" Vim indent file
" Language: PoV-Ray Scene Description Language
" Maintainer: David Necas (Yeti) <[email protected]>
" Last Change: 2002-10-20
" URI: http://trific.ath.cx/Ftp/vim/indent/pov.vim

" Only load this indent file when no other was loaded.
if exists("b:did_indent")
finish
endif
let b:did_indent = 1

" Some preliminary settings.
setlocal nolisp " Make sure lisp indenting doesn't supersede us.

setlocal indentexpr=GetPoVRayIndent()
setlocal indentkeys+==else,=end,0]

" Only define the function once.
if exists("*GetPoVRayIndent")
finish
endif

" Counts matches of a regexp <rexp> in line number <line>.
" Doesn't count matches inside strings and comments (as defined by current
" syntax).
function! s:MatchCount(line, rexp)
let str = getline(a:line)
let i = 0
let n = 0
while i >= 0
let i = matchend(str, a:rexp, i)
if i >= 0 && synIDattr(synID(a:line, i, 0), "name") !~? "string\|comment"
let n = n + 1
endif
endwhile
return n
endfunction

" The main function. Returns indent amount.
function GetPoVRayIndent()
" If we are inside a comment (may be nested in obscure ways), give up
if synIDattr(synID(v:lnum, indent(v:lnum)+1, 0), "name") =~? "string\|comment"
return -1
endif

" Search backwards for the frist non-empty, non-comment line.
let plnum = prevnonblank(v:lnum - 1)
let plind = indent(plnum)
while plnum > 0 && synIDattr(synID(plnum, plind+1, 0), "name") =~? "comment"
let plnum = prevnonblank(plnum - 1)
let plind = indent(plnum)
endwhile

" Start indenting from zero
if plnum == 0
return 0
endif

" Analyse previous nonempty line.
let chg = 0
let chg = chg + s:MatchCount(plnum, '[[{(]')
let chg = chg + s:MatchCount(plnum, '#\s*\%(if\|ifdef\|ifndef\|switch\|while\|macro\|else\)\>')
let chg = chg - s:MatchCount(plnum, '#\s*end\>')
let chg = chg - s:MatchCount(plnum, '[]})]')
" Dirty hack for people writing #if and #else on the same line.
let chg = chg - s:MatchCount(plnum, '#\s*\%(if\|ifdef\|ifndef\|switch\)\>.*#\s*else\>')
" When chg > 0, then we opened groups and we should indent more, but when
" chg < 0, we closed groups and this already affected the previous line,
" so we should not dedent. And when everything else fails, scream.
let chg = chg > 0 ? chg : 0

" Analyse current line
" FIXME: If we have to dedent, we should try to find the indentation of the
" opening line.
let cur = s:MatchCount(v:lnum, '^\s*\%(#\s*\%(end\|else\)\>\|[]})]\)')
if cur > 0
let final = plind + (chg - cur) * &sw
else
let final = plind + chg * &sw
endif

return final < 0 ? 0 : final
endfunction