Wed, 08 Feb 2023 20:26:09 +0100
implement swap function for list elements - fixes #218
1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
3 *
4 * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are met:
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27 */
29 #include "cx/array_list.h"
30 #include <assert.h>
31 #include <string.h>
32 #include <stdint.h>
34 // LOW LEVEL ARRAY LIST FUNCTIONS
36 enum cx_array_copy_result cx_array_copy(
37 void **target,
38 size_t *size,
39 size_t *capacity,
40 size_t index,
41 void const *src,
42 size_t elem_size,
43 size_t elem_count,
44 struct cx_array_reallocator_s *reallocator
45 ) {
46 // assert pointers
47 assert(target != NULL);
48 assert(size != NULL);
49 assert(src != NULL);
51 // determine capacity
52 size_t cap = capacity == NULL ? *size : *capacity;
54 // check if resize is required
55 size_t minsize = index + elem_count;
56 size_t newsize = *size < minsize ? minsize : *size;
57 bool needrealloc = newsize > cap;
59 // reallocate if possible
60 if (needrealloc) {
61 // a reallocator and a capacity variable must be available
62 if (reallocator == NULL || capacity == NULL) {
63 return CX_ARRAY_COPY_REALLOC_NOT_SUPPORTED;
64 }
66 // check, if we need to repair the src pointer
67 uintptr_t targetaddr = (uintptr_t) *target;
68 uintptr_t srcaddr = (uintptr_t) src;
69 bool repairsrc = targetaddr <= srcaddr
70 && srcaddr < targetaddr + cap * elem_size;
72 // calculate new capacity (next number divisible by 16)
73 cap = newsize - (newsize % 16) + 16;
74 assert(cap > newsize);
76 // perform reallocation
77 void *newmem = reallocator->realloc(
78 *target, cap, elem_size, reallocator
79 );
80 if (newmem == NULL) {
81 return CX_ARRAY_COPY_REALLOC_FAILED;
82 }
84 // repair src pointer, if necessary
85 if (repairsrc) {
86 src = ((char *) newmem) + (srcaddr - targetaddr);
87 }
89 // store new pointer and capacity
90 *target = newmem;
91 *capacity = cap;
92 }
94 // determine target pointer
95 char *start = *target;
96 start += index * elem_size;
98 // copy elements and set new size
99 memmove(start, src, elem_count * elem_size);
100 *size = newsize;
102 // return successfully
103 return CX_ARRAY_COPY_SUCCESS;
104 }
106 #ifndef CX_ARRAY_SWAP_SBO_SIZE
107 #define CX_ARRAY_SWAP_SBO_SIZE 512
108 #endif
110 void cx_array_swap(
111 void *arr,
112 size_t elem_size,
113 size_t idx1,
114 size_t idx2
115 ) {
116 // short circuit
117 if (idx1 == idx2) return;
119 char sbo_mem[CX_ARRAY_SWAP_SBO_SIZE];
120 void *tmp;
122 // decide if we can use the local buffer
123 if (elem_size > CX_ARRAY_SWAP_SBO_SIZE) {
124 tmp = malloc(elem_size);
125 // we don't want to enforce error handling
126 if (tmp == NULL) abort();
127 } else {
128 tmp = sbo_mem;
129 }
131 // calculate memory locations
132 char *left = arr, *right = arr;
133 left += idx1 * elem_size;
134 right += idx2 * elem_size;
136 // three-way swap
137 memcpy(tmp, left, elem_size);
138 memcpy(left, right, elem_size);
139 memcpy(right, tmp, elem_size);
141 // free dynamic memory, if it was needed
142 if (tmp != sbo_mem) {
143 free(tmp);
144 }
145 }
147 // HIGH LEVEL ARRAY LIST FUNCTIONS
149 typedef struct {
150 struct cx_list_s base;
151 void *data;
152 struct cx_array_reallocator_s reallocator;
153 } cx_array_list;
155 static void *cx_arl_realloc(
156 void *array,
157 size_t capacity,
158 size_t elem_size,
159 struct cx_array_reallocator_s *alloc
160 ) {
161 // retrieve the pointer to the list allocator
162 CxAllocator const *al = alloc->ptr1;
164 // use the list allocator to reallocate the memory
165 return cxRealloc(al, array, capacity * elem_size);
166 }
168 static void cx_arl_destructor(struct cx_list_s *list) {
169 cx_array_list *arl = (cx_array_list *) list;
170 cxFree(list->allocator, arl->data);
171 }
173 static size_t cx_arl_insert_array(
174 struct cx_list_s *list,
175 size_t index,
176 void const *array,
177 size_t n
178 ) {
179 // out of bounds and special case check
180 if (index > list->size || n == 0) return 0;
182 // get a correctly typed pointer to the list
183 cx_array_list *arl = (cx_array_list *) list;
185 // do we need to move some elements?
186 if (index < list->size) {
187 char const *first_to_move = (char const *) arl->data;
188 first_to_move += index * list->itemsize;
189 size_t elems_to_move = list->size - index;
190 size_t start_of_moved = index + n;
192 if (CX_ARRAY_COPY_SUCCESS != cx_array_copy(
193 &arl->data,
194 &list->size,
195 &list->capacity,
196 start_of_moved,
197 first_to_move,
198 list->itemsize,
199 elems_to_move,
200 &arl->reallocator
201 )) {
202 // if moving existing elems is unsuccessful, abort
203 return 0;
204 }
205 }
207 // note that if we had to move the elements, the following operation
208 // is guaranteed to succeed, because we have the memory already allocated
209 // therefore, it is impossible to leave this function with an invalid array
211 // place the new elements
212 if (CX_ARRAY_COPY_SUCCESS == cx_array_copy(
213 &arl->data,
214 &list->size,
215 &list->capacity,
216 index,
217 array,
218 list->itemsize,
219 n,
220 &arl->reallocator
221 )) {
222 return n;
223 } else {
224 // array list implementation is "all or nothing"
225 return 0;
226 }
227 }
229 static int cx_arl_insert_element(
230 struct cx_list_s *list,
231 size_t index,
232 void const *element
233 ) {
234 return 1 != cx_arl_insert_array(list, index, element, 1);
235 }
237 static int cx_arl_insert_iter(
238 struct cx_mut_iterator_s *iter,
239 void const *elem,
240 int prepend
241 ) {
242 struct cx_list_s *list = iter->src_handle;
243 if (iter->index < list->size) {
244 int result = cx_arl_insert_element(
245 list,
246 iter->index + 1 - prepend,
247 elem
248 );
249 if (result == 0 && prepend != 0) {
250 iter->index++;
251 iter->elem_handle = ((char *) iter->elem_handle) + list->itemsize;
252 }
253 return result;
254 } else {
255 int result = cx_arl_insert_element(list, list->size, elem);
256 iter->index = list->size;
257 return result;
258 }
259 }
261 static int cx_arl_remove(
262 struct cx_list_s *list,
263 size_t index
264 ) {
265 // out-of-bounds check
266 if (index >= list->size) {
267 return 1;
268 }
270 // short-circuit removal of last element
271 if (index == list->size - 1) {
272 list->size--;
273 return 0;
274 }
276 // just move the elements starting at index to the left
277 cx_array_list *arl = (cx_array_list *) list;
278 int result = cx_array_copy(
279 &arl->data,
280 &list->size,
281 &list->capacity,
282 index,
283 ((char *) arl->data) + (index + 1) * list->itemsize,
284 list->itemsize,
285 list->size - index - 1,
286 &arl->reallocator
287 );
288 if (result == 0) {
289 // decrease the size
290 list->size--;
291 }
292 return result;
293 }
295 static int cx_arl_swap(
296 struct cx_list_s *list,
297 size_t i,
298 size_t j
299 ) {
300 if (i >= list->size || j >= list->size) return 1;
301 cx_array_list *arl = (cx_array_list *) list;
302 cx_array_swap(arl->data, list->itemsize, i, j);
303 return 0;
304 }
306 static void *cx_arl_at(
307 struct cx_list_s const *list,
308 size_t index
309 ) {
310 if (index < list->size) {
311 cx_array_list const *arl = (cx_array_list const *) list;
312 char *space = arl->data;
313 return space + index * list->itemsize;
314 } else {
315 return NULL;
316 }
317 }
319 static size_t cx_arl_find(
320 struct cx_list_s const *list,
321 void const *elem
322 ) {
323 char *cur = ((cx_array_list const *) list)->data;
325 for (size_t i = 0; i < list->size; i++) {
326 if (0 == list->cmpfunc(elem, cur)) {
327 return i;
328 }
329 cur += list->itemsize;
330 }
332 return list->size;
333 }
335 static void cx_arl_sort(struct cx_list_s *list) {
336 qsort(((cx_array_list *) list)->data,
337 list->size,
338 list->itemsize,
339 list->cmpfunc
340 );
341 }
343 static int cx_arl_compare(
344 struct cx_list_s const *list,
345 struct cx_list_s const *other
346 ) {
347 if (list->size == other->size) {
348 char const *left = ((cx_array_list const *) list)->data;
349 char const *right = ((cx_array_list const *) other)->data;
350 for (size_t i = 0; i < list->size; i++) {
351 int d = list->cmpfunc(left, right);
352 if (d != 0) {
353 return d;
354 }
355 left += list->itemsize;
356 right += other->itemsize;
357 }
358 return 0;
359 } else {
360 return list->size < other->size ? -1 : 1;
361 }
362 }
364 static void cx_arl_reverse(struct cx_list_s *list) {
365 if (list->size < 2) return;
366 void *data = ((cx_array_list const *) list)->data;
367 size_t half = list->size / 2;
368 for (size_t i = 0; i < half; i++) {
369 cx_array_swap(data, list->itemsize, i, list->size - 1 - i);
370 }
371 }
373 static bool cx_arl_iter_valid(void const *it) {
374 struct cx_iterator_s const *iter = it;
375 struct cx_list_s const *list = iter->src_handle;
376 return iter->index < list->size;
377 }
379 static void *cx_arl_iter_current(void const *it) {
380 struct cx_iterator_s const *iter = it;
381 return iter->elem_handle;
382 }
384 static void cx_arl_iter_next(void *it) {
385 struct cx_iterator_base_s *itbase = it;
386 if (itbase->remove) {
387 struct cx_mut_iterator_s *iter = it;
388 itbase->remove = false;
389 cx_arl_remove(iter->src_handle, iter->index);
390 } else {
391 struct cx_iterator_s *iter = it;
392 iter->index++;
393 iter->elem_handle =
394 ((char *) iter->elem_handle)
395 + ((struct cx_list_s const *) iter->src_handle)->itemsize;
396 }
397 }
399 static bool cx_arl_iter_flag_rm(void *it) {
400 struct cx_iterator_base_s *iter = it;
401 if (iter->mutating) {
402 iter->remove = true;
403 return true;
404 } else {
405 return false;
406 }
407 }
409 static struct cx_iterator_s cx_arl_iterator(
410 struct cx_list_s const *list,
411 size_t index
412 ) {
413 struct cx_iterator_s iter;
415 iter.index = index;
416 iter.src_handle = list;
417 iter.elem_handle = cx_arl_at(list, index);
418 iter.base.valid = cx_arl_iter_valid;
419 iter.base.current = cx_arl_iter_current;
420 iter.base.next = cx_arl_iter_next;
421 iter.base.flag_removal = cx_arl_iter_flag_rm;
422 iter.base.remove = false;
423 iter.base.mutating = false;
425 return iter;
426 }
428 static cx_list_class cx_array_list_class = {
429 cx_arl_destructor,
430 cx_arl_insert_element,
431 cx_arl_insert_array,
432 cx_arl_insert_iter,
433 cx_arl_remove,
434 cx_arl_swap,
435 cx_arl_at,
436 cx_arl_find,
437 cx_arl_sort,
438 cx_arl_compare,
439 cx_arl_reverse,
440 cx_arl_iterator,
441 };
443 CxList *cxArrayListCreate(
444 CxAllocator const *allocator,
445 CxListComparator comparator,
446 size_t item_size,
447 size_t initial_capacity
448 ) {
449 cx_array_list *list = cxCalloc(allocator, 1, sizeof(cx_array_list));
450 if (list == NULL) return NULL;
452 list->data = cxCalloc(allocator, initial_capacity, item_size);
453 if (list->data == NULL) {
454 cxFree(allocator, list);
455 return NULL;
456 }
458 list->base.cl = &cx_array_list_class;
459 list->base.allocator = allocator;
460 list->base.cmpfunc = comparator;
461 list->base.itemsize = item_size;
462 list->base.capacity = initial_capacity;
464 // configure the reallocator
465 list->reallocator.realloc = cx_arl_realloc;
466 list->reallocator.ptr1 = (void *) allocator;
468 return (CxList *) list;
469 }