" IDL (Interactive Data Language) indent file.
" Language: IDL (ft=idlang)
" Last change: 2012 May 18
" Maintainer: Aleksandar Jelenak <ajelenak AT yahoo.com>

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

setlocal indentkeys=o,O,0=endif,0=ENDIF,0=endelse,0=ENDELSE,0=endwhile,0=ENDWHILE,0=endfor,0=ENDFOR,0=endrep,0=ENDREP

setlocal indentexpr=GetIdlangIndent(v:lnum)

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

function GetIdlangIndent(lnum)
" First non-empty line above the current line.
let pnum = prevnonblank(v:lnum-1)
" v:lnum is the first non-empty line -- zero indent.
if pnum == 0
return 0
endif
" Second non-empty line above the current line.
let pnum2 = prevnonblank(pnum-1)

" Current indent.
let curind = indent(pnum)

" Indenting of continued lines.
if getline(pnum) =~ '\$\s*\(;.*\)\=$'
if getline(pnum2) !~ '\$\s*\(;.*\)\=$'
let curind = curind+&sw
endif
else
if getline(pnum2) =~ '\$\s*\(;.*\)\=$'
let curind = curind-&sw
endif
endif

" Indenting blocks of statements.
if getline(v:lnum) =~? '^\s*\(endif\|endelse\|endwhile\|endfor\|endrep\)\>'
if getline(pnum) =~? 'begin\>'
elseif indent(v:lnum) > curind-&sw
let curind = curind-&sw
else
return -1
endif
elseif getline(pnum) =~? 'begin\>'
if indent(v:lnum) < curind+&sw
let curind = curind+&sw
else
return -1
endif
endif
return curind
endfunction