" Vim indent file
" Language: Lua script
" Maintainer: Marcus Aurelius Farias <marcus.cf 'at' bol.com.br>
" First Author: Max Ischenko <mfi 'at' ukr.net>
" Last Change: 2007 Jul 23

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

setlocal indentexpr=GetLuaIndent()

" To make Vim call GetLuaIndent() when it finds '\s*end' or '\s*until'
" on the current line ('else' is default and includes 'elseif').
setlocal indentkeys+=0=end,0=until

setlocal autoindent

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

function! GetLuaIndent()
" Find a non-blank line above the current line.
let prevlnum = prevnonblank(v:lnum - 1)

" Hit the start of the file, use zero indent.
if prevlnum == 0
return 0
endif

" Add a 'shiftwidth' after lines that start a block:
" 'function', 'if', 'for', 'while', 'repeat', 'else', 'elseif', '{'
let ind = indent(prevlnum)
let prevline = getline(prevlnum)
let midx = match(prevline, '^\s*\%(if\>\|for\>\|while\>\|repeat\>\|else\>\|elseif\>\|do\>\|then\>\)')
if midx == -1
let midx = match(prevline, '{\s*$')
if midx == -1
let midx = match(prevline, '\<function\>\s*\%(\k\|[.:]\)\{-}\s*(')
endif
endif

if midx != -1
" Add 'shiftwidth' if what we found previously is not in a comment and
" an "end" or "until" is not present on the same line.
if synIDattr(synID(prevlnum, midx + 1, 1), "name") != "luaComment" && prevline !~ '\<end\>\|\<until\>'
let ind = ind + &shiftwidth
endif
endif

" Subtract a 'shiftwidth' on end, else (and elseif), until and '}'
" This is the part that requires 'indentkeys'.
let midx = match(getline(v:lnum), '^\s*\%(end\|else\|until\|}\)')
if midx != -1 && synIDattr(synID(v:lnum, midx + 1, 1), "name") != "luaComment"
let ind = ind - &shiftwidth
endif

return ind
endfunction