Make % jump between identical delimiters

Question

I use Vim to edit LaTeX files frequently. I want to use % to jump between matching $ which can be used to delimit where mathematical expressions are written.

I have tried using matchit and, separately, I have tried using a filetype.vim (tex.vim) file to add a match to the matchpairs variable (au FileType tex setmps+=$:$). I have managed to get both attempts to jump from the $. However, the match that is found is for a different delimiter.

For example, considering the string $ { test text } $, placing my cursor over the first $ and pressing % would jump me to the closing }, not the last $. Continued use of % jumps me between { and }. Thus, I am stuck inside the match that I want to consider.

Does anyone know how I might accomplish a jump from the first $ to the last $?

Answer 1

What you ask is possible, but the solution is nontrivial. Both LaTeX-Box and vimtex has implemented solutions for this, see here:

• LaTeX-Box/ftplugin/latex-box/motion.vim:57 (s:FindMatchingPair)
• vimtex/autoload/vimtex/motion.vim:303 (s:highlight_matching_pair)

These functions are run by autocommands whenever the cursor is moved, see here (LaTeX-Box) and here (vimtex). The original matchparen plugin is disabled, and the LaTeX-specific function, e.g. s:highlight_matching_pair, is enabled as a custom matchparen-plugin. Note that both these functions also enable matching of other LaTeX-delimiters such as begin/end pairs and pairs like \left(..\right).

Note: The links above are linked to line numbers in evolving codes. These line numbers might change in the future. The function names will probably stay the same.

Note: Other LaTeX-plugins might also implement this feature.

Disclaimer: I'm the author of vimtex.

Answer 2

Your $ match is ignored, % searches forward for the first character in a pair that it knows about: so it finds { and then the matching }, and moves between them.

From :h mps:

Only character pairs are allowed that are different,
thus you cannot jump between two double quotes.

One solution would be: to use the 'matchit' plugin (which allows for regular expressions as pairs, but has the same start != end delimiter) AND use the LaTeX math delimiters \( \), which are different. Or, define two new TeX different commands for start & end inline math environment, that both resolve to $, and use them as pairs.

So, you can do in your vimrc:

runtime! macros/matchit.vim

And, for TeX files (e.g. in a function called from a BufEnter autocmd):

let b:match_words = '\\(:\\)'

---

If you have to use the $ sign, you can cheat a little and use this:

let b:match_words = '\s\$:\$\s'

... which will match a $ preceded by space as start delimiter with a $ followed by a space as end delimiter. But then you'll have to be consistent inside your formulas and use no space after the start delimiter, or before the end one. E.g.:

 ␣$\cos (2\theta) = \cos^2 \theta - \sin^2 \theta$␣ 

Answer 3

Add

runtime! macros/matchit.vim

into ~/.vimrc and into ~/.vim/after/ftplugin/tex.vim the lines

let b:match_words = &l:matchpairs .
  \ ',' . '\(^\|[ (]\)\@<=\$\$\?' . ':' . '\$\?\$\($\|[ ).\,;\:?!\-]\)' .
  \ ',' . '\(' . ':' . '\)' .
  \ ',' . '\[' . ':' . '\]' .
  \ ',' . '\(^\s*\)\@<=\\begin{\w\+\*\?}' . ':' . '\(^\s*\)\@<=\\end{\w\+\*\?}'

This lets you jump between all TeX environment delimiters by % (but isn't yet entirely robust).