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90 lines
3.2 KiB
Markdown
90 lines
3.2 KiB
Markdown
---
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permalink: /grammar
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title: Grammar
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classes: wide
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---
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This is the complete syntax grammar for Luau in EBNF. More information about the terminal nodes String and Number
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is available in the [syntax section](syntax).
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```ebnf
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chunk = block
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block = {stat [';']} [laststat [';']]
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stat = varlist '=' explist |
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var compoundop exp |
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functioncall |
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'do' block 'end' |
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'while' exp 'do' block 'end' |
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'repeat' block 'until' exp |
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'if' exp 'then' block {'elseif' exp 'then' block} ['else' block] 'end' |
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'for' binding '=' exp ',' exp [',' exp] 'do' block 'end' |
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'for' bindinglist 'in' explist 'do' block 'end' |
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'function' funcname funcbody |
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'local' 'function' NAME funcbody |
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'local' bindinglist ['=' explist] |
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['export'] 'type' NAME ['<' GenericTypeParameterList '>'] '=' Type
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laststat = 'return' [explist] | 'break' | 'continue'
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funcname = NAME {'.' NAME} [':' NAME]
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funcbody = ['<' GenericTypeParameterList '>'] '(' [parlist] ')' [':' ReturnType] block 'end'
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parlist = bindinglist [',' '...'] | '...'
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explist = {exp ','} exp
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namelist = NAME {',' NAME}
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binding = NAME [':' Type]
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bindinglist = binding [',' bindinglist] (* equivalent of Lua 5.1 'namelist', except with optional type annotations *)
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var = NAME | prefixexp '[' exp ']' | prefixexp '.' NAME
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varlist = var {',' var}
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prefixexp = var | functioncall | '(' exp ')'
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functioncall = prefixexp funcargs | prefixexp ':' NAME funcargs
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exp = asexp { binop exp } | unop exp { binop exp }
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ifelseexp = 'if' exp 'then' exp {'elseif' exp 'then' exp} 'else' exp
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asexp = simpleexp ['::' Type]
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stringinterp = INTERP_BEGIN exp { INTERP_MID exp } INTERP_END
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simpleexp = NUMBER | STRING | 'nil' | 'true' | 'false' | '...' | tableconstructor | 'function' funcbody | prefixexp | ifelseexp | stringinterp
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funcargs = '(' [explist] ')' | tableconstructor | STRING
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tableconstructor = '{' [fieldlist] '}'
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fieldlist = field {fieldsep field} [fieldsep]
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field = '[' exp ']' '=' exp | NAME '=' exp | exp
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fieldsep = ',' | ';'
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compoundop :: '+=' | '-=' | '*=' | '/=' | '%=' | '^=' | '..='
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binop = '+' | '-' | '*' | '/' | '^' | '%' | '..' | '<' | '<=' | '>' | '>=' | '==' | '~=' | 'and' | 'or'
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unop = '-' | 'not' | '#'
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SimpleType =
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'nil' |
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SingletonType |
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NAME ['.' NAME] [ '<' [TypeParams] '>' ] |
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'typeof' '(' exp ')' |
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TableType |
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FunctionType
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SingletonType = STRING | 'true' | 'false'
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Type =
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SimpleType ['?'] |
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Type ['|' Type] |
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Type ['&' Type]
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GenericTypePackParameter = NAME '...' ['=' (TypePack | VariadicTypePack | GenericTypePack)]
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GenericTypeParameterList = NAME ['=' Type] [',' GenericTypeParameterList] | GenericTypePackParameter {',' GenericTypePackParameter}
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TypeList = Type [',' TypeList] | '...' Type
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TypeParams = (Type | TypePack | VariadicTypePack | GenericTypePack) [',' TypeParams]
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TypePack = '(' [TypeList] ')'
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GenericTypePack = NAME '...'
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VariadicTypePack = '...' Type
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ReturnType = Type | TypePack
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TableIndexer = '[' Type ']' ':' Type
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TableProp = NAME ':' Type
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TablePropOrIndexer = TableProp | TableIndexer
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PropList = TablePropOrIndexer {fieldsep TablePropOrIndexer} [fieldsep]
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TableType = '{' PropList '}'
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FunctionType = ['<' GenericTypeParameterList '>'] '(' [TypeList] ')' '->' ReturnType
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```
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