Limit vim syntax highlighting to diff - vim

I am making changes to an existing C code. If I just want to check my changes, I can easily use vimdiff for that, with old & modified files.
What I want is to limit some syntax highlighting to just the diff part.
Particularly I need to highlight TABS, but only those TABS contained within DiffAdd & DiffChange sections/regions.
What I tried:
syntax region TESTRGN start="TESTRGN_START" end="TESTRGN_END"
highlight TESTRGN ctermbg=lightgreen guibg=lightgreen
syntax match LeadingTabsInRegion display contained containedin=TESTRGN /^\( *\t\+\)\+/
highlight LeadingTabsInRegion ctermbg=darkred guibg=darkred
Above snippet highlights the leading TABS within TESTRGN & tabs in remaining file remain un-highlighted.
However, if I change TESTRGN to DiffAdd in the syntax match line, it does not work as I expected.
My understanding is that DiffAdd is not a region defined using syntax region ... & hence containedin=DiffAdd does not work.
So is there any method/work-around for doing what I am trying to do?

First, what's so bad about having the highlighting everywhere? The diff highlighting stands out well and therefore provides visible scope; couldn't you just ignore the highlighting elsewhere?
In Vim, syntax groups are defined and then linked to colors and attributes defined in highlight groups. The diff stuff uses the second part of that mechanism, but not the syntax part. Therefore, you unfortunately cannot refer to the diff regions within :syntax commands.
There's only a very ugly workaround for this: You have to determine the line numbers that have diff highlighting (via repeatedly stepping through the changes with the ]c motion, and/or using synID() to check for diff highlighting). With those line numbers, you can then define :syntax match commands with the special \%l atom that only matches certain lines. Of course, any addition / deletion of lines would invalidate your definitions, which would need to be frequently re-synchronized (triggered by :autocmd). That's a lot of effort vs. just ignoring the highlighting elsewhere.

Though you need to reset whenever the line was changed, this is just a tip for one of line number based ideas, you can get a list of all diff highlighted lines with:
let dl = filter(range(1, line('$')),
\'index([hlID("DiffChange"), hlID("DiffText"), hlID("DiffAdd")],
\diff_hlID(v:val, 1)) != -1')
And using this, it might be possible to set your TESTRGN with:
exec "syntax match TESTRGN /\\(" . join(map(dl, '"\\%" . v:val . "l"'), "\\|") . "\\).*/"

Related

vim automatic hard wrap for fortran with line-continuation

I'm a Fortran programmer who uses both free-form and fixed form. Since I have to mix them, usually I write code in a common form between free and fixed format, so in this way I can tell to vim that all my files are in the free format.
Vim is great in doing things like autoindentation, but I would like to type and let vim automatically wrap my code, and placing the Fortran continuation character & at column 73 (or greater), and at column 6 in the new line. Is it possible, or does it exist a plugin for this?
Currently I'm using textwidth=72 in fortran files to hard wrap the lines.
Thanks in advance.
One way to make vim insert text when going to a new line is to use formatexpr. Set it so to capture the line and replace it with itself with & and new line appended, when at/beyond a given column. In this case you are handling line breaks and textwidth does not apply. I didn't yet get to test some simple code for it, but here is a related example.
Another way would be to write general code so that when in a given column it inserts & and <CR>.
However, making any such approach respect Fortran-specific exclusions (comments, for one thing) will make it more complicated. The best solution would be to find suitable existing option(s) for Fortran, but I haven't so far.
This is a comment on indentation in general. It should allow you to directly set up a desired rule for a new line. Here is one standard set of files that set up a lot of indentation rules and features.
The usual entry point is this vim script, which requires another standard set of files. The link given on that page for the other files is broken though, so here is where to find them: unpack this zip file (found on this page), right into your ~/.vim/ directory. It will create subdirectories indent/, syntax/, and ftpplugin/, or put files into them if they exist, so be careful if you have stuff there already.
Then you can put the first script linked above into .vim/after/indent/. In this file, there are specific calculations of where to put the cursor when a new line is entered. Find the right place(s) and change to your desired indent, or preferably set up a snippet from it in another file (so not to change this file). In this case you also need to set things up so that it overrides settings from the first file.
A useful resource is indentexpr (or :help indentexpr).
Here is also a tutorial on that.
These are comments on syntax in general, posted initially. They contain items of help related to what you want and should be generally useful, but probably have not much to say about adding &.
There are plugins for fortran. Here is the syntax file, with many things to tweak.
This may already be on your system. (It was on mine.) Thus I would go through and pick and choose things to add to your .vimrc. Here are a few options that are directly related
syn match fortranContinueMark display "&"
syn sync linecont "&" minlines=20
Here are paragraphs that seem to me relevant in their entirety
if (b:fortran_fixed_source == 1)
if !exists("fortran_have_tabs")
"Flag items beyond column 72
syn match fortranSerialNumber excludenl "^.\{73,}$"lc=72
"Flag left margin errors
syn match fortranLabelError "^.\{-,4}[^0-9 ]" contains=fortranTab
syn match fortranLabelError "^.\{4}\d\S"
endif
syn match fortranComment excludenl "^[!c*].*$" contains=#fortranCommentGroup
syn match fortranLeftMargin transparent "^ \{5}"
syn match fortranContinueMark display "^.\{5}\S"lc=5
else
syn match fortranContinueMark display "&"
endif
if b:fortran_dialect != "f77"
syn match fortranComment excludenl "!.*$" contains=#fortranCommentGroup,#spell
endif
Then a block of syn match statements follow for common cpp-like settings, and then
"Synchronising limits assume that comment and continuation lines are not mixed
if exists("fortran_fold") || exists("fortran_more_precise")
syn sync fromstart
elseif (b:fortran_fixed_source == 0)
syn sync linecont "&" minlines=20
else
syn sync minlines=20
endif
By your question it appears that you know how to set up .vimrc but here are a few comments.
Syntax support need be enabled with appropriate enable and autogroup statements, for example
syntax enable
" au BufRead,BufNewFile *.f90 FileType=fortran
au FileType fortran setlocal ...
Here are some common formatting options that I have for fortran
autocmd FileType fortran setlocal formatoptions=croql comments=:/!/
There can also be a t among options, for textwidth
Here are some specific settings I have, which I see in this syntax file with far more sophistication
let fortran_free_source=1
" Said to need fortran.vim and/or fortran support packages (they work)
let fortran_do_enddo=1
let fortran_more_precise=1
Standard vim help is of course extensive, but try :help fortran -- it has a number of useful settings right up front and is not overwhelming at all. Also see ft-fortran-syntax from help.
See this post with some troubleshooting if things aren't working right. Here is another useful post, even as it appears unrelated by its title.

error when defining a new vim syntax

Why can't this line correctly highlight all things between (* and *) as comments in vim?
syn region datsComment start="(\*" end="\*)" contains=datsComment,datsTodo
hi def link datsComment Comment
It does for me (in a fresh buffer without other syntax definitions). You probably have other syntax elements there that prevent a match.
You need to find out which syntax group causes that. :syn list shows all active groups, but it's easier when you install the SyntaxAttr.vim - Show syntax highlighting attributes of character under cursor plugin. If you find other syntax groups obscuring the match, you probably should include them in the contains=datsComment,datsTodo,... part.

highlight sub-match in vim

I'm trying to figure out how to highlight a specific portion of a match in vim.
Given the following example rule (taken from the coffeescript syntax file source):
syn match coffeeExtendedOp /\%(\S\s*\)\#<=[+\-*/%&|\^=!<>?.]\+\|[-=]>\|--\|++\|:/ display
This regular expression matches various coffeescript operators. The operators are highlighted (in my vimrc) like this:
hi Operator guifg=#ff0000
For example, since coffeeExtendedOp is linked to coffeeOperator which is linked to Operator, in the above source file. This all works, but I'm wondering how to specifically highlight the ++ operator matched in the above syn match with a different color, say blue, within my vimrc (that is, without altering the original source file above). I'm simply wondering if this is possible.
EDIT: I think the rules are placed under a cluster, so perhaps that's why it's not affecting anything. Is there a way to access the rule within the cluster?
EDIT: Question was clarified.
Solution:
syn match plusplus /++/ contained containedin=coffeeExtendedOp display
hi plusplus guifg=#0000ff
The problem now is that this only works when I run them as commands in vim, but not when I put it in my vimrc file. Any ideas? Could it be that the stuff is hidden behind the cluster? But then why is it visible in vim through a command? I tried including the syntax file but it didn't seem to have any effect.
Looking at the coffee.vim you linked to it seems like the dot belongs to the coffeeDotAccess syntax item. So you can highlight it just by doing this:
:hi coffeeDotAccess ctermfg=blue
I'm going to guess a bit at what you need. (I don't speak Coffeescript and your sample regex is way too complicated for me to start reading at the moment).
Transparent syntax items
You could have a look at transparent syntax rules: (http://vimdoc.sourceforge.net/htmldoc/usr_44.html)
In a C language file you would like to highlight the () text after a "while"
differently from the () text after a "for". In both of these there can be
nested () items, which should be highlighted in the same way. You must make
sure the () highlighting stops at the matching ). This is one way to do this:
:syntax region cWhile matchgroup=cWhile start=/while\s*(/ end=/)/
\ contains=cCondNest
:syntax region cFor matchgroup=cFor start=/for\s*(/ end=/)/
\ contains=cCondNest
:syntax region cCondNest start=/(/ end=/)/ contained transparent
Partial matches in regex
If you really just meant highlighting submatches, have a look at the the
\zs start match
\ze end match
In short,
:match Error /foo\zsbar\zered/
would highlight only 'bar' in 'foobarred'

extend/modify vim highlighting for all filetypes at once?

How do I extend/modify vim highlighting for all filetypes at once?
I have certain relatively simple patterns which I'd like highlight differently, that can occur in any filetype. So rather than adding something like the below to every conceivable filetype I might use (~/.vim/syntax/python.vim, .../css.vim, .../html.vim, ...) is there some way I can define it once for all filetypes?
syn match SpecialComment "#[#\-+].*" containedin=Comment
syn match Comment "\* .*$"hs=s+1 containedin=SpecialComment
update:
As suggested I saved my changes to ~/.vim/after/filetype.vim, with the result that it works in Cream but not stock Gvim or Vim. The actual code I'm using here, a sample python file to test against here, and the desired result:
You could try putting those two lines in ~/.vim/after/filetype.vim. That should get sourced after any of the top level syntax files. It's possibly not the 'correct' place to put it, but it should work.
filetype.vim seems to be sourced BEFORE the syntax files, so it gets overwritten by the default syntax file. Therefore, I'd recommend you create a new file called something like:
~/.vim/after/common_syntax.vim
with the highlight lines that you're interested in. Then, add this to ~/.vim/after/filetype.vim:
if !exists("after_autocmds_loaded")
let after_autocmds_loaded = 1
au BufNewFile,BufRead * source ~/.vim/after/common_syntax.vim
endif
This will cause the file to be sourced once the file has been read.
P.S. Responding to the comment in your sample code: "why can't we use plain ol 'comment' group instead of 'pythoncomment' etc. ?", it's because the syntax highlight group is pythonComment, which is merely coloured in the same way as Comment. If your syntax is unique enough for it not to be a problem, you could just do containedin=ALL. If it is close, but not quite unique, you could do containedin=ALLBUT,conflictgroup where conflictgroup is the highlight group you want to steer clear of.

Vim: C++ symbols' color

VIM: Is it possible to change the color of these symbols:
~!%^&*()-+=[]{},.<>?:/;
like Visual Studio does?
The C/C++ syntaxes are defined in syntax/c.vim and syntax/cpp.vim. If you're using Linux, the main syntax directory is in /usr/share/vimXX/, where XX is the version (e.g. mine are in vim72). I don't know about installation directories on other OSes, but I'm sure you can find it. I'd suggest making a copy of these and placing them in your user vim directory (for example, in Linux, $HOME/.vim/syntax/c.vim and so on). You can then add whatever you like.
The C++ syntax sources the C syntax, so any symbols you want highlighted in both should go in c.vim, and anything for C++ only should be in cpp.vim.
To get syntax highlighting for specific symbols, you'll need to use a syntax match statement, something like:
syn match cUserSpecialCharacter display "[~!%^&*()-+=[\]{},.<>?:;]"
syn match cUserSpecialCharacter display "/[^*/]"me=e-1
syn match cUserSpecialCharacter display "/$"
I called it cUserSpecialCharacter since cCharacter and cSpecialCharacter are already used. The second and third matches are a bit of a kludge to highlight '/' without it matching comment prefixes, which would then override the comment highlighting and break everything. The "display" option tells Vim that it doesn't need to look for this match if it's not going to be displayed - see :help syn-display for an explanation if you like!
Once you've defined a syntax match, you can link it to a highlight group, for example:
hi def link cUserSpecialCharacter cCharacter
This will put it in with the already defined cCharacter group, so it'll get whatever highlighting that gets - in this case, Character. You can see a nice list of highlight groups at the bottom of c.vim for examples. If you really want, you can also hardcode a highlight by doing something like:
hi cUserSpecialCharacter term=reverse ctermfg=15 ctermbg=1 guifg=#ffffff guibg=#800000
(Arbitrary example - my current highlighting for the Error group.) See :help hi for more information on this, or simply :hi to see the list of defined highlighting - plenty of examples. I'd recommend against doing this, though, since it won't change with color schemes.
Yes, you need to edit the C color theme in vimfiles/colors/c.vim I don't know all the theme options one can use, but I'm sure they are documented on http://vim.org/

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