Customizing Syntax Highlighting in Vim

Question

How I can keep all the current formatting for a file type but add functionality.

I would like to highlight colors in .vim files so that each color is highlighted how the terminal will resolve it.

I created a vim.vim file containing:

syn keyword yellow yellow containedin=All                                                    
highlight yellow ctermfg=yellow                                                              

syn keyword red red containedin=all                                                          
highlight red ctermfg=red                                                                    

and put it into ~/.vim/after/syntax/vim.vim

As suggested here.

This has no effect.

---

Update

In fact I was mistaken when I said my changes had no effect. If you type yellow by itself on a line it will be highlighted yellow. Unfortunately this does not solve my problem.

I added the F3 functionality described by Al.

When I f3 over yellow (in the context ctermfg=yellow) it returns:

hi<vimHiCtermColor> trans<vimHiCtermColor> lo<vimHiCtermColor> FG:-1 BG:-1

Then :syn list vimHiCtermColor returns:

--- Syntax items ---
vimHiCtermColor xxx contained lightmagenta darkgray lightgrey darkgrey lightgreen lightgray darkmagenta gray white red grey darkred brown darkblue darkgreen lightblue yellow cyan
                   contained lightcyan lightred black blue green magenta darkcyan darkyellow

I checked :syn list darkgray (something I have not defined) to see if it exists:

--- Syntax items ---
E28: No such highlight group name: darkgray
Hit ENTER or type command to continue

Where should I go from here?

Answer 1

I would expect the ~/.vim/after/syntax/vim.vim approach to work, but if the keyword (yellow) is already highlighted, you may need to change the matcher with something like:

syn keyword yellow yellow containedin=ALL

What is the file you're trying to highlight?

Edit

I've had a look at the java.vim file and it looks like there's a lot of overlapping syntax groups, which can make highlight customisation quite difficult. Here's what I did, in case it's helpful.

A useful mapping is:

" What is the current syntax highlighting group?
map <F3> :echo "hi<" . synIDattr(synID(line("."),col("."),1),"name") . '> trans<' . synIDattr(synID(line("."),col("."),0),"name") . "> lo<" . synIDattr(synIDtrans(synID(line("."),col("."),1)),"name") . ">" . " FG:" . synIDattr(synIDtrans(synID(line("."),col("."),1)),"fg#") . " BG:" . synIDattr(synIDtrans(synID(line("."),col("."),1)),"bg#")<CR>

You can then move the cursor over something you're interested in and press F3 to see what the current highlight group is. As a test, I opened java.vim in the syntax directory and went to line 52, which defines a javaStorageClass. I decided to highlight the word transient on that line (as yellow wasn't in the file anywhere and I needed something to work with).

I moved the cursor over transient and pressed F3. Vim reported:

hi<vimSynKeyRegion> trans<vimSynKeyRegion> lo<vimSynKeyRegion> FG: BG:

It is obviously part of a vimSynKeyRegion, which one would guess from the name is a syn region. I decided to look at this further, so I interrogated the current highlighting configuration:

:redir @a>
:silent syn list
:redir END
:vnew
"ap

This produces a file containing all of the syntax information. I searched for vimSynKeyRegion and found this line:

vimSynKeyRegion xxx matchgroup=vimGroupName start=/\k\+/ skip=/\\\\\|\\|/ matchgroup=vimSep end=/|\|$/  contained oneline keepend contains=@vimSynKeyGroup 

The vimSynKeyRegion has been configured to contain items from the syntax cluster named vimSynKeyGroup. Therefore, we can highlight transient by making it a keyword in this group:

:syn keyword MyNewGroup transient
:hi MyNewGroup guifg=#ff00ff
:syn cluster vimSynKeyGroup add=MyNewGroup

---

Although this may not fit exactly into what you're wanting to do, hopefully it will give you something to work with. You may find some parts cannot be overridden (if they're matched with keywords or similar), but you can always redefine the highlighting to change the colour, e.g.

:hi vimGroupName guifg=#ffff00

Hope all of that helps.

Answer 2

Solution

Here's a direct answer for coloring just the word yellow.

syn cluster vimHiCtermColors contains=vimHiCtermColorYellow
syn keyword vimHiCtermColorYellow yellow contained

syn match  vimHiCtermFgBg   contained   "\ccterm[fb]g="he=e-1   nextgroup=vimNumber,vimHiCtermColor,@vimHiCtermColors,vimFgBgAttrib,vimHiCtermError

highlight vimHiCtermColorYellow ctermfg=yellow

And here's a solution for coloring all the color terminal names. They are only colored in the terminal (not the GUI), and other attributes (256-color terminal, GUI colors, attributes such as bold) are not highlighted at all. To extend this further, you'd probably want some sort of script to iterate over all the possible values.

syn cluster vimHiCtermColors contains=vimHiCtermColorBlack,vimHiCtermColorBlue,vimHiCtermColorBrown,vimHiCtermColorCyan,vimHiCtermColorDarkBlue,vimHiCtermColorDarkcyan,vimHiCtermColorDarkgray,vimHiCtermColorDarkgreen,vimHiCtermColorDarkgrey,vimHiCtermColorDarkmagenta,vimHiCtermColorDarkred,vimHiCtermColorDarkyellow,vimHiCtermColorGray,vimHiCtermColorGreen,vimHiCtermColorGrey,vimHiCtermColorLightblue,vimHiCtermColorLightcyan,vimHiCtermColorLightgray,vimHiCtermColorLightgreen,vimHiCtermColorLightgrey,vimHiCtermColorLightmagenta,vimHiCtermColorLightred,vimHiCtermColorMagenta,vimHiCtermColorRed,vimHiCtermColorWhite,vimHiCtermColorYellow

syn keyword vimHiCtermColorBlack black contained
syn keyword vimHiCtermColorBlue blue contained
syn keyword vimHiCtermColorBrown brown contained
syn keyword vimHiCtermColorCyan cyan contained
syn keyword vimHiCtermColorDarkBlue darkBlue contained
syn keyword vimHiCtermColorDarkcyan darkcyan contained
syn keyword vimHiCtermColorDarkgray darkgray contained
syn keyword vimHiCtermColorDarkgreen darkgreen contained
syn keyword vimHiCtermColorDarkgrey darkgrey contained
syn keyword vimHiCtermColorDarkmagenta darkmagenta contained
syn keyword vimHiCtermColorDarkred darkred contained
syn keyword vimHiCtermColorDarkyellow darkyellow contained
syn keyword vimHiCtermColorGray gray contained
syn keyword vimHiCtermColorGreen green contained
syn keyword vimHiCtermColorGrey grey contained
syn keyword vimHiCtermColorLightblue lightblue contained
syn keyword vimHiCtermColorLightcyan lightcyan contained
syn keyword vimHiCtermColorLightgray lightgray contained
syn keyword vimHiCtermColorLightgreen lightgreen contained
syn keyword vimHiCtermColorLightgrey lightgrey contained
syn keyword vimHiCtermColorLightmagenta lightmagenta contained
syn keyword vimHiCtermColorLightred lightred contained
syn keyword vimHiCtermColorMagenta magenta contained
syn keyword vimHiCtermColorRed red contained
syn keyword vimHiCtermColorWhite white contained
syn keyword vimHiCtermColorYellow yellow contained

syn match  vimHiCtermFgBg   contained   "\ccterm[fb]g="he=e-1   nextgroup=vimNumber,@vimHiCtermColors,vimFgBgAttrib,vimHiCtermError

highlight vimHiCtermColorBlack ctermfg=black
highlight vimHiCtermColorBlue ctermfg=blue
highlight vimHiCtermColorBrown ctermfg=brown
highlight vimHiCtermColorCyan ctermfg=cyan
highlight vimHiCtermColorDarkBlue ctermfg=darkBlue
highlight vimHiCtermColorDarkcyan ctermfg=darkcyan
highlight vimHiCtermColorDarkgray ctermfg=darkgray
highlight vimHiCtermColorDarkgreen ctermfg=darkgreen
highlight vimHiCtermColorDarkgrey ctermfg=darkgrey
highlight vimHiCtermColorDarkmagenta ctermfg=darkmagenta
highlight vimHiCtermColorDarkred ctermfg=darkred
highlight vimHiCtermColorDarkyellow ctermfg=darkyellow
highlight vimHiCtermColorGray ctermfg=gray
highlight vimHiCtermColorGreen ctermfg=green
highlight vimHiCtermColorGrey ctermfg=grey
highlight vimHiCtermColorLightblue ctermfg=lightblue
highlight vimHiCtermColorLightcyan ctermfg=lightcyan
highlight vimHiCtermColorLightgray ctermfg=lightgray
highlight vimHiCtermColorLightgreen ctermfg=lightgreen
highlight vimHiCtermColorLightgrey ctermfg=lightgrey
highlight vimHiCtermColorLightmagenta ctermfg=lightmagenta
highlight vimHiCtermColorLightred ctermfg=lightred
highlight vimHiCtermColorMagenta ctermfg=magenta
highlight vimHiCtermColorRed ctermfg=red
highlight vimHiCtermColorWhite ctermfg=white
highlight vimHiCtermColorYellow ctermfg=yellow

Explanation

If you look in colors/vim.vim and search for cterm, you'll see a line

syn match  vimHiCtermFgBg   contained   "\ccterm[fb]g="he=e-1   nextgroup=vimNumber,vimHiCtermColor,vimFgBgAttrib,vimHiCtermError

This says that, when ctermfg= or ctermbg= is encountered, highlight the next word as vimNumber, vimHiCtermColor, vimFgBgAttrib, or vimHiCtermError. Looking at vimHiCtermColor (a few lines above), we see

syn keyword vimHiCtermColor contained   black blue brown cyan darkBlue darkcyan darkgray darkgreen darkgrey darkmagenta darkred darkyellow gray green grey lightblue lightcyan lightgray lightgreen lightgrey lightmagenta lightred magenta red white yellow

This lists all of the color terminal names, and they are highlighted as keywords with the same syntax group. So, instead of highlighting them all together, we can highlight them separately. The four lines of the first solution above describe the steps:

1. Create a new cluster, @vimHiCtermColors containing each of the groups in step 2.
2. Add a new keyword for each color value.
3. Modify the vimHiCtermFgBg definition to use @vimHiCtermColors instead of vimHiCtermColor.
4. Highlight each keyword as you wish.

The reason why what you tried did not work is twofold. First, the syntax groups specified in the nextgroup are preferred over general groups (your yellow group, in particular). But, you may say, "What about containedin=ALL?" This is the second point. Keywords are individual units and cannot contain anything else. The original vimHiCtermColor group was all keywords, so your containedin=ALL could not override it. If vimHiCtermColor had been a match instead of a keyword, it may have worked.