- Make sure it's impossible to initialize an OAHashMap with 0 capacity (would cause division by 0)

- Added possibility to copy an OAHashMap
- Added unit tests

This code is generously donated by IMVU.

core/oa_hash_map.h

@@ -48,17 +48,19 @@
  *
  * Only used keys and values are constructed. For free positions there's space
  * in the arrays for each, but that memory is kept uninitialized.
+ * 
+ * The assignment operator copy the pairs from one map to the other.
  */
 template <class TKey, class TValue,
 		class Hasher = HashMapHasherDefault,
 		class Comparator = HashMapComparatorDefault<TKey>>
 class OAHashMap {
 private:
-	TValue *values;
-	TKey *keys;
-	uint32_t *hashes;
+	TValue *values = nullptr;
+	TKey *keys = nullptr;
+	uint32_t *hashes = nullptr;
 
-	uint32_t capacity;
+	uint32_t capacity = 0;
 
 	uint32_t num_elements = 0;
 
@@ -142,7 +144,9 @@ private:
 
 	void _resize_and_rehash(uint32_t p_new_capacity) {
 		uint32_t old_capacity = capacity;
-		capacity = p_new_capacity;
+
+		// Capacity can't be 0.
+		capacity = MAX(1, p_new_capacity);
 
 		TKey *old_keys = keys;
 		TValue *old_values = values;
@@ -157,6 +161,11 @@ private:
 			hashes[i] = 0;
 		}
 
+		if (old_capacity == 0) {
+			// Nothing to do.
+			return;
+		}
+
 		for (uint32_t i = 0; i < old_capacity; i++) {
 			if (old_hashes[i] == EMPTY_HASH) {
 				continue;
@@ -341,17 +350,32 @@ public:
 		return it;
 	}
 
-	OAHashMap(const OAHashMap &) = delete; // Delete the copy constructor so we don't get unexpected copies and dangling pointers.
-	OAHashMap &operator=(const OAHashMap &) = delete; // Same for assignment operator.
+	OAHashMap(const OAHashMap &p_other) {
+		(*this) = p_other;
+	}
+
+	OAHashMap &operator=(const OAHashMap &p_other) {
+		if (capacity != 0) {
+			clear();
+		}
+
+		_resize_and_rehash(p_other.capacity);
+
+		for (Iterator it = p_other.iter(); it.valid; it = p_other.next_iter(it)) {
+			set(*it.key, *it.value);
+		}
+		return *this;
+	}
 
 	OAHashMap(uint32_t p_initial_capacity = 64) {
-		capacity = p_initial_capacity;
+		// Capacity can't be 0.
+		capacity = MAX(1, p_initial_capacity);
 
 		keys = static_cast<TKey *>(Memory::alloc_static(sizeof(TKey) * capacity));
 		values = static_cast<TValue *>(Memory::alloc_static(sizeof(TValue) * capacity));
 		hashes = static_cast<uint32_t *>(Memory::alloc_static(sizeof(uint32_t) * capacity));
 
-		for (uint32_t i = 0; i < p_initial_capacity; i++) {
+		for (uint32_t i = 0; i < capacity; i++) {
 			hashes[i] = EMPTY_HASH;
 		}
 	}

main/tests/test_oa_hash_map.cpp

@@ -210,6 +210,89 @@ MainLoop *test() {
 		}
 	}
 
+	// Test map with 0 capacity.
+	{
+		OAHashMap<int, String> original_map(0);
+		original_map.set(1, "1");
+		OS::get_singleton()->print("OAHashMap 0 capacity initialization passed.\n");
+	}
+
+	// Test copy constructor.
+	{
+		OAHashMap<int, String> original_map;
+		original_map.set(1, "1");
+		original_map.set(2, "2");
+		original_map.set(3, "3");
+		original_map.set(4, "4");
+		original_map.set(5, "5");
+
+		OAHashMap<int, String> map_copy(original_map);
+
+		bool pass = true;
+		for (
+				OAHashMap<int, String>::Iterator it = original_map.iter();
+				it.valid;
+				it = original_map.next_iter(it)) {
+			if (map_copy.lookup_ptr(*it.key) == nullptr) {
+				pass = false;
+			}
+			if (*it.value != *map_copy.lookup_ptr(*it.key)) {
+				pass = false;
+			}
+		}
+		if (pass) {
+			OS::get_singleton()->print("OAHashMap copy constructor test passed.\n");
+		} else {
+			OS::get_singleton()->print("OAHashMap copy constructor test FAILED.\n");
+		}
+
+		map_copy.set(1, "Random String");
+		if (*map_copy.lookup_ptr(1) == *original_map.lookup_ptr(1)) {
+			OS::get_singleton()->print("OAHashMap copy constructor, atomic copy test FAILED.\n");
+		} else {
+			OS::get_singleton()->print("OAHashMap copy constructor, atomic copy test passed.\n");
+		}
+	}
+
+	// Test assign operator.
+	{
+		OAHashMap<int, String> original_map;
+		original_map.set(1, "1");
+		original_map.set(2, "2");
+		original_map.set(3, "3");
+		original_map.set(4, "4");
+		original_map.set(5, "5");
+
+		OAHashMap<int, String> map_copy(100000);
+		map_copy.set(1, "Just a string.");
+		map_copy = original_map;
+
+		bool pass = true;
+		for (
+				OAHashMap<int, String>::Iterator it = map_copy.iter();
+				it.valid;
+				it = map_copy.next_iter(it)) {
+			if (original_map.lookup_ptr(*it.key) == nullptr) {
+				pass = false;
+			}
+			if (*it.value != *original_map.lookup_ptr(*it.key)) {
+				pass = false;
+			}
+		}
+		if (pass) {
+			OS::get_singleton()->print("OAHashMap assign operation test passed.\n");
+		} else {
+			OS::get_singleton()->print("OAHashMap assign operation test FAILED.\n");
+		}
+
+		map_copy.set(1, "Random String");
+		if (*map_copy.lookup_ptr(1) == *original_map.lookup_ptr(1)) {
+			OS::get_singleton()->print("OAHashMap assign operation atomic copy test FAILED.\n");
+		} else {
+			OS::get_singleton()->print("OAHashMap assign operation atomic copy test passed.\n");
+		}
+	}
+
 	return nullptr;
 }