vim-sleuth/plugin/sleuth.vim

" sleuth.vim - Heuristically set buffer options
" Maintainer:   Tim Pope <http://tpo.pe/>
" Version:      1.1
" GetLatestVimScripts: 4375 1 :AutoInstall: sleuth.vim

if exists("g:loaded_sleuth") || v:version < 700 || &cp
  finish
endif
let g:loaded_sleuth = 1

function! s:guess(lines) abort
  let options = {}
  let heuristics = {'spaces': 0, 'hard': 0, 'soft': 0}
  let ccomment = 0
  let podcomment = 0
  let triplequote = 0
  let backtick = 0
  let softtab = repeat(' ', 4)

  for line in a:lines
    if !len(line) || line =~# '^\s*$'
      continue
    endif

    if line =~# '^\s*/\*'
      let ccomment = 1
    endif
    if ccomment
      if line =~# '\*/'
        let ccomment = 0
      endif
      continue
    endif

    if line =~# '^=\w'
      let podcomment = 1
    endif
    if podcomment
      if line =~# '^=\%(end\|cut\)\>'
        let podcomment = 0
      endif
      continue
    endif

    if triplequote
      if line =~# '^[^"]*"""[^"]*$'
        let triplequote = 0
      endif
      continue
    elseif line =~# '^[^"]*"""[^"]*$'
      let triplequote = 1
    endif

    if backtick
      if line =~# '^[^`]*`[^`]*$'
        let backtick = 0
      endif
      continue
    elseif line =~# '^[^`]*`[^`]*$'
      let backtick = 1
    endif

    if line =~# '^\t'
      let heuristics.hard += 1
    elseif line =~# '^' . softtab
      let heuristics.soft += 1
    endif
    if line =~# '^  '
      let heuristics.spaces += 1
    endif
    let indent = len(matchstr(substitute(line, '\t', softtab, 'g'), '^ *'))
    if indent > 1 && get(options, 'shiftwidth', 99) > indent
      let options.shiftwidth = indent
    endif
  endfor

  if heuristics.hard && !heuristics.spaces
    return {'expandtab': 0, 'shiftwidth': &tabstop}
  elseif heuristics.soft != heuristics.hard
    let options.expandtab = heuristics.soft > heuristics.hard
    if heuristics.hard
      let options.tabstop = 4
    endif
  endif

  return options
endfunction

function! s:patterns_for(type) abort
  if a:type ==# ''
    return []
  endif
  if !exists('s:patterns')
    redir => capture
    silent autocmd BufRead
    redir END
    let patterns = {
          \ 'c': ['*.c'],
          \ 'html': ['*.html'],
          \ 'sh': ['*.sh'],
          \ }
    let setfpattern = '\s\+\%(setf\%[iletype]\s\+\|set\%[local]\s\+\%(ft\|filetype\)=\|call SetFileTypeSH(["'']\%(ba\|k\)\=\%(sh\)\@=\)'
    for line in split(capture, "\n")
      let match = matchlist(line, '^\s*\(\S\+\)\='.setfpattern.'\(\w\+\)')
      if !empty(match)
        call extend(patterns, {match[2]: []}, 'keep')
        call extend(patterns[match[2]], [match[1] ==# '' ? last : match[1]])
      endif
      let last = matchstr(line, '\S.*')
    endfor
    let s:patterns = patterns
  endif
  return copy(get(s:patterns, a:type, []))
endfunction

function! s:apply_if_ready(options) abort
  if !has_key(a:options, 'expandtab') || !has_key(a:options, 'shiftwidth')
    return 0
  else
    for [option, value] in items(a:options)
      call setbufvar('', '&'.option, value)
    endfor
    return 1
  endif
endfunction

function! s:detect() abort
  if &modifiable == 0
    return
  endif

  let options = s:guess(getline(1, 1024))
  if s:apply_if_ready(options)
    return
  endif
  let patterns = s:patterns_for(&filetype)
  call filter(patterns, 'v:val !~# "/"')
  let dir = expand('%:p:h')
  while isdirectory(dir) && dir !=# fnamemodify(dir, ':h')
    for pattern in patterns
      for neighbor in split(glob(dir.'/'.pattern), "\n")[0:7]
        if neighbor !=# expand('%:p') && filereadable(neighbor)
          call extend(options, s:guess(readfile(neighbor, '', 256)), 'keep')
        endif
        if s:apply_if_ready(options)
          let b:sleuth_culprit = neighbor
          return
        endif
      endfor
    endfor
    let dir = fnamemodify(dir, ':h')
  endwhile
  if has_key(options, 'shiftwidth')
    return s:apply_if_ready(extend({'expandtab': 1}, options))
  endif
endfunction

setglobal smarttab

function! SleuthIndicator() abort
  if &expandtab
    return 'sw='.&shiftwidth
  elseif &tabstop == &shiftwidth
    return 'ts='.&tabstop
  else
    return 'sw='.&shiftwidth.',ts='.&tabstop
  endif
endfunction

augroup sleuth
  autocmd!
  autocmd FileType * if get(g:, 'sleuth_automatic', 1) | call s:detect() | endif
  autocmd FileType * call s:detect()
  autocmd User Flags call Hoist('buffer', 5, 'SleuthIndicator')
augroup END

command! -bar -bang Sleuth call s:detect()

if exists('g:did_indent_on')
  filetype indent off
endif
filetype indent on

" vim:set et sw=2: