1 files changed, 194 insertions, 0 deletions
diff --git a/src/ptr_set.cpp b/src/ptr_set.cpp
new file mode 100644
index 000000000..1eecee33e
--- /dev/null
+++ b/src/ptr_set.cpp
@@ -0,0 +1,194 @@
+struct PtrSetFindResult {
+	isize hash_index;
+	isize entry_prev;
+	isize entry_index;
+};
+
+
+template <typename T>
+struct PtrSetEntry {
+	T       ptr;
+	isize   next;
+};
+
+template <typename T>
+struct PtrSet {
+	Array<isize>          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> void 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) {
+	array_init(&s->hashes,  a, capacity);
+	array_init(&s->entries, a, capacity);
+}
+
+template <typename T>
+void ptr_set_destroy(PtrSet<T> *s) {
+	array_free(&s->hashes);
+	array_free(&s->entries);
+}
+
+template <typename T>
+gb_internal isize ptr_set__add_entry(PtrSet<T> *s, T ptr) {
+	PtrSetEntry<T> e = {};
+	e.ptr = ptr;
+	e.next = -1;
+	array_add(&s->entries, e);
+	return s->entries.count-1;
+}
+
+
+template <typename T>
+gb_internal PtrSetFindResult ptr_set__find(PtrSet<T> *s, T ptr) {
+	PtrSetFindResult fr = {-1, -1, -1};
+	if (s->hashes.count > 0) {
+		uintptr p = cast(uintptr)ptr;
+		uintptr n = cast(uintptr)s->hashes.count;
+		fr.hash_index = cast(isize)(p % n);
+		fr.entry_index = s->hashes[fr.hash_index];
+		while (fr.entry_index >= 0) {
+			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 PtrSetFindResult ptr_set__find_from_entry(PtrSet<T> *s, PtrSetEntry<T> *e) {
+	PtrSetFindResult fr = {-1, -1, -1};
+	if (s->hashes.count > 0) {
+		fr.hash_index  = e->key.key % s->hashes.count;
+		fr.entry_index = s->hashes[fr.hash_index];
+		while (fr.entry_index >= 0) {
+			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;
+}
+
+template <typename T>
+gb_internal b32 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 = ARRAY_GROW_FORMULA(s->entries.count);
+	ptr_set_rehash(s, new_count);
+}
+
+template <typename T>
+void ptr_set_rehash(PtrSet<T> *s, isize new_count) {
+	isize 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] = -1;
+	}
+	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 < 0) {
+			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 >= 0;
+}
+
+template <typename T>
+void ptr_set_add(PtrSet<T> *s, T ptr) {
+	isize index;
+	PtrSetFindResult fr;
+	if (s->hashes.count == 0) {
+		ptr_set_grow(s);
+	}
+	fr = ptr_set__find(s, ptr);
+	if (fr.entry_index >= 0) {
+		index = fr.entry_index;
+	} else {
+		index = ptr_set__add_entry(s, ptr);
+		if (fr.entry_prev >= 0) {
+			s->entries[fr.entry_prev].next = index;
+		} else {
+			s->hashes[fr.hash_index] = index;
+		}
+	}
+	if (ptr_set__full(s)) {
+		ptr_set_grow(s);
+	}
+}
+
+
+template <typename T>
+void ptr_set__erase(PtrSet<T> *s, PtrSetFindResult fr) {
+	PtrSetFindResult last;
+	if (fr.entry_prev < 0) {
+		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 >= 0) {
+		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 >= 0) {
+		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);
+}