Godot 4 source code analysis - code auto-completion process

In the process of using Godot 4, there is one thing that attracts me: code auto-completion

When developing with RAD, the code auto-completion function has been complained about, mainly because of the slow speed

But I see that in the script writing process in Godot 4, the code completion is very fast, this can be studied.

The research code can be found, and the code completion triggers the process

1) Create a clock code_complete_timer in CodeTextEditor, and its timeout timeout signal is bound to the _code_complete_timer_timeout function. The default value of timeout is 0.3, and the unit should be seconds.

	code_complete_timer = memnew(Timer);
	add_child(code_complete_timer);
	code_complete_timer->set_one_shot(true);
	code_complete_timer->set_wait_time(EDITOR_GET("text_editor/completion/code_complete_delay"));
    ...
    code_complete_timer->connect("timeout", callable_mp(this, &CodeTextEditor::_code_complete_timer_timeout));

2) When the text in the editor changes, CodeTextEditor::_text_changed is triggered, and the clock code_complete_timer starts timing.

void CodeTextEditor::_text_changed() {
	if (text_editor->is_insert_text_operation()) {
		code_complete_timer_line = text_editor->get_caret_line();
		code_complete_timer->start();
	}

	idle->start();

	if (find_replace_bar) {
		find_replace_bar->needs_to_count_results = true;
	}
}

And the _line_col_changed function (bound caret_changed event) will stop the clock.

void CodeTextEditor::_line_col_changed() {
	if (!code_complete_timer->is_stopped() && code_complete_timer_line != text_editor->get_caret_line()) {
		code_complete_timer->stop();
	}

	String line = text_editor->get_line(text_editor->get_caret_line());

	int positional_column = 0;
	for (int i = 0; i < text_editor->get_caret_column(); i++) {
		if (line[i] == '\t') {
			positional_column += text_editor->get_indent_size(); //tab size
		} else {
			positional_column += 1;
		}
	}

	StringBuilder sb;
	sb.append(itos(text_editor->get_caret_line() + 1).lpad(4));
	sb.append(" : ");
	sb.append(itos(positional_column + 1).lpad(3));

	line_and_col_txt->set_text(sb.as_string());

	if (find_replace_bar) {
		if (!find_replace_bar->line_col_changed_for_result) {
			find_replace_bar->needs_to_count_results = true;
		}

		find_replace_bar->line_col_changed_for_result = false;
	}
}

3) If the clock is not suspended within the timeout period after the clock is started, the timeout signal will be triggered and _code_complete_timer_timeout will be called

void CodeTextEditor::_code_complete_timer_timeout() {
	if (!is_visible_in_tree()) {
		return;
	}
	text_editor->request_code_completion();
}

Signal code_completion_requested in the CodeEdit::request_code_completion function

void CodeEdit::request_code_completion(bool p_force) {
	if (GDVIRTUAL_CALL(_request_code_completion, p_force)) {
		return;
	}

	/* Don't re-query if all existing options are quoted types, eg path, signal. */
	bool ignored = code_completion_active && !code_completion_options.is_empty();
	if (ignored) {
		ScriptLanguage::CodeCompletionKind kind = ScriptLanguage::CODE_COMPLETION_KIND_PLAIN_TEXT;
		const ScriptLanguage::CodeCompletionOption *previous_option = nullptr;
		for (int i = 0; i < code_completion_options.size(); i++) {
			const ScriptLanguage::CodeCompletionOption &current_option = code_completion_options[i];
			if (!previous_option) {
				previous_option = &current_option;
				kind = current_option.kind;
			}
			if (previous_option->kind != current_option.kind) {
				ignored = false;
				break;
			}
		}
		ignored = ignored && (kind == ScriptLanguage::CODE_COMPLETION_KIND_FILE_PATH || kind == ScriptLanguage::CODE_COMPLETION_KIND_NODE_PATH || kind == ScriptLanguage::CODE_COMPLETION_KIND_SIGNAL);
	}

	if (ignored) {
		return;
	}

	if (p_force) {
		emit_signal(SNAME("code_completion_requested"));
		return;
	}

	String line = get_line(get_caret_line());
	int ofs = CLAMP(get_caret_column(), 0, line.length());

	if (ofs > 0 && (is_in_string(get_caret_line(), ofs) != -1 || !is_symbol(line[ofs - 1]) || code_completion_prefixes.has(line[ofs - 1]))) {
		emit_signal(SNAME("code_completion_requested"));
	} else if (ofs > 1 && line[ofs - 1] == ' ' && code_completion_prefixes.has(line[ofs - 2])) {
		emit_signal(SNAME("code_completion_requested"));
	}
}

The signal code_completion_requested is bound to the function _complete_request, which calls the proxy function code_complete_func for processing

void CodeTextEditor::_complete_request() {
	List<ScriptLanguage::CodeCompletionOption> entries;
	String ctext = text_editor->get_text_for_code_completion();
	_code_complete_script(ctext, &entries);
	bool forced = false;
	if (code_complete_func) {
		code_complete_func(code_complete_ud, ctext, &entries, forced);
	}
	if (entries.size() == 0) {
		return;
	}

	for (const ScriptLanguage::CodeCompletionOption &e : entries) {
		Color font_color = completion_font_color;
		if (e.insert_text.begins_with("\"") || e.insert_text.begins_with("\'")) {
			font_color = completion_string_color;
		} else if (e.insert_text.begins_with("#") || e.insert_text.begins_with("//")) {
			font_color = completion_comment_color;
		}
		text_editor->add_code_completion_option((CodeEdit::CodeCompletionKind)e.kind, e.display, e.insert_text, font_color, _get_completion_icon(e), e.default_value);
	}
	text_editor->update_code_completion_options(forced);
}

For the Script editor, code_complete_func points to ScriptTextEditor::_code_complete_scripts, essentially calling the GDScriptLanguage::complete_code function

void ScriptTextEditor::_code_complete_script(const String &p_code, List<ScriptLanguage::CodeCompletionOption> *r_options, bool &r_force) {
	if (color_panel->is_visible()) {
		return;
	}
	Node *base = get_tree()->get_edited_scene_root();
	if (base) {
		base = _find_node_for_script(base, base, script);
	}
	String hint;
	Error err = script->get_language()->complete_code(p_code, script->get_path(), base, r_options, r_force, hint);

	r_options->sort_custom_inplace<CodeCompletionOptionCompare>();

	if (err == OK) {
		code_editor->get_text_editor()->set_code_hint(hint);
	}
}

In GDScriptLanguage::complete_code, perform code analysis and semantic analysis to obtain candidate codes that meet the conditions

::Error GDScriptLanguage::complete_code(const String &p_code, const String &p_path, Object *p_owner, List<ScriptLanguage::CodeCompletionOption> *r_options, bool &r_forced, String &r_call_hint) {
	const String quote_style = EDITOR_GET("text_editor/completion/use_single_quotes") ? "'" : "\"";

	GDScriptParser parser;
	GDScriptAnalyzer analyzer(&parser);

	parser.parse(p_code, p_path, true);
	analyzer.analyze();

	r_forced = false;
	HashMap<String, ScriptLanguage::CodeCompletionOption> options;

	GDScriptParser::CompletionContext completion_context = parser.get_completion_context();
	completion_context.base = p_owner;
	bool is_function = false;

	switch (completion_context.type) {
		case GDScriptParser::COMPLETION_NONE:
			break;
		case GDScriptParser::COMPLETION_ANNOTATION: {
			List<MethodInfo> annotations;
			parser.get_annotation_list(&annotations);
			for (const MethodInfo &E : annotations) {
				ScriptLanguage::CodeCompletionOption option(E.name.substr(1), ScriptLanguage::CODE_COMPLETION_KIND_PLAIN_TEXT);
				if (E.arguments.size() > 0) {
					option.insert_text += "(";
				}
				options.insert(option.display, option);
			}
			r_forced = true;
		} break;
		case GDScriptParser::COMPLETION_ANNOTATION_ARGUMENTS: {
			if (completion_context.node == nullptr || completion_context.node->type != GDScriptParser::Node::ANNOTATION) {
				break;
			}
			const GDScriptParser::AnnotationNode *annotation = static_cast<const GDScriptParser::AnnotationNode *>(completion_context.node);
			_find_annotation_arguments(annotation, completion_context.current_argument, quote_style, options);
			r_forced = true;
		} break;
		case GDScriptParser::COMPLETION_BUILT_IN_TYPE_CONSTANT_OR_STATIC_METHOD: {
			// Constants.
			{
				List<StringName> constants;
				Variant::get_constants_for_type(completion_context.builtin_type, &constants);
				for (const StringName &E : constants) {
					ScriptLanguage::CodeCompletionOption option(E, ScriptLanguage::CODE_COMPLETION_KIND_CONSTANT);
					bool valid = false;
					Variant default_value = Variant::get_constant_value(completion_context.builtin_type, E, &valid);
					if (valid) {
						option.default_value = default_value;
					}
					options.insert(option.display, option);
				}
			}
			// Methods.
			{
				List<StringName> methods;
				Variant::get_builtin_method_list(completion_context.builtin_type, &methods);
				for (const StringName &E : methods) {
					if (Variant::is_builtin_method_static(completion_context.builtin_type, E)) {
						ScriptLanguage::CodeCompletionOption option(E, ScriptLanguage::CODE_COMPLETION_KIND_FUNCTION);
						if (Variant::get_builtin_method_argument_count(completion_context.builtin_type, E) > 0 || Variant::is_builtin_method_vararg(completion_context.builtin_type, E)) {
							option.insert_text += "(";
						} else {
							option.insert_text += "()";
						}
						options.insert(option.display, option);
					}
				}
			}
		} break;
		case GDScriptParser::COMPLETION_INHERIT_TYPE: {
			_list_available_types(true, completion_context, options);
			r_forced = true;
		} break;
		case GDScriptParser::COMPLETION_TYPE_NAME_OR_VOID: {
			ScriptLanguage::CodeCompletionOption option("void", ScriptLanguage::CODE_COMPLETION_KIND_PLAIN_TEXT);
			options.insert(option.display, option);
		}
			[[fallthrough]];
		case GDScriptParser::COMPLETION_TYPE_NAME: {
			_list_available_types(false, completion_context, options);
			r_forced = true;
		} break;
		case GDScriptParser::COMPLETION_PROPERTY_DECLARATION_OR_TYPE: {
			_list_available_types(false, completion_context, options);
			ScriptLanguage::CodeCompletionOption get("get", ScriptLanguage::CODE_COMPLETION_KIND_PLAIN_TEXT);
			options.insert(get.display, get);
			ScriptLanguage::CodeCompletionOption set("set", ScriptLanguage::CODE_COMPLETION_KIND_PLAIN_TEXT);
			options.insert(set.display, set);
			r_forced = true;
		} break;
		case GDScriptParser::COMPLETION_PROPERTY_DECLARATION: {
			ScriptLanguage::CodeCompletionOption get("get", ScriptLanguage::CODE_COMPLETION_KIND_PLAIN_TEXT);
			options.insert(get.display, get);
			ScriptLanguage::CodeCompletionOption set("set", ScriptLanguage::CODE_COMPLETION_KIND_PLAIN_TEXT);
			options.insert(set.display, set);
			r_forced = true;
		} break;
		case GDScriptParser::COMPLETION_PROPERTY_METHOD: {
			if (!completion_context.current_class) {
				break;
			}
			for (int i = 0; i < completion_context.current_class->members.size(); i++) {
				const GDScriptParser::ClassNode::Member &member = completion_context.current_class->members[i];
				if (member.type != GDScriptParser::ClassNode::Member::FUNCTION) {
					continue;
				}
				if (member.function->is_static) {
					continue;
				}
				ScriptLanguage::CodeCompletionOption option(member.function->identifier->name, ScriptLanguage::CODE_COMPLETION_KIND_FUNCTION);
				options.insert(option.display, option);
			}
			r_forced = true;
		} break;
		case GDScriptParser::COMPLETION_ASSIGN: {
			GDScriptCompletionIdentifier type;
			if (!completion_context.node || completion_context.node->type != GDScriptParser::Node::ASSIGNMENT) {
				break;
			}
			if (!_guess_expression_type(completion_context, static_cast<const GDScriptParser::AssignmentNode *>(completion_context.node)->assignee, type)) {
				_find_identifiers(completion_context, false, options, 0);
				r_forced = true;
				break;
			}

			if (!type.enumeration.is_empty()) {
				_find_enumeration_candidates(completion_context, type.enumeration, options);
				r_forced = options.size() > 0;
			} else {
				_find_identifiers(completion_context, false, options, 0);
				r_forced = true;
			}
		} break;
		case GDScriptParser::COMPLETION_METHOD:
			is_function = true;
			[[fallthrough]];
		case GDScriptParser::COMPLETION_IDENTIFIER: {
			_find_identifiers(completion_context, is_function, options, 0);
		} break;
		case GDScriptParser::COMPLETION_ATTRIBUTE_METHOD:
			is_function = true;
			[[fallthrough]];
		case GDScriptParser::COMPLETION_ATTRIBUTE: {
			r_forced = true;
			const GDScriptParser::SubscriptNode *attr = static_cast<const GDScriptParser::SubscriptNode *>(completion_context.node);
			if (attr->base) {
				GDScriptCompletionIdentifier base;
				bool found_type = _get_subscript_type(completion_context, attr, base.type);
				if (!found_type && !_guess_expression_type(completion_context, attr->base, base)) {
					break;
				}

				_find_identifiers_in_base(base, is_function, options, 0);
			}
		} break;
		case GDScriptParser::COMPLETION_SUBSCRIPT: {
			const GDScriptParser::SubscriptNode *subscript = static_cast<const GDScriptParser::SubscriptNode *>(completion_context.node);
			GDScriptCompletionIdentifier base;
			if (!_guess_expression_type(completion_context, subscript->base, base)) {
				break;
			}

			_find_identifiers_in_base(base, false, options, 0);
		} break;
		case GDScriptParser::COMPLETION_TYPE_ATTRIBUTE: {
			if (!completion_context.current_class) {
				break;
			}
			const GDScriptParser::TypeNode *type = static_cast<const GDScriptParser::TypeNode *>(completion_context.node);
			bool found = true;
			GDScriptCompletionIdentifier base;
			base.type.kind = GDScriptParser::DataType::CLASS;
			base.type.type_source = GDScriptParser::DataType::INFERRED;
			base.type.is_constant = true;
			base.type.class_type = completion_context.current_class;
			base.value = completion_context.base;

			for (int i = 0; i < completion_context.current_argument; i++) {
				GDScriptCompletionIdentifier ci;
				if (!_guess_identifier_type_from_base(completion_context, base, type->type_chain[i]->name, ci)) {
					found = false;
					break;
				}
				base = ci;
			}

			// TODO: Improve this to only list types.
			if (found) {
				_find_identifiers_in_base(base, false, options, 0);
			}
			r_forced = true;
		} break;
		case GDScriptParser::COMPLETION_RESOURCE_PATH: {
			if (EDITOR_GET("text_editor/completion/complete_file_paths")) {
				_get_directory_contents(EditorFileSystem::get_singleton()->get_filesystem(), options);
				r_forced = true;
			}
		} break;
		case GDScriptParser::COMPLETION_CALL_ARGUMENTS: {
			if (!completion_context.node) {
				break;
			}
			_find_call_arguments(completion_context, completion_context.node, completion_context.current_argument, options, r_forced, r_call_hint);
		} break;
		case GDScriptParser::COMPLETION_OVERRIDE_METHOD: {
			GDScriptParser::DataType native_type = completion_context.current_class->base_type;
			while (native_type.is_set() && native_type.kind != GDScriptParser::DataType::NATIVE) {
				switch (native_type.kind) {
					case GDScriptParser::DataType::CLASS: {
						native_type = native_type.class_type->base_type;
					} break;
					default: {
						native_type.kind = GDScriptParser::DataType::UNRESOLVED;
					} break;
				}
			}

			if (!native_type.is_set()) {
				break;
			}

			StringName class_name = native_type.native_type;
			if (!ClassDB::class_exists(class_name)) {
				break;
			}

			bool use_type_hint = EditorSettings::get_singleton()->get_setting("text_editor/completion/add_type_hints").operator bool();

			List<MethodInfo> virtual_methods;
			ClassDB::get_virtual_methods(class_name, &virtual_methods);
			for (const MethodInfo &mi : virtual_methods) {
				String method_hint = mi.name;
				if (method_hint.contains(":")) {
					method_hint = method_hint.get_slice(":", 0);
				}
				method_hint += "(";

				if (mi.arguments.size()) {
					for (int i = 0; i < mi.arguments.size(); i++) {
						if (i > 0) {
							method_hint += ", ";
						}
						String arg = mi.arguments[i].name;
						if (arg.contains(":")) {
							arg = arg.substr(0, arg.find(":"));
						}
						method_hint += arg;
						if (use_type_hint && mi.arguments[i].type != Variant::NIL) {
							method_hint += ": ";
							if (mi.arguments[i].type == Variant::OBJECT && mi.arguments[i].class_name != StringName()) {
								method_hint += mi.arguments[i].class_name.operator String();
							} else {
								method_hint += Variant::get_type_name(mi.arguments[i].type);
							}
						}
					}
				}
				method_hint += ")";
				if (use_type_hint && (mi.return_val.type != Variant::NIL || !(mi.return_val.usage & PROPERTY_USAGE_NIL_IS_VARIANT))) {
					method_hint += " -> ";
					if (mi.return_val.type == Variant::NIL) {
						method_hint += "void";
					} else if (mi.return_val.type == Variant::OBJECT && mi.return_val.class_name != StringName()) {
						method_hint += mi.return_val.class_name.operator String();
					} else {
						method_hint += Variant::get_type_name(mi.return_val.type);
					}
				}
				method_hint += ":";

				ScriptLanguage::CodeCompletionOption option(method_hint, ScriptLanguage::CODE_COMPLETION_KIND_FUNCTION);
				options.insert(option.display, option);
			}
		} break;
		case GDScriptParser::COMPLETION_GET_NODE: {
			// Handles the `$Node/Path` or `$"Some NodePath"` syntax specifically.
			if (p_owner) {
				List<String> opts;
				p_owner->get_argument_options("get_node", 0, &opts);

				for (const String &E : opts) {
					r_forced = true;
					String opt = E.strip_edges();
					if (opt.is_quoted()) {
						// Remove quotes so that we can handle user preferred quote style,
						// or handle NodePaths which are valid identifiers and don't need quotes.
						opt = opt.unquote();
					}
					// The path needs quotes if it's not a valid identifier (with an exception
					// for "/" as path separator, which also doesn't require quotes).
					if (!opt.replace("/", "_").is_valid_identifier()) {
						// Ignore quote_style and just use double quotes for paths with apostrophes.
						// Double quotes don't need to be checked because they're not valid in node and property names.
						opt = opt.quote(opt.contains("'") ? "\"" : quote_style); // Handle user preference.
					}
					ScriptLanguage::CodeCompletionOption option(opt, ScriptLanguage::CODE_COMPLETION_KIND_NODE_PATH);
					options.insert(option.display, option);
				}

				// Get autoloads.
				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);
				}
			}
		} break;
		case GDScriptParser::COMPLETION_SUPER_METHOD: {
			if (!completion_context.current_class) {
				break;
			}
			_find_identifiers_in_class(completion_context.current_class, true, false, true, options, 0);
		} break;
	}

	for (const KeyValue<String, ScriptLanguage::CodeCompletionOption> &E : options) {
		r_options->push_back(E.value);
	}

	return OK;
}

After sorting

r_options->sort_custom_inplace<CodeCompletionOptionCompare>();

Then add it to the editor's code completion options collection

	for (const ScriptLanguage::CodeCompletionOption &e : entries) {
		Color font_color = completion_font_color;
		if (e.insert_text.begins_with("\"") || e.insert_text.begins_with("\'")) {
			font_color = completion_string_color;
		} else if (e.insert_text.begins_with("#") || e.insert_text.begins_with("//")) {
			font_color = completion_comment_color;
		}
		text_editor->add_code_completion_option((CodeEdit::CodeCompletionKind)e.kind, e.display, e.insert_text, font_color, _get_completion_icon(e), e.default_value);
	}
	text_editor->update_code_completion_options(forced);

According to the display logic, the code prompt interface appears

 Therefore, Godot code completion logic mainly focuses on its processing flow, code analysis, semantic analysis, candidate option processing, and display