Edit: I just discovered the vim-textobject-latex plugin, which adds the exact functionality you're looking for (in addition to a few other things). From the plugin's README:
Currently supported text objects are:
a i Description
a\\ i\\ Inline math surrounded by ``\\(`` and ``\\)``.
a$ i$ Inline math surrounded by dollar signs.
aq iq Single-quoted text ``\`like this'``.
aQ iQ Double-quoted text ``\``like this''``.
ae ie Environment ``\begin{...}–\end{...}``
So you can use caq and the like as you wanted. I tested it, and it works as advertised, but note that it is dependent on the vim-textobject-user plugin. Also note you must make sure that the textobject-user plugin loads first, otherwise things won't work.
If you don't want to mess with plugins, however, my original answer remains useful:
Adding these two lines to your .vimrc will cover most of what you want.
onoremap aq :<c-u>normal! F`vf'<cr>
onoremap iq :<c-u>normal! T`vt'<cr>
These create new text objects (aq and iq) which go back to the previous `, enter visual selection mode, then select up to the next '.
This will work for ciq, caq, yiq, and diq. However, yaq and daq will not yank/delete the outer quotes, so I created another text object, a", to handle that (i" is not needed, but I added to keep things consistent:
onoremap a" :<c-u>normal! 2F`v2f'<cr>
onoremap i" :<c-u>normal! 2T`v2t'<cr>
The major downside here is that this will break normal ca", etc. use. If you preface them with au FileType tex, you'll only have that issue in .tex files, but it still might occasionally be an annoyance. You could also name the object something like ad/id ('d' for 'double' quote), but that seemed less intuitive to me (I was aiming for the least difference from normal operation).
The only way I can think of to wrap these up into just two text objects would be to write a function that checks for another quote outside of the first set and set the aq text objects to call that.
Note: There are a couple other minor issues with these:
- Yanking might leave your cursor in an unexpected place (this could be fixed by adding using a mark in the commands (e.g.
ma2F`v2f'<cr>`a), just make sure not to use one you frequently use manually)
- The cursor must be inside the quotes; weird things happen if it is on the quotes.
To wrap all of that up, this is what I personally would add to my .vimrc for this issue:
augroup filetype_latex
au!
au FileType tex,plaintex onoremap a' :<c-u>normal! muF`vf'<cr>`u
au FileType tex,plaintex onoremap i' :<c-u>normal! muT`vt'<cr>`u
au FileType tex,plaintex onoremap a" :<c-u>normal! mu2F`v2f'<cr>`u
au FileType tex,plaintex onoremap i" :<c-u>normal! mu2T`v2t'<cr>`u
end augroup
As you can see, I opted for breaking normal ca'/ya"/etc functionality so I wouldn't have to learn new commands for them since I wouldn't be using the normal functionality as much within LaTeX anyways. That's just a personal preference; not hard to switch the object names. I also added in the filetype detection and marks.
