" HiCursorWords -- Highlights words under the cursor.
"
" Maintainer: Shuhei Kubota <kubota.shuhei+vim@gmail.com>
" Description:
"   This script highlights words under the cursor like many IDEs.
"
"   This doesn't provide scope-aware highlighting nor language specific one.
"   You can control highlighting by highlighting group names.
"
" Variables:
"
"   (A right hand side value is a default value.)
"
"   g:HiCursorWords_delay = 200
"       A delay for highlighting in milliseconds.
"       Smaller value may cause your machine slow down.
"
"   g:HiCursorWords_hiGroupRegexp = ''
"       If empty, all words are highlighted.
"       If not empty, only the specified highlight group is highlighted.
"       (my memo: 'Identifier\|vimOperParen')
"
"       To investigate highlight group name, the next variable may help you.
"
"   g:HiCursorWords_debugEchoHiName = 0
"       If not 0, echoes the highlight group name under the cursor.
"
" Hightlight groups:
"
"   (Do :highlight! as you like.)
"
"   WordUnderTheCursor
"
"

if !exists('g:HiCursorWords_delay')
    let g:HiCursorWords_delay = 200
endif

if !exists('g:HiCursorWords_hiGroupRegexp')
    let g:HiCursorWords_hiGroupRegexp = ''
endif

if !exists('g:HiCursorWords_debugEchoHiName')
    let g:HiCursorWords_debugEchoHiName = 0
endif


highlight! link WordUnderTheCursor Underlined

augroup HiCursorWords
    autocmd!
    autocmd  CursorMoved,CursorMovedI  *  call s:HiCursorWords__startHilighting()
augroup END


function! s:HiCursorWords__getHiName(linenum, colnum)
    let hiname = synIDattr(synID(a:linenum, a:colnum, 0), "name")
    let hiname = s:HiCursorWords__resolveHiName(hiname)
    return hiname
endfunction

function! s:HiCursorWords__resolveHiName(hiname)
    redir => resolved
    silent execute 'highlight ' . a:hiname
    redir END

    if stridx(resolved, 'links to') == -1
        return a:hiname
    endif

    return substitute(resolved, '\v(.*) links to ([^ ]+).*$', '\2', '')
endfunction

function! s:HiCursorWords__getWordUnderTheCursor(linestr, linenum, colnum)
    "let word = substitute(a:linestr, '.*\(\<\k\{-}\%' . a:colnum . 'c\k\{-}\>\).*', '\1', '') "expand('<word>')
    let word = matchstr(a:linestr, '\k*\%' . a:colnum . 'c\k\+')
    if a:linestr == word
        return ''
    endif
    return '\V\<' . word . '\>'
endfunction

function! s:HiCursorWords__execute()
    if exists("w:HiCursorWords__matchId")
        call matchdelete(w:HiCursorWords__matchId)
        unlet w:HiCursorWords__matchId
    endif

    let linestr = getline('.')
    let linenum = line('.')
    let colnum = col('.')

    if g:HiCursorWords_debugEchoHiName
        echo s:HiCursorWords__getHiName(linenum, colnum)
    endif

    let word = s:HiCursorWords__getWordUnderTheCursor(linestr, linenum, colnum)
    if strlen(word) != 0
        if strlen(g:HiCursorWords_hiGroupRegexp) != 0
                    \ && match(s:HiCursorWords__getHiName(linenum, colnum), g:HiCursorWords_hiGroupRegexp) == -1
                return
        endif
        let w:HiCursorWords__matchId = matchadd('WordUnderTheCursor', word, 0)
    endif
endfunction

function! s:HiCursorWords__startHilighting()
    let b:HiCursorWords__oldUpdatetime = &updatetime
    let &updatetime = g:HiCursorWords_delay
    augroup HiCursorWordsUpdate
        autocmd!
        autocmd CursorHold,CursorHoldI  *
                    \ let &updatetime = b:HiCursorWords__oldUpdatetime
                    \ | call s:HiCursorWords__execute()
    augroup END
endfunction

" vim: set et ft=vim sts=4 sw=4 ts=4 tw=78 :