Refactor code editors

[KoBeWi]

Godot version:
3.1.x

Steps to reproduce:
script_text_editor.cpp
shader_editor_plugin.cpp
text_editor.cpp

What these 3 files have in common is that they implement literally the same thing 3 times. Some examples:

Same set of enums:

godot/editor/plugins/script_text_editor.h

Lines 99 to 104 in 21e2419

	EDIT_UNDO,
	EDIT_REDO,
	EDIT_CUT,
	EDIT_COPY,
	EDIT_PASTE,
	EDIT_SELECT_ALL,

godot/editor/plugins/shader_editor_plugin.h

Lines 72 to 77 in 21e2419

	EDIT_UNDO,
	EDIT_REDO,
	EDIT_CUT,
	EDIT_COPY,
	EDIT_PASTE,
	EDIT_SELECT_ALL,

godot/editor/plugins/text_editor.h

Lines 64 to 69 in 21e2419

	EDIT_UNDO,
	EDIT_REDO,
	EDIT_CUT,
	EDIT_COPY,
	EDIT_PASTE,
	EDIT_SELECT_ALL,

Same edit menu:

godot/editor/plugins/shader_editor_plugin.cpp

Lines 502 to 508 in 21e2419

	edit_menu = memnew(MenuButton);
	edit_menu->set_text(TTR("Edit"));
	edit_menu->set_switch_on_hover(true);
	edit_menu->get_popup()->set_hide_on_window_lose_focus(true);
	edit_menu->get_popup()->add_shortcut(ED_GET_SHORTCUT("script_text_editor/undo"), EDIT_UNDO);
	edit_menu->get_popup()->add_shortcut(ED_GET_SHORTCUT("script_text_editor/redo"), EDIT_REDO);
	edit_menu->get_popup()->add_separator();

godot/editor/plugins/text_editor.cpp

Lines 577 to 584 in 21e2419

	edit_menu = memnew(MenuButton);
	edit_menu->set_text(TTR("Edit"));
	edit_menu->get_popup()->connect("id_pressed", this, "_edit_option");
	edit_hb->add_child(edit_menu);
	edit_menu->get_popup()->add_shortcut(ED_GET_SHORTCUT("script_text_editor/undo"), EDIT_UNDO);
	edit_menu->get_popup()->add_shortcut(ED_GET_SHORTCUT("script_text_editor/redo"), EDIT_REDO);
	edit_menu->get_popup()->add_separator();

godot/editor/plugins/script_text_editor.cpp

Lines 1581 to 1587 in 21e2419

	edit_menu = memnew(MenuButton);
	edit_menu->set_text(TTR("Edit"));
	edit_menu->set_switch_on_hover(true);
	edit_menu->get_popup()->set_hide_on_window_lose_focus(true);
	edit_menu->get_popup()->add_shortcut(ED_GET_SHORTCUT("script_text_editor/undo"), EDIT_UNDO);
	edit_menu->get_popup()->add_shortcut(ED_GET_SHORTCUT("script_text_editor/redo"), EDIT_REDO);
	edit_menu->get_popup()->add_separator();

Same menu actions:

godot/editor/plugins/shader_editor_plugin.cpp

Lines 245 to 250 in 21e2419

	case EDIT_MOVE_LINE_UP: {
	shader_editor->move_lines_up();
	} break;
	case EDIT_MOVE_LINE_DOWN: {
	shader_editor->move_lines_down();
	} break;

godot/editor/plugins/text_editor.cpp

Lines 358 to 365 in 21e2419

	case EDIT_MOVE_LINE_UP: {
	code_editor->move_lines_up();
	} break;
	case EDIT_MOVE_LINE_DOWN: {
	code_editor->move_lines_down();
	} break;

godot/editor/plugins/script_text_editor.cpp

Lines 924 to 931 in 21e2419

	case EDIT_MOVE_LINE_UP: {
	code_editor->move_lines_up();
	} break;
	case EDIT_MOVE_LINE_DOWN: {
	code_editor->move_lines_down();
	} break;

There's muuuch more of it. And the worst part is when you want to add some feature to code editor. You basically need to repeat the code 3 times.

IMO the editors should be refactored to cut the repetitions as much as possible. There are differences here and there, but I bet it's possible to rewrite them in a way that doesn't repeat 80% of lines 3 times.

[Calinou]

Closing in favor of #31739, which has more information about the issue at hand. Nonetheless, splitting into a code editing-focused class has already begun.

@Paulb23 did outstanding work to address this, with more to come in the future: #40973, #42775, #45393, #49238

[KoBeWi]

Reopening, as the PR that will close #31739 doesn't resolve this issue. The refactoring work so far only touched CodeEdit and TextEdit, it's not related to editor classes.

[akien-mga]

There have been improvements but there's still more work pending here. Won't happen for 4.0 though, and doesn't need to be tied to a specific milestone as it's internal refactoring.

[Paulb23]

This will probably be my main focus for now, given TextEdit / CodeEdit are in a somewhat decent place for the time being.

Given this is going to be quite a large refactor, it would be ideal if as part of these changes we can hit several big features / proposals at the the same time.

This is the roughly the current class diagram:

Several pain points are:

• ShaderTextEditor is a CodeTextEditor, whereas ScriptTextEditor and TextEditor has a CodeTextEdit this makes it awkward to support both use cases, and everybody forgets about the Shader editor
• Each editor only edits one type of resource without creating lots of exceptions or duplicating code (Support editing JSON in ScriptEditor #72259)
• Even within resource types there are variations, currently ScriptTextEditor has a lot of GDScript specific code.
• ShaderEditorPlugin and ScriptEditorPlugin share zero code now they do the same thing (Improvements to the shader editor #61459)
• There is currently no way to expand this via plugins (Extending the functionality of the script editor: editing shaders and more. godot-proposals#2472)

The main feature, that is currently not possible that I'd like to tackle as part of this, is godotengine/godot-proposals/issues/414 allowing split views and having the same file open multiple times.

Secondly, the ShaderEditor is located where is is to allow viewing the scene and editing the Shader at the same time. If this become detachable (godotengine/godot-proposals/issues/28) then this assumption no longer holds. So allowing shaders to be opened in the ScriptEditor (godotengine/godot-proposals/issues/5071) would be neat.

Bear in mind this might change as I get into the details, I'm also not expecting to need to create all the classes on the following diagram but should serve as a guide / context for what I would like to move towards:

ScriptEditorManager will be the main view with the script list, managing multiple ScriptEditorWindows, any Shader / Script specific code can stay in their respective plugin classes.

ScriptEditorWindow will handle the split view. There will be at least one baked into the ScriptEditorManager, others could pop out into a separate windows.

Having the ScriptEditorResource will allow multiple ScriptEditors to sync changes. It also provides an abstraction layer so TextEditor can interact with several resource types without creating a specific editor for it. There still may be exceptions however, in these cases a new editor can extend the existing one's without duplicating everything.

[Paulb23]

Yes, still under heavy WIP, see: https://github.com/Paulb23/godot/tree/script-editor-resource