// Based on https://www.lua.org/manual/5.4/manual.html#9

token BreakKw='break' ReturnKw='return' FunctionKw='function' EndKw='end' GotoKw='goto'
      DoKw='do' WhileKw='while' RepeatKw='repeat' IfKw='if' ThenKw='then' UntilKw='until'
      ElseifKw='elseif' ElseKw='else' ForKw='for' InKw='in' LocalKw='local' AndKw='and'
      OrKw='or' NotKw='not' NilKw='nil' FalseKw='false' TrueKw='true';
token Semi=';' ColonColon='::' Colon=':' Dot='.' Comma=',' Ellipsis='...'
      Equal='=' Plus='+' Minus='-' Star='*' Slash='/' SlashSlash='//' Hat='^' Percent='%'
      And='&' Tilde='~' Pipe='|' GtGt='>>' LtLt='<<' DotDot='..' Less='<' LessEqual='<='
      Greater='>' GreaterEqual='>=' EqualEqual='==' TildeEqual='~=' Hash='#';
token LBrak='[' RBrak=']' LParen='(' RParen=')' LBrace='{' RBrace='}';
token Name='<name>' LiteralString='<string>'
      Numeral='<numeral>';
token Comment Whitespace;

skip Comment Whitespace;
right '..';

start chunk;

chunk: block;
block: stat* [retstat];
stat:
  emptystat
| expstat
| label
| breakstat
| gotostat
| dostat
| whilestat
| repeatstat
| ifstat
| forstat
| funcstat
| localstat
;
emptystat: ';';
/// superset of official grammar, check in cst that syntax is valid
expstat: prefixexp [(',' prefixexp)* '=' explist @assignstat] @;

breakstat: 'break';
gotostat: 'goto' Name;
dostat: 'do' block 'end';
whilestat: 'while' exp 'do' block 'end';
repeatstat: 'repeat' block 'until' exp;
ifstat:
  'if' exp 'then' block
  ('elseif' exp 'then' block)*
  ['else' block] 'end'
;
forstat:
  'for' (
    ?1 Name '=' exp ',' exp [',' exp] 'do' block 'end' // resolve LL(1) conflict with extra lookahead
  | namelist 'in' explist 'do' block 'end')
;
funcstat: 'function' funcname pars funcbody;
localstat:
  'local' (
    'function' Name pars funcbody
  | attnamelist ['=' explist]
  )
;
attnamelist: Name attrib (',' Name attrib)*;
attrib: ['<' Name '>'];
retstat: 'return' [explist] [';'];
label: '::' Name '::';
funcname: Name ('.' Name)* [':' Name];
namelist: Name (',' Name)* @;
explist: exp (',' exp)* @;
args_explist: '(' [exp (',' exp)*] ')'; // extra rule for better error handling

exp: binexp;
binexp:
  binexp ('*' | '/' | '//' | '%') binexp
| binexp ('+' | '-') binexp
| binexp '..' binexp
| binexp ('<<' | '>>') binexp
| binexp '&' binexp
| binexp '~' binexp
| binexp '|' binexp
| binexp ('<' | '>' | '<=' | '>=' | '~=' | '==') binexp
| binexp 'and' binexp
| binexp 'or' binexp
| unaryexp
;
unaryexp:
  ('not' | '-' | '#' | '~') unaryexp
| powexp
;
powexp:
  (literalexp | prefixexp | tableconstructor | functiondef) ['^' unaryexp]
;
literalexp:
  'nil'
| 'false'
| 'true'
| '...'
| Numeral
| LiteralString
;
nameexp: Name;
parenexp: '(' exp ')';
prefixexp:
  prefixexp '[' exp ']' @indexexp
| prefixexp '.' Name @fieldexp
| ?1 prefixexp (args | ':' Name args) @callexp // resolve ambiguity described in section 3.3.1
| nameexp
| parenexp
;
args:
  args_explist
| tableconstructor
| stringarg
;
stringarg: LiteralString;
functiondef: 'function' pars funcbody;
pars: '(' [Name (?1 ',' Name)* [',' '...'] | '...'] ')'; // resolve LL(1) conflict with extra lookahead
funcbody: block 'end';
tableconstructor: '{' fieldlist '}';
fieldlist: [field (?1 (',' | ';') field)* [',' | ';']]; // resolve LL(1) conflict with extra lookahead
field:
  '[' exp ']' '=' exp
| ?1 Name '=' exp // resolve LL(1) conflict with extra lookahead
| exp
;