9 – The Complete Syntax of Lua

Here is the complete syntax of Lua in extended BNF. As usual in extended BNF, {A} means 0 or more As, and [A] means an optional A. (For operator precedences, see §3.4.8; for a description of the terminals Name, Numeral, and LiteralString, see §3.1.)

chunk ::= block

block ::= {stat} [retstat]

stat ::=  ‘;’ | 
	 varlist ‘=’ explist | 
	 functioncall | 
	 label | 
	 break | 
	 goto Name | 
	 do block end | 
	 while exp do block end | 
	 repeat block until exp | 
	 if exp then block {elseif exp then block} [else block] end | 
	 for Name ‘=’ exp ‘,’ exp [‘,’ exp] do block end | 
	 for namelist in explist do block end | 
	 function funcname funcbody | 
	 local function Name funcbody | 
	 local namelist [‘=’ explist] 

retstat ::= return [explist] [‘;’]

label ::= ‘::’ Name ‘::’

funcname ::= Name {‘.’ Name} [‘:’ Name]

varlist ::= var {‘,’ var}

var ::=  Name | prefixexp ‘[’ exp ‘]’ | prefixexp ‘.’ Name 

namelist ::= Name {‘,’ Name}

explist ::= exp {‘,’ exp}

exp ::=  nil | false | true | Numeral | LiteralString | ‘...’ | functiondef | 
	 prefixexp | tableconstructor | exp binop exp | unop exp 

prefixexp ::= var | functioncall | ‘(’ exp ‘)’

functioncall ::=  prefixexp args | prefixexp ‘:’ Name args 

args ::=  ‘(’ [explist] ‘)’ | tableconstructor | LiteralString 

functiondef ::= function funcbody

funcbody ::= ‘(’ [parlist] ‘)’ block end

parlist ::= namelist [‘,’ ‘...’] | ‘...’

tableconstructor ::= ‘{’ [fieldlist] ‘}’

fieldlist ::= field {fieldsep field} [fieldsep]

field ::= ‘[’ exp ‘]’ ‘=’ exp | Name ‘=’ exp | exp

fieldsep ::= ‘,’ | ‘;’

binop ::=  ‘+’ | ‘-’ | ‘*’ | ‘/’ | ‘//’ | ‘^’ | ‘%’ | 
	 ‘&’ | ‘~’ | ‘|’ | ‘>>’ | ‘<<’ | ‘..’ | 
	 ‘<’ | ‘<=’ | ‘>’ | ‘>=’ | ‘==’ | ‘~=’ | 
	 and | or

unop ::= ‘-’ | not | ‘#’ | ‘~’