logo

Grammar

Legend

Legend for Fan BNF Grammar:

:=      is defined as
<x>     non-terminal
"x"     literal
[x]     optional
(x)     grouping
x*      zero or more times
x|x     or

Compilation Unit

<compilationUnit> :=  <using>* <typeDef>*

<using>          :=  <usingPod> | <usingType> | <usingAs>
<usingPod>       :=  "using" <id> <eos>
<usingType>      :=  "using" <id> "::" <id> <eos>
<usingAs>        :=  "using" <id> "::" <id> "as" <id> <eos>

Type Def

<typeDef>        :=  <classDef> | <mixinDef> | <enumDef>

<classDef>       :=  <classHeader> <classBody>
<classHeader>    :=  [<doc>] <facets> <classFlags> "class" [<inheritance>]
<classFlags>     :=  [<protection>] ["abstract"] ["final"] ["const"]
<classBody>      :=  "{" <slotDefs> "}"

<enumDef>        :=  <enumHeader> <enumBody>
<enumHeader>     :=  [<doc>] <facets> [<protection>] "enum" [<inheritance>]
<enumBody>       :=  "{" <enumDefs> <slotDefs> "}"

<mixinDef>       :=  <enumHeader> <enumBody>
<mixinHeader>    :=  [<doc>] <facets> [<protection>] "mixin" [<inheritance>]
<mixinBody>      :=  "{" <slotDefs> "}"

<protection>     :=  "public" | "protected" | "private" | "internal"
<inheritance>    :=  ":" <typeList>

Slot Def

<enumDefs>       :=  <enumDef> ("," <enumDef>)* <eos>
<enumDef>        :=  <id> ["(" <args> ")"]

<slotDefs>       :=  <slotDef>*
<slotDef>        :=  <fieldDef> | <methodDef> | <ctorDef>

<fieldDef>       :=  <facets> <fieldFlags> [<type>] <id> [":=" <expr>]
                     [ "{" [<fieldGetter>] [<fieldSetter>] "}" ] <eos>
<fieldFlags>     :=  [<protection>] ["readonly"] ["static"]
<fieldGetter>    :=  "get" (<eos> | <block>)
<fieldSetter>    :=  <protection> "set" (<eos> | <block>)

<methodDef>      :=  <facets> <methodFlags> <type> <id> "(" <params> ")" <methodBody>
<methodFlags>    :=  [<protection>] ["virtual"] ["override"] ["abstract"] ["static"]
<params>         :=  [<param> ("," <param>)*]
<param>          :=  <type> <id> [":=" <expr>]
<methodBody>     :=  <eos> | ( "{" <stmts> "}" )

<ctorDef>        :=  <facets> <ctorFlags> "new" <id> "(" <params> ")" [ctorChain] <methodBody>
<ctorFlags>      :=  [<protection>]
<ctorChain>      :=  <ctorChainThis> | <ctorChainSuper>
<ctorChainThis>  :=  "this" "." <id> "(" <args> ")"
<ctorChainSuper> :=  "super" ["." <id>] "(" <args> ")"

Stmt

<block>          :=  <stmt> | ( "{" <stmts> "}" )
<stmts>          :=  <stmt>*
<stmt>           :=  <break> | <continue> | <for> | <if> | <return> | <switch> |
                     <throw> | <while> | <try> | <exprStmt> | <localDef>
<break>          :=  "break" <eos>
<continue>       :=  "continue" <eos>
<for>            :=  "for" "(" [<forInit> ";" [<expr>] ";" [<expr>] ")" <block>
<forInit>        :=  <expr> | <localDef>
<if>             :=  "if" "(" <expr> ")" <block> [ "else" <block> ]
<return>         :=  "return" [<expr>] <eos>
<throw>          :=  "throw" <expr> <eos>
<while>          :=  "while" "(" <expr> ")" <block>
<exprStmt>       :=  <expr> <eos>
<localDef>       :=  [<type>] <id> [":=" <expr>] <eos>

<try>            :=  "try" "{" <stmt>* "}" <catch>* [<finally>]
<catch>          :=  "catch" [<catchDef>] "{" <stmt>* "}"
<catchDef>       :=  "(" <type> <id> ")"
<finally>        :=  "finally" "{" <stmt>* "}"

<switch>         :=  "switch" "(" <expr> ")" "{" <case>* [<default>] "}"
<case>           :=  "case" <expr> ":" <stmts>
<default>        :=  "default" ":" <stmts>

Expr

<expr>           :=  <assignExpr>
<assignExpr>     :=  <condOrExpr> [<assignOp> <assignExpr>]
<assignOp>       :=  "=" | "*=" | "/=" | "%=" | "+=" | "-=" | "<<=" | ">>="  | "&=" | "^=" | "|="
<ternaryExpr>    :=  <condOrExpr> "?" <condOrExpr> ":" <condOrExpr>
<condOrExpr>     :=  <condAndExpr>  ("||" <condAndExpr>)*
<condAndExpr>    :=  <equalityExpr> ("&&" <equalityExpr>)*
<equalityExpr>   :=  <relationalExpr> (("==" | "!=" | "===" | "!==") <relationalExpr>)*
<relationalExpr> :=  <rangeExpr> (("is" | "as" | "<" | "<=" | ">" | ">=" | "<=>") <rangeExpr>)*
<rangeExpr>      :=  <bitOrExpr> ((".." | "...") <bitOrExpr>)*
<bitOrExpr>      :=  <bitAndExpr> (("^" | "|") <bitAndExpr>)*
<bitAndExpr>     :=  <shiftExpr> (("&" <shiftExpr>)*
<shiftExpr>      :=  <addExpr> (("<<" | ">>") <addExpr>)*
<addExpr>        :=  <multExpr> (("+" | "-") <multExpr>)*
<multExpr>       :=  <parenExpr> (("*" | "/" | "%") <parenExpr>)*
<parenExpr>      :=  <unaryExpr> | <castExpr> | <groupedExpr>
<castExpr>       :=  "(" <type> ")" <parenExpr>
<groupedExpr>    :=  "(" <expr> ")" <termChain>*
<unaryExpr>      :=  <prefixExpr> | <termExpr> | <postfixExpr>
<prefixExpr>     :=  ("!" | "+" | "-" | "~" | "&" | "++" | "--") <parenExpr>
<postfixExpr>    :=  <termExpr> ("++" | "--")
<termExpr>       :=  <termBase> <termChain>* [withBlock]
<termBase>       :=  <literal> | <idExpr> | <closure>
<termChain>      :=  <compiledCall> | <dynamicCall> | <indexExpr> | <callOp>
<withBlock>      :=  "{" <withSub>* "}"
<withSub>        :=  <expr> <eos>    // expr is restricted
<compiledCall>   :=  "." <idExpr>
<dynamicCall>    :=  "->" <idExpr>
<idExpr>         :=  <local> | <field> | <call>
<local>          :=  <id>
<field>          :=  ["@"] <id>
<call>           :=  <id> ["(" <args> ")"] [<closure>]
<args>           :=  [<expr> ("," <expr>)*]
<closure>        :=  <funcType> "{" <stmts> "}"
<indexExpr>      :=  "[" <expr> "]"
<callOp>         :=  "(" <args> ")" [<closure>]
<literal>        :=  "null" | "this" | "super" | <namedSuper> | <bool> | <int> |
                     <float> | <str> | <duration> | <uri> | <list> | <map> | <simple>
<namedSuper>     :=  <type> "." "super"
<list>           :=  [<type>] "[" <listItems> "]"
<listItems>      :=  "," | (<expr> ("," <expr>)*)
<map>            :=  [<mapType>] "[" <mapItems> "]"
<mapItems>       :=  ":" | (<mapPair> ("," <mapPair>)*)
<mapPair>        :=  <expr> ":" <expr>
<simple>         :=  <type> "(" <expr> ")"

Type

<type>           :=  <simpleType> | <listType> | <mapType> | <funcType>
<typeList>       :=  <type> ("," <type>)*
<simpleType>     :=  <id> ["::" <id>]
<listType>       :=  <type> "[]"
<mapType>        :=  ["["] <type> ":" <type> ["]"]
<funcType>       :=  "|" <formals> ["->" <type> "|"
<formals>        :=  [<formal> ("," <formal>)*]
<formal>         :=  <type> <id>

Misc

<id>             := <idStart> (idChar)*
<idStart>        := A-Z | a-z | _
<idChar>         := A-Z | a-z | _ | 0-9
<eos>            := ; | \n | }

Keywords

abstract       finally        readonly
as             for            return
assert         foreach        static
break          goto           super
case           if             switch
catch          internal       this
class          is             throw
const          mixin          true
continue       native         try
default        new            using
do             null           virtual
else           override       volatile
enum           private        void
false          protected      while
final          public