Vim使用一种巨大的启发式算法来确定普通文本与其他变种Tex之间的区别。
如果您查看$VIMRUNTIME/filetype.vim,则会找到以下函数。
" Choose context, plaintex, or tex (LaTeX) based on these rules:
" 1. Check the first line of the file for "%&<format>".
" 2. Check the first 1000 non-comment lines for LaTeX or ConTeXt keywords.
" 3. Default to "latex" or to g:tex_flavor, can be set in user's vimrc.
func! s:FTtex()
let firstline = getline(1)
if firstline =~ '^%&\s*\a\+'
let format = tolower(matchstr(firstline, '\a\+'))
let format = substitute(format, 'pdf', '', '')
if format == 'tex'
let format = 'plain'
endif
else
" Default value, may be changed later:
let format = exists("g:tex_flavor") ? g:tex_flavor : 'plain'
" Save position, go to the top of the file, find first non-comment line.
let save_cursor = getpos('.')
call cursor(1,1)
let firstNC = search('^\s*[^[:space:]%]', 'c', 1000)
if firstNC " Check the next thousand lines for a LaTeX or ConTeXt keyword.
let lpat = 'documentclass\>\|usepackage\>\|begin{\|newcommand\>\|renewcommand\>'
let cpat = 'start\a\+\|setup\a\+\|usemodule\|enablemode\|enableregime\|setvariables\|useencoding\|usesymbols\|stelle\a\+\|verwende\a\+\|stel\a\+\|gebruik\a\+\|usa\a\+\|imposta\a\+\|regle\a\+\|utilisemodule\>'
let kwline = search('^\s*\\\%(' . lpat . '\)\|^\s*\\\(' . cpat . '\)',
\ 'cnp', firstNC + 1000)
if kwline == 1 " lpat matched
let format = 'latex'
elseif kwline == 2 " cpat matched
let format = 'context'
endif " If neither matched, keep default set above.
" let lline = search('^\s*\\\%(' . lpat . '\)', 'cn', firstNC + 1000)
" let cline = search('^\s*\\\%(' . cpat . '\)', 'cn', firstNC + 1000)
" if cline > 0
" let format = 'context'
" endif
" if lline > 0 && (cline == 0 || cline > lline)
" let format = 'tex'
" endif
endif " firstNC
call setpos('.', save_cursor)
endif " firstline =~ '^%&\s*\a\+'
" Translation from formats to file types. TODO: add AMSTeX, RevTex, others?
if format == 'plain'
setf plaintex
elseif format == 'context'
setf context
else " probably LaTeX
setf tex
endif
return
endfunc
这个函数确定使用哪种tex的版本。如果你看一下它,你会发现默认值是从g:tex_flavor
中获取的(如果存在,默认为plain)。如果你在vimrc中将这个变量设置为tex,vim将默认使用tex文件类型。
let g:tex_flavor = 'tex'