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/*
* Simple & stupid dynamic array single-header implementation. You can use the
* macros defined in this file with any structure that has the following fields:
*
* struct dyn_array {
* T *buf // Array of items
* N len // Length of array
* N cap // Capacity of array
* }
*
* The type ‘T’ is whatever type you want to store. The type ‘N’ is any numeric
* type — most likely ‘size_t’ — but it could be sized as well.
*
* You should include ‘err.h’ and ‘stdlib.h’ along with this file. If you want
* to use da_remove(), include ‘string.h’. The da_remove() macro also doesn’t
* bother with shrinking your array when the length is far lower than the
* capacity. If you care about that, do it yourself. To use the da_foreach()
* macro, you need to have ptrdiff_t defined; to be absolutely sure you can
* include ‘stddef.h’.
*
* Remember to call free() on your dynamic arrays ‘buf’ field after use.
*
* Macro Overview
* ――――――――――――――
* The argument ‘a’ to all of the below macros is a pointer to the dynamic array
* structure.
*
* da_init(a, n) Initialize the array with a capacity of ‘n’ items.
* da_append(a, x) Append the item ‘x’ to the array
* da_remove(a, x) Remove the item ‘x’ from the array
* da_remove_range(a, x, y) Remove the items between the range [x, y)
* da_foreach(a, t, i) Iterate the pointer ‘i’ of type ‘t’ over each
* element of the array.
*
* The ‘da_append()’ macro will by default double the arrays capacity when it
* gets full. If you would like to use a different growth factor instead of 2,
* you can define the DA_FACTOR macro to your desired growth factor before
* including this file.
*
*
* Example
* ―――――――
*
* struct {
* int *buf;
* size_t len, cap;
* } nums;
*
* // Initialize nums with capacity == 4
* da_init(&nums, 4);
*
* // Append 69, 1337, and 420 to nums
* da_append(&nums, 69);
* da_append(&nums, 1337);
* da_append(&nums, 420);
*
* da_foreach (&nums, int *, n) {
* int x = *n << 1;
* printf("n = %d; n² = %d\n", *n, x);
* }
*
* // Remove 1337 and 420 from nums
* da_remove_range(&nums, 1, 3);
*
* // Remove 69 from nums
* da_remove(&nums, 0);
*/
#ifndef MANGO_DA_H
#define MANGO_DA_H
#ifndef DA_FACTOR
# define DA_FACTOR 2
#endif
#define __da_s(a) (sizeof(*(a)->buf))
#define da_init(a, n) \
do { \
(a)->cap = n; \
(a)->len = 0; \
(a)->buf = malloc((a)->cap * __da_s(a)); \
if ((a)->buf == NULL) \
err(EXIT_FAILURE, "malloc"); \
} while (0)
#define da_append(a, x) \
do { \
if ((a)->len >= (a)->cap) { \
(a)->cap = (a)->cap * DA_FACTOR + 1; \
(a)->buf = realloc((a)->buf, (a)->cap * __da_s(a)); \
if ((a)->buf == NULL) \
err(EXIT_FAILURE, "realloc"); \
} \
(a)->buf[(a)->len++] = (x); \
} while (0)
#define da_remove(a, i) da_remove_range((a), (i), (i) + 1)
#define da_remove_range(a, i, j) \
do { \
memmove((a)->buf + (i), (a)->buf + (j), ((a)->len - (j)) * __da_s(a)); \
(a)->len -= j - i; \
} while (0)
#define da_foreach(a, t, i) \
for (t i = (a)->buf; i - (a)->buf < (ptrdiff_t)(a)->len; i++)
#endif /* !MANGO_DA_H */
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