Utility functions for keeping flexible-sized arrays of locations in a tree of Inter code.

§1. Unlike linked lists, these are accessible in O(1) time, and can easily be sorted by index.

typedef struct inter_tree_location_list {
    int list_extent;
    int list_used;
    struct itl_entry *list;
    CLASS_DEFINITION
} inter_tree_location_list;

typedef struct itl_entry {
    int sort_key;
    struct inter_tree_node *node;
} itl_entry;

inter_tree_location_list *TreeLists::new(void) {
    inter_tree_location_list *NL = CREATE(inter_tree_location_list);
    NL->list_extent = 0;
    NL->list_used = 0;
    NL->list = NULL;
    return NL;
}

int TreeLists::len?Usage of TreeLists::len:
§3(inter_tree_location_list *NL) {
    if (NL == NULL) internal_error("null inter_tree_location_list");
    return NL->list_used;
}

• The structure inter_tree_location_list is private to this section.
• The structure itl_entry is private to this section.

§2. The capacity quadruples each time it is exhausted.

void TreeLists::add(inter_tree_location_list *NL, inter_tree_node *P) {
    if (NL == NULL) internal_error("null inter_tree_location_list");
    if (NL->list_extent == 0) {
        NL->list_extent = 256;
        NL->list = (itl_entry *)
            (Memory::calloc(NL->list_extent,
                sizeof(itl_entry), TREE_LIST_MREASON));
    }
    if (NL->list_used >= NL->list_extent) {
        int old_extent = NL->list_extent;
        NL->list_extent *= 4;
        itl_entry *new_list = (itl_entry *)
            (Memory::calloc(NL->list_extent,
                sizeof(itl_entry), TREE_LIST_MREASON));
        for (int i=0; i<NL->list_used; i++)
            new_list[i] = NL->list[i];
        Memory::I7_free(NL->list, TREE_LIST_MREASON, old_extent);
        NL->list = new_list;
    }
    NL->list[NL->list_used].sort_key = NL->list_used;
    NL->list[NL->list_used++].node = P;
}

void TreeLists::sort(inter_tree_location_list *NL, int (*cmp)(const void *, const void *)) {
    if (NL == NULL) internal_error("null inter_tree_location_list");
    if (NL->list_used > 0)
        qsort(NL->list, (size_t) NL->list_used, sizeof(itl_entry), cmp);
}

§3. And this macro conveniently loops through packages in a node list of their definitions:

define LOOP_OVER_INVENTORY_PACKAGES(pack, i, node_list)
    for (int i=0; i<TreeLists::len(node_list); i++)
        if ((pack = Inter::Package::defined_by_frame(node_list->list[i].node)))