676 lines
10 KiB
Plaintext
676 lines
10 KiB
Plaintext
// Rust Un-Grammar.
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//
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// This grammar specifies the structure of Rust's concrete syntax tree.
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// It does not specify parsing rules (ambiguities, precedence, etc are out of scope).
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// Tokens are processed -- contextual keywords are recognised, compound operators glued.
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//
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// Legend:
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//
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// // -- comment
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// Name = -- non-terminal definition
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// 'ident' -- token (terminal)
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// A B -- sequence
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// A | B -- alternation
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// A* -- zero or more repetition
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// A? -- zero or one repetition
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// (A) -- same as A
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// label:A -- suggested name for field of AST node
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//*************************//
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// Names, Paths and Macros //
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//*************************//
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Name =
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'ident' | 'self'
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NameRef =
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'ident' | 'int_number' | 'self' | 'super' | 'crate' | 'Self'
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Lifetime =
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'lifetime_ident'
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Path =
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(qualifier:Path '::')? segment:PathSegment
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PathSegment =
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'::'? NameRef
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| NameRef GenericArgList?
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| NameRef ParamList RetType?
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| '<' PathType ('as' PathType)? '>'
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GenericArgList =
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'::'? '<' (GenericArg (',' GenericArg)* ','?)? '>'
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GenericArg =
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TypeArg
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| AssocTypeArg
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| LifetimeArg
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| ConstArg
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TypeArg =
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Type
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AssocTypeArg =
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NameRef GenericArgList? (':' TypeBoundList | ('=' Type | ConstArg))
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LifetimeArg =
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Lifetime
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ConstArg =
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Expr
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MacroCall =
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Attr* Path '!' TokenTree ';'?
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TokenTree =
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'(' ')'
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| '{' '}'
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| '[' ']'
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MacroItems =
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Item*
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MacroStmts =
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statements:Stmt*
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Expr?
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//*************************//
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// Items //
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//*************************//
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SourceFile =
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'shebang'?
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Attr*
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Item*
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Item =
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Const
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| Enum
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| ExternBlock
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| ExternCrate
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| Fn
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| Impl
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| MacroCall
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| MacroRules
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| MacroDef
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| Module
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| Static
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| Struct
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| Trait
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| TraitAlias
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| TypeAlias
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| Union
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| Use
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MacroRules =
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Attr* Visibility?
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'macro_rules' '!' Name
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TokenTree
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MacroDef =
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Attr* Visibility?
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'macro' Name args:TokenTree?
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body:TokenTree
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Module =
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Attr* Visibility?
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'mod' Name
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(ItemList | ';')
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ItemList =
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'{' Attr* Item* '}'
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ExternCrate =
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Attr* Visibility?
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'extern' 'crate' NameRef Rename? ';'
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Rename =
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'as' (Name | '_')
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Use =
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Attr* Visibility?
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'use' UseTree ';'
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UseTree =
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(Path? '::')? ('*' | UseTreeList)
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| Path Rename?
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UseTreeList =
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'{' (UseTree (',' UseTree)* ','?)? '}'
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Fn =
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Attr* Visibility?
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'default'? 'const'? 'async'? 'unsafe'? Abi?
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'fn' Name GenericParamList? ParamList RetType? WhereClause?
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(body:BlockExpr | ';')
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Abi =
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'extern' 'string'?
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ParamList =
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'('(
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SelfParam
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| (SelfParam ',')? (Param (',' Param)* ','?)?
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)')'
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| '|' (Param (',' Param)* ','?)? '|'
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SelfParam =
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Attr* (
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('&' Lifetime?)? 'mut'? Name
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| 'mut'? Name ':' Type
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)
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Param =
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Attr* (
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Pat (':' Type)?
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| Type
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| '...'
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)
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RetType =
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'->' Type
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TypeAlias =
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Attr* Visibility?
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'default'?
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'type' Name GenericParamList? (':' TypeBoundList?)? WhereClause?
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('=' Type)? ';'
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Struct =
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Attr* Visibility?
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'struct' Name GenericParamList? (
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WhereClause? (RecordFieldList | ';')
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| TupleFieldList WhereClause? ';'
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)
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RecordFieldList =
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'{' fields:(RecordField (',' RecordField)* ','?)? '}'
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RecordField =
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Attr* Visibility?
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Name ':' Type
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TupleFieldList =
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'(' fields:(TupleField (',' TupleField)* ','?)? ')'
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TupleField =
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Attr* Visibility?
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Type
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FieldList =
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RecordFieldList
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| TupleFieldList
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Enum =
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Attr* Visibility?
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'enum' Name GenericParamList? WhereClause?
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VariantList
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VariantList =
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'{' (Variant (',' Variant)* ','?)? '}'
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Variant =
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Attr* Visibility?
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Name FieldList? ('=' Expr)?
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Union =
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Attr* Visibility?
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'union' Name GenericParamList? WhereClause?
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RecordFieldList
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// A Data Type.
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//
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// Not used directly in the grammar, but handy to have anyway.
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Adt =
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Enum
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| Struct
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| Union
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Const =
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Attr* Visibility?
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'default'?
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'const' (Name | '_') ':' Type
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('=' body:Expr)? ';'
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Static =
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Attr* Visibility?
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'static' 'mut'? Name ':' Type
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('=' body:Expr)? ';'
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Trait =
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Attr* Visibility?
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'unsafe'? 'auto'?
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'trait' Name GenericParamList?
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(':' TypeBoundList?)? WhereClause? AssocItemList
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TraitAlias =
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Attr* Visibility?
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'trait' Name GenericParamList? '=' TypeBoundList? WhereClause? ';'
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AssocItemList =
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'{' Attr* AssocItem* '}'
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AssocItem =
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Const
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| Fn
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| MacroCall
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| TypeAlias
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Impl =
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Attr* Visibility?
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'default'? 'unsafe'?
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'impl' GenericParamList? ('const'? '!'? trait:Type 'for')? self_ty:Type WhereClause?
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AssocItemList
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ExternBlock =
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Attr* 'unsafe'? Abi ExternItemList
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ExternItemList =
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'{' Attr* ExternItem* '}'
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ExternItem =
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Fn
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| MacroCall
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| Static
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| TypeAlias
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GenericParamList =
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'<' (GenericParam (',' GenericParam)* ','?)? '>'
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GenericParam =
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ConstParam
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| LifetimeParam
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| TypeParam
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TypeParam =
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Attr* Name (':' TypeBoundList?)?
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('=' default_type:Type)?
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ConstParam =
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Attr* 'const' Name ':' Type
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('=' default_val:Expr)?
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LifetimeParam =
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Attr* Lifetime (':' TypeBoundList?)?
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WhereClause =
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'where' predicates:(WherePred (',' WherePred)* ','?)
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WherePred =
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('for' GenericParamList)? (Lifetime | Type) ':' TypeBoundList?
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Visibility =
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'pub' ('(' 'in'? Path ')')?
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Attr =
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'#' '!'? '[' Meta ']'
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Meta =
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Path ('=' Expr | TokenTree)?
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//****************************//
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// Statements and Expressions //
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//****************************//
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Stmt =
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';'
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| ExprStmt
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| Item
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| LetStmt
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LetStmt =
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Attr* 'let' Pat (':' Type)?
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'=' initializer:Expr
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LetElse?
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';'
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LetElse =
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'else' BlockExpr
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ExprStmt =
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Expr ';'?
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Expr =
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ArrayExpr
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| AwaitExpr
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| BinExpr
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| BlockExpr
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| BoxExpr
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| BreakExpr
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| CallExpr
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| CastExpr
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| ClosureExpr
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| ContinueExpr
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| FieldExpr
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| ForExpr
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| IfExpr
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| IndexExpr
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| Literal
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| LoopExpr
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| MacroExpr
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| MatchExpr
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| MethodCallExpr
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| ParenExpr
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| PathExpr
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| PrefixExpr
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| RangeExpr
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| RecordExpr
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| RefExpr
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| ReturnExpr
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| TryExpr
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| TupleExpr
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| WhileExpr
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| YieldExpr
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| YeetExpr
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| LetExpr
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| UnderscoreExpr
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MacroExpr =
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MacroCall
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Literal =
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Attr* value:(
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'int_number' | 'float_number'
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| 'string' | 'raw_string'
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| 'byte_string' | 'raw_byte_string'
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| 'true' | 'false'
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| 'char' | 'byte'
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)
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PathExpr =
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Attr* Path
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StmtList =
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'{'
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Attr*
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statements:Stmt*
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tail_expr:Expr?
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'}'
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RefExpr =
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Attr* '&' ('raw' | 'mut' | 'const') Expr
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TryExpr =
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Attr* Expr '?'
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BlockExpr =
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Attr* Label? ('try' | 'unsafe' | 'async' | 'const') StmtList
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PrefixExpr =
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Attr* op:('-' | '!' | '*') Expr
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BinExpr =
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Attr*
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lhs:Expr
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op:(
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'||' | '&&'
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| '==' | '!=' | '<=' | '>=' | '<' | '>'
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| '+' | '*' | '-' | '/' | '%' | '<<' | '>>' | '^' | '|' | '&'
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| '=' | '+=' | '/=' | '*=' | '%=' | '>>=' | '<<=' | '-=' | '|=' | '&=' | '^='
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)
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rhs:Expr
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CastExpr =
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Attr* Expr 'as' Type
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ParenExpr =
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Attr* '(' Attr* Expr ')'
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ArrayExpr =
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Attr* '[' Attr* (
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(Expr (',' Expr)* ','?)?
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| Expr ';' Expr
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) ']'
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IndexExpr =
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Attr* base:Expr '[' index:Expr ']'
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TupleExpr =
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Attr* '(' Attr* fields:(Expr (',' Expr)* ','?)? ')'
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RecordExpr =
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Path RecordExprFieldList
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RecordExprFieldList =
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'{'
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Attr*
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fields:(RecordExprField (',' RecordExprField)* ','?)?
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('..' spread:Expr?)?
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'}'
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RecordExprField =
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Attr* (NameRef ':')? Expr
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CallExpr =
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Attr* Expr ArgList
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ArgList =
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'(' args:(Expr (',' Expr)* ','?)? ')'
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MethodCallExpr =
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Attr* receiver:Expr '.' NameRef GenericArgList? ArgList
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FieldExpr =
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Attr* Expr '.' NameRef
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ClosureExpr =
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Attr* ('for' GenericParamList)? 'const'? 'static'? 'async'? 'move'? ParamList RetType?
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body:Expr
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IfExpr =
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Attr* 'if' condition:Expr then_branch:BlockExpr
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('else' else_branch:(IfExpr | BlockExpr))?
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LoopExpr =
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Attr* Label? 'loop'
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loop_body:BlockExpr
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ForExpr =
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Attr* Label? 'for' Pat 'in' iterable:Expr
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loop_body:BlockExpr
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WhileExpr =
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Attr* Label? 'while' condition:Expr
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loop_body:BlockExpr
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Label =
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Lifetime ':'
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BreakExpr =
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Attr* 'break' Lifetime? Expr?
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ContinueExpr =
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Attr* 'continue' Lifetime?
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RangeExpr =
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Attr* start:Expr? op:('..' | '..=') end:Expr?
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MatchExpr =
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Attr* 'match' Expr MatchArmList
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MatchArmList =
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'{'
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Attr*
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arms:MatchArm*
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'}'
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MatchArm =
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Attr* Pat guard:MatchGuard? '=>' Expr ','?
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MatchGuard =
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'if' condition:Expr
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ReturnExpr =
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Attr* 'return' Expr?
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YieldExpr =
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Attr* 'yield' Expr?
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YeetExpr =
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Attr* 'do' 'yeet' Expr?
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LetExpr =
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Attr* 'let' Pat '=' Expr
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UnderscoreExpr =
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Attr* '_'
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AwaitExpr =
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Attr* Expr '.' 'await'
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BoxExpr =
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Attr* 'box' Expr
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//*************************//
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// Types //
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//*************************//
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Type =
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ArrayType
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| DynTraitType
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| FnPtrType
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| ForType
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| ImplTraitType
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| InferType
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| MacroType
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| NeverType
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| ParenType
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| PathType
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| PtrType
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| RefType
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| SliceType
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| TupleType
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ParenType =
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'(' Type ')'
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NeverType =
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'!'
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MacroType =
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MacroCall
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PathType =
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Path
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TupleType =
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'(' fields:(Type (',' Type)* ','?)? ')'
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PtrType =
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'*' ('const' | 'mut') Type
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RefType =
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'&' Lifetime? 'mut'? Type
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ArrayType =
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'[' Type ';' Expr ']'
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SliceType =
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'[' Type ']'
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InferType =
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'_'
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FnPtrType =
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'const'? 'async'? 'unsafe'? Abi? 'fn' ParamList RetType?
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ForType =
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'for' GenericParamList Type
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ImplTraitType =
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'impl' TypeBoundList
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DynTraitType =
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'dyn' TypeBoundList
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TypeBoundList =
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bounds:(TypeBound ('+' TypeBound)* '+'?)
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TypeBound =
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Lifetime
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| ('?' | '~' 'const')? Type
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//************************//
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// Patterns //
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//************************//
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Pat =
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IdentPat
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| BoxPat
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| RestPat
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| LiteralPat
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| MacroPat
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| OrPat
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| ParenPat
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| PathPat
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| WildcardPat
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| RangePat
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| RecordPat
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| RefPat
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| SlicePat
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| TuplePat
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| TupleStructPat
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| ConstBlockPat
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LiteralPat =
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Literal
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IdentPat =
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Attr* 'ref'? 'mut'? Name ('@' Pat)?
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WildcardPat =
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'_'
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RangePat =
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// 1..
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start:Pat op:('..' | '..=')
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// 1..2
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| start:Pat op:('..' | '..=') end:Pat
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// ..2
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| op:('..' | '..=') end:Pat
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RefPat =
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'&' 'mut'? Pat
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RecordPat =
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Path RecordPatFieldList
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RecordPatFieldList =
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'{'
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fields:(RecordPatField (',' RecordPatField)* ','?)?
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RestPat?
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'}'
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RecordPatField =
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Attr* (NameRef ':')? Pat
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TupleStructPat =
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Path '(' fields:(Pat (',' Pat)* ','?)? ')'
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TuplePat =
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'(' fields:(Pat (',' Pat)* ','?)? ')'
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ParenPat =
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'(' Pat ')'
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SlicePat =
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'[' (Pat (',' Pat)* ','?)? ']'
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PathPat =
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Path
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OrPat =
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(Pat ('|' Pat)* '|'?)
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BoxPat =
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'box' Pat
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RestPat =
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Attr* '..'
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MacroPat =
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MacroCall
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ConstBlockPat =
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'const' BlockExpr
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