Reduce and prevent unnecessary random-access to `List`

Random-access access to `List` when iterating is `O(n^2)` (`O(n)` when
accessing a single element)

* Removed subscript operator, in favor of a more explicit `get`
* Added conversion from `Iterator` to `ConstIterator`
* Remade existing operations into other solutions when applicable

5 files changed, 23 insertions, 22 deletions

diff --git a/editor/debugger/debug_adapter/debug_adapter_parser.cpp b/editor/debugger/debug_adapter/debug_adapter_parser.cpp
index b75e5c1c0d..3c0420d2f0 100644
--- a/editor/debugger/debug_adapter/debug_adapter_parser.cpp
+++ b/editor/debugger/debug_adapter/debug_adapter_parser.cpp
@@ -407,9 +407,10 @@ Dictionary DebugAdapterParser::req_scopes(const Dictionary &p_params) const {
 	HashMap<DAP::StackFrame, List<int>, DAP::StackFrame>::Iterator E = DebugAdapterProtocol::get_singleton()->stackframe_list.find(frame);
 	if (E) {
 		ERR_FAIL_COND_V(E->value.size() != 3, prepare_error_response(p_params, DAP::ErrorType::UNKNOWN));
-		for (int i = 0; i < 3; i++) {
+		List<int>::ConstIterator itr = E->value.begin();
+		for (int i = 0; i < 3; ++itr, ++i) {
 			DAP::Scope scope;
-			scope.variablesReference = E->value[i];
+			scope.variablesReference = *itr;
 			switch (i) {
 				case 0:
 					scope.name = "Locals";
diff --git a/editor/debugger/debug_adapter/debug_adapter_protocol.cpp b/editor/debugger/debug_adapter/debug_adapter_protocol.cpp
index c86ca7aaad..56cb3b6c73 100644
--- a/editor/debugger/debug_adapter/debug_adapter_protocol.cpp
+++ b/editor/debugger/debug_adapter/debug_adapter_protocol.cpp
@@ -967,7 +967,7 @@ void DebugAdapterProtocol::on_debug_stack_frame_var(const Array &p_data) {
 	List<int> scope_ids = stackframe_list.find(frame)->value;
 	ERR_FAIL_COND(scope_ids.size() != 3);
 	ERR_FAIL_INDEX(stack_var.type, 3);
-	int var_id = scope_ids[stack_var.type];
+	int var_id = scope_ids.get(stack_var.type);
 
 	DAP::Variable variable;
 
diff --git a/editor/debugger/editor_debugger_inspector.cpp b/editor/debugger/editor_debugger_inspector.cpp
index b2fd84d2ed..816bd6b72c 100644
--- a/editor/debugger/editor_debugger_inspector.cpp
+++ b/editor/debugger/editor_debugger_inspector.cpp
@@ -146,9 +146,9 @@ ObjectID EditorDebuggerInspector::add_object(const Array &p_arr) {
 	debug_obj->prop_list.clear();
 	int new_props_added = 0;
 	HashSet<String> changed;
-	for (int i = 0; i < obj.properties.size(); i++) {
-		PropertyInfo &pinfo = obj.properties[i].first;
-		Variant &var = obj.properties[i].second;
+	for (SceneDebuggerObject::SceneDebuggerProperty &property : obj.properties) {
+		PropertyInfo &pinfo = property.first;
+		Variant &var = property.second;
 
 		if (pinfo.type == Variant::OBJECT) {
 			if (var.get_type() == Variant::STRING) {
diff --git a/editor/debugger/editor_debugger_tree.cpp b/editor/debugger/editor_debugger_tree.cpp
index de2e51ee81..63053d2574 100644
--- a/editor/debugger/editor_debugger_tree.cpp
+++ b/editor/debugger/editor_debugger_tree.cpp
@@ -147,17 +147,16 @@ void EditorDebuggerTree::update_scene_tree(const SceneDebuggerTree *p_tree, int
 
 	// Nodes are in a flatten list, depth first. Use a stack of parents, avoid recursion.
 	List<Pair<TreeItem *, int>> parents;
-	for (int i = 0; i < p_tree->nodes.size(); i++) {
+	for (const SceneDebuggerTree::RemoteNode &node : p_tree->nodes) {
 		TreeItem *parent = nullptr;
 		if (parents.size()) { // Find last parent.
-			Pair<TreeItem *, int> &p = parents[0];
+			Pair<TreeItem *, int> &p = parents.front()->get();
 			parent = p.first;
 			if (!(--p.second)) { // If no child left, remove it.
 				parents.pop_front();
 			}
 		}
 		// Add this node.
-		const SceneDebuggerTree::RemoteNode &node = p_tree->nodes[i];
 		TreeItem *item = create_item(parent);
 		item->set_text(0, node.name);
 		if (node.scene_file_path.is_empty()) {
@@ -244,8 +243,8 @@ void EditorDebuggerTree::update_scene_tree(const SceneDebuggerTree *p_tree, int
 				item = parent;
 				parent = item->get_parent();
 				// Check if parent expects more children.
-				for (int j = 0; j < parents.size(); j++) {
-					if (parents[j].first == item) {
+				for (const Pair<TreeItem *, int> &pair : parents) {
+					if (pair.first == item) {
 						parent = nullptr;
 						break; // Might have more children.
 					}
@@ -326,8 +325,8 @@ void EditorDebuggerTree::_item_menu_id_pressed(int p_option) {
 			Ref<PackedScene> sd = memnew(PackedScene);
 			ResourceSaver::get_recognized_extensions(sd, &extensions);
 			file_dialog->clear_filters();
-			for (int i = 0; i < extensions.size(); i++) {
-				file_dialog->add_filter("*." + extensions[i], extensions[i].to_upper());
+			for (const String &extension : extensions) {
+				file_dialog->add_filter("*." + extension, extension.to_upper());
 			}
 
 			String filename = get_selected_path().get_file() + "." + extensions.front()->get().to_lower();
diff --git a/editor/debugger/script_editor_debugger.cpp b/editor/debugger/script_editor_debugger.cpp
index 2b880274f8..d5cf887a4e 100644
--- a/editor/debugger/script_editor_debugger.cpp
+++ b/editor/debugger/script_editor_debugger.cpp
@@ -440,13 +440,14 @@ void ScriptEditorDebugger::_parse_message(const String &p_msg, uint64_t p_thread
 
 		Array stack_dump_info;
 
-		for (int i = 0; i < stack.frames.size(); i++) {
+		int i = 0;
+		for (List<ScriptLanguage::StackInfo>::Iterator itr = stack.frames.begin(); itr != stack.frames.end(); ++itr, ++i) {
 			TreeItem *s = stack_dump->create_item(r);
 			Dictionary d;
 			d["frame"] = i;
-			d["file"] = stack.frames[i].file;
-			d["function"] = stack.frames[i].func;
-			d["line"] = stack.frames[i].line;
+			d["file"] = itr->file;
+			d["function"] = itr->func;
+			d["line"] = itr->line;
 			stack_dump_info.push_back(d);
 			s->set_metadata(0, d);
 
@@ -725,20 +726,20 @@ void ScriptEditorDebugger::_parse_message(const String &p_msg, uint64_t p_thread
 			metric.categories.push_back(frame_time);
 		}
 
-		for (int i = 0; i < frame.servers.size(); i++) {
-			const ServersDebugger::ServerInfo &srv = frame.servers[i];
+		for (const ServersDebugger::ServerInfo &srv : frame.servers) {
 			EditorProfiler::Metric::Category c;
 			const String name = srv.name;
 			c.name = EditorPropertyNameProcessor::get_singleton()->process_name(name, EditorPropertyNameProcessor::STYLE_CAPITALIZED);
 			c.items.resize(srv.functions.size());
 			c.total_time = 0;
 			c.signature = "categ::" + name;
-			for (int j = 0; j < srv.functions.size(); j++) {
+			int j = 0;
+			for (List<ServersDebugger::ServerFunctionInfo>::ConstIterator itr = srv.functions.begin(); itr != srv.functions.end(); ++itr, ++j) {
 				EditorProfiler::Metric::Category::Item item;
 				item.calls = 1;
 				item.line = 0;
-				item.name = srv.functions[j].name;
-				item.self = srv.functions[j].time;
+				item.name = itr->name;
+				item.self = itr->time;
 				item.total = item.self;
 				item.signature = "categ::" + name + "::" + item.name;
 				item.name = EditorPropertyNameProcessor::get_singleton()->process_name(item.name, EditorPropertyNameProcessor::STYLE_CAPITALIZED);