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typedef u32 PtrSetIndex;
struct PtrSetFindResult {
PtrSetIndex hash_index;
PtrSetIndex entry_prev;
PtrSetIndex entry_index;
};
enum : PtrSetIndex { PTR_SET_SENTINEL = ~(PtrSetIndex)0 };
template <typename T>
struct PtrSetEntry {
T ptr;
PtrSetIndex next;
};
template <typename T>
struct PtrSet {
Array<PtrSetIndex> hashes;
Array<PtrSetEntry<T>> entries;
};
template <typename T> void ptr_set_init (PtrSet<T> *s, gbAllocator a, isize capacity = 16);
template <typename T> void ptr_set_destroy(PtrSet<T> *s);
template <typename T> T ptr_set_add (PtrSet<T> *s, T ptr);
template <typename T> bool ptr_set_exists (PtrSet<T> *s, T ptr);
template <typename T> void ptr_set_remove (PtrSet<T> *s, T ptr);
template <typename T> void ptr_set_clear (PtrSet<T> *s);
template <typename T> void ptr_set_grow (PtrSet<T> *s);
template <typename T> void ptr_set_rehash (PtrSet<T> *s, isize new_count);
template <typename T>
void ptr_set_init(PtrSet<T> *s, gbAllocator a, isize capacity) {
capacity = next_pow2(gb_max(16, capacity));
array_init(&s->hashes, a, capacity);
array_init(&s->entries, a, 0, capacity);
for (isize i = 0; i < capacity; i++) {
s->hashes.data[i] = PTR_SET_SENTINEL;
}
}
template <typename T>
void ptr_set_destroy(PtrSet<T> *s) {
array_free(&s->hashes);
array_free(&s->entries);
}
template <typename T>
gb_internal PtrSetIndex ptr_set__add_entry(PtrSet<T> *s, T ptr) {
PtrSetEntry<T> e = {};
e.ptr = ptr;
e.next = PTR_SET_SENTINEL;
array_add(&s->entries, e);
return cast(PtrSetIndex)(s->entries.count-1);
}
template <typename T>
gb_internal PtrSetFindResult ptr_set__find(PtrSet<T> *s, T ptr) {
PtrSetFindResult fr = {PTR_SET_SENTINEL, PTR_SET_SENTINEL, PTR_SET_SENTINEL};
if (s->hashes.count != 0) {
u64 hash = 0xcbf29ce484222325ull ^ cast(u64)cast(uintptr)ptr;
u64 n = cast(u64)s->hashes.count;
fr.hash_index = cast(PtrSetIndex)(hash & (n-1));
fr.entry_index = s->hashes[fr.hash_index];
while (fr.entry_index != PTR_SET_SENTINEL) {
if (s->entries[fr.entry_index].ptr == ptr) {
return fr;
}
fr.entry_prev = fr.entry_index;
fr.entry_index = s->entries[fr.entry_index].next;
}
}
return fr;
}
template <typename T>
gb_internal bool ptr_set__full(PtrSet<T> *s) {
return 0.75f * s->hashes.count <= s->entries.count;
}
template <typename T>
gb_inline void ptr_set_grow(PtrSet<T> *s) {
isize new_count = s->hashes.count*2;
ptr_set_rehash(s, new_count);
}
template <typename T>
void ptr_set_rehash(PtrSet<T> *s, isize new_count) {
PtrSetIndex i, j;
PtrSet<T> ns = {};
ptr_set_init(&ns, s->hashes.allocator);
array_resize(&ns.hashes, new_count);
array_reserve(&ns.entries, s->entries.count);
for (i = 0; i < new_count; i++) {
ns.hashes[i] = PTR_SET_SENTINEL;
}
for (i = 0; i < s->entries.count; i++) {
PtrSetEntry<T> *e = &s->entries[i];
PtrSetFindResult fr;
if (ns.hashes.count == 0) {
ptr_set_grow(&ns);
}
fr = ptr_set__find(&ns, e->ptr);
j = ptr_set__add_entry(&ns, e->ptr);
if (fr.entry_prev == PTR_SET_SENTINEL) {
ns.hashes[fr.hash_index] = j;
} else {
ns.entries[fr.entry_prev].next = j;
}
ns.entries[j].next = fr.entry_index;
if (ptr_set__full(&ns)) {
ptr_set_grow(&ns);
}
}
ptr_set_destroy(s);
*s = ns;
}
template <typename T>
gb_inline bool ptr_set_exists(PtrSet<T> *s, T ptr) {
isize index = ptr_set__find(s, ptr).entry_index;
return index != PTR_SET_SENTINEL;
}
// Returns true if it already exists
template <typename T>
T ptr_set_add(PtrSet<T> *s, T ptr) {
PtrSetIndex index;
PtrSetFindResult fr;
if (s->hashes.count == 0) {
ptr_set_grow(s);
}
fr = ptr_set__find(s, ptr);
if (fr.entry_index != PTR_SET_SENTINEL) {
index = fr.entry_index;
} else {
index = ptr_set__add_entry(s, ptr);
if (fr.entry_prev != PTR_SET_SENTINEL) {
s->entries[fr.entry_prev].next = index;
} else {
s->hashes[fr.hash_index] = index;
}
}
if (ptr_set__full(s)) {
ptr_set_grow(s);
}
return ptr;
}
template <typename T>
void ptr_set__erase(PtrSet<T> *s, PtrSetFindResult fr) {
PtrSetFindResult last;
if (fr.entry_prev == PTR_SET_SENTINEL) {
s->hashes[fr.hash_index] = s->entries[fr.entry_index].next;
} else {
s->entries[fr.entry_prev].next = s->entries[fr.entry_index].next;
}
if (fr.entry_index == s->entries.count-1) {
array_pop(&s->entries);
return;
}
s->entries[fr.entry_index] = s->entries[s->entries.count-1];
last = ptr_set__find(s, s->entries[fr.entry_index].ptr);
if (last.entry_prev != PTR_SET_SENTINEL) {
s->entries[last.entry_prev].next = fr.entry_index;
} else {
s->hashes[last.hash_index] = fr.entry_index;
}
}
template <typename T>
void ptr_set_remove(PtrSet<T> *s, T ptr) {
PtrSetFindResult fr = ptr_set__find(s, ptr);
if (fr.entry_index != PTR_SET_SENTINEL) {
ptr_set__erase(s, fr);
}
}
template <typename T>
gb_inline void ptr_set_clear(PtrSet<T> *s) {
array_clear(&s->hashes);
array_clear(&s->entries);
}
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