Files
Odin/src/map.cpp
2020-05-21 16:27:40 +01:00

348 lines
8.6 KiB
C++

// A `Map` is an unordered hash table which can allow for a key to point to multiple values
// with the use of the `multi_*` procedures.
// TODO(bill): I should probably allow the `multi_map_*` stuff to be #ifdefed out
#define MAP_ENABLE_MULTI_MAP 1
#ifndef MAP_UTIL_STUFF
#define MAP_UTIL_STUFF
// NOTE(bill): This util stuff is the same for every `Map`
struct MapFindResult {
isize hash_index;
isize entry_prev;
isize entry_index;
};
struct HashKey {
u64 key;
};
GB_STATIC_ASSERT(gb_size_of(u64) >= gb_size_of(void *));
gb_inline HashKey hashing_proc(void const *data, isize len) {
HashKey h = {};
// h.key = u128_from_u64(gb_fnv64a(data, len));
h.key = gb_fnv64a(data, len);
return h;
}
gb_inline HashKey hash_pointer(void const *ptr) {
HashKey h = {};
h.key = cast(u64)cast(uintptr)ptr;
return h;
}
gb_inline HashKey hash_integer(u64 u) {
HashKey h = {};
h.key = u;
return h;
}
gb_inline HashKey hash_f64(f64 f) {
HashKey h = {};
h.key = bit_cast<u64>(f);
return h;
}
gb_inline bool hash_key_equal(HashKey a, HashKey b) {
return a.key == b.key;
}
gb_inline bool operator==(HashKey a, HashKey b) { return hash_key_equal(a, b); }
gb_inline bool operator!=(HashKey a, HashKey b) { return !hash_key_equal(a, b); }
#endif
template <typename T>
struct MapEntry {
HashKey key;
isize next;
T value;
};
template <typename T>
struct Map {
Array<isize> hashes;
Array<MapEntry<T> > entries;
};
template <typename T> void map_init (Map<T> *h, gbAllocator a, isize capacity = 16);
template <typename T> void map_destroy (Map<T> *h);
template <typename T> T * map_get (Map<T> *h, HashKey const &key);
template <typename T> void map_set (Map<T> *h, HashKey const &key, T const &value);
template <typename T> void map_remove (Map<T> *h, HashKey const &key);
template <typename T> void map_clear (Map<T> *h);
template <typename T> void map_grow (Map<T> *h);
template <typename T> void map_rehash (Map<T> *h, isize new_count);
#if MAP_ENABLE_MULTI_MAP
// Mutlivalued map procedure
template <typename T> MapEntry<T> * multi_map_find_first(Map<T> *h, HashKey const &key);
template <typename T> MapEntry<T> * multi_map_find_next (Map<T> *h, MapEntry<T> *e);
template <typename T> isize multi_map_count (Map<T> *h, HashKey const &key);
template <typename T> void multi_map_get_all (Map<T> *h, HashKey const &key, T *items);
template <typename T> void multi_map_insert (Map<T> *h, HashKey const &key, T const &value);
template <typename T> void multi_map_remove (Map<T> *h, HashKey const &key, MapEntry<T> *e);
template <typename T> void multi_map_remove_all(Map<T> *h, HashKey const &key);
#endif
template <typename T>
gb_inline void map_init(Map<T> *h, gbAllocator a, isize capacity) {
array_init(&h->hashes, a, capacity);
array_init(&h->entries, a, 0, capacity);
for (isize i = 0; i < capacity; i++) {
h->hashes.data[i] = -1;
}
}
template <typename T>
gb_inline void map_destroy(Map<T> *h) {
array_free(&h->entries);
array_free(&h->hashes);
}
template <typename T>
gb_internal isize map__add_entry(Map<T> *h, HashKey const &key) {
MapEntry<T> e = {};
e.key = key;
e.next = -1;
array_add(&h->entries, e);
return h->entries.count-1;
}
template <typename T>
gb_internal MapFindResult map__find(Map<T> *h, HashKey const &key) {
MapFindResult fr = {-1, -1, -1};
if (h->hashes.count > 0) {
// fr.hash_index = u128_to_i64(key.key % u128_from_i64(h->hashes.count));
fr.hash_index = key.key % h->hashes.count;
fr.entry_index = h->hashes[fr.hash_index];
while (fr.entry_index >= 0) {
if (hash_key_equal(h->entries[fr.entry_index].key, key)) {
return fr;
}
fr.entry_prev = fr.entry_index;
fr.entry_index = h->entries[fr.entry_index].next;
}
}
return fr;
}
template <typename T>
gb_internal MapFindResult map__find_from_entry(Map<T> *h, MapEntry<T> *e) {
MapFindResult fr = {-1, -1, -1};
if (h->hashes.count > 0) {
fr.hash_index = e->key.key % h->hashes.count;
fr.entry_index = h->hashes[fr.hash_index];
while (fr.entry_index >= 0) {
if (&h->entries[fr.entry_index] == e) {
return fr;
}
fr.entry_prev = fr.entry_index;
fr.entry_index = h->entries[fr.entry_index].next;
}
}
return fr;
}
template <typename T>
gb_internal b32 map__full(Map<T> *h) {
return 0.75f * h->hashes.count <= h->entries.count;
}
#define MAP_ARRAY_GROW_FORMULA(x) (4*(x) + 7)
GB_STATIC_ASSERT(MAP_ARRAY_GROW_FORMULA(0) > 0);
template <typename T>
gb_inline void map_grow(Map<T> *h) {
isize new_count = MAP_ARRAY_GROW_FORMULA(h->entries.count);
map_rehash(h, new_count);
}
template <typename T>
void map_rehash(Map<T> *h, isize new_count) {
isize i, j;
Map<T> nh = {};
map_init(&nh, h->hashes.allocator, new_count);
array_resize(&nh.hashes, new_count);
array_reserve(&nh.entries, h->entries.count);
for (i = 0; i < new_count; i++) {
nh.hashes[i] = -1;
}
for (i = 0; i < h->entries.count; i++) {
MapEntry<T> *e = &h->entries[i];
MapFindResult fr;
if (nh.hashes.count == 0) {
map_grow(&nh);
}
fr = map__find(&nh, e->key);
j = map__add_entry(&nh, e->key);
if (fr.entry_prev < 0) {
nh.hashes[fr.hash_index] = j;
} else {
nh.entries[fr.entry_prev].next = j;
}
nh.entries[j].next = fr.entry_index;
nh.entries[j].value = e->value;
if (map__full(&nh)) {
map_grow(&nh);
}
}
map_destroy(h);
*h = nh;
}
template <typename T>
T *map_get(Map<T> *h, HashKey const &key) {
isize index = map__find(h, key).entry_index;
if (index >= 0) {
return &h->entries[index].value;
}
return nullptr;
}
template <typename T>
void map_set(Map<T> *h, HashKey const &key, T const &value) {
isize index;
MapFindResult fr;
if (h->hashes.count == 0) {
map_grow(h);
}
fr = map__find(h, key);
if (fr.entry_index >= 0) {
index = fr.entry_index;
} else {
index = map__add_entry(h, key);
if (fr.entry_prev >= 0) {
h->entries[fr.entry_prev].next = index;
} else {
h->hashes[fr.hash_index] = index;
}
}
h->entries[index].value = value;
if (map__full(h)) {
map_grow(h);
}
}
template <typename T>
void map__erase(Map<T> *h, MapFindResult const &fr) {
MapFindResult last;
if (fr.entry_prev < 0) {
h->hashes[fr.hash_index] = h->entries[fr.entry_index].next;
} else {
h->entries[fr.entry_prev].next = h->entries[fr.entry_index].next;
}
if (fr.entry_index == h->entries.count-1) {
array_pop(&h->entries);
return;
}
h->entries[fr.entry_index] = h->entries[h->entries.count-1];
last = map__find(h, h->entries[fr.entry_index].key);
if (last.entry_prev >= 0) {
h->entries[last.entry_prev].next = fr.entry_index;
} else {
h->hashes[last.hash_index] = fr.entry_index;
}
}
template <typename T>
void map_remove(Map<T> *h, HashKey const &key) {
MapFindResult fr = map__find(h, key);
if (fr.entry_index >= 0) {
map__erase(h, fr);
}
}
template <typename T>
gb_inline void map_clear(Map<T> *h) {
array_clear(&h->hashes);
array_clear(&h->entries);
}
#if MAP_ENABLE_MULTI_MAP
template <typename T>
MapEntry<T> *multi_map_find_first(Map<T> *h, HashKey const &key) {
isize i = map__find(h, key).entry_index;
if (i < 0) {
return nullptr;
}
return &h->entries[i];
}
template <typename T>
MapEntry<T> *multi_map_find_next(Map<T> *h, MapEntry<T> *e) {
isize i = e->next;
while (i >= 0) {
if (hash_key_equal(h->entries[i].key, e->key)) {
return &h->entries[i];
}
i = h->entries[i].next;
}
return nullptr;
}
template <typename T>
isize multi_map_count(Map<T> *h, HashKey const &key) {
isize count = 0;
MapEntry<T> *e = multi_map_find_first(h, key);
while (e != nullptr) {
count++;
e = multi_map_find_next(h, e);
}
return count;
}
template <typename T>
void multi_map_get_all(Map<T> *h, HashKey const &key, T *items) {
isize i = 0;
MapEntry<T> *e = multi_map_find_first(h, key);
while (e != nullptr) {
items[i++] = e->value;
e = multi_map_find_next(h, e);
}
}
template <typename T>
void multi_map_insert(Map<T> *h, HashKey const &key, T const &value) {
MapFindResult fr;
isize i;
if (h->hashes.count == 0) {
map_grow(h);
}
// Make
fr = map__find(h, key);
i = map__add_entry(h, key);
if (fr.entry_prev < 0) {
h->hashes[fr.hash_index] = i;
} else {
h->entries[fr.entry_prev].next = i;
}
h->entries[i].next = fr.entry_index;
h->entries[i].value = value;
// Grow if needed
if (map__full(h)) {
map_grow(h);
}
}
template <typename T>
void multi_map_remove(Map<T> *h, HashKey const &key, MapEntry<T> *e) {
MapFindResult fr = map__find_from_entry(h, e);
if (fr.entry_index >= 0) {
map__erase(h, fr);
}
}
template <typename T>
void multi_map_remove_all(Map<T> *h, HashKey const &key) {
while (map_get(h, key) != nullptr) {
map_remove(h, key);
}
}
#endif