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struct StringSetEntry {
u32 hash;
MapIndex next;
String value;
};
struct StringSet {
Slice<MapIndex> hashes;
Array<StringSetEntry> entries;
};
void string_set_init (StringSet *s, gbAllocator a, isize capacity = 16);
void string_set_destroy(StringSet *s);
void string_set_add (StringSet *s, String const &str);
bool string_set_update (StringSet *s, String const &str); // returns true if it previously existed
bool string_set_exists (StringSet *s, String const &str);
void string_set_remove (StringSet *s, String const &str);
void string_set_clear (StringSet *s);
void string_set_grow (StringSet *s);
void string_set_rehash (StringSet *s, isize new_count);
gb_inline void string_set_init(StringSet *s, gbAllocator a, isize capacity) {
capacity = next_pow2_isize(gb_max(16, capacity));
slice_init(&s->hashes, a, capacity);
array_init(&s->entries, a, 0, capacity);
for (isize i = 0; i < capacity; i++) {
s->hashes.data[i] = MAP_SENTINEL;
}
}
gb_inline void string_set_destroy(StringSet *s) {
slice_free(&s->hashes, s->entries.allocator);
array_free(&s->entries);
}
gb_internal MapIndex string_set__add_entry(StringSet *s, StringHashKey const &key) {
StringSetEntry e = {};
e.hash = key.hash;
e.next = MAP_SENTINEL;
e.value = key.string;
array_add(&s->entries, e);
return cast(MapIndex)(s->entries.count-1);
}
gb_internal MapFindResult string_set__find(StringSet *s, StringHashKey const &key) {
MapFindResult fr = {MAP_SENTINEL, MAP_SENTINEL, MAP_SENTINEL};
if (s->hashes.count > 0) {
fr.hash_index = cast(MapIndex)(((u64)key.hash) % s->hashes.count);
fr.entry_index = s->hashes[fr.hash_index];
while (fr.entry_index != MAP_SENTINEL) {
auto const &entry = s->entries[fr.entry_index];
if (entry.hash == key.hash && entry.value == key.string) {
return fr;
}
fr.entry_prev = fr.entry_index;
fr.entry_index = s->entries[fr.entry_index].next;
}
}
return fr;
}
gb_internal MapFindResult string_set__find_from_entry(StringSet *s, StringSetEntry *e) {
MapFindResult fr = {MAP_SENTINEL, MAP_SENTINEL, MAP_SENTINEL};
if (s->hashes.count > 0) {
fr.hash_index = cast(MapIndex)(e->hash % s->hashes.count);
fr.entry_index = s->hashes[fr.hash_index];
while (fr.entry_index != MAP_SENTINEL) {
if (&s->entries[fr.entry_index] == e) {
return fr;
}
fr.entry_prev = fr.entry_index;
fr.entry_index = s->entries[fr.entry_index].next;
}
}
return fr;
}
gb_internal b32 string_set__full(StringSet *s) {
return 0.75f * s->hashes.count <= s->entries.count;
}
gb_inline void string_set_grow(StringSet *s) {
isize new_count = gb_max(s->hashes.count<<1, 16);
string_set_rehash(s, new_count);
}
void string_set_reset_entries(StringSet *s) {
for (isize i = 0; i < s->hashes.count; i++) {
s->hashes.data[i] = MAP_SENTINEL;
}
for (isize i = 0; i < s->entries.count; i++) {
MapFindResult fr;
StringSetEntry *e = &s->entries.data[i];
e->next = MAP_SENTINEL;
fr = string_set__find_from_entry(s, e);
if (fr.entry_prev == MAP_SENTINEL) {
s->hashes[fr.hash_index] = cast(MapIndex)i;
} else {
s->entries[fr.entry_prev].next = cast(MapIndex)i;
}
}
}
void string_set_reserve(StringSet *s, isize cap) {
array_reserve(&s->entries, cap);
if (s->entries.count*2 < s->hashes.count) {
return;
}
slice_resize(&s->hashes, s->entries.allocator, cap*2);
string_set_reset_entries(s);
}
void string_set_rehash(StringSet *s, isize new_count) {
string_set_reserve(s, new_count);
}
gb_inline bool string_set_exists(StringSet *s, String const &str) {
StringHashKey key = string_hash_string(str);
isize index = string_set__find(s, key).entry_index;
return index != MAP_SENTINEL;
}
void string_set_add(StringSet *s, String const &str) {
MapIndex index;
MapFindResult fr;
StringHashKey key = string_hash_string(str);
if (s->hashes.count == 0) {
string_set_grow(s);
}
fr = string_set__find(s, key);
if (fr.entry_index != MAP_SENTINEL) {
index = fr.entry_index;
} else {
index = string_set__add_entry(s, key);
if (fr.entry_prev != MAP_SENTINEL) {
s->entries[fr.entry_prev].next = index;
} else {
s->hashes[fr.hash_index] = index;
}
}
s->entries[index].value = str;
if (string_set__full(s)) {
string_set_grow(s);
}
}
bool string_set_update(StringSet *s, String const &str) {
bool exists = false;
MapIndex index;
MapFindResult fr;
StringHashKey key = string_hash_string(str);
if (s->hashes.count == 0) {
string_set_grow(s);
}
fr = string_set__find(s, key);
if (fr.entry_index != MAP_SENTINEL) {
index = fr.entry_index;
exists = true;
} else {
index = string_set__add_entry(s, key);
if (fr.entry_prev != MAP_SENTINEL) {
s->entries[fr.entry_prev].next = index;
} else {
s->hashes[fr.hash_index] = index;
}
}
s->entries[index].value = str;
if (string_set__full(s)) {
string_set_grow(s);
}
return exists;
}
void string_set__erase(StringSet *s, MapFindResult fr) {
MapFindResult last;
if (fr.entry_prev == MAP_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;
}
auto *entry = &s->entries[fr.entry_index];
*entry = s->entries[s->entries.count-1];
StringHashKey key = {entry->hash, entry->value};
last = string_set__find(s, key);
if (last.entry_prev != MAP_SENTINEL) {
s->entries[last.entry_prev].next = fr.entry_index;
} else {
s->hashes[last.hash_index] = fr.entry_index;
}
}
void string_set_remove(StringSet *s, String const &str) {
StringHashKey key = string_hash_string(str);
MapFindResult fr = string_set__find(s, key);
if (fr.entry_index != MAP_SENTINEL) {
string_set__erase(s, fr);
}
}
gb_inline void string_set_clear(StringSet *s) {
array_clear(&s->entries);
for_array(i, s->hashes) {
s->hashes.data[i] = MAP_SENTINEL;
}
}
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