Update: for a more general solution take a look at vim-match-control

Vim Excess Lines

This is kind of a frontend to the the matchadd() mechanism in Vim with the focus on one particular use case: Highlighting surplus characters in long lines.

The configuration is a bit involved, but in return you can specify what you want to see when and where. Actually, you can use it to highlight anything. Not just excess lines.

Features:

• Configure different highlighting for buffers of different filetype
• Match different patterns during insert and normal mode
• Turn highlighting on/off or toggle it
• Select in which filetypes to start in on/off mode
• Start in off mode when the buffer is not modifiable, has the wrap option set, or has a particular buffer-type (configurable)
• Extract patterns of installed matches to search for or act on affected lines

Configuration

The dictionary g:excess_lines_match_setup can be used to configure the matches. The keys are filetypes to which the values apply. Each value is another dictionary where the keys are the mode in which the list of match-specifications they map to are active.

There is one special key * that applies to all filetypes without a key.

The three valid modes are:

• 'permanent' : active in all modes
• 'insert' : only active in insert mode
• 'normal' : only active when not in insert mode

Note that each of the missing mode-keys of a specific filetype falls back to the one in the default entry * individually.

For example, to add special behavior for markdown files you can add an entry similar to this one:

let g:excess_lines_match_setup['markdown'] = {
    \   'permanent': s:expl_permanent_matches,
    \   'insert': s:expl_insert_mode_matches,
    \   'normal': [],
    \ }

The match specifications consist of arguments to matchadd().

[['highlight-group', 'pattern', priority], ...]

To highlight all characters beyond column 80 you could use this list of match specifications:

let s:expl_permanent_matches = [
    \   ["LineNr", '\%81v.\+', -70],
    \ ]

In insert mode, you might want to override the permanent match from above with an unobtrusive undercurl and place a warning sign at column 70. This is what the following list of match-specifications does.

let s:expl_insert_mode_matches = [
    \   ["Todo",  '\zs\%70v.\ze.*\%#', -50],
    \   ["Todo",  '\%#.*\zs\%70v.\ze', -50],
    \   ["Undercurl",  '\%81v.\+\%#.*$', -50],
    \   ["Undercurl",  '\%#.*\zs\%81v.\+\ze$', -50],
    \ ]

So there is a lot possible, but if you just want to highlight excess chars in selected filetypes starting at different columns, you can use something like this:

let g:excess_lines_match_setup = {
    \ '*': { 'permanent': ["Error", '\%81v.\+', -50]},
    \ 'html': { 'permanent': ["Error", '\%91v.\+', -50]},
    \ 'text': { 'permanent': ["Error", '\%101v.\+', -50]},
    \ }

Display

Use the following commands to turn the display in one buffer on/off or toggle it:

ElShowExcessLines
ElHideExcessLines
ElToggleExcessLines

Active Patterns

You can extract the patterns of active matches by index (zero based). The permanent patterns come first and then either insert or normal mode patterns.

The idea is to have one special position (most likely the first) with the main pattern, so that you can work with it. This is the command defined by this plugin to set the search pattern to the first match:

ElSetSearchPatternToFirstActivePattern

Use the following function to access any active match pattern.

g:EL_GetActivePattern(index)

Override Patterns

It is possible to temporarily install a different match-setup in a buffer. This can be useful if you repeatedly work with the same set of patterns. For example, you could highlight several different patterns and copy each of them to the search register to jump to the matches.

Use these functions to work with override patterns. The argument match_setup is a dictionary with the same format as g:excess_lines_match_setup:

call g:EL_InstallOverridePatterns(match_setup)
call g:EL_UninstallOverridePatterns()

Documentation

There is documentation in the plugin-file plugin/excess-lines.vim. See the top for configuration, and the bottom for public functions and commands.