vim-polyglot/ftplugin/latex-box/findmain.vim

if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'latex') == -1
  
" LatexBox_GetMainFileName: gets the name of the main file being compiled. {{{
" Description:  returns the full path name of the main file.
"               This function checks for the existence of a .latexmain file
"               which might point to the location of a "main" latex file.
"               If .latexmain exists, then return the full path name of the
"               file being pointed to by it.
"
"               Otherwise, return the full path name of the current buffer.
"
"               You can supply an optional "modifier" argument to the
"               function, which will optionally modify the file name before
"               returning.
"               NOTE: From version 1.6 onwards, this function always trims
"               away the .latexmain part of the file name before applying the
"               modifier argument.
"               NOTE: This function is copied from the Latex-Suite project!
function! LatexBox_GetMainFileName(...)
	if a:0 > 0
		let modifier = a:1
	else
		let modifier = ':p'
	endif

	let s:origdir = fnameescape(getcwd())

	let dirmodifier = '%:p:h'
	let dirLast = fnameescape(expand(dirmodifier))
	exe 'cd '.dirLast

	" move up the directory tree until we find a .latexmain file.
	" TODO: Should we be doing this recursion by default, or should there be a
	"       setting?
	while glob('*.latexmain',1) == ''
		let dirmodifier = dirmodifier.':h'
		let dirNew = fnameescape(expand(dirmodifier))
		" break from the loop if we cannot go up any further.
		if dirNew == dirLast
			break
		endif
		let dirLast = dirNew
		exe 'cd '.dirLast
	endwhile

	let lheadfile = glob('*.latexmain',1)
	if lheadfile != ''
		" Remove the trailing .latexmain part of the filename... We never want
		" that.
		let lheadfile = fnamemodify(substitute(lheadfile, '\.latexmain$', '', ''), modifier)
	else
		" If we cannot find any main file, just modify the filename of the
		" current buffer.
		let lheadfile = expand('%'.modifier)
	endif

	exe 'cd '.s:origdir

	" NOTE: The caller of this function needs to escape the file name with
	"       fnameescape() . The reason its not done here is that escaping is not
	"       safe if this file is to be used as part of an external command on
	"       certain platforms.
	return lheadfile
endfunction

endif