Scala 3 Syntax Summary
The following description of Scala tokens uses literal characters ‘c’ when referring to the ASCII fragment \u0000 – \u007F.
Informal descriptions are typeset as “some comment”.
Lexical Syntax
The lexical syntax of Scala is given by the following grammar in EBNF form:
whiteSpace ::= ‘\u0020’ | ‘\u0009’ | ‘\u000D’ | ‘\u000A’
upper ::= ‘A’ | ... | ‘Z’ | ‘$’ and any character in Unicode categories Lu, Lt or Nl,
and any character in Unicode categories Lo and Lm that doesn't have
contributory property Other_Lowercase
lower ::= ‘a’ | ... | ‘z’ | ‘_’ and any character in Unicode category Ll,
and any character in Unicode categories Lo or Lm that has contributory
property Other_Lowercase
letter ::= upper | lower
digit ::= ‘0’ | ... | ‘9’
paren ::= ‘(’ | ‘)’ | ‘[’ | ‘]’ | ‘{’ | ‘}’
delim ::= ‘`’ | ‘'’ | ‘"’ | ‘.’ | ‘;’ | ‘,’
opchar ::= ‘!’ | ‘#’ | ‘%’ | ‘&’ | ‘*’ | ‘+’ | ‘-’ | ‘/’ | ‘:’ |
‘<’ | ‘=’ | ‘>’ | ‘?’ | ‘@’ | ‘\’ | ‘^’ | ‘|’ | ‘~’
and any character in Unicode categories Sm or So
printableChar ::= all characters in [\u0020, \u007E] inclusive
UnicodeEscape ::= ‘\’ ‘u’ {‘u’} hexDigit hexDigit hexDigit hexDigit
hexDigit ::= ‘0’ | ... | ‘9’ | ‘A’ | ... | ‘F’ | ‘a’ | ... | ‘f’
charEscapeSeq ::= ‘\’ (‘b’ | ‘t’ | ‘n’ | ‘f’ | ‘r’ | ‘"’ | ‘'’ | ‘\’)
escapeSeq ::= UnicodeEscape | charEscapeSeq
op ::= opchar {opchar}
varid ::= lower idrest
boundvarid ::= varid
| ‘`’ varid ‘`’
plainid ::= alphaid
| op
id ::= plainid
| ‘`’ { charNoBackQuoteOrNewline | escapeSeq } ‘`’
idrest ::= {letter | digit} [‘_’ op]
quoteId ::= ‘'’ alphaid
spliceId ::= ‘$’ alphaid ;
integerLiteral ::= (decimalNumeral | hexNumeral | binaryNumeral) [‘L’ | ‘l’]
decimalNumeral ::= ‘0’ | digit [{digit | ‘_’} digit]
hexNumeral ::= ‘0’ (‘x’ | ‘X’) hexDigit [{hexDigit | ‘_’} hexDigit]
binaryNumeral ::= ‘0’ (‘b’ | ‘B’) binaryDigit [{binaryDigit | ‘_’} binaryDigit]
floatingPointLiteral
::= [decimalNumeral] ‘.’ digit [{digit | ‘_’} digit] [exponentPart] [floatType]
| decimalNumeral exponentPart [floatType]
| decimalNumeral floatType
exponentPart ::= (‘E’ | ‘e’) [‘+’ | ‘-’] digit [{digit | ‘_’} digit]
floatType ::= ‘F’ | ‘f’ | ‘D’ | ‘d’
booleanLiteral ::= ‘true’ | ‘false’
characterLiteral ::= ‘'’ (charNoQuoteOrNewline | escapeSeq) ‘'’
stringLiteral ::= ‘"’ {stringElement} ‘"’
| ‘"""’ multiLineChars ‘"""’
stringElement ::= charNoDoubleQuoteOrNewline
| escapeSeq
multiLineChars ::= {[‘"’] [‘"’] charNoDoubleQuote} {‘"’}
interpolatedString
::= alphaid ‘"’ {[‘\’] interpolatedStringPart | ‘\\’ | ‘\"’} ‘"’
| alphaid ‘"""’ {[‘"’] [‘"’] char \ (‘"’ | ‘\$’) | escape} {‘"’} ‘"""’
interpolatedStringPart
::= printableChar \ (‘"’ | ‘$’ | ‘\’) | escape
escape ::= ‘\$\$’
| ‘\$"’
| ‘\$’ alphaid
| ‘\$’ BlockExpr
alphaid ::= upper idrest
| varid
comment ::= ‘/*’ “any sequence of characters; nested comments are allowed” ‘*/’
| ‘//’ “any sequence of characters up to end of line”
nl ::= “new line character”
semi ::= ‘;’ | nl {nl}
Optional Braces
The principle of optional braces is that any keyword that can be followed by { can also be followed by an indented block, without needing an intervening :. (Allowing an optional : would be counterproductive since it would introduce several ways to do the same thing.)
The lexical analyzer inserts indent and outdent tokens that represent regions of indented code at certain points.
In the context-free productions below we use the notation <<< ts >>> to indicate a token sequence ts that is either enclosed in a pair of braces { ts } or that constitutes an indented region indent ts outdent. Analogously, the notation :<<< ts >>> indicates a token sequence ts that is either enclosed in a pair of braces { ts } or that constitutes an indented region indent ts outdent that follows a colon token.
A colon token reads as the standard colon ":" but is generated instead of it where colon is legal according to the context free syntax, but only if the previous token is an alphanumeric identifier, a backticked identifier, or one of the tokens this, super, new, ")", and "]".
colon ::= ':' -- with side conditions explained above
<<< ts >>> ::= ‘{’ ts ‘}’
| indent ts outdent
:<<< ts >>> ::= [nl] ‘{’ ts ‘}’
| colon indent ts outdent
Keywords
Regular keywords
abstract case catch class def do else
enum export extends false final finally for
given if implicit import lazy match new
null object override package private protected return
sealed super then throw trait true try
type val var while with yield
: = <- => <: >: #
@ =>> ?=>
Soft keywords
as consume derives end erased extension infix initially inline
opaque open throws tracked transparent update using | * + -
See the separate section on soft keywords for additional details on where a soft keyword is recognized.
Context-free Syntax
The context-free syntax of Scala is given by the following EBNF grammar:
Literals and Paths
SimpleLiteral ::= [‘-’] integerLiteral
| [‘-’] floatingPointLiteral
| booleanLiteral
| characterLiteral
| stringLiteral
Literal ::= SimpleLiteral
| interpolatedStringLiteral
| symbolLiteral
| ‘null’
QualId ::= id {‘.’ id}
ids ::= id {‘,’ id}
SimpleRef ::= id
| [id ‘.’] ‘this’
| [id ‘.’] ‘super’ [ClassQualifier] ‘.’ id
ClassQualifier ::= ‘[’ id ‘]’
Types
Type ::= FunType
| TypTypeParamClause ‘=>>’ Type LambdaTypeTree(ps, t)
| FunParamClause ‘=>>’ Type TermLambdaTypeTree(ps, t)
| MatchType
| InfixType
FunType ::= FunTypeArgs (‘=>’ | ‘?=>’) Type Function(ts, t) | FunctionWithMods(ts, t, mods, erasedParams)
| FunTypeArgs (‘->’ | ‘?->’) [CaptureSet] Type -- under pureFunctions and captureChecking
| TypTypeParamClause ‘=>’ Type PolyFunction(ps, t)
| TypTypeParamClause ‘->’ [CaptureSet] Type -- under pureFunctions and captureChecking
FunTypeArgs ::= InfixType
| ‘(’ [ FunArgTypes ] ‘)’
| FunParamClause
FunParamClause ::= ‘(’ TypedFunParam {‘,’ TypedFunParam } ‘)’
TypedFunParam ::= [`erased`] id ‘:’ Type
MatchType ::= InfixType `match` <<< TypeCaseClauses >>>
InfixType ::= RefinedType {id [nl] RefinedType} InfixOp(t1, op, t2)
| RefinedType ‘^’ -- under captureChecking
RefinedType ::= AnnotType {[nl] Refinement} RefinedTypeTree(t, ds)
| AnnotType {[nl] Refinement} ‘^’ CaptureSet -- under captureChecking
AnnotType ::= SimpleType {Annotation} Annotated(t, annot)
AnnotType1 ::= SimpleType1 {Annotation} Annotated(t, annot)
SimpleType ::= SimpleLiteral SingletonTypeTree(l)
| ‘?’ TypeBounds
| SimpleType1 {ParArgumentExprs}
SimpleType1 ::= id Ident(name)
| Singleton ‘.’ id Select(t, name)
| Singleton ‘.’ ‘type’ SingletonTypeTree(p)
| ‘(’ [Types | NamesAndTypes] ‘)’ Tuple(ts)
| Refinement RefinedTypeTree(EmptyTree, refinement)
| TypeSplice -- deprecated syntax
| SimpleType1 TypeArgs AppliedTypeTree(t, args)
| SimpleType1 ‘#’ id Select(t, name)
Singleton ::= SimpleRef
| SimpleLiteral
| Singleton ‘.’ id
FunArgType ::= Type
| ‘=>’ Type PrefixOp(=>, t)
| ‘->’ [CaptureSet] Type -- under captureChecking
FunArgTypes ::= FunArgType { ‘,’ FunArgType }
ParamType ::= [‘=>’] ParamValueType
| ‘->’ [CaptureSet] ParamValueType -- under captureChecking
ParamValueType ::= Type [‘*’] PostfixOp(t, "*")
TypeArgs ::= ‘[’ TypeArg {‘,’ TypeArg} ‘]’ ts
Refinement ::= :<<< [RefineDcl] {semi [RefineDcl]} >>> ds
TypeBounds ::= [‘>:’ TypeBound] [‘<:’ TypeBound] TypeBoundsTree(lo, hi)
TypeAndCtxBounds ::= TypeBounds [‘:’ ContextBounds] ContextBounds(typeBounds, tps)
ContextBounds ::= ContextBound
| ContextBound `:` ContextBounds -- to be deprecated
| '{' ContextBound {',' ContextBound} '}'
ContextBound ::= Type ['as' id]
Types ::= Type {‘,’ Type}
TypeArg ::= Type
| CaptureSet -- under captureChecking
TypeBound ::= Type
| CaptureSet -- under captureChecking
NamesAndTypes ::= NameAndType {‘,’ NameAndType}
NameAndType ::= id ':' Type
CaptureSet ::= '{' CaptureRef {',' CaptureRef} '}' -- under captureChecking
CaptureRef ::= { SimpleRef '.' } SimpleRef ['*'] [CapFilter] ['.' 'rd'] -- under captureChecking
CapFilter ::= '.' 'only' '[' QualId ']' -- under captureChecking
Expressions
Expr ::= FunParams (‘=>’ | ‘?=>’) Expr Function(args, expr), Function(ValDef([implicit], id, TypeTree(), EmptyTree), expr)
| TypTypeParamClause ‘=>’ Expr PolyFunction(ts, expr)
| ExprCaseClause
| Expr1
BlockResult ::= FunParams (‘=>’ | ‘?=>’) Block
| TypTypeParamClause ‘=>’ Block
| Expr1
FunParams ::= Bindings
| id
| ‘_’
Expr1 ::= [‘inline’] ‘if’ ‘(’ Expr ‘)’ {nl} Expr [[semi] ‘else’ Expr] If(Parens(cond), thenp, elsep?)
| [‘inline’] ‘if’ Expr ‘then’ Expr [[semi] ‘else’ Expr] If(cond, thenp, elsep?)
| ‘while’ ‘(’ Expr ‘)’ {nl} Expr WhileDo(Parens(cond), body)
| ‘while’ Expr ‘do’ Expr WhileDo(cond, body)
| ‘try’ Expr Catches [‘finally’ Expr] Try(expr, catches, expr?)
| ‘try’ Expr [‘finally’ Expr] Try(expr, Nil, expr?)
| ‘throw’ Expr Throw(expr)
| ‘return’ [Expr] Return(expr?)
| ForExpr
| [SimpleExpr ‘.’] id ‘=’ Expr Assign(expr, expr)
| PrefixOperator SimpleExpr ‘=’ Expr Assign(expr, expr)
| InfixExpr id [nl] `=' Expr Assign(expr, expr) -- only if language.postfixOps is enabled
| SimpleExpr ArgumentExprs ‘=’ Expr Assign(expr, expr)
| PostfixExpr [Ascription]
| ‘inline’ InfixExpr MatchClause
Ascription ::= ‘:’ InfixType Typed(expr, tp)
| ‘:’ Annotation {Annotation} Typed(expr, Annotated(EmptyTree, annot)*)
Catches ::= ‘catch’ (Expr | ExprCaseClause)
PostfixExpr ::= InfixExpr [id] PostfixOp(expr, op) -- only if language.postfixOperators is enabled
InfixExpr ::= PrefixExpr
| InfixExpr id [nl] InfixExpr InfixOp(expr, op, expr)
| InfixExpr id ColonArgument
| InfixExpr MatchClause
MatchClause ::= ‘match’ <<< CaseClauses >>> Match(expr, cases)
PrefixExpr ::= [PrefixOperator] SimpleExpr PrefixOp(expr, op)
PrefixOperator ::= ‘-’ | ‘+’ | ‘~’ | ‘!’ -- unless backquoted
SimpleExpr ::= SimpleRef
| Literal
| ‘_’
| BlockExpr
| ExprSplice
| Quoted
| quoteId -- only inside splices
| ‘new’ ConstrApp {‘with’ ConstrApp} [TemplateBody] New(constr | templ)
| ‘new’ TemplateBody
| ‘(’ ExprsInParens ‘)’ Parens(exprs)
| SimpleExpr ‘.’ id Select(expr, id)
| SimpleExpr ‘.’ MatchClause
| SimpleExpr TypeArgs TypeApply(expr, args)
| SimpleExpr ArgumentExprs Apply(expr, args)
| SimpleExpr ColonArgument -- under language.experimental.fewerBraces
| SimpleExpr ‘_’ PostfixOp(expr, _) (to be dropped)
| XmlExpr -- to be dropped
ColonArgument ::= colon {LambdaStart}
indent (CaseClauses | Block) outdent
| colon LambdaStart {LambdaStart} expr ENDlambda -- ENDlambda is inserted for each production at next EOL
-- does not apply if enclosed in parens
| colon ExprCaseClause
LambdaStart ::= FunParams (‘=>’ | ‘?=>’)
| TypTypeParamClause ‘=>’
Quoted ::= ‘'’ ‘{’ Block ‘}’
| ‘'’ ‘[’ TypeBlock ‘]’
ExprSplice ::= spliceId -- if inside quoted block
| ‘$’ ‘{’ Block ‘}’ -- unless inside quoted pattern
| ‘$’ ‘{’ Pattern ‘}’ -- when inside quoted pattern
TypeSplice ::= spliceId -- if inside quoted type -- deprecated syntax
| ‘$’ ‘{’ Block ‘}’ -- unless inside quoted type pattern -- deprecated syntax
| ‘$’ ‘{’ Pattern ‘}’ -- when inside quoted type pattern -- deprecated syntax
ExprsInParens ::= ExprInParens {‘,’ ExprInParens}
| NamedExprInParens {‘,’ NamedExprInParens}
ExprInParens ::= PostfixExpr ‘:’ Type -- normal Expr allows only RefinedType here
| Expr
NamedExprInParens ::= id '=' ExprInParens
ParArgumentExprs ::= ‘(’ [ExprsInParens] ‘)’ exprs
| ‘(’ ‘using’ ExprsInParens ‘)’
| ‘(’ [ExprsInParens ‘,’] PostfixExpr ‘*’ ‘)’ exprs :+ Typed(expr, Ident(wildcardStar))
ArgumentExprs ::= ParArgumentExprs
| BlockExpr
BlockExpr ::= <<< CaseClauses | Block >>>
Block ::= {BlockStat semi} [BlockResult] Block(stats, expr?)
BlockStat ::= Import
| {Annotation {nl}} {LocalModifier} Def
| Extension
| Expr1
| EndMarker
TypeBlock ::= {TypeBlockStat semi} Type
TypeBlockStat ::= ‘type’ {nl} TypeDef
ForExpr ::= ‘for’ ‘(’ Enumerators0 ‘)’ {nl} [‘do‘ | ‘yield’] Expr ForYield(enums, expr) / ForDo(enums, expr)
| ‘for’ ‘{’ Enumerators0 ‘}’ {nl} [‘do‘ | ‘yield’] Expr
| ‘for’ Enumerators0 (‘do‘ | ‘yield’) Expr
Enumerators0 ::= {nl} Enumerators [semi]
Enumerators ::= Generator {semi Enumerator | Guard}
Enumerator ::= Generator
| Guard {Guard}
| Pattern1 ‘=’ Expr GenAlias(pat, expr)
Generator ::= [‘case’] Pattern1 ‘<-’ Expr GenFrom(pat, expr)
Guard ::= ‘if’ PostfixExpr
CaseClauses ::= CaseClause { CaseClause } Match(EmptyTree, cases)
CaseClause ::= ‘case’ Pattern [Guard] ‘=>’ Block CaseDef(pat, guard?, block) // block starts at =>
ExprCaseClause ::= ‘case’ Pattern [Guard] ‘=>’ Expr
TypeCaseClauses ::= TypeCaseClause { TypeCaseClause }
TypeCaseClause ::= ‘case’ (InfixType | ‘_’) ‘=>’ Type [semi]
Pattern ::= Pattern1 { ‘|’ Pattern1 } Alternative(pats)
Pattern1 ::= PatVar ‘:’ RefinedType Bind(name, Typed(Ident(wildcard), tpe))
| [‘-’] integerLiteral ‘:’ RefinedType Typed(pat, tpe)
| [‘-’] floatingPointLiteral ‘:’ RefinedType Typed(pat, tpe)
| Pattern2
Pattern2 ::= [id ‘@’] InfixPattern Bind(name, pat)
InfixPattern ::= SimplePattern { id [nl] SimplePattern } InfixOp(pat, op, pat)
SimplePattern ::= PatVar Ident(wildcard)
| Literal Bind(name, Ident(wildcard))
| ‘(’ [Patterns] ‘)’ Parens(pats) Tuple(pats)
| Quoted
| XmlPattern (to be dropped)
| SimplePattern1 [TypeArgs] [ArgumentPatterns]
| ‘given’ RefinedType
SimplePattern1 ::= SimpleRef
| SimplePattern1 ‘.’ id
PatVar ::= varid
| ‘_’
Patterns ::= Pattern {‘,’ Pattern}
| NamedPattern {‘,’ NamedPattern}
NamedPattern ::= id '=' Pattern
ArgumentPatterns ::= ‘(’ [Patterns] ‘)’ Apply(fn, pats)
| ‘(’ [Patterns ‘,’] PatVar ‘*’ [‘,’ Patterns]‘)’
Type and Value Parameters
ClsTypeParamClause::= ‘[’ ClsTypeParam {‘,’ ClsTypeParam} ‘]’
ClsTypeParam ::= {Annotation} [‘+’ | ‘-’] TypeDef(Modifiers, name, tparams, bounds)
id [HkTypeParamClause] TypeAndCtxBounds Bound(below, above, context)
| {Annotation} [‘+’ | ‘-’] id `^` TypeAndCtxBounds -- under captureChecking
DefTypeParamClause::= [nl] ‘[’ DefTypeParam {‘,’ DefTypeParam} ‘]’
DefTypeParam ::= {Annotation} id [HkTypeParamClause] TypeAndCtxBounds
| {Annotation} id `^` TypeAndCtxBounds -- under captureChecking
TypTypeParamClause::= ‘[’ TypTypeParam {‘,’ TypTypeParam} ‘]’
TypTypeParam ::= {Annotation} (id | ‘_’) [HkTypeParamClause] TypeAndCtxBounds
| {Annotation} id `^` TypeAndCtxBounds -- under captureChecking
HkTypeParamClause ::= ‘[’ HkTypeParam {‘,’ HkTypeParam} ‘]’
HkTypeParam ::= {Annotation} [‘+’ | ‘-’] (id | ‘_’) [HkTypeParamClause]
TypeBounds
| {Annotation} [‘+’ | ‘-’] id `^` TypeBounds -- under captureChecking
ClsParamClauses ::= {ClsParamClause} [[nl] ‘(’ [‘implicit’] ClsParams ‘)’]
ClsParamClause ::= [nl] ‘(’ ClsParams ‘)’
| [nl] ‘(’ ‘using’ (ClsParams | FunArgTypes) ‘)’
ClsParams ::= ClsParam {‘,’ ClsParam}
ClsParam ::= {Annotation} ValDef(mods, id, tpe, expr) -- point of mods on val/var
[{Modifier} (‘val’ | ‘var’)] Param
DefParamClauses ::= DefParamClause { DefParamClause } -- and two DefTypeParamClause cannot be adjacent
DefParamClause ::= DefTypeParamClause
| DefTermParamClause
| UsingParamClause
ConstrParamClauses::= ConstrParamClause {ConstrParamClause}
ConstrParamClause ::= DefTermParamClause
| UsingParamClause
DefTermParamClause::= [nl] ‘(’ [DefTermParams] ‘)’
UsingParamClause ::= [nl] ‘(’ ‘using’ (DefTermParams | FunArgTypes) ‘)’
DefImplicitClause ::= [nl] ‘(’ ‘implicit’ DefTermParams ‘)’
DefTermParams ::= DefTermParam {‘,’ DefTermParam}
DefTermParam ::= {Annotation} TermParamMods Param ValDef(mods, id, tpe, expr) -- point of mods at id.
TermParamMods ::= [‘erased‘] [‘inline’] | [‘consume‘]
Param ::= id ‘:’ ParamType [‘=’ Expr]
Bindings and Imports
Bindings ::= ‘(’ [Binding {‘,’ Binding}] ‘)’
Binding ::= [`erased`] (id | ‘_’) [‘:’ Type] ValDef(_, id, tpe, EmptyTree)
Modifier ::= LocalModifier
| AccessModifier
| ‘override’
| ‘opaque’
LocalModifier ::= ‘abstract’
| ‘final’
| ‘sealed’
| ‘open’
| ‘implicit’
| ‘lazy’
| ‘inline’
| ‘transparent’
| ‘infix’
| ‘erased’
| ‘tracked’
| ‘update’ -- under captureChecking
| ‘consume’
AccessModifier ::= (‘private’ | ‘protected’) [AccessQualifier]
AccessQualifier ::= ‘[’ id ‘]’
Annotation ::= ‘@’ SimpleType1 {ParArgumentExprs} Apply(tpe, args)
Import ::= ‘import’ ImportExpr {‘,’ ImportExpr}
Export ::= ‘export’ ImportExpr {‘,’ ImportExpr}
ImportExpr ::= SimpleRef {‘.’ id} ‘.’ ImportSpec Import(expr, sels)
| SimpleRef ‘as’ id Import(EmptyTree, ImportSelector(ref, id))
ImportSpec ::= NamedSelector
| WildCardSelector
| ‘{’ ImportSelectors) ‘}’
NamedSelector ::= id [‘as’ (id | ‘_’)]
WildCardSelector ::= ‘*’ | ‘given’ [InfixType]
ImportSelectors ::= NamedSelector [‘,’ ImportSelectors]
| WildCardSelector {‘,’ WildCardSelector}
EndMarker ::= ‘end’ EndMarkerTag -- when followed by EOL
EndMarkerTag ::= id | ‘if’ | ‘while’ | ‘for’ | ‘match’ | ‘try’
| ‘new’ | ‘this’ | ‘given’ | ‘extension’ | ‘val’
Definitions
RefineDcl ::= ‘val’ ValDcl
| ‘var’ ValDcl
| ‘def’ DefDcl
| ‘type’ {nl} TypeDef
ValDcl ::= ids ‘:’ Type
DefDcl ::= DefSig ‘:’ Type
Def ::= ‘val’ PatDef
| ‘var’ PatDef
| ‘def’ DefDef
| ‘type’ {nl} TypeDef
| TmplDef
PatDef ::= ids [‘:’ Type] [‘=’ Expr]
| Pattern2 [‘:’ Type] [‘=’ Expr] PatDef(_, pats, tpe?, expr)
DefDef ::= DefSig [‘:’ Type] [‘=’ Expr] DefDef(_, name, paramss, tpe, expr)
| ‘this’ ConstrParamClauses [DefImplicitClause] ‘=’ ConstrExpr DefDef(_, <init>, vparamss, EmptyTree, expr | Block)
DefSig ::= id [DefParamClauses] [DefImplicitClause]
TypeDef ::= id [HkTypeParamClause] {FunParamClause} TypeAndCtxBounds TypeDefTree(_, name, tparams, bound
[‘=’ TypeDefRHS]
| id `^` TypeAndCtxBounds [‘=’ TypeDefRHS] -- under captureChecking
TypeDefRHS ::= Type
| CaptureSet -- under captureChecking
TmplDef ::= ([‘case’] ‘class’ | ‘trait’) ClassDef
| [‘case’] ‘object’ ObjectDef
| ‘enum’ EnumDef
| ‘given’ (GivenDef | OldGivenDef)
ClassDef ::= id ClassConstr [Template] ClassDef(mods, name, tparams, templ)
ClassConstr ::= [ClsTypeParamClause] [ConstrMods] ClsParamClauses with DefDef(_, <init>, Nil, vparamss, EmptyTree, EmptyTree) as first stat
ConstrMods ::= {Annotation} [AccessModifier]
ObjectDef ::= id [Template] ModuleDef(mods, name, template) // no constructor
EnumDef ::= id ClassConstr InheritClauses EnumBody
GivenDef ::= [id ':'] GivenSig
GivenSig ::= GivenImpl
| '(' ')' '=>' GivenImpl
| GivenConditional '=>' GivenSig
GivenImpl ::= GivenType ([‘=’ Expr] | TemplateBody)
| ConstrApps TemplateBody
GivenConditional ::= DefTypeParamClause
| DefTermParamClause
| '(' FunArgTypes ')'
| GivenType
GivenType ::= AnnotType1 {id [nl] AnnotType1}
OldGivenDef ::= [OldGivenSig] (AnnotType [‘=’ Expr] | StructuralInstance) -- syntax up to Scala 3.5, to be deprecated in the future
OldGivenSig ::= [id] [DefTypeParamClause] {UsingParamClause} ‘:’ -- one of `id`, `DefTypeParamClause`, `UsingParamClause` must be present
StructuralInstance ::= ConstrApp {‘with’ ConstrApp} [‘with’ WithTemplateBody]
Extension ::= ‘extension’ [DefTypeParamClause] {UsingParamClause}
‘(’ DefTermParam ‘)’ {UsingParamClause} ExtMethods
ExtMethods ::= ExtMethod | [nl] <<< ExtMethod {semi ExtMethod} >>>
ExtMethod ::= {Annotation [nl]} {Modifier} ‘def’ DefDef
| Export
Template ::= InheritClauses [TemplateBody]
InheritClauses ::= [‘extends’ ConstrApps]
[‘derives’ QualId {‘,’ QualId}]
[‘uses’ UseRef {‘,’ UseRef}]
ConstrApps ::= ConstrApp ({‘,’ ConstrApp} | {‘with’ ConstrApp})
ConstrApp ::= SimpleType1 {Annotation} {ParArgumentExprs}
ConstrExpr ::= SelfInvocation
| <<< SelfInvocation {semi BlockStat} >>>
SelfInvocation ::= ‘this’ ArgumentExprs {ArgumentExprs}
UseRef ::= CaptureRef [‘initially’]
WithTemplateBody ::= <<< [SelfType] TemplateStat {semi TemplateStat} >>>
TemplateBody ::= :<<< [SelfType] TemplateStat {semi TemplateStat} >>>
TemplateStat ::= Import
| Export
| {Annotation [nl]} {Modifier} Def
| Extension
| Expr1
| EndMarker
|
SelfType ::= id [‘:’ InfixType] ‘=>’ ValDef(_, name, tpt, _)
| ‘this’ ‘:’ InfixType ‘=>’
EnumBody ::= :<<< [SelfType] EnumStat {semi EnumStat} >>>
EnumStat ::= TemplateStat
| {Annotation [nl]} {Modifier} EnumCase
EnumCase ::= ‘case’ (id ClassConstr [‘extends’ ConstrApps]] | ids)
TopStats ::= TopStat {semi TopStat}
TopStat ::= Import
| Export
| {Annotation [nl]} {Modifier} Def
| Extension
| Packaging
| PackageObject
| EndMarker
|
Packaging ::= ‘package’ QualId :<<< TopStats >>>
PackageObject ::= ‘package’ ‘object’ ObjectDef
CompilationUnit ::= {‘package’ QualId semi} TopStats
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