Add a new HashMap implementation

Adds a new, cleaned up, HashMap implementation.

* Uses Robin Hood Hashing (https://en.wikipedia.org/wiki/Hash_table#Robin_Hood_hashing).
* Keeps elements in a double linked list for simpler, ordered, iteration.
* Allows keeping iterators for later use in removal (Unlike Map<>, it does not do much
  for performance vs keeping the key, but helps replace old code).
* Uses a more modern C++ iterator API, deprecates the old one.
* Supports custom allocator (in case there is a wish to use a paged one).

This class aims to unify all the associative template usage and replace it by this one:
* Map<> (whereas key order does not matter, which is 99% of cases)
* HashMap<>
* OrderedHashMap<>
* OAHashMap<>

12 files changed, 78 insertions, 109 deletions

diff --git a/modules/gdscript/editor/gdscript_highlighter.cpp b/modules/gdscript/editor/gdscript_highlighter.cpp
index e3f0ddfc35..191568661d 100644
--- a/modules/gdscript/editor/gdscript_highlighter.cpp
+++ b/modules/gdscript/editor/gdscript_highlighter.cpp
@@ -510,9 +510,8 @@ void GDScriptSyntaxHighlighter::_update_cache() {
 	}
 
 	/* Autoloads. */
-	OrderedHashMap<StringName, ProjectSettings::AutoloadInfo> autoloads = ProjectSettings::get_singleton()->get_autoload_list();
-	for (OrderedHashMap<StringName, ProjectSettings::AutoloadInfo>::Element E = autoloads.front(); E; E = E.next()) {
-		const ProjectSettings::AutoloadInfo &info = E.value();
+	for (const KeyValue<StringName, ProjectSettings::AutoloadInfo> &E : ProjectSettings::get_singleton()->get_autoload_list()) {
+		const ProjectSettings::AutoloadInfo &info = E.value;
 		if (info.is_singleton) {
 			keywords[info.name] = usertype_color;
 		}
diff --git a/modules/gdscript/gdscript_analyzer.cpp b/modules/gdscript/gdscript_analyzer.cpp
index d346264933..85ad08ea4f 100644
--- a/modules/gdscript/gdscript_analyzer.cpp
+++ b/modules/gdscript/gdscript_analyzer.cpp
@@ -4218,13 +4218,11 @@ Error GDScriptAnalyzer::resolve_program() {
 	resolve_class_interface(parser->head);
 	resolve_class_body(parser->head);
 
-	List<String> parser_keys;
-	depended_parsers.get_key_list(&parser_keys);
-	for (const String &E : parser_keys) {
-		if (depended_parsers[E].is_null()) {
+	for (KeyValue<String, Ref<GDScriptParserRef>> &K : depended_parsers) {
+		if (K.value.is_null()) {
 			return ERR_PARSE_ERROR;
 		}
-		depended_parsers[E]->raise_status(GDScriptParserRef::FULLY_SOLVED);
+		K.value->raise_status(GDScriptParserRef::FULLY_SOLVED);
 	}
 	return parser->errors.is_empty() ? OK : ERR_PARSE_ERROR;
 }
diff --git a/modules/gdscript/gdscript_byte_codegen.cpp b/modules/gdscript/gdscript_byte_codegen.cpp
index e72069bcd5..3d5a39bf38 100644
--- a/modules/gdscript/gdscript_byte_codegen.cpp
+++ b/modules/gdscript/gdscript_byte_codegen.cpp
@@ -196,10 +196,8 @@ GDScriptFunction *GDScriptByteCodeGenerator::write_end() {
 		function->_constant_count = constant_map.size();
 		function->constants.resize(constant_map.size());
 		function->_constants_ptr = function->constants.ptrw();
-		const Variant *K = nullptr;
-		while ((K = constant_map.next(K))) {
-			int idx = constant_map[*K];
-			function->constants.write[idx] = *K;
+		for (const KeyValue<Variant, int> &K : constant_map) {
+			function->constants.write[K.value] = K.key;
 		}
 	} else {
 		function->_constants_ptr = nullptr;
diff --git a/modules/gdscript/gdscript_compiler.cpp b/modules/gdscript/gdscript_compiler.cpp
index 37a988ee4c..c194fbf9b8 100644
--- a/modules/gdscript/gdscript_compiler.cpp
+++ b/modules/gdscript/gdscript_compiler.cpp
@@ -336,7 +336,7 @@ GDScriptCodeGenerator::Address GDScriptCompiler::_parse_expression(CodeGen &code
 			if (GDScriptLanguage::get_singleton()->get_global_map().has(identifier)) {
 				// If it's an autoload singleton, we postpone to load it at runtime.
 				// This is so one autoload doesn't try to load another before it's compiled.
-				OrderedHashMap<StringName, ProjectSettings::AutoloadInfo> autoloads = ProjectSettings::get_singleton()->get_autoload_list();
+				HashMap<StringName, ProjectSettings::AutoloadInfo> autoloads = ProjectSettings::get_singleton()->get_autoload_list();
 				if (autoloads.has(identifier) && autoloads[identifier].is_singleton) {
 					GDScriptCodeGenerator::Address global = codegen.add_temporary(_gdtype_from_datatype(in->get_datatype()));
 					int idx = GDScriptLanguage::get_singleton()->get_global_map()[identifier];
diff --git a/modules/gdscript/gdscript_editor.cpp b/modules/gdscript/gdscript_editor.cpp
index 0197bf9ea3..7021f0aa1e 100644
--- a/modules/gdscript/gdscript_editor.cpp
+++ b/modules/gdscript/gdscript_editor.cpp
@@ -851,9 +851,10 @@ static void _list_available_types(bool p_inherit_only, GDScriptParser::Completio
 	}
 
 	// Autoload singletons
-	OrderedHashMap<StringName, ProjectSettings::AutoloadInfo> autoloads = ProjectSettings::get_singleton()->get_autoload_list();
-	for (OrderedHashMap<StringName, ProjectSettings::AutoloadInfo>::Element E = autoloads.front(); E; E = E.next()) {
-		const ProjectSettings::AutoloadInfo &info = E.get();
+	HashMap<StringName, ProjectSettings::AutoloadInfo> autoloads = ProjectSettings::get_singleton()->get_autoload_list();
+
+	for (const KeyValue<StringName, ProjectSettings::AutoloadInfo> &E : autoloads) {
+		const ProjectSettings::AutoloadInfo &info = E.value;
 		if (!info.is_singleton || info.path.get_extension().to_lower() != "gd") {
 			continue;
 		}
@@ -1219,12 +1220,11 @@ static void _find_identifiers(const GDScriptParser::CompletionContext &p_context
 		r_result.insert(option.display, option);
 	}
 
-	OrderedHashMap<StringName, ProjectSettings::AutoloadInfo> autoloads = ProjectSettings::get_singleton()->get_autoload_list();
-	for (OrderedHashMap<StringName, ProjectSettings::AutoloadInfo>::Element E = autoloads.front(); E; E = E.next()) {
-		if (!E.value().is_singleton) {
+	for (const KeyValue<StringName, ProjectSettings::AutoloadInfo> &E : ProjectSettings::get_singleton()->get_autoload_list()) {
+		if (!E.value.is_singleton) {
 			continue;
 		}
-		ScriptLanguage::CodeCompletionOption option(E.key(), ScriptLanguage::CODE_COMPLETION_KIND_CONSTANT);
+		ScriptLanguage::CodeCompletionOption option(E.key, ScriptLanguage::CODE_COMPLETION_KIND_CONSTANT);
 		r_result.insert(option.display, option);
 	}
 
@@ -1517,12 +1517,10 @@ static bool _guess_expression_type(GDScriptParser::CompletionContext &p_context,
 												r_type = _type_from_variant(GDScriptLanguage::get_singleton()->get_named_globals_map()[which]);
 												found = true;
 											} else {
-												OrderedHashMap<StringName, ProjectSettings::AutoloadInfo> autoloads = ProjectSettings::get_singleton()->get_autoload_list();
-
-												for (OrderedHashMap<StringName, ProjectSettings::AutoloadInfo>::Element E = autoloads.front(); E; E = E.next()) {
-													String name = E.key();
+												for (const KeyValue<StringName, ProjectSettings::AutoloadInfo> &E : ProjectSettings::get_singleton()->get_autoload_list()) {
+													String name = E.key;
 													if (name == which) {
-														String script = E.value().path;
+														String script = E.value.path;
 
 														if (!script.begins_with("res://")) {
 															script = "res://" + script;
@@ -2882,10 +2880,8 @@ static void _find_call_arguments(GDScriptParser::CompletionContext &p_context, c
 				}
 
 				// Get autoloads.
-				OrderedHashMap<StringName, ProjectSettings::AutoloadInfo> autoloads = ProjectSettings::get_singleton()->get_autoload_list();
-
-				for (OrderedHashMap<StringName, ProjectSettings::AutoloadInfo>::Element E = autoloads.front(); E; E = E.next()) {
-					String path = "/root/" + E.key();
+				for (const KeyValue<StringName, ProjectSettings::AutoloadInfo> &E : ProjectSettings::get_singleton()->get_autoload_list()) {
+					String path = "/root/" + E.key;
 					ScriptLanguage::CodeCompletionOption option(path.quote(quote_style), ScriptLanguage::CODE_COMPLETION_KIND_NODE_PATH);
 					options.insert(option.display, option);
 				}
diff --git a/modules/gdscript/gdscript_parser.cpp b/modules/gdscript/gdscript_parser.cpp
index a2dc9bb8a8..b6bf523a67 100644
--- a/modules/gdscript/gdscript_parser.cpp
+++ b/modules/gdscript/gdscript_parser.cpp
@@ -100,10 +100,8 @@ void GDScriptParser::cleanup() {
 }
 
 void GDScriptParser::get_annotation_list(List<MethodInfo> *r_annotations) const {
-	List<StringName> keys;
-	valid_annotations.get_key_list(&keys);
-	for (const StringName &E : keys) {
-		r_annotations->push_back(valid_annotations[E].info);
+	for (const KeyValue<StringName, AnnotationInfo> &E : valid_annotations) {
+		r_annotations->push_back(E.value.info);
 	}
 }
 
@@ -1894,11 +1892,8 @@ GDScriptParser::MatchBranchNode *GDScriptParser::parse_match_branch() {
 
 	SuiteNode *suite = alloc_node<SuiteNode>();
 	if (branch->patterns.size() > 0) {
-		List<StringName> binds;
-		branch->patterns[0]->binds.get_key_list(&binds);
-
-		for (const StringName &E : binds) {
-			SuiteNode::Local local(branch->patterns[0]->binds[E], current_function);
+		for (const KeyValue<StringName, IdentifierNode *> &E : branch->patterns[0]->binds) {
+			SuiteNode::Local local(E.value, current_function);
 			local.type = SuiteNode::Local::PATTERN_BIND;
 			suite->add_local(local);
 		}
@@ -3566,14 +3561,15 @@ bool GDScriptParser::export_annotations(const AnnotationNode *p_annotation, Node
 				variable->export_info.hint = PROPERTY_HINT_ENUM;
 
 				String enum_hint_string;
-				for (OrderedHashMap<StringName, int>::Element E = export_type.enum_values.front(); E; E = E.next()) {
-					enum_hint_string += E.key().operator String().capitalize().xml_escape();
-					enum_hint_string += ":";
-					enum_hint_string += String::num_int64(E.value()).xml_escape();
-
-					if (E.next()) {
+				bool first = true;
+				for (const KeyValue<StringName, int> &E : export_type.enum_values) {
+					if (!first) {
 						enum_hint_string += ",";
+						first = false;
 					}
+					enum_hint_string += E.key.operator String().capitalize().xml_escape();
+					enum_hint_string += ":";
+					enum_hint_string += String::num_int64(E.value).xml_escape();
 				}
 
 				variable->export_info.hint_string = enum_hint_string;
diff --git a/modules/gdscript/gdscript_parser.h b/modules/gdscript/gdscript_parser.h
index ab05ac5f51..857e06440c 100644
--- a/modules/gdscript/gdscript_parser.h
+++ b/modules/gdscript/gdscript_parser.h
@@ -132,7 +132,7 @@ public:
 		ClassNode *class_type = nullptr;
 
 		MethodInfo method_info; // For callable/signals.
-		OrderedHashMap<StringName, int> enum_values; // For enums.
+		HashMap<StringName, int> enum_values; // For enums.
 
 		_FORCE_INLINE_ bool is_set() const { return kind != UNRESOLVED; }
 		_FORCE_INLINE_ bool has_no_type() const { return type_source == UNDETECTED; }
diff --git a/modules/gdscript/language_server/gdscript_extend_parser.cpp b/modules/gdscript/language_server/gdscript_extend_parser.cpp
index 5516f59fe9..bc1f001d86 100644
--- a/modules/gdscript/language_server/gdscript_extend_parser.cpp
+++ b/modules/gdscript/language_server/gdscript_extend_parser.cpp
@@ -89,16 +89,16 @@ void ExtendGDScriptParser::update_symbols() {
 
 		for (int i = 0; i < class_symbol.children.size(); i++) {
 			const lsp::DocumentSymbol &symbol = class_symbol.children[i];
-			members.set(symbol.name, &symbol);
+			members.insert(symbol.name, &symbol);
 
 			// cache level one inner classes
 			if (symbol.kind == lsp::SymbolKind::Class) {
 				ClassMembers inner_class;
 				for (int j = 0; j < symbol.children.size(); j++) {
 					const lsp::DocumentSymbol &s = symbol.children[j];
-					inner_class.set(s.name, &s);
+					inner_class.insert(s.name, &s);
 				}
-				inner_classes.set(symbol.name, inner_class);
+				inner_classes.insert(symbol.name, inner_class);
 			}
 		}
 	}
@@ -661,30 +661,22 @@ const List<lsp::DocumentLink> &ExtendGDScriptParser::get_document_links() const
 
 const Array &ExtendGDScriptParser::get_member_completions() {
 	if (member_completions.is_empty()) {
-		const String *name = members.next(nullptr);
-		while (name) {
-			const lsp::DocumentSymbol *symbol = members.get(*name);
+		for (const KeyValue<String, const lsp::DocumentSymbol *> &E : members) {
+			const lsp::DocumentSymbol *symbol = E.value;
 			lsp::CompletionItem item = symbol->make_completion_item();
-			item.data = JOIN_SYMBOLS(path, *name);
+			item.data = JOIN_SYMBOLS(path, E.key);
 			member_completions.push_back(item.to_json());
-
-			name = members.next(name);
 		}
 
-		const String *_class = inner_classes.next(nullptr);
-		while (_class) {
-			const ClassMembers *inner_class = inner_classes.getptr(*_class);
-			const String *member_name = inner_class->next(nullptr);
-			while (member_name) {
-				const lsp::DocumentSymbol *symbol = inner_class->get(*member_name);
+		for (const KeyValue<String, ClassMembers> &E : inner_classes) {
+			const ClassMembers *inner_class = &E.value;
+
+			for (const KeyValue<String, const lsp::DocumentSymbol *> &F : *inner_class) {
+				const lsp::DocumentSymbol *symbol = F.value;
 				lsp::CompletionItem item = symbol->make_completion_item();
-				item.data = JOIN_SYMBOLS(path, JOIN_SYMBOLS(*_class, *member_name));
+				item.data = JOIN_SYMBOLS(path, JOIN_SYMBOLS(E.key, F.key));
 				member_completions.push_back(item.to_json());
-
-				member_name = inner_class->next(member_name);
 			}
-
-			_class = inner_classes.next(_class);
 		}
 	}
 
diff --git a/modules/gdscript/language_server/gdscript_language_protocol.cpp b/modules/gdscript/language_server/gdscript_language_protocol.cpp
index cdddab319d..7460f8edff 100644
--- a/modules/gdscript/language_server/gdscript_language_protocol.cpp
+++ b/modules/gdscript/language_server/gdscript_language_protocol.cpp
@@ -126,7 +126,7 @@ Error GDScriptLanguageProtocol::on_client_connected() {
 	ERR_FAIL_COND_V_MSG(clients.size() >= LSP_MAX_CLIENTS, FAILED, "Max client limits reached");
 	Ref<LSPeer> peer = memnew(LSPeer);
 	peer->connection = tcp_peer;
-	clients.set(next_client_id, peer);
+	clients.insert(next_client_id, peer);
 	next_client_id++;
 	EditorNode::get_log()->add_message("[LSP] Connection Taken", EditorLog::MSG_TYPE_EDITOR);
 	return OK;
@@ -229,28 +229,33 @@ void GDScriptLanguageProtocol::poll() {
 	if (server->is_connection_available()) {
 		on_client_connected();
 	}
-	const int *id = nullptr;
-	while ((id = clients.next(id))) {
-		Ref<LSPeer> peer = clients.get(*id);
+
+	HashMap<int, Ref<LSPeer>>::Iterator E = clients.begin();
+	while (E != clients.end()) {
+		Ref<LSPeer> peer = E->value;
 		StreamPeerTCP::Status status = peer->connection->get_status();
 		if (status == StreamPeerTCP::STATUS_NONE || status == StreamPeerTCP::STATUS_ERROR) {
-			on_client_disconnected(*id);
-			id = nullptr;
+			on_client_disconnected(E->key);
+			E = clients.begin();
+			continue;
 		} else {
 			if (peer->connection->get_available_bytes() > 0) {
-				latest_client_id = *id;
+				latest_client_id = E->key;
 				Error err = peer->handle_data();
 				if (err != OK && err != ERR_BUSY) {
-					on_client_disconnected(*id);
-					id = nullptr;
+					on_client_disconnected(E->key);
+					E = clients.begin();
+					continue;
 				}
 			}
 			Error err = peer->send_data();
 			if (err != OK && err != ERR_BUSY) {
-				on_client_disconnected(*id);
-				id = nullptr;
+				on_client_disconnected(E->key);
+				E = clients.begin();
+				continue;
 			}
 		}
+		++E;
 	}
 }
 
@@ -259,9 +264,8 @@ Error GDScriptLanguageProtocol::start(int p_port, const IPAddress &p_bind_ip) {
 }
 
 void GDScriptLanguageProtocol::stop() {
-	const int *id = nullptr;
-	while ((id = clients.next(id))) {
-		Ref<LSPeer> peer = clients.get(*id);
+	for (const KeyValue<int, Ref<LSPeer>> &E : clients) {
+		Ref<LSPeer> peer = clients.get(E.key);
 		peer->connection->disconnect_from_host();
 	}
 
diff --git a/modules/gdscript/language_server/gdscript_text_document.cpp b/modules/gdscript/language_server/gdscript_text_document.cpp
index c42bd58aeb..1f02943480 100644
--- a/modules/gdscript/language_server/gdscript_text_document.cpp
+++ b/modules/gdscript/language_server/gdscript_text_document.cpp
@@ -109,23 +109,15 @@ void GDScriptTextDocument::notify_client_show_symbol(const lsp::DocumentSymbol *
 
 void GDScriptTextDocument::initialize() {
 	if (GDScriptLanguageProtocol::get_singleton()->is_smart_resolve_enabled()) {
-		const HashMap<StringName, ClassMembers> &native_members = GDScriptLanguageProtocol::get_singleton()->get_workspace()->native_members;
+		for (const KeyValue<StringName, ClassMembers> &E : GDScriptLanguageProtocol::get_singleton()->get_workspace()->native_members) {
+			const ClassMembers &members = E.value;
 
-		const StringName *class_ptr = native_members.next(nullptr);
-		while (class_ptr) {
-			const ClassMembers &members = native_members.get(*class_ptr);
-
-			const String *name = members.next(nullptr);
-			while (name) {
-				const lsp::DocumentSymbol *symbol = members.get(*name);
+			for (const KeyValue<String, const lsp::DocumentSymbol *> &F : members) {
+				const lsp::DocumentSymbol *symbol = members.get(F.key);
 				lsp::CompletionItem item = symbol->make_completion_item();
-				item.data = JOIN_SYMBOLS(String(*class_ptr), *name);
+				item.data = JOIN_SYMBOLS(String(E.key), F.key);
 				native_member_completions.push_back(item.to_json());
-
-				name = members.next(name);
 			}
-
-			class_ptr = native_members.next(class_ptr);
 		}
 	}
 }
diff --git a/modules/gdscript/language_server/gdscript_workspace.cpp b/modules/gdscript/language_server/gdscript_workspace.cpp
index 89ee6b35e5..378dc6d04b 100644
--- a/modules/gdscript/language_server/gdscript_workspace.cpp
+++ b/modules/gdscript/language_server/gdscript_workspace.cpp
@@ -404,9 +404,9 @@ Error GDScriptWorkspace::initialize() {
 			const lsp::DocumentSymbol &class_symbol = E.value;
 			for (int i = 0; i < class_symbol.children.size(); i++) {
 				const lsp::DocumentSymbol &symbol = class_symbol.children[i];
-				members.set(symbol.name, &symbol);
+				members.insert(symbol.name, &symbol);
 			}
-			native_members.set(E.key, members);
+			native_members.insert(E.key, members);
 		}
 
 		// cache member completions
@@ -682,13 +682,11 @@ void GDScriptWorkspace::resolve_related_symbols(const lsp::TextDocumentPositionP
 		Vector2i offset;
 		symbol_identifier = parser->get_identifier_under_position(p_doc_pos.position, offset);
 
-		const StringName *class_ptr = native_members.next(nullptr);
-		while (class_ptr) {
-			const ClassMembers &members = native_members.get(*class_ptr);
+		for (const KeyValue<StringName, ClassMembers> &E : native_members) {
+			const ClassMembers &members = native_members.get(E.key);
 			if (const lsp::DocumentSymbol *const *symbol = members.getptr(symbol_identifier)) {
 				r_list.push_back(*symbol);
 			}
-			class_ptr = native_members.next(class_ptr);
 		}
 
 		for (const KeyValue<String, ExtendGDScriptParser *> &E : scripts) {
@@ -698,15 +696,11 @@ void GDScriptWorkspace::resolve_related_symbols(const lsp::TextDocumentPositionP
 				r_list.push_back(*symbol);
 			}
 
-			const HashMap<String, ClassMembers> &inner_classes = script->get_inner_classes();
-			const String *_class = inner_classes.next(nullptr);
-			while (_class) {
-				const ClassMembers *inner_class = inner_classes.getptr(*_class);
+			for (const KeyValue<String, ClassMembers> &F : script->get_inner_classes()) {
+				const ClassMembers *inner_class = &F.value;
 				if (const lsp::DocumentSymbol *const *symbol = inner_class->getptr(symbol_identifier)) {
 					r_list.push_back(*symbol);
 				}
-
-				_class = inner_classes.next(_class);
 			}
 		}
 	}
diff --git a/modules/gdscript/tests/gdscript_test_runner.cpp b/modules/gdscript/tests/gdscript_test_runner.cpp
index ea51990237..71dc5de7e4 100644
--- a/modules/gdscript/tests/gdscript_test_runner.cpp
+++ b/modules/gdscript/tests/gdscript_test_runner.cpp
@@ -48,11 +48,11 @@
 namespace GDScriptTests {
 
 void init_autoloads() {
-	OrderedHashMap<StringName, ProjectSettings::AutoloadInfo> autoloads = ProjectSettings::get_singleton()->get_autoload_list();
+	HashMap<StringName, ProjectSettings::AutoloadInfo> autoloads = ProjectSettings::get_singleton()->get_autoload_list();
 
 	// First pass, add the constants so they exist before any script is loaded.
-	for (OrderedHashMap<StringName, ProjectSettings::AutoloadInfo>::Element E = autoloads.front(); E; E = E.next()) {
-		const ProjectSettings::AutoloadInfo &info = E.get();
+	for (const KeyValue<StringName, ProjectSettings::AutoloadInfo> &E : ProjectSettings::get_singleton()->get_autoload_list()) {
+		const ProjectSettings::AutoloadInfo &info = E.value;
 
 		if (info.is_singleton) {
 			for (int i = 0; i < ScriptServer::get_language_count(); i++) {
@@ -62,8 +62,8 @@ void init_autoloads() {
 	}
 
 	// Second pass, load into global constants.
-	for (OrderedHashMap<StringName, ProjectSettings::AutoloadInfo>::Element E = autoloads.front(); E; E = E.next()) {
-		const ProjectSettings::AutoloadInfo &info = E.get();
+	for (const KeyValue<StringName, ProjectSettings::AutoloadInfo> &E : ProjectSettings::get_singleton()->get_autoload_list()) {
+		const ProjectSettings::AutoloadInfo &info = E.value;
 
 		if (!info.is_singleton) {
 			// Skip non-singletons since we don't have a scene tree here anyway.