Ubuntu – What plaintext editor with math symbols integration is available

The editor geany, also useful as an IDE, has indentation based folding for python source files.

It should be a way to associate .dsl files with this type of representation

...why not use a script? Check xclip (sudo apt-get install xclip)

 xclip -o -selection clipboard  

will send the clipboard to standard output, and with -i you can replace the clipboard. So

 xclip -o -selection clipboard | sed "s/change this/to this/" | xclip -i -selection clipboard 

will apply the change to the selection, and now you can paste it.

If you want a graphical thing, you can embed the script with yad:

#! /bin/bash 
#
yad --title Choose --button One:1 --button Two:2 --button Three:3
choice=$?
case $choice in
        1) 
        xclip -o -selection clipboard | 
                sed "s/one/uno/" | 
                xclip -i -selection clipboard
        xclip -o selection clipboard
        ;;
        2)      
        xclip -o -selection clipboard | 
                sed "s/two/dos/" | 
                xclip -i -selection clipboard
        xclip -o selection clipboard
        ;;
        3)
        echo "executing 3 --- well, you got the idea"
        ;;
esac

That will show you a dialog like this:

Notice that the script will both modify the clipboard (paste) buffer and print it. To embed this in an editor, for example vim, you can do the following:

1. Add to your .vimrc:

   nmap <F4> :r ! /path/to/the/script <CR>
   

2. run for example gvim.

3. Now you copy the text, go the the editor, press F4. Choose the change you want to apply.

4. The text will appear in the editor. If it's ok as is, you can paste it. Otherwise

5. Edit the text and copy it again. (In gvim, you can select the text with the mouse and simply choose paste --- or learn the vim commands, whatever).

It could be optimized for sure (you probably can easily define another key to select and paste the modified text so that you have even less keypress to use)