How would I implement auto indentation for a code editor

IdkIjustwannausethething

im making a lua code editor made with luart i dont need colors i just need auto indentation for things like
"while true do
print("ex")
end"

but I don't know what modules to even use because the basic Edit doesn't have any functions that let me see the last word of a line that i know of

IdkIjustwannausethething

I was thinking of using the last word of a line to determine if it was going to be auto indented but there unfortunately is no way to look at words so that wasnt an option then i thought to try to use a c library to do it like Scintillia but i have very little knowledge of the C FFI module so that unfortunately wasnt an option so i thought i should just ask the community for help

IdkIjustwannausethething

i was also wondering how i would detect when the user pressed the return key but i have no idea how i would implement that

IdkIjustwannausethething

i tried doing
function input:onChange() print("changed") local newlines = #input.lines local text = input.text if lines < newlines then print("worked?") input.text = text .. " " end end
but i guess its not even firing the onchange when i press anything atall

IdkIjustwannausethething

i did also put local lines = 0

Samir

Hi,

I'm not completely sure what you're trying to achieve from the different messages above.

If your goal is to build a Lua code editor with automatic indentation, could you clarify:

Which LuaRT version are you using?
Which control are you using (ui.Edit ?) ?
Do you simply want to insert spaces/tabs when the user presses Enter?
Or do you want Lua-aware indentation (after do, then, function, repeat, etc.)?

Also, please show a minimal runnable example of your current code.

At the moment you're describing several approaches you've considered, but not the actual problem you're blocked on. The easier it is for other members to reproduce the issue, the easier it will be to help.

IdkIjustwannausethething

I am trying to build a Lua code editor similar to something like VS code.
I need a system that detects when a user inputs more text and which text and I currently can't find an event that works for this.
I'm using this system to make features like auto indentation and i wanted to use a C library that would handle this for me but I have no knowledge of C.

I'm using LuaRT 2.2.0 (x64 version) and I'm using RT builder for the GUI.
I'm using ui.Edit.
Ive been trying to do Lua-aware indentation.

and a small example would be:
`local ui = require("ui")

local window = ui.Window("Lua Code editor", 200, 300)
local Edit = ui.Edit(window, "", 200, 300)
Edit.align = "all"
local lines = 1

function Edit.onChange()
local text = Edit.text
if Edit:searchup("do", true, true) or Edit:searchup("then", true, true) then
Edit.text = text .. " "
end
end

window:show()

while window.visible do
ui.update()
end`

Samir

Thanks for the details, it's more clear now.

ui.Edit does support an onChange() event, so your approach is valid.

The first thing I'd try is changing:

function myEdit.onChange()
    print("changed")
end

to:

function myEdit:onChange()
    print("changed")
end

Most LuaRT event handlers are declared using the : syntax so that self is passed automatically.

Also, before working on auto-indentation, can you verify that the event is actually firing:

function myEdit:onChange()
    ui.info("changed: "..self.text)
end

If that works, the next step is to get the current line number and caret:

ui.info(myEdit.line)
ui.info(myEdit.caret)

Both the current line number and caret position are exposed by ui.Edit.

One other thing: searchup("do") searches the whole editor content upwards from the caret. For indentation you'll usually want to inspect only the previous line, otherwise a do somewhere earlier in the file could incorrectly trigger indentation.

Can you confirm whether ui.info("changed") appears when you type after switching to the : syntax?

IdkIjustwannausethething

for some reason it appears that the Edit:onChange() function doesnt fire when the text changes and im not sure why

IdkIjustwannausethething

well actually does fire once when the Edit is created but doesnt fire afterwards.

IdkIjustwannausethething

it fires correctly for the ui.Entry but not ui.Edit

Samir

Ok then you found a bug.
I will investigate it thank you

IdkIjustwannausethething

i made a fixed version of the onchanged event
local ui = require("ui")

local window = ui.Window("Lua Code editor", 200, 300)
local Edit = ui.Edit(window, "", 200, 300)
Edit.align = "all"

local last_text = Edit.text

function fixedonchangeiguess(text)
print(text)
end

window:show()

while window.visible do
if Edit.text ~= last_text then
last_text = Edit.text
fixedonchangeiguess(last_text)
end
ui.update()
end

Samir

I haven't had time to look at the onChange bug, but this code seems like a good idea for the time being.