Documentation generation for GDScript

- ClassDoc added to GDScript and property reflection data were extracted
from parse tree

- GDScript comments are collected from tokenizer for documentation and
applied to the ClassDoc by the GDScript compiler

- private docs were excluded (name with underscore prefix and doesn't
have any doc comments)

- default values (of non exported vars), arguments are extraced from the
parser

- Integrated with GDScript 2.0 and new enums were added.

- merge conflicts fixed

13 files changed, 749 insertions, 20 deletions

diff --git a/modules/gdnative/nativescript/nativescript.h b/modules/gdnative/nativescript/nativescript.h
index 2aaa4be325..7f736bdea7 100644
--- a/modules/gdnative/nativescript/nativescript.h
+++ b/modules/gdnative/nativescript/nativescript.h
@@ -152,6 +152,13 @@ public:
 	virtual void set_source_code(const String &p_code) override;
 	virtual Error reload(bool p_keep_state = false) override;
 
+#ifdef TOOLS_ENABLED
+	virtual const Vector<DocData::ClassDoc> &get_documentation() const override {
+		static Vector<DocData::ClassDoc> docs;
+		return docs;
+	}
+#endif // TOOLS_ENABLED
+
 	virtual bool has_method(const StringName &p_method) const override;
 	virtual MethodInfo get_method_info(const StringName &p_method) const override;
 
diff --git a/modules/gdnative/pluginscript/pluginscript_script.h b/modules/gdnative/pluginscript/pluginscript_script.h
index 150de05e74..790e4d5ffb 100644
--- a/modules/gdnative/pluginscript/pluginscript_script.h
+++ b/modules/gdnative/pluginscript/pluginscript_script.h
@@ -97,6 +97,13 @@ public:
 	// TODO: load_source_code only allow utf-8 file, should handle bytecode as well ?
 	virtual Error load_source_code(const String &p_path);
 
+#ifdef TOOLS_ENABLED
+	virtual const Vector<DocData::ClassDoc> &get_documentation() const override {
+		static Vector<DocData::ClassDoc> docs;
+		return docs;
+	}
+#endif // TOOLS_ENABLED
+
 	virtual bool has_method(const StringName &p_method) const override;
 	virtual MethodInfo get_method_info(const StringName &p_method) const override;
 
diff --git a/modules/gdscript/gdscript.cpp b/modules/gdscript/gdscript.cpp
index 53602f7a9b..8524ec276a 100644
--- a/modules/gdscript/gdscript.cpp
+++ b/modules/gdscript/gdscript.cpp
@@ -39,6 +39,8 @@
 #include "core/io/file_access_encrypted.h"
 #include "core/os/file_access.h"
 #include "core/os/os.h"
+#include "editor/editor_help.h"
+#include "editor/plugins/script_editor_plugin.h"
 #include "gdscript_analyzer.h"
 #include "gdscript_cache.h"
 #include "gdscript_compiler.h"
@@ -231,7 +233,7 @@ void GDScript::_placeholder_erased(PlaceHolderScriptInstance *p_placeholder) {
 }
 #endif
 
-void GDScript::get_script_method_list(List<MethodInfo> *p_list) const {
+void GDScript::_get_script_method_list(List<MethodInfo> *r_list, bool p_include_base) const {
 	const GDScript *current = this;
 	while (current) {
 		for (const Map<StringName, GDScriptFunction *>::Element *E = current->member_functions.front(); E; E = E->next()) {
@@ -239,18 +241,29 @@ void GDScript::get_script_method_list(List<MethodInfo> *p_list) const {
 			MethodInfo mi;
 			mi.name = E->key();
 			for (int i = 0; i < func->get_argument_count(); i++) {
-				mi.arguments.push_back(func->get_argument_type(i));
+				PropertyInfo arginfo = func->get_argument_type(i);
+#if TOOLS_ENABLED
+				arginfo.name = func->get_argument_name(i);
+#endif
+				mi.arguments.push_back(arginfo);
 			}
 
 			mi.return_val = func->get_return_type();
-			p_list->push_back(mi);
+			r_list->push_back(mi);
+		}
+		if (!p_include_base) {
+			return;
 		}
 
 		current = current->_base;
 	}
 }
 
-void GDScript::get_script_property_list(List<PropertyInfo> *p_list) const {
+void GDScript::get_script_method_list(List<MethodInfo> *r_list) const {
+	_get_script_method_list(r_list, true);
+}
+
+void GDScript::_get_script_property_list(List<PropertyInfo> *r_list, bool p_include_base) const {
 	const GDScript *sptr = this;
 	List<PropertyInfo> props;
 
@@ -269,15 +282,22 @@ void GDScript::get_script_property_list(List<PropertyInfo> *p_list) const {
 		for (int i = 0; i < msort.size(); i++) {
 			props.push_front(sptr->member_info[msort[i].name]);
 		}
+		if (!p_include_base) {
+			break;
+		}
 
 		sptr = sptr->_base;
 	}
 
 	for (List<PropertyInfo>::Element *E = props.front(); E; E = E->next()) {
-		p_list->push_back(E->get());
+		r_list->push_back(E->get());
 	}
 }
 
+void GDScript::get_script_property_list(List<PropertyInfo> *r_list) const {
+	_get_script_property_list(r_list, true);
+}
+
 bool GDScript::has_method(const StringName &p_method) const {
 	return member_functions.has(p_method);
 }
@@ -383,6 +403,193 @@ void GDScript::_update_exports_values(Map<StringName, Variant> &values, List<Pro
 		propnames.push_back(E->get());
 	}
 }
+
+void GDScript::_add_doc(const DocData::ClassDoc &p_inner_class) {
+	if (_owner) {
+		_owner->_add_doc(p_inner_class);
+	} else {
+		for (int i = 0; i < docs.size(); i++) {
+			if (docs[i].name == p_inner_class.name) {
+				docs.remove(i);
+				break;
+			}
+		}
+		docs.append(p_inner_class);
+	}
+}
+
+void GDScript::_clear_doc() {
+	if (EditorHelp::get_doc_data() && EditorHelp::get_doc_data()->has_doc(doc.name)) {
+		EditorHelp::get_doc_data()->remove_doc(doc.name);
+		doc = DocData::ClassDoc();
+	}
+	docs.clear();
+}
+
+void GDScript::_update_doc() {
+	_clear_doc();
+
+	doc.script_path = "\"" + get_path().get_slice("://", 1) + "\"";
+	if (!name.empty()) {
+		doc.name = name;
+	} else {
+		doc.name = doc.script_path;
+	}
+
+	if (_owner) {
+		doc.name = _owner->doc.name + "." + doc.name;
+		doc.script_path = doc.script_path + "." + doc.name;
+	}
+
+	doc.is_script_doc = true;
+
+	if (base.is_valid() && base->is_valid()) {
+		if (base->doc.name != String()) {
+			doc.inherits = base->doc.name;
+		} else {
+			doc.inherits = base->get_instance_base_type();
+		}
+	} else if (native.is_valid()) {
+		doc.inherits = native->get_name();
+	}
+
+	doc.brief_description = doc_brief_description;
+	doc.description = doc_description;
+	doc.tutorials = doc_tutorials;
+
+	for (Map<String, DocData::EnumDoc>::Element *E = doc_enums.front(); E; E = E->next()) {
+		if (E->value().description != "") {
+			doc.enums[E->key()] = E->value().description;
+		}
+	}
+
+	List<MethodInfo> methods;
+	_get_script_method_list(&methods, false);
+	for (int i = 0; i < methods.size(); i++) {
+		// Ignore internal methods.
+		if (methods[i].name[0] == '@') {
+			continue;
+		}
+
+		DocData::MethodDoc method_doc;
+		const String &class_name = methods[i].name;
+		if (member_functions.has(class_name)) {
+			GDScriptFunction *fn = member_functions[class_name];
+
+			// Change class name if return type is script reference.
+			GDScriptDataType return_type = fn->get_return_type();
+			if (return_type.kind == GDScriptDataType::GDSCRIPT) {
+				methods[i].return_val.class_name = _get_gdscript_reference_class_name(Object::cast_to<GDScript>(return_type.script_type));
+			}
+
+			// Change class name if argumetn is script reference.
+			for (int j = 0; j < fn->get_argument_count(); j++) {
+				GDScriptDataType arg_type = fn->get_argument_type(j);
+				if (arg_type.kind == GDScriptDataType::GDSCRIPT) {
+					methods[i].arguments[j].class_name = _get_gdscript_reference_class_name(Object::cast_to<GDScript>(arg_type.script_type));
+				}
+			}
+		}
+		if (doc_functions.has(methods[i].name)) {
+			DocData::method_doc_from_methodinfo(method_doc, methods[i], doc_functions[methods[i].name]);
+		} else {
+			DocData::method_doc_from_methodinfo(method_doc, methods[i], String());
+		}
+		doc.methods.push_back(method_doc);
+	}
+
+	List<PropertyInfo> props;
+	_get_script_property_list(&props, false);
+	for (int i = 0; i < props.size(); i++) {
+		ScriptMemberInfo scr_member_info;
+		scr_member_info.propinfo = props[i];
+		scr_member_info.propinfo.usage |= PROPERTY_USAGE_NIL_IS_VARIANT;
+		if (member_indices.has(props[i].name)) {
+			const MemberInfo &mi = member_indices[props[i].name];
+			scr_member_info.setter = mi.setter;
+			scr_member_info.getter = mi.getter;
+			if (mi.data_type.kind == GDScriptDataType::GDSCRIPT) {
+				scr_member_info.propinfo.class_name = _get_gdscript_reference_class_name(
+						Object::cast_to<GDScript>(mi.data_type.script_type));
+			}
+		}
+		if (member_default_values.has(props[i].name)) {
+			scr_member_info.has_default_value = true;
+			scr_member_info.default_value = member_default_values[props[i].name];
+		}
+		if (doc_variables.has(props[i].name)) {
+			scr_member_info.doc_string = doc_variables[props[i].name];
+		}
+
+		DocData::PropertyDoc prop_doc;
+		DocData::property_doc_from_scriptmemberinfo(prop_doc, scr_member_info);
+		doc.properties.push_back(prop_doc);
+	}
+
+	List<MethodInfo> signals;
+	_get_script_signal_list(&signals, false);
+	for (int i = 0; i < signals.size(); i++) {
+		DocData::MethodDoc signal_doc;
+		if (doc_signals.has(signals[i].name)) {
+			DocData::signal_doc_from_methodinfo(signal_doc, signals[i], signals[i].name);
+		} else {
+			DocData::signal_doc_from_methodinfo(signal_doc, signals[i], String());
+		}
+		doc.signals.push_back(signal_doc);
+	}
+
+	for (Map<StringName, Variant>::Element *E = constants.front(); E; E = E->next()) {
+		if (subclasses.has(E->key())) {
+			continue;
+		}
+
+		// Enums.
+		bool is_enum = false;
+		if (E->value().get_type() == Variant::DICTIONARY) {
+			if (doc_enums.has(E->key())) {
+				is_enum = true;
+				for (int i = 0; i < doc_enums[E->key()].values.size(); i++) {
+					doc_enums[E->key()].values.write[i].enumeration = E->key();
+					doc.constants.push_back(doc_enums[E->key()].values[i]);
+				}
+			}
+		}
+		if (!is_enum && doc_enums.has("@unnamed_enums")) {
+			for (int i = 0; i < doc_enums["@unnamed_enums"].values.size(); i++) {
+				if (E->key() == doc_enums["@unnamed_enums"].values[i].name) {
+					is_enum = true;
+					DocData::ConstantDoc constant_doc;
+					constant_doc.enumeration = "@unnamed_enums";
+					DocData::constant_doc_from_variant(constant_doc, E->key(), E->value(), doc_enums["@unnamed_enums"].values[i].description);
+					doc.constants.push_back(constant_doc);
+					break;
+				}
+			}
+		}
+		if (!is_enum) {
+			DocData::ConstantDoc constant_doc;
+			String doc_description;
+			if (doc_constants.has(E->key())) {
+				doc_description = doc_constants[E->key()];
+			}
+			DocData::constant_doc_from_variant(constant_doc, E->key(), E->value(), doc_description);
+			doc.constants.push_back(constant_doc);
+		}
+	}
+
+	for (Map<StringName, Ref<GDScript>>::Element *E = subclasses.front(); E; E = E->next()) {
+		E->get()->_update_doc();
+	}
+
+	if (EditorHelp::get_doc_data()) {
+		EditorHelp::get_doc_data()->add_doc(doc);
+	}
+	if (ScriptEditor::get_singleton()) {
+		ScriptEditor::get_singleton()->update_doc(doc.name);
+	}
+
+	_add_doc(doc);
+}
 #endif
 
 bool GDScript::_update_exports(bool *r_err, bool p_recursive_call) {
@@ -638,6 +845,10 @@ Error GDScript::reload(bool p_keep_state) {
 	GDScriptCompiler compiler;
 	err = compiler.compile(&parser, this, p_keep_state);
 
+#if TOOLS_ENABLED
+	this->_update_doc();
+#endif
+
 	if (err) {
 		if (can_run) {
 			if (EngineDebugger::is_active()) {
@@ -911,7 +1122,7 @@ bool GDScript::has_script_signal(const StringName &p_signal) const {
 	return false;
 }
 
-void GDScript::get_script_signal_list(List<MethodInfo> *r_signals) const {
+void GDScript::_get_script_signal_list(List<MethodInfo> *r_list, bool p_include_base) const {
 	for (const Map<StringName, Vector<StringName>>::Element *E = _signals.front(); E; E = E->next()) {
 		MethodInfo mi;
 		mi.name = E->key();
@@ -920,20 +1131,43 @@ void GDScript::get_script_signal_list(List<MethodInfo> *r_signals) const {
 			arg.name = E->get()[i];
 			mi.arguments.push_back(arg);
 		}
-		r_signals->push_back(mi);
+		r_list->push_back(mi);
+	}
+
+	if (!p_include_base) {
+		return;
 	}
 
 	if (base.is_valid()) {
-		base->get_script_signal_list(r_signals);
+		base->get_script_signal_list(r_list);
 	}
 #ifdef TOOLS_ENABLED
 	else if (base_cache.is_valid()) {
-		base_cache->get_script_signal_list(r_signals);
+		base_cache->get_script_signal_list(r_list);
 	}
 
 #endif
 }
 
+void GDScript::get_script_signal_list(List<MethodInfo> *r_signals) const {
+	_get_script_signal_list(r_signals, true);
+}
+
+String GDScript::_get_gdscript_reference_class_name(const GDScript *p_gdscript) {
+	ERR_FAIL_NULL_V(p_gdscript, String());
+
+	String class_name;
+	while (p_gdscript) {
+		if (class_name == "") {
+			class_name = p_gdscript->get_script_class_name();
+		} else {
+			class_name = p_gdscript->get_script_class_name() + "." + class_name;
+		}
+		p_gdscript = p_gdscript->_owner;
+	}
+	return class_name;
+}
+
 GDScript::GDScript() :
 		script_list(this) {
 	valid = false;
@@ -1061,6 +1295,13 @@ GDScript::~GDScript() {
 
 	_save_orphaned_subclasses();
 
+#ifdef TOOLS_ENABLED
+	// Clearing inner class doc, script doc only cleared when the script source deleted.
+	if (_owner) {
+		_clear_doc();
+	}
+#endif
+
 #ifdef DEBUG_ENABLED
 	{
 		MutexLock lock(GDScriptLanguage::get_singleton()->lock);
diff --git a/modules/gdscript/gdscript.h b/modules/gdscript/gdscript.h
index b69a6e39c0..a7052914ba 100644
--- a/modules/gdscript/gdscript.h
+++ b/modules/gdscript/gdscript.h
@@ -36,6 +36,7 @@
 #include "core/io/resource_loader.h"
 #include "core/io/resource_saver.h"
 #include "core/object/script_language.h"
+#include "editor/doc_data.h"
 #include "gdscript_function.h"
 
 class GDScriptNativeClass : public Reference {
@@ -91,9 +92,7 @@ class GDScript : public Script {
 #ifdef TOOLS_ENABLED
 
 	Map<StringName, int> member_lines;
-
 	Map<StringName, Variant> member_default_values;
-
 	List<PropertyInfo> members_cache;
 	Map<StringName, Variant> member_default_values_cache;
 	Ref<GDScript> base_cache;
@@ -102,6 +101,20 @@ class GDScript : public Script {
 	bool placeholder_fallback_enabled;
 	void _update_exports_values(Map<StringName, Variant> &values, List<PropertyInfo> &propnames);
 
+	DocData::ClassDoc doc;
+	Vector<DocData::ClassDoc> docs;
+	String doc_brief_description;
+	String doc_description;
+	Vector<DocData::TutorialDoc> doc_tutorials;
+	Map<String, String> doc_functions;
+	Map<String, String> doc_variables;
+	Map<String, String> doc_constants;
+	Map<String, String> doc_signals;
+	Map<String, DocData::EnumDoc> doc_enums;
+	void _clear_doc();
+	void _update_doc();
+	void _add_doc(const DocData::ClassDoc &p_inner_class);
+
 #endif
 	Map<StringName, PropertyInfo> member_info;
 
@@ -141,6 +154,13 @@ class GDScript : public Script {
 	void _save_orphaned_subclasses();
 	void _init_rpc_methods_properties();
 
+	void _get_script_property_list(List<PropertyInfo> *r_list, bool p_include_base) const;
+	void _get_script_method_list(List<MethodInfo> *r_list, bool p_include_base) const;
+	void _get_script_signal_list(List<MethodInfo> *r_list, bool p_include_base) const;
+
+	// This method will map the class name from "Reference" to "MyClass.InnerClass".
+	static String _get_gdscript_reference_class_name(const GDScript *p_gdscript);
+
 protected:
 	bool _get(const StringName &p_name, Variant &r_ret) const;
 	bool _set(const StringName &p_name, const Variant &p_value);
@@ -191,6 +211,12 @@ public:
 	virtual void set_source_code(const String &p_code) override;
 	virtual void update_exports() override;
 
+#ifdef TOOLS_ENABLED
+	virtual const Vector<DocData::ClassDoc> &get_documentation() const override {
+		return docs;
+	}
+#endif // TOOLS_ENABLED
+
 	virtual Error reload(bool p_keep_state = false) override;
 
 	void set_script_path(const String &p_path) { path = p_path; } //because subclasses need a path too...
diff --git a/modules/gdscript/gdscript_analyzer.cpp b/modules/gdscript/gdscript_analyzer.cpp
index 3f2fdc04a5..fcbab9e3a1 100644
--- a/modules/gdscript/gdscript_analyzer.cpp
+++ b/modules/gdscript/gdscript_analyzer.cpp
@@ -860,7 +860,12 @@ void GDScriptAnalyzer::resolve_function_signature(GDScriptParser::FunctionNode *
 			parser->push_warning(p_function->parameters[i]->identifier, GDScriptWarning::UNUSED_PARAMETER, p_function->identifier->name, p_function->parameters[i]->identifier->name);
 		}
 		is_shadowing(p_function->parameters[i]->identifier, "function parameter");
-#endif
+#endif // DEBUG_ENABLED
+#ifdef TOOLS_ENABLED
+		if (p_function->parameters[i]->default_value && p_function->parameters[i]->default_value->is_constant) {
+			p_function->default_arg_values.push_back(p_function->parameters[i]->default_value->reduced_value);
+		}
+#endif // TOOLS_ENABLED
 	}
 
 	if (p_function->identifier->name == "_init") {
diff --git a/modules/gdscript/gdscript_compiler.cpp b/modules/gdscript/gdscript_compiler.cpp
index b41dc15324..3de09eec05 100644
--- a/modules/gdscript/gdscript_compiler.cpp
+++ b/modules/gdscript/gdscript_compiler.cpp
@@ -1883,6 +1883,7 @@ Error GDScriptCompiler::_parse_function(GDScript *p_script, const GDScriptParser
 		codegen.generator->set_initial_line(p_func->start_line);
 #ifdef TOOLS_ENABLED
 		p_script->member_lines[func_name] = p_func->start_line;
+		p_script->doc_functions[func_name] = p_func->doc_description;
 #endif
 	} else {
 		codegen.generator->set_initial_line(0);
@@ -1896,6 +1897,21 @@ Error GDScriptCompiler::_parse_function(GDScript *p_script, const GDScriptParser
 		p_script->implicit_initializer = gd_function;
 	}
 
+	if (p_func) {
+		// if no return statement -> return type is void not unresolved Variant
+		if (p_func->body->has_return) {
+			gd_function->return_type = _gdtype_from_datatype(p_func->get_datatype());
+		} else {
+			gd_function->return_type = GDScriptDataType();
+			gd_function->return_type.has_type = true;
+			gd_function->return_type.kind = GDScriptDataType::BUILTIN;
+			gd_function->return_type.builtin_type = Variant::NIL;
+		}
+#ifdef TOOLS_ENABLED
+		gd_function->default_arg_values = p_func->default_arg_values;
+#endif
+	}
+
 	p_script->member_functions[func_name] = gd_function;
 
 	memdelete(codegen.generator);
@@ -1993,6 +2009,24 @@ Error GDScriptCompiler::_parse_class_level(GDScript *p_script, const GDScriptPar
 		}
 	}
 
+#if TOOLS_ENABLED
+	p_script->doc_functions.clear();
+	p_script->doc_variables.clear();
+	p_script->doc_constants.clear();
+	p_script->doc_enums.clear();
+	p_script->doc_signals.clear();
+	p_script->doc_tutorials.clear();
+
+	p_script->doc_brief_description = p_class->doc_brief_description;
+	p_script->doc_description = p_class->doc_description;
+	for (int i = 0; i < p_class->doc_tutorials.size(); i++) {
+		DocData::TutorialDoc td;
+		td.title = p_class->doc_tutorials[i].first;
+		td.link = p_class->doc_tutorials[i].second;
+		p_script->doc_tutorials.append(td);
+	}
+#endif
+
 	p_script->native = Ref<GDScriptNativeClass>();
 	p_script->base = Ref<GDScript>();
 	p_script->_base = nullptr;
@@ -2105,20 +2139,23 @@ Error GDScriptCompiler::_parse_class_level(GDScript *p_script, const GDScriptPar
 					prop_info.hint = export_info.hint;
 					prop_info.hint_string = export_info.hint_string;
 					prop_info.usage = export_info.usage;
-#ifdef TOOLS_ENABLED
-					if (variable->initializer != nullptr && variable->initializer->type == GDScriptParser::Node::LITERAL) {
-						p_script->member_default_values[name] = static_cast<const GDScriptParser::LiteralNode *>(variable->initializer)->value;
-					}
-#endif
 				} else {
 					prop_info.usage = PROPERTY_USAGE_SCRIPT_VARIABLE;
 				}
+#if TOOLS_ENABLED
+				p_script->doc_variables[name] = variable->doc_description;
+#endif
 
 				p_script->member_info[name] = prop_info;
 				p_script->member_indices[name] = minfo;
 				p_script->members.insert(name);
 
 #ifdef TOOLS_ENABLED
+				if (variable->initializer != nullptr && variable->initializer->is_constant) {
+					p_script->member_default_values[name] = variable->initializer->reduced_value;
+				} else {
+					p_script->member_default_values.erase(name);
+				}
 				p_script->member_lines[name] = variable->start_line;
 #endif
 			} break;
@@ -2129,8 +2166,10 @@ Error GDScriptCompiler::_parse_class_level(GDScript *p_script, const GDScriptPar
 
 				p_script->constants.insert(name, constant->initializer->reduced_value);
 #ifdef TOOLS_ENABLED
-
 				p_script->member_lines[name] = constant->start_line;
+				if (constant->doc_description != String()) {
+					p_script->doc_constants[name] = constant->doc_description;
+				}
 #endif
 			} break;
 
@@ -2141,6 +2180,15 @@ Error GDScriptCompiler::_parse_class_level(GDScript *p_script, const GDScriptPar
 				p_script->constants.insert(name, enum_value.value);
 #ifdef TOOLS_ENABLED
 				p_script->member_lines[name] = enum_value.identifier->start_line;
+				if (!p_script->doc_enums.has("@unnamed_enums")) {
+					p_script->doc_enums["@unnamed_enums"] = DocData::EnumDoc();
+					p_script->doc_enums["@unnamed_enums"].name = "@unnamed_enums";
+				}
+				DocData::ConstantDoc const_doc;
+				const_doc.name = enum_value.identifier->name;
+				const_doc.value = Variant(enum_value.value).operator String(); // TODO-DOC: enum value currently is int.
+				const_doc.description = enum_value.doc_description;
+				p_script->doc_enums["@unnamed_enums"].values.push_back(const_doc);
 #endif
 			} break;
 
@@ -2176,6 +2224,11 @@ Error GDScriptCompiler::_parse_class_level(GDScript *p_script, const GDScriptPar
 					parameters_names.write[j] = signal->parameters[j]->identifier->name;
 				}
 				p_script->_signals[name] = parameters_names;
+#if TOOLS_ENABLED
+				if (!signal->doc_description.empty()) {
+					p_script->doc_signals[name] = signal->doc_description;
+				}
+#endif
 			} break;
 
 			case GDScriptParser::ClassNode::Member::ENUM: {
@@ -2192,6 +2245,16 @@ Error GDScriptCompiler::_parse_class_level(GDScript *p_script, const GDScriptPar
 				p_script->constants.insert(enum_n->identifier->name, new_enum);
 #ifdef TOOLS_ENABLED
 				p_script->member_lines[enum_n->identifier->name] = enum_n->start_line;
+				p_script->doc_enums[enum_n->identifier->name] = DocData::EnumDoc();
+				p_script->doc_enums[enum_n->identifier->name].name = enum_n->identifier->name;
+				p_script->doc_enums[enum_n->identifier->name].description = enum_n->doc_description;
+				for (int j = 0; j < enum_n->values.size(); j++) {
+					DocData::ConstantDoc const_doc;
+					const_doc.name = enum_n->values[j].identifier->name;
+					const_doc.value = Variant(enum_n->values[j].value).operator String();
+					const_doc.description = enum_n->values[j].doc_description;
+					p_script->doc_enums[enum_n->identifier->name].values.push_back(const_doc);
+				}
 #endif
 			} break;
 			default:
diff --git a/modules/gdscript/gdscript_function.h b/modules/gdscript/gdscript_function.h
index bb5cc1284d..7bc20672d5 100644
--- a/modules/gdscript/gdscript_function.h
+++ b/modules/gdscript/gdscript_function.h
@@ -379,6 +379,7 @@ private:
 
 #ifdef TOOLS_ENABLED
 	Vector<StringName> arg_names;
+	Vector<Variant> default_arg_values;
 #endif
 
 	List<StackDebug> stack_debug;
@@ -458,6 +459,11 @@ public:
 		ERR_FAIL_INDEX_V(p_idx, default_arguments.size(), Variant());
 		return default_arguments[p_idx];
 	}
+#ifdef TOOLS_ENABLED
+	const Vector<Variant> &get_default_arg_values() const {
+		return default_arg_values;
+	}
+#endif // TOOLS_ENABLED
 
 	Variant call(GDScriptInstance *p_instance, const Variant **p_args, int p_argcount, Callable::CallError &r_err, CallState *p_state = nullptr);
 
diff --git a/modules/gdscript/gdscript_parser.cpp b/modules/gdscript/gdscript_parser.cpp
index 372af204f5..5259e831e9 100644
--- a/modules/gdscript/gdscript_parser.cpp
+++ b/modules/gdscript/gdscript_parser.cpp
@@ -558,6 +558,21 @@ void GDScriptParser::parse_program() {
 
 	parse_class_body();
 
+#ifdef TOOLS_ENABLED
+	for (Map<int, GDScriptTokenizer::CommentData>::Element *E = tokenizer.get_comments().front(); E; E = E->next()) {
+		if (E->get().new_line && E->get().comment.begins_with("##")) {
+			if (class_doc_line == -1) {
+				class_doc_line = E->key();
+			} else {
+				class_doc_line = MIN(class_doc_line, E->key());
+			}
+		}
+	}
+	if (has_comment(class_doc_line)) {
+		get_class_doc_comment(class_doc_line, head->doc_brief_description, head->doc_description, head->doc_tutorials, false);
+	}
+#endif // TOOLS_ENABLED
+
 	if (!check(GDScriptTokenizer::Token::TK_EOF)) {
 		push_error("Expected end of file.");
 	}
@@ -668,6 +683,10 @@ void GDScriptParser::parse_class_member(T *(GDScriptParser::*p_parse_function)()
 	if (member == nullptr) {
 		return;
 	}
+#ifdef TOOLS_ENABLED
+	int doc_comment_line = member->start_line - 1;
+#endif // TOOLS_ENABLED
+
 	// Consume annotations.
 	while (!annotation_stack.empty()) {
 		AnnotationNode *last_annotation = annotation_stack.back()->get();
@@ -680,7 +699,24 @@ void GDScriptParser::parse_class_member(T *(GDScriptParser::*p_parse_function)()
 			clear_unused_annotations();
 			return;
 		}
+#ifdef TOOLS_ENABLED
+		if (last_annotation->start_line == doc_comment_line) {
+			doc_comment_line--;
+		}
+#endif // TOOLS_ENABLED
+	}
+
+#ifdef TOOLS_ENABLED
+	// Consume doc comments.
+	if (has_comment(doc_comment_line)) {
+		if constexpr (std::is_same_v<T, ClassNode>) {
+			get_class_doc_comment(doc_comment_line, member->doc_brief_description, member->doc_description, member->doc_tutorials, true);
+		} else {
+			member->doc_description = get_doc_comment(doc_comment_line);
+		}
 	}
+#endif // TOOLS_ENABLED
+
 	if (member->identifier != nullptr) {
 		// Enums may be unnamed.
 		// TODO: Consider names in outer scope too, for constants and classes (and static functions?)
@@ -1050,6 +1086,7 @@ GDScriptParser::EnumNode *GDScriptParser::parse_enum() {
 			item.parent_enum = enum_node;
 			item.line = previous.start_line;
 			item.leftmost_column = previous.leftmost_column;
+			item.rightmost_column = previous.rightmost_column;
 
 			if (elements.has(item.identifier->name)) {
 				push_error(vformat(R"(Name "%s" was already in this enum (at line %d).)", item.identifier->name, elements[item.identifier->name]), item.identifier);
@@ -1088,6 +1125,31 @@ GDScriptParser::EnumNode *GDScriptParser::parse_enum() {
 	pop_multiline();
 	consume(GDScriptTokenizer::Token::BRACE_CLOSE, R"(Expected closing "}" for enum.)");
 
+#ifdef TOOLS_ENABLED
+	// Enum values documentaion.
+	for (int i = 0; i < enum_node->values.size(); i++) {
+		if (i == enum_node->values.size() - 1) {
+			// If close bracket is same line as last value.
+			if (enum_node->values[i].line != previous.start_line && has_comment(enum_node->values[i].line)) {
+				if (named) {
+					enum_node->values.write[i].doc_description = get_doc_comment(enum_node->values[i].line, true);
+				} else {
+					current_class->set_enum_value_doc(enum_node->values[i].identifier->name, get_doc_comment(enum_node->values[i].line, true));
+				}
+			}
+		} else {
+			// If two values are same line.
+			if (enum_node->values[i].line != enum_node->values[i + 1].line && has_comment(enum_node->values[i].line)) {
+				if (named) {
+					enum_node->values.write[i].doc_description = get_doc_comment(enum_node->values[i].line, true);
+				} else {
+					current_class->set_enum_value_doc(enum_node->values[i].identifier->name, get_doc_comment(enum_node->values[i].line, true));
+				}
+			}
+		}
+	}
+#endif // TOOLS_ENABLED
+
 	end_statement("enum");
 
 	return enum_node;
@@ -2624,6 +2686,229 @@ GDScriptParser::TypeNode *GDScriptParser::parse_type(bool p_allow_void) {
 	return type;
 }
 
+#ifdef TOOLS_ENABLED
+static bool _in_codeblock(String p_line, bool p_already_in, int *r_block_begins = nullptr) {
+	int start_block = p_line.rfind("[codeblock]");
+	int end_block = p_line.rfind("[/codeblock]");
+
+	if (start_block != -1 && r_block_begins) {
+		*r_block_begins = start_block;
+	}
+
+	if (p_already_in) {
+		if (end_block == -1) {
+			return true;
+		} else if (start_block == -1) {
+			return false;
+		} else {
+			return start_block > end_block;
+		}
+	} else {
+		if (start_block == -1) {
+			return false;
+		} else if (end_block == -1) {
+			return true;
+		} else {
+			return start_block > end_block;
+		}
+	}
+}
+
+bool GDScriptParser::has_comment(int p_line) {
+	return tokenizer.get_comments().has(p_line);
+}
+
+String GDScriptParser::get_doc_comment(int p_line, bool p_single_line) {
+	const Map<int, GDScriptTokenizer::CommentData> &comments = tokenizer.get_comments();
+	ERR_FAIL_COND_V(!comments.has(p_line), String());
+
+	if (p_single_line) {
+		if (comments[p_line].comment.begins_with("##")) {
+			return comments[p_line].comment.trim_prefix("##").strip_edges();
+		}
+		return "";
+	}
+
+	String doc;
+
+	int line = p_line;
+	bool in_codeblock = false;
+
+	while (comments.has(line - 1)) {
+		if (!comments[line - 1].new_line || !comments[line - 1].comment.begins_with("##")) {
+			break;
+		}
+		line--;
+	}
+
+	if (class_doc_line == -1) {
+		class_doc_line = line - 1;
+	} else {
+		class_doc_line = MIN(class_doc_line, line) - 1;
+	}
+
+	int codeblock_begins = 0;
+	while (comments.has(line)) {
+		if (!comments[line].new_line || !comments[line].comment.begins_with("##")) {
+			break;
+		}
+		String doc_line = comments[line].comment.trim_prefix("##");
+
+		in_codeblock = _in_codeblock(doc_line, in_codeblock, &codeblock_begins);
+
+		if (in_codeblock) {
+			int i = 0;
+			for (; i < codeblock_begins; i++) {
+				if (doc_line[i] != ' ') {
+					break;
+				}
+			}
+			doc_line = doc_line.substr(i);
+		} else {
+			doc_line = doc_line.strip_edges();
+		}
+		String line_join = (in_codeblock) ? "\n" : " ";
+
+		doc = (doc.empty()) ? doc_line : doc + line_join + doc_line;
+		line++;
+	}
+
+	return doc;
+}
+
+void GDScriptParser::get_class_doc_comment(int p_line, String &p_brief, String &p_desc, Vector<Pair<String, String>> &p_tutorials, bool p_inner_class) {
+	const Map<int, GDScriptTokenizer::CommentData> &comments = tokenizer.get_comments();
+	if (!comments.has(p_line)) {
+		return;
+	}
+	ERR_FAIL_COND(p_brief != "" || p_desc != "" || p_tutorials.size() != 0);
+
+	int line = p_line;
+	bool in_codeblock = false;
+	enum Mode {
+		BRIEF,
+		DESC,
+		TUTORIALS,
+		DONE,
+	};
+	Mode mode = BRIEF;
+
+	if (p_inner_class) {
+		while (comments.has(line - 1)) {
+			if (!comments[line - 1].new_line || !comments[line - 1].comment.begins_with("##")) {
+				break;
+			}
+			line--;
+		}
+		if (class_doc_line == -1) {
+			class_doc_line = line - 1;
+		} else {
+			class_doc_line = MIN(class_doc_line, line) - 1;
+		}
+	}
+
+	int codeblock_begins = 0;
+	while (comments.has(line)) {
+		if (!comments[line].new_line || !comments[line].comment.begins_with("##")) {
+			break;
+		}
+
+		String title, link; // For tutorials.
+		String doc_line = comments[line++].comment.trim_prefix("##");
+		String striped_line = doc_line.strip_edges();
+
+		// Set the read mode.
+		if (striped_line.begins_with("@desc:") && p_desc == "") {
+			mode = DESC;
+			striped_line = striped_line.trim_prefix("@desc:");
+			in_codeblock = _in_codeblock(doc_line, in_codeblock);
+
+		} else if (striped_line.begins_with("@tutorial")) {
+			int begin_scan = String("@tutorial").length();
+			if (begin_scan >= striped_line.length()) {
+				continue; // invalid syntax.
+			}
+
+			if (striped_line[begin_scan] == ':') { // No title.
+				// Syntax: ## @tutorial: https://godotengine.org/ // The title argument is optional.
+				title = "";
+				link = striped_line.trim_prefix("@tutorial:").strip_edges();
+
+			} else {
+				/* Syntax:
+				   @tutorial ( The Title Here )         :         http://the.url/
+				             ^ open           ^ close   ^ colon   ^ url
+				*/
+				int open_bracket_pos = begin_scan, close_bracket_pos = 0;
+				while (open_bracket_pos < striped_line.length() && (striped_line[open_bracket_pos] == ' ' || striped_line[open_bracket_pos] == '\t')) {
+					open_bracket_pos++;
+				}
+				if (open_bracket_pos == striped_line.length() || striped_line[open_bracket_pos++] != '(') {
+					continue; // invalid syntax.
+				}
+				close_bracket_pos = open_bracket_pos;
+				while (close_bracket_pos < striped_line.length() && striped_line[close_bracket_pos] != ')') {
+					close_bracket_pos++;
+				}
+				if (close_bracket_pos == striped_line.length()) {
+					continue; // invalid syntax.
+				}
+
+				int colon_pos = close_bracket_pos + 1;
+				while (colon_pos < striped_line.length() && (striped_line[colon_pos] == ' ' || striped_line[colon_pos] == '\t')) {
+					colon_pos++;
+				}
+				if (colon_pos == striped_line.length() || striped_line[colon_pos++] != ':') {
+					continue; // invalid syntax.
+				}
+
+				title = striped_line.substr(open_bracket_pos, close_bracket_pos - open_bracket_pos).strip_edges();
+				link = striped_line.substr(colon_pos).strip_edges();
+			}
+
+			mode = TUTORIALS;
+			in_codeblock = false;
+		} else if (striped_line.empty()) {
+			continue;
+		} else {
+			// Tutorial docs are single line, we need a @tag after it.
+			if (mode == TUTORIALS) {
+				mode = DONE;
+			}
+
+			in_codeblock = _in_codeblock(doc_line, in_codeblock, &codeblock_begins);
+		}
+
+		if (in_codeblock) {
+			int i = 0;
+			for (; i < codeblock_begins; i++) {
+				if (doc_line[i] != ' ') {
+					break;
+				}
+			}
+			doc_line = doc_line.substr(i);
+		} else {
+			doc_line = striped_line;
+		}
+		String line_join = (in_codeblock) ? "\n" : " ";
+
+		switch (mode) {
+			case BRIEF:
+				p_brief = (p_brief.length() == 0) ? doc_line : p_brief + line_join + doc_line;
+				break;
+			case DESC:
+				p_desc = (p_desc.length() == 0) ? doc_line : p_desc + line_join + doc_line;
+				break;
+			case TUTORIALS:
+				p_tutorials.append(Pair<String, String>(title, link));
+				break;
+			case DONE:
+				return;
+		}
+	}
+}
+#endif // TOOLS_ENABLED
+
 GDScriptParser::ParseRule *GDScriptParser::get_rule(GDScriptTokenizer::Token::Type p_token_type) {
 	// Function table for expression parsing.
 	// clang-format destroys the alignment here, so turn off for the table.
diff --git a/modules/gdscript/gdscript_parser.h b/modules/gdscript/gdscript_parser.h
index b24acc4778..598ac9cd34 100644
--- a/modules/gdscript/gdscript_parser.h
+++ b/modules/gdscript/gdscript_parser.h
@@ -413,9 +413,16 @@ public:
 			int line = 0;
 			int leftmost_column = 0;
 			int rightmost_column = 0;
+#ifdef TOOLS_ENABLED
+			String doc_description;
+#endif // TOOLS_ENABLED
 		};
+
 		IdentifierNode *identifier = nullptr;
 		Vector<Value> values;
+#ifdef TOOLS_ENABLED
+		String doc_description;
+#endif // TOOLS_ENABLED
 
 		EnumNode() {
 			type = ENUM;
@@ -568,6 +575,17 @@ public:
 		Vector<StringName> extends; // List for indexing: extends A.B.C
 		DataType base_type;
 		String fqcn; // Fully-qualified class name. Identifies uniquely any class in the project.
+#ifdef TOOLS_ENABLED
+		String doc_description;
+		String doc_brief_description;
+		Vector<Pair<String, String>> doc_tutorials;
+
+		// EnumValue docs are parsed after itself, so we need a method to add/modify the doc property later.
+		void set_enum_value_doc(const StringName &p_name, const String &p_doc_description) {
+			ERR_FAIL_INDEX(members_indices[p_name], members.size());
+			members.write[members_indices[p_name]].enum_value.doc_description = p_doc_description;
+		}
+#endif // TOOLS_ENABLED
 
 		bool resolved_interface = false;
 		bool resolved_body = false;
@@ -602,6 +620,9 @@ public:
 		TypeNode *datatype_specifier = nullptr;
 		bool infer_datatype = false;
 		int usages = 0;
+#ifdef TOOLS_ENABLED
+		String doc_description;
+#endif // TOOLS_ENABLED
 
 		ConstantNode() {
 			type = CONSTANT;
@@ -653,6 +674,10 @@ public:
 		bool is_coroutine = false;
 		MultiplayerAPI::RPCMode rpc_mode = MultiplayerAPI::RPC_MODE_DISABLED;
 		MethodInfo info;
+#ifdef TOOLS_ENABLED
+		Vector<Variant> default_arg_values;
+		String doc_description;
+#endif // TOOLS_ENABLED
 
 		bool resolved_signature = false;
 		bool resolved_body = false;
@@ -820,6 +845,9 @@ public:
 		IdentifierNode *identifier = nullptr;
 		Vector<ParameterNode *> parameters;
 		HashMap<StringName, int> parameters_indices;
+#ifdef TOOLS_ENABLED
+		String doc_description;
+#endif // TOOLS_ENABLED
 
 		SignalNode() {
 			type = SIGNAL;
@@ -1012,6 +1040,9 @@ public:
 		MultiplayerAPI::RPCMode rpc_mode = MultiplayerAPI::RPC_MODE_DISABLED;
 		int assignments = 0;
 		int usages = 0;
+#ifdef TOOLS_ENABLED
+		String doc_description;
+#endif // TOOLS_ENABLED
 
 		VariableNode() {
 			type = VARIABLE;
@@ -1270,6 +1301,13 @@ private:
 	ExpressionNode *parse_subscript(ExpressionNode *p_previous_operand, bool p_can_assign);
 	ExpressionNode *parse_invalid_token(ExpressionNode *p_previous_operand, bool p_can_assign);
 	TypeNode *parse_type(bool p_allow_void = false);
+#ifdef TOOLS_ENABLED
+	// Doc comments.
+	int class_doc_line = -1;
+	bool has_comment(int p_line);
+	String get_doc_comment(int p_line, bool p_single_line = false);
+	void get_class_doc_comment(int p_line, String &p_brief, String &p_desc, Vector<Pair<String, String>> &p_tutorials, bool p_inner_class);
+#endif // TOOLS_ENABLED
 
 public:
 	Error parse(const String &p_source_code, const String &p_script_path, bool p_for_completion);
diff --git a/modules/gdscript/gdscript_tokenizer.cpp b/modules/gdscript/gdscript_tokenizer.cpp
index b91777ede1..ac43105254 100644
--- a/modules/gdscript/gdscript_tokenizer.cpp
+++ b/modules/gdscript/gdscript_tokenizer.cpp
@@ -1014,9 +1014,17 @@ void GDScriptTokenizer::check_indent() {
 		}
 		if (_peek() == '#') {
 			// Comment. Advance to the next line.
+#ifdef TOOLS_ENABLED
+			String comment;
+			while (_peek() != '\n' && !_is_at_end()) {
+				comment += _advance();
+			}
+			comments[line] = CommentData(comment, true);
+#else
 			while (_peek() != '\n' && !_is_at_end()) {
 				_advance();
 			}
+#endif // TOOLS_ENABLED
 			if (_is_at_end()) {
 				// Reached the end with an empty line, so just dedent as much as needed.
 				pending_indents -= indent_level();
@@ -1125,18 +1133,26 @@ void GDScriptTokenizer::_skip_whitespace() {
 				newline(!is_bol); // Don't create new line token if line is empty.
 				check_indent();
 				break;
-			case '#':
+			case '#': {
 				// Comment.
+#ifdef TOOLS_ENABLED
+				String comment;
+				while (_peek() != '\n' && !_is_at_end()) {
+					comment += _advance();
+				}
+				comments[line] = CommentData(comment, is_bol);
+#else
 				while (_peek() != '\n' && !_is_at_end()) {
 					_advance();
 				}
+#endif // TOOLS_ENABLED
 				if (_is_at_end()) {
 					return;
 				}
 				_advance(); // Consume '\n'
 				newline(!is_bol);
 				check_indent();
-				break;
+			} break;
 			default:
 				return;
 		}
diff --git a/modules/gdscript/gdscript_tokenizer.h b/modules/gdscript/gdscript_tokenizer.h
index d51f1f250f..f236c86f9f 100644
--- a/modules/gdscript/gdscript_tokenizer.h
+++ b/modules/gdscript/gdscript_tokenizer.h
@@ -32,6 +32,7 @@
 #define GDSCRIPT_TOKENIZER_H
 
 #include "core/templates/list.h"
+#include "core/templates/map.h"
 #include "core/templates/set.h"
 #include "core/templates/vector.h"
 #include "core/variant/variant.h"
@@ -181,6 +182,21 @@ public:
 		}
 	};
 
+#ifdef TOOLS_ENABLED
+	struct CommentData {
+		String comment;
+		bool new_line = false;
+		CommentData() {}
+		CommentData(const String &p_comment, bool p_new_line) {
+			comment = p_comment;
+			new_line = p_new_line;
+		}
+	};
+	const Map<int, CommentData> &get_comments() const {
+		return comments;
+	}
+#endif // TOOLS_ENABLED
+
 private:
 	String source;
 	const char32_t *_source = nullptr;
@@ -207,6 +223,10 @@ private:
 	int position = 0;
 	int length = 0;
 
+#ifdef TOOLS_ENABLED
+	Map<int, CommentData> comments;
+#endif // TOOLS_ENABLED
+
 	_FORCE_INLINE_ bool _is_at_end() { return position >= length; }
 	_FORCE_INLINE_ char32_t _peek(int p_offset = 0) { return position + p_offset >= 0 && position + p_offset < length ? _current[p_offset] : '\0'; }
 	int indent_level() const { return indent_stack.size(); }
diff --git a/modules/mono/csharp_script.h b/modules/mono/csharp_script.h
index 3e4e6c3f86..4c6e624b8a 100644
--- a/modules/mono/csharp_script.h
+++ b/modules/mono/csharp_script.h
@@ -189,6 +189,14 @@ public:
 	String get_source_code() const override;
 	void set_source_code(const String &p_code) override;
 
+#ifdef TOOLS_ENABLED
+	virtual const Vector<DocData::ClassDoc> &get_documentation() const override {
+		// TODO
+		static Vector<DocData::ClassDoc> docs;
+		return docs;
+	}
+#endif // TOOLS_ENABLED
+
 	Error reload(bool p_keep_state = false) override;
 
 	bool has_script_signal(const StringName &p_signal) const override;
diff --git a/modules/visual_script/visual_script.h b/modules/visual_script/visual_script.h
index 85dab4e6cf..b34f6df113 100644
--- a/modules/visual_script/visual_script.h
+++ b/modules/visual_script/visual_script.h
@@ -342,6 +342,13 @@ public:
 	virtual void set_source_code(const String &p_code) override;
 	virtual Error reload(bool p_keep_state = false) override;
 
+#ifdef TOOLS_ENABLED
+	virtual const Vector<DocData::ClassDoc> &get_documentation() const override {
+		static Vector<DocData::ClassDoc> docs;
+		return docs;
+	}
+#endif // TOOLS_ENABLED
+
 	virtual bool is_tool() const override;
 	virtual bool is_valid() const override;