9 – The Complete Syntax of Lua

Here is the complete syntax of Lua in extended BNF. (It does not describe operator precedences.)

    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 | Number | String | ‘...’ | functiondef | 
         prefixexp | tableconstructor | exp binop exp | unop exp 
 
    prefixexp ::= var | functioncall | ‘(’ exp ‘)’
 
    functioncall ::=  prefixexp args | prefixexp ‘:’ Name args 
 
    args ::=  ‘(’ [explist] ‘)’ | tableconstructor | String 
 
    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 | ‘#’