if !exists('main_syntax')
  if exists('b:current_syntax')
      finish
  endif
  let main_syntax = 'ats'
endif

" comment highlighting
syn keyword atsTodo TODO FIXME NOTE contained
syn match   atscCommentError display "\*/"
syn match   atscCommentStartError display "/\*"me=e-1 contained
syn region  atscComment matchgroup=atscCommentStart start="/\*" end="\*/" contains=atsTodo,@Spell,atscCommentStartError
syn match   atsNestedCommentError display "\*)"
" mercilessly ripped from d.vim
syn region  atsNestedComment start="(\*" end="\*)" contains=atsNestedComment,atsTodo,@Spell
syn match   atsComment "//.*" contains=atsTodo

"
" denotation highlighting
"

" special characters
syn match   atsSpecial display contained "\\\(x\x\+\|\o\{1,3}\|.\|$\)"
syn match   atsSpecial display contained "\\\(u\x\{4}\|U\x\{8}\)"
syn match   atsSpecial '\\n'
syn match   atsSpecial '@'
" syn match   atsSpecial '#'
syn match   atsFormat display "%\(\d\+\$\)\=[-+' #0*]*\(\d*\|\*\|\*\d\+\$\)\(\.\(\d*\|\*\|\*\d\+\$\)\)\=\([hlL]\|ll\)\=\([bdiuoxXDOUfeEgGcCsSpn]\|\[\^\=.[^]]*\]\)" contained
syn region  atsStringDenot start=+"+ skip=+\\\\\|\\"+ end=+"+ contains=atsSpecial,atsFormat,atsSpecial,@Spell
syn match   atsCharDenot "'[^\\]'"
syn match   atsCharDenot "'[^']*'" contains=atsSpecial

syn keyword atsBoolDenot true false
syn case ignore
syn match   atsNumbers display transparent "\<\d\|\.\d" contains=atsNumber,atsFloat,atsOctalError,atsOctal
syn match   atsNumber display contained "\d\+\(u\=l\{0,2}\|ll\=u\)\>"
syn match   atsNumber display contained "0x\x\+\(u\=l\{0,2}\ll\=\u\)\>"
" flag the first zero of an octal number as something special
syn match   atsOctal display contained "0\o\+\(u\=l\{0,2}\|ll\=u\)\>" contains=atsOctalZero
syn match   atsFloat display contained "\d\+\.\d*\(e[-+]\=\d\+\)\="
syn match   atsFloat display contained "\.\d\+\(e[-+]\=\d\+\)\>"
syn match   atsFloat display contained "\d\+e[-+]\=\d\+\>"

" flag an octal number with wrong digits
syn match   atsOctalError display contained "0\o*[89]\d*"
syn case match

syn region  atsIncludes oneline start='#include' end='"' contains=atsStringDenot
syn match   atsIdent "[A-Za-z_][0-9A-Za-z_\']*"

" embedded C
" %{^ %} %{ %} %{$ %} %{# %}
if main_syntax !=# 'c' || exists('c')
    syn include @atsC syntax/c.vim
    unlet b:current_syntax
    syn region embC start=+%{[^#$]\=+ keepend end=+%}+ contains=@atsC
endif

"
" keyword highlighting
"

" keyword highlighting
syn keyword atsKeyword prefix postfix infix infixl infixr op addr
syn keyword atsKeyword staload stadef sta dynload stacst assertloc macdef
syn keyword atsCond if then else case sif when
syn keyword atsRepeat while
syn keyword atsOperator mod
syn keyword atsException exception raise try
syn keyword atsStatement let in where local
syn keyword atsStatement val and fnx fun fn llam lam fix rec var of assume castfn prfun prfn
syn keyword atsStatement begin end
syn keyword atsTypedef typedef sortdef viewtypedef vtypedef viewdef
syn keyword atsStructure datatype datavtype abstype dataviewtype dataprop dataview propdef absview
syn keyword atsExternal extern implement primplmnt

syn keyword atsKeyword symintr overload with
syn keyword atsKeyword prval praxi datasort

syn keyword atsSorts bool char int absprop prop type view viewtype nat absvtype absviewtype vtype

syn keyword atsTypes string float double void

syn match   atsSym "[%&+-\./:=@~`^|*!$#?]+\|[%&+-\./:=@~`^|*<>]+"

" C preprocessor directives
syn region  atsPreCondit start="^\s*\(%:\|#\)\s*\(if\|ifdef\|ifndef\|elif\)\>" skip="\\$" end="$" end="//"me=s-1 contains=atsComment,atsCommentError
syn match   atsPreCondit display "^\s*\(%:\|#\)\s*\(else\|endif\)\>"
syn region  atsCppOut start="^\s*\(%\|#\)\s*if\s\+0\+\>" end=".\@=\|$" contains=atsCppOut2
syn region  atsCppOut2 contained start="0" end="^\s*\(%:\|#\)\s*\(endif\>\|else\>\|elif\>\)" contains=atsCppSkip
syn region  atsCppSkip contained start="^\s*\(%:\|#\)\s*\(if\>\|ifdef\>\|print\>\|ifndef\>\)" skip="\\$" end="^\s*\(%:\|#\)\s*endif\>" contains=atsCppSkip
syn region  atsIncluded display contained start=+"+ skip=+\\\\\|\\"+ end=+"+
syn match   atsIncluded display contained "<[^>]*>"
syn match   atsInclude "^\s*\(%:\|#\)\s*include\>\s*["<]" contains=atsIncluded
syn cluster atsPreProcGroup contains=atsPreCondit,atsIncluded,atsInclude,atsDefine,atsCppOut,atsCppOut2,atsCppSkip
syn region  atsDefine matchgroup=atsPreCondit start="\s*\(%:\|#\)\s*\(define\|undef\)\>" skip="\\$" end="$"
syn region  atsPreProc matchgroup=atsPreCondit start="^\s*\(%:\|#\)\s*\(pragma\>\|line\>warning\>\|warn\>\|error\>\)" skip="\\$" end="$" keepend

"
" linking
"

" don't use standard HiLink, it won't work with included syntax files
command! -nargs=+ AtsHiLink hi def link <args>

" includes
AtsHiLink atsIncludes Special
AtsHiLink atsSpecial Special

" comments
AtsHiLink atsCommentStart atsComment
AtsHiLink atsNestedComment Comment
AtsHiLink atscCommentStart Comment
AtsHiLink atscComment Comment
AtsHiLink atsComment Comment
" delimiters
AtsHiLink atsEncl Keyword
" constants and denotations
AtsHiLink atsBoolDenot   Boolean
AtsHiLink atsCharsDenot  String
AtsHiLink atsCharDenot   Character
AtsHiLink atsStringDenot String
AtsHiLink atsNumber Number
AtsHiLink atsOctal Number
AtsHiLink atsOctalZero PreProc " link this to Error if you want
AtsHiLink atsFloat Float
AtsHiLink atsOctalError atsError
" identifiers
AtsHiLink atsIdent Identifier
" various keywords
AtsHiLink atsKey Keyword
AtsHiLink atsOperator Operator
AtsHiLink atsCond Conditional
AtsHiLink atsRepeat Repeat
AtsHiLink atsException Exception
AtsHiLink atsStatement Statement
AtsHiLink atsKeyword Statement
AtsHiLink atsTypedef Typedef
AtsHiLink atsStructure Structure
AtsHiLink atsExternal StorageClass
AtsHiLink atsTypes Type
AtsHiLink atsSorts Type
AtsHiLink atsSym Operator
AtsHiLink atsEncl Keyword
" embedded C
AtsHiLink embC Special

AtsHiLink atsPreProc PreProc

AtsHiLink atsCommentError atsError
AtsHiLink atscCommentStartError atsError
AtsHiLink atscCommentError atsError
AtsHiLink atsNestedCommentError atsError
AtsHiLink atsError Error
AtsHiLink atsAllErrs Error

delcommand AtsHiLink

let b:current_syntax = 'ats'

if main_syntax ==# 'ats'
    unlet main_syntax
endif