 224 | { |
| 225 | SList *result = 0; |
| 226 | SList *next; |
| 227 | |
| 228 | while (slist) |
| 229 | { |
| 230 | next = slist->next; |
| 231 | slist->next = result; |
| 232 | result = slist; |
| 233 | slist = next; |
| 234 | } |
| 235 | |
| 236 | return result; |
| 237 | } |
| 238 | |
| 239 | /* Call FOREACH once for each item in SLIST, passing both the item and |
| 240 | USERDATA on each call. */ |
| 241 | void * |
| 242 | slist_foreach (SList *slist, SListCallback *foreach, void *userdata) |
| 243 | { |
| 244 | void *result = 0; |
| 245 | |
| 246 | assert (foreach); |
| 247 | |
| 248 | while (slist) |
| 249 | { |
| 250 | SList *next = slist->next; |
| 251 | result = (*foreach) (slist, userdata); |
| 252 | |
| 253 | if (result) |
| 254 | break; |
| 255 | |
| 256 | slist = next; |
| 257 | } |
| 258 | |
| 259 | return result; |
| 260 | } |
| 261 | |
| 262 | /* Destructively merge the items of two ordered lists LEFT and RIGHT, |
| 263 | returning a single sorted list containing the items of both -- Part of |
| 264 | the quicksort algorithm. The values of LEFT and RIGHT are undefined |
| 265 | after calling this function. |
| 266 | |
| 267 | At each iteration, add another item to the merged list by taking the |
| 268 | lowest valued item from the head of either LEFT or RIGHT, determined |
| 269 | by passing those items and USERDATA to COMPARE. COMPARE should return |
| 270 | less than 0 if the head of LEFT has the lower value, greater than 0 if |
| 271 | the head of RIGHT has the lower value, otherwise 0. */ |
| 272 | static SList * |
| 273 | slist_sort_merge (SList *left, SList *right, SListCompare *compare, |
| 274 | void *userdata) |
| 275 | { |
| 276 | SList merged, *insert; |
| 277 | |
| 278 | insert = &merged; |
| 279 | |
| 280 | while (left && right) |
| 281 | { |
| 282 | if ((*compare) (left, right, userdata) <= 0) |
| 283 | { |
| 284 | insert = insert->next = left; |
| 285 | left = left->next; |
| 286 | } |
| 287 | else |
| 288 | { |
| 289 | insert = insert->next = right; |
| 290 | right = right->next; |
| 291 | } |
| 292 | } |
| 293 | |
| 294 | insert->next = left ? left : right; |
| 295 | |
| 296 | return merged.next; |
| 297 | } |
| 298 | |
| 299 | /* Perform a destructive quicksort on the items in SLIST, by repeatedly |
cristy | cee9711 | 2010-05-28 00:44:52 +0000 | [diff] [blame] | 300 | calling COMPARE with a pair of items from SLIST along with USERDATA |
cristy | 3ed852e | 2009-09-05 21:47:34 +0000 | [diff] [blame] | 301 | at every iteration. COMPARE is a function as defined above for |
| 302 | slist_sort_merge(). The value of SLIST is undefined after calling |
| 303 | this function. |
| 304 | |
| 305 | e.g. slist = slist_sort (slist, compare, 0); */ |
| 306 | SList * |
| 307 | slist_sort (SList *slist, SListCompare *compare, void *userdata) |
| 308 | { |
| 309 | SList *left, *right; |
| 310 | |
| 311 | if (!slist) |
| 312 | return slist; |
| 313 | |
| 314 | /* Be sure that LEFT and RIGHT never contain the same item. */ |
| 315 | left = slist; |
| 316 | right = slist->next; |
| 317 | |
cristy | 98dddb5 | 2010-11-04 00:30:15 +0000 | [diff] [blame] | 318 | if (!right) |
| 319 | return left; |
| 320 | |
cristy | 3ed852e | 2009-09-05 21:47:34 +0000 | [diff] [blame] | 321 | /* Skip two items with RIGHT and one with SLIST, until RIGHT falls off |
cristy | cee9711 | 2010-05-28 00:44:52 +0000 | [diff] [blame] | 322 | the end. SLIST must be about half way along. */ |
cristy | 3ed852e | 2009-09-05 21:47:34 +0000 | [diff] [blame] | 323 | while (right && (right = right->next)) |
| 324 | { |
| 325 | if (!right || !(right = right->next)) |
| 326 | break; |
| 327 | slist = slist->next; |
| 328 | } |
| 329 | right = slist->next; |
| 330 | slist->next = 0; |
| 331 | |
| 332 | /* Sort LEFT and RIGHT, then merge the two. */ |
| 333 | return slist_sort_merge (slist_sort (left, compare, userdata), |
| 334 | slist_sort (right, compare, userdata), |
| 335 | compare, userdata); |
| 336 | } |
| 337 | |
| 338 | |
| 339 | /* Aside from using the functions above to manage chained structures of |
| 340 | any type that has a NEXT pointer as its first field, SLISTs can |
| 341 | be comprised of boxed items. The boxes are chained together in |
| 342 | that case, so there is no need for a NEXT field in the item proper. |
| 343 | Some care must be taken to slist_box and slist_unbox each item in |
| 344 | a boxed list at the appropriate points to avoid leaking the memory |
| 345 | used for the boxes. It us usually a very bad idea to mix boxed and |
| 346 | non-boxed items in a single list. */ |
| 347 | |
| 348 | /* Return a `boxed' freshly mallocated 1 element list containing |
| 349 | USERDATA. */ |
| 350 | SList * |
| 351 | slist_box (const void *userdata) |
| 352 | { |
| 353 | SList *item = (SList *) malloc (sizeof *item); |
| 354 | |
| 355 | if (item) |
| 356 | { |
| 357 | item->next = 0; |
| 358 | item->userdata = userdata; |
| 359 | } |
| 360 | |
| 361 | return item; |
| 362 | } |
| 363 | |
| 364 | /* Return the contents of a `boxed' ITEM, recycling the box itself. */ |
| 365 | void * |
| 366 | slist_unbox (SList *item) |
| 367 | { |
| 368 | void *userdata = 0; |
| 369 | |
| 370 | if (item) |
| 371 | { |
| 372 | /* Strip the const, because responsibility for this memory |
| 373 | passes to the caller on return. */ |
| 374 | userdata = (void *) item->userdata; |
| 375 | free (item); |
| 376 | } |
| 377 | |
| 378 | return userdata; |
| 379 | } |