boids-playground/src/boid-list.cpp

#include <algorithm>

#include "boid-list.hpp"

void boid_list_init(BoidList *list)
{
	list->node.next = NULL;
	list->count = 0;
}

BoidsListNodeIterator boid_list_get_iterator(BoidList *list) {
	return { .count = list->count, .i = 0, .node = &list->node  };
}

bool boid_list_iterator_next(BoidsListNodeIterator *iterator, uboid_t *value) {
	if (iterator->count == 0) {
		return false;
	}

	if (iterator->i == BOIDS_PER_NODE) {
		iterator->i = 0;
		iterator->node = iterator->node->next;
	}

	*value = iterator->node->boid_ids[iterator->i];
	iterator->i++;
	iterator->count--;
	return true;
}

void boid_list_append(MemoryArena *arena, BoidList *list, uboid_t new_boid) {
	int left_count = list->count;
	BoidListNode *prev = &list->node;
	BoidListNode *curr = &list->node;
	while (left_count >= BOIDS_PER_NODE && curr) {
		prev = curr;
		curr = curr->next;
		left_count -= BOIDS_PER_NODE;
	}

	if (curr == NULL) {
		curr = (BoidListNode*)arena_malloc(arena, sizeof(BoidListNode));
		curr->next = NULL;
		prev->next = curr;
	}

	curr->boid_ids[left_count] = new_boid;
	list->count++;
}

void boid_list_append_unique(MemoryArena *arena, BoidList *list, uboid_t new_boid) {
	int left_count = list->count;
	BoidListNode *last = &list->node;
	BoidListNode *curr = &list->node;
	while (left_count > 0 && curr) {
		for (int i = 0; i < std::min(left_count, BOIDS_PER_NODE); i++) {
			if (curr->boid_ids[i] == new_boid) return;
		}

		last = curr;
		curr = curr->next;
		left_count -= BOIDS_PER_NODE;
	}

	int idx = list->count % BOIDS_PER_NODE;
	if (idx == BOIDS_PER_NODE-1) {
		last->next = (BoidListNode*)arena_malloc(arena, sizeof(BoidListNode));
		last->next->next = NULL;
	}

	last->boid_ids[idx] = new_boid;
	list->count++;
}

void boid_list_to_array(uboid_t *result, BoidList *list) {
	int i = 0;
	uboid_t boid;
	BoidsListNodeIterator it = boid_list_get_iterator(list);
	while (boid_list_iterator_next(&it, &boid)) {
		result[i] = boid;
		i++;
	}
}