# 2023-10-11

## Adventures in writing a text editor

I was thinking on the drive into work about a few things:

1. Now that I have a frame, what comes next? The next logical step is
   have an Editor to hold the frames, I think. Actually, a Window -
   which leads to my next point.
2. kepp could really the text mode for kge, so I can reuse a lot of the
   editor components. Time to switch the repo over.
3. Thinking about #2 makes me think: you basically have a few subsystems
   here. The ones that I can think of are

   + The Frame/File subsystem: basically, the editor's subject.
   + The Window as a container holds a map of names -> frames, as well as
     the currently active frame.
   + The current KeyboardMode defines how input is processed.
   + In the case of kepp, you need a TerminalMode. I think the GUI version
     will have something similar.
   + You need an Editor to tie it all together.

4. I can start with using a std::vector<std::vector<uint8_t>> to store data
   in the Frame to start with. This is where terminology starts to trip me
   up a little. In emacs, a frame is a window, and a buffer is what I call a
   Frame. However, I think of the buffer as a member of Frame. Maybe I can
   call it contents, rename Frame->Buffer, rename Window->Frame. Then the
   terminology will be more consistent with what I know.

### On files

After working with the Dictionary in klib, I briefly thought about
memory mapping, but that brings a whole host of issues and it honestly
doesn't make sense because you don't need to _immediately_ reflect
changes from the editor to the file. I think you could have an
autosave timer going, but I think you can just keep changes in memory
until you're ready.

This leads to a what I think is the next sequence of events:

1. Import kepp into kge.
2. Remove the dependency on klib. It's a complication I don't need right 
   now.
3. Update Frame to have a backing buffer^wcontents.
4. Rename Frame->Buffer.
5. Add Frame to store Buffers.
6. Add an Editor that stores a Frame.
7. Start working on KeyboardMode.

Next challenge: getting kge to build on my work Ubuntu machine, which uses
NVIDIA drivers. I'm taking the time to make the backends configurable; the
code is sdl2/opengl3 specific right now, but that's easy enough to abstract
out.

Another note: I'm using CLion a lot for development and it's pretty annoying
that it flushes to disk every few seconds. This reinforces my thoughts about
how to back files in the editor.