Warwick/dynamic-array
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Shrink array when capacity is double length

Browse source
This commit is contained in:
Warwick 2024-12-18 17:03:08 +00:00
parent ed9e7b31e3
commit db37ccedb3
3 changed files with 12 additions and 7 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

13
src/dyn_arr.c
View file

@ -6,6 +6,7 @@
#include <string.h> #include <string.h>
#define ARRAY_GROWTH_MULTIPLIER 1.3 #define ARRAY_GROWTH_MULTIPLIER 1.3
#define ARRAY_SHRINK_TRIGGER 2
void *dyn_arr_init(size_t item_size, size_t capacity) { void *dyn_arr_init(size_t item_size, size_t capacity) {
void *dyna_ptr = NULL; void *dyna_ptr = NULL;
@ -27,16 +28,20 @@ void *dyna_ensure_capacity(void *array, int64_t item_count) {
dyna_header *header = dyna_get_header(array); dyna_header *header = dyna_get_header(array);
size_t minimum_capacity = header->length + item_count; size_t minimum_capacity = header->length + item_count;
size_t maximum_capacity = size_t maximum_capacity =
header->length + item_count * ARRAY_GROWTH_MULTIPLIER; (header->length + item_count) * ARRAY_SHRINK_TRIGGER;
// Return if capacity is in acceptable range.
if (header->capacity > minimum_capacity && if (header->capacity > minimum_capacity &&
header->capacity < maximum_capacity) { header->capacity < maximum_capacity) {
return header + 1; return header + 1;
} }
size_t new_capacity = header->capacity * ARRAY_GROWTH_MULTIPLIER; size_t new_capacity = minimum_capacity * ARRAY_GROWTH_MULTIPLIER;
while (new_capacity < minimum_capacity) {
new_capacity *= ARRAY_GROWTH_MULTIPLIER; // Return if the array is valid and so small it's not worth reallocating
if (header->capacity > minimum_capacity &&
new_capacity <= ARRAY_INITIAL_CAPACITY) {
return header + 1;
} }
size_t new_size = sizeof(dyna_header) + new_capacity * item_size; size_t new_size = sizeof(dyna_header) + new_capacity * item_size;

2
src/dyn_arr.h
View file

@ -3,7 +3,7 @@
#include <stdbool.h> #include <stdbool.h>
#include <stdlib.h> #include <stdlib.h>
#define ARRAY_INITIAL_CAPACITY 4 #define ARRAY_INITIAL_CAPACITY 10
/* TODO: /* TODO:
* Functions to implement to match what I want: * Functions to implement to match what I want:

4
src/main.c
View file

@ -6,13 +6,13 @@
int main() { int main() {
uint64_t *dyna_array = dyna_init(uint64_t); uint64_t *dyna_array = dyna_init(uint64_t);
for (uint64_t i = 0; i < 19; i++) { for (uint64_t i = 0; i < 100; i++) {
dyna_append(dyna_array, i); dyna_append(dyna_array, i);
printf("length: %zu capacity: %zu value: %lu\n", dyna_length(dyna_array), printf("length: %zu capacity: %zu value: %lu\n", dyna_length(dyna_array),
dyna_capacity(dyna_array), dyna_array[i - 1]); dyna_capacity(dyna_array), dyna_array[i - 1]);
} }
for (uint64_t i = 19; i > 0; i--) { for (uint64_t i = 100; i > 0; i--) {
printf("length: %zu capacity: %zu value: %lu\n", dyna_length(dyna_array), printf("length: %zu capacity: %zu value: %lu\n", dyna_length(dyna_array),
dyna_capacity(dyna_array), dyna_array[i - 1]); dyna_capacity(dyna_array), dyna_array[i - 1]);
dyna_pop(dyna_array); dyna_pop(dyna_array);