Rollup merge of #25297 - carols10cents:grammar-todos, r=steveklabnik
Hiiii, I've got another chunk of updates to the grammar documentation! ⭐ 🌟 🌠 Chipping away at #22445, still have some more to go. I'm learning so much!!!
This commit is contained in:
Manish Goregaokar
commit
2b0191e6d5
@ -253,7 +253,7 @@ The two values of the boolean type are written `true` and `false`.
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### Symbols
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```antlr
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symbol : "::" "->"
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symbol : "::" | "->"
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| '#' | '[' | ']' | '(' | ')' | '{' | '}'
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| ',' | ';' ;
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```
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@ -304,7 +304,7 @@ transcriber : '(' transcriber * ')' | '[' transcriber * ']'
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## Items
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```antlr
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item : mod_item | fn_item | type_item | struct_item | enum_item
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item : vis ? mod_item | fn_item | type_item | struct_item | enum_item
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| const_item | static_item | trait_item | impl_item | extern_block ;
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```
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@ -322,7 +322,7 @@ mod : [ view_item | item ] * ;
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#### View items
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```antlr
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view_item : extern_crate_decl | use_decl ;
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view_item : extern_crate_decl | use_decl ';' ;
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```
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##### Extern crate declarations
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@ -335,14 +335,14 @@ crate_name: ident | ( ident "as" ident )
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##### Use declarations
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```antlr
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use_decl : "pub" ? "use" [ path "as" ident
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| path_glob ] ;
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use_decl : vis ? "use" [ path "as" ident
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| path_glob ] ;
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path_glob : ident [ "::" [ path_glob
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| '*' ] ] ?
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| '{' path_item [ ',' path_item ] * '}' ;
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path_item : ident | "mod" ;
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path_item : ident | "self" ;
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```
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### Functions
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@ -414,16 +414,17 @@ extern_block : [ foreign_fn ] * ;
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## Visibility and Privacy
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**FIXME:** grammar?
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```antlr
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vis : "pub" ;
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```
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### Re-exporting and Visibility
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**FIXME:** grammar?
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See [Use declarations](#use-declarations).
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## Attributes
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```antlr
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attribute : "#!" ? '[' meta_item ']' ;
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attribute : '#' '!' ? '[' meta_item ']' ;
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meta_item : ident [ '=' literal
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| '(' meta_seq ')' ] ? ;
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meta_seq : meta_item [ ',' meta_seq ] ? ;
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@ -433,26 +434,19 @@ meta_seq : meta_item [ ',' meta_seq ] ? ;
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## Statements
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**FIXME:** grammar?
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```antlr
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stmt : decl_stmt | expr_stmt ;
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```
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### Declaration statements
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**FIXME:** grammar?
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A _declaration statement_ is one that introduces one or more *names* into the
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enclosing statement block. The declared names may denote new variables or new
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items.
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```antlr
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decl_stmt : item | let_decl ;
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```
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#### Item declarations
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**FIXME:** grammar?
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An _item declaration statement_ has a syntactic form identical to an
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[item](#items) declaration within a module. Declaring an item — a
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function, enumeration, structure, type, static, trait, implementation or module
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— locally within a statement block is simply a way of restricting its
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scope to a narrow region containing all of its uses; it is otherwise identical
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in meaning to declaring the item outside the statement block.
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See [Items](#items).
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#### Variable declarations
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@ -463,11 +457,21 @@ init : [ '=' ] expr ;
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### Expression statements
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**FIXME:** grammar?
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```antlr
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expr_stmt : expr ';' ;
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```
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## Expressions
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**FIXME:** grammar?
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```antlr
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expr : literal | path | tuple_expr | unit_expr | struct_expr
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| block_expr | method_call_expr | field_expr | array_expr
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| idx_expr | range_expr | unop_expr | binop_expr
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| paren_expr | call_expr | lambda_expr | while_expr
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| loop_expr | break_expr | continue_expr | for_expr
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| if_expr | match_expr | if_let_expr | while_let_expr
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| return_expr ;
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```
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#### Lvalues, rvalues and temporaries
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@ -479,19 +483,23 @@ init : [ '=' ] expr ;
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### Literal expressions
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**FIXME:** grammar?
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See [Literals](#literals).
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### Path expressions
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**FIXME:** grammar?
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See [Paths](#paths).
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### Tuple expressions
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**FIXME:** grammar?
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```antlr
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tuple_expr : '(' [ expr [ ',' expr ] * | expr ',' ] ? ')' ;
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```
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### Unit expressions
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**FIXME:** grammar?
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```antlr
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unit_expr : "()" ;
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```
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### Structure expressions
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@ -507,8 +515,7 @@ struct_expr : expr_path '{' ident ':' expr
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### Block expressions
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```antlr
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block_expr : '{' [ view_item ] *
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[ stmt ';' | item ] *
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block_expr : '{' [ stmt ';' | item ] *
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[ expr ] '}' ;
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```
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@ -529,7 +536,7 @@ field_expr : expr '.' ident ;
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```antlr
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array_expr : '[' "mut" ? array_elems? ']' ;
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array_elems : [expr [',' expr]*] | [expr ',' ".." expr] ;
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array_elems : [expr [',' expr]*] | [expr ';' expr] ;
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```
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### Index expressions
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@ -549,66 +556,61 @@ range_expr : expr ".." expr |
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### Unary operator expressions
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**FIXME:** grammar?
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```antlr
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unop_expr : unop expr ;
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unop : '-' | '*' | '!' ;
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```
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### Binary operator expressions
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```antlr
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binop_expr : expr binop expr ;
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binop_expr : expr binop expr | type_cast_expr
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| assignment_expr | compound_assignment_expr ;
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binop : arith_op | bitwise_op | lazy_bool_op | comp_op
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```
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#### Arithmetic operators
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**FIXME:** grammar?
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```antlr
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arith_op : '+' | '-' | '*' | '/' | '%' ;
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```
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#### Bitwise operators
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**FIXME:** grammar?
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```antlr
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bitwise_op : '&' | '|' | '^' | "<<" | ">>" ;
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```
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#### Lazy boolean operators
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**FIXME:** grammar?
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```antlr
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lazy_bool_op : "&&" | "||" ;
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```
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#### Comparison operators
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**FIXME:** grammar?
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```antlr
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comp_op : "==" | "!=" | '<' | '>' | "<=" | ">=" ;
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```
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#### Type cast expressions
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**FIXME:** grammar?
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```antlr
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type_cast_expr : value "as" type ;
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```
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#### Assignment expressions
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**FIXME:** grammar?
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```antlr
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assignment_expr : expr '=' expr ;
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```
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#### Compound assignment expressions
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**FIXME:** grammar?
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#### Operator precedence
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The precedence of Rust binary operators is ordered as follows, going from
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strong to weak:
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```text
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* / %
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as
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+ -
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<< >>
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&
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^
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< > <= >=
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== !=
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&&
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=
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```antlr
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compound_assignment_expr : expr [ arith_op | bitwise_op ] '=' expr ;
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```
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Operators at the same precedence level are evaluated left-to-right. [Unary
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operators](#unary-operator-expressions) have the same precedence level and it
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is stronger than any of the binary operators'.
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### Grouped expressions
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```antlr
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