EBNF Grammar for JavaScript (aka ECMAScript)

README.md

I needed to write some sort of 'syntax transformer' for my job, long story, but genrally I needed to have a tree in the style that I wanted. A halway between an abstract syntax tree, and an 'style definition' tree. So I needed to capture the comments, the style of variables, etc. Neither Babel, nor ESPrima, and not Acorn, none of them were any help. On the other hand, I was not a master of JS, so I decided to peruse through ECMA-262 and write the EBNF grammar. I hope to feed this grammar to various AI models, and have them make tree specs and parser genrators with it.

Meanwhile I will release this grammar under the Unlicense so people can use it for whatever they want, maybe do similar things I wish to do with it.

Don't bother looking for an old-timy parser generator that accepts EBNF. AI models have opened a vast array of optiions on how EBNF can be utilized, that goes beyond the usage that tools like BNFC offer.

Enjoy.

How to Read EBNF Gramamrs

It's pretty simple.

• Ellipses mark ranges,
• Text between two question marks mean it's a free-style 'whatever goes' type of rule,
• Rules between parethensis mark grouping,
• Curly braces mean sequence
• Brackets mean optional

Thanks bascialyl it.

ECMAScript.ebnf

# Syntactic Grammar for ECMAScript

ecma-script-module		::= { top-level | ignorable }

top-level			::= statement
				 | function-declaration
				 | class-declaration

function-declaration		::= [ "async" ] "function" identifier function-params-postfix compound-statement

class-declaration		::= "class" identifier [ "extends" comma-separated-expressions ] class-body

class-body			::= '{' { class-member } '}'

class-member			::= [ "static" 
					| "getter" 
					| "setter" 
					| "public" 
					| "private" ] ( class-method | class-property )

class-property			::= [ '#' ] null-join identifier [ '=' expression ] [ ';' ]

class-method			::= [ '#' ] null-join identifier function-params-postfix compound-statement

compound-statement		::= '{' { statement } '}'

statement			::= expression-statement
				 | declaration-statement
				 | if-statement
				 | switch-statement
				 | for-statement
				 | for-in-statement
				 | for-of-statement
				 | do-while-statement
				 | control-flow-statement
				 | try-catch-finally-statement
				 | label-statement
				 | export-statement
				 | import-statement


export-statement		::= "export" [ "default" ] declaration-statement [ ';' ]
				 | "export" module-element "from" module-element [ ';' ]
				

import-statement		::= "import" module-element [ ';' ]
				 | "import" paren-enclosed-string [ ';' ]
				 | "import" module-element "from" module-element [ ';' ]

label-statement			::= identifier ':' { statement }

with-statement			::= "with" '(' expression ')' compound-statement

try-catch-finally-statemnt	::= "try" compound-statement 
						[ "catch" [ '(' expression ')' ] compound-statement ]
						[ "finally" compound-statement ]

control-flow-statement		::= "break"  [ ';' ]
				 | "continue" [ ';' ]
				 | "return" expression [ ';' ]
				 | "throw" expression [ ';' ]

do-while-statement		::= "do" compound-statement "while" '(' expression ')' [ ';' ]

for-of-stetement		::= "for" '(' expression "of" expression ')' compound-statement

for-in-statement		::= "for" '(' expression "in" expression ')' compound-statement

for-statement			::= "for" '(' declaration-statement ';' expression ';' expression ')' compound-statement

switch-statement		::= "switch" '(' expression ')' { case-clause }

case-clause			::= "case" expression ':' { statement }
				 | "defualt" ':' { statement }

if-statement			::= "if" '(' expression ')' 
					compound-statement [ { "else" if-statement } | "else" compound-statement ]

declaration-statement		::= ( "var" | "let" | "const" | "static" ) lvalue '=' expression [ ';' ]

lvalue				::= identifier
				 | destructure-target

destructure-target		::= object-literal
				 | array-literal

expression-statement		::= expression ';'

expression			::= ternary-expression
				 | binary-expression
				 | unary-expression
				 | primary-expression
				 | assignment-expression

assignment-expression		::= primary-expression '=' expression
				 | primary-expression "+=" expression
				 | primary-expression "-=" expression
				 | primary-expression "*=" expression
				 | primary-expression "/=" expression
				 | primary-expression "%=" expression
				 | primary-expression "**=" expression
				 | primary-expression ">>=" expression
				 | primary-expression "<<=" expression
				 | primary-expression ">>>=" expression
				 | primary-expression "&=" expression
				 | primary-expression "^=" expression
				 | primary-expression "|=" expression
				 | primary-expression "&&=" expression
				 | primary-expression "||=" expression
				 | primary-expression "??=" expression

ternary-expression		::= binary-expression '?' binary-expression ':' binary-expression

binary-expression		::= nullish-binary-expression

nullish-binary-expression	::= logical-or-binary-expression "??" nullish-binary-expression

logical-or-binary-expression	::= logical-and-binary-expression "||" logical-or-binary-expression

logical-and-binary-expression	::= bitwise-xor-binary-expression "&&" logical-and-binary-expression

bitwise-or-binary-expression	::= bitwise-xor-binary-expression '|' bitwise-or-binary-expression

bitwise-xor-binary-expression	::= bitwise-and-binary-expression '^' bitwise-xor-binary-expression

bitwise-and-binary-expression	::= equality-binary-expression '&' bitwise-and-binary-expression

equality-binary-expression	::= relational-binary-expression "==" equality-binary-expression
				 | relational-binary-expression "===" equality-binary-expression
				 | relational-binary-expression "!=" equality-binary-expression
				 | relational-binary-expression "!==" equality-binary-expression

relational-binary-expression	::= bitwise-shift-binary-expression '<' relational-binary-expression
				 | bitwise-shift-binary-expressipn "<=" relational-binary-expression
				 | bitwise-shift-binary-expression '>' relational-binary-expression
				 | bitwise-shift-binary-expression ">=" relational-binary-exression
				 | bitwise-shift-binary-expresssion "??" relational-binary-expression

bitwise-shift-binary-expression	::= additive-binary-expression ">>" bitwise-shift-binary-expression
				 | additive-binary-expression "<<" bitwise-shift-binary-expression
				 | additive-binary-expression ">>>" bitwise-shift-binary-expression

additive-binary-expression	::= multiplicative-binary-expression '+' additive-binary-expression
				 | multiplicative-binary-expression '-' additive-binary-expression

multiplicative-binary-expression ::= unary-expression '*' multiplicative-binary-expression
				 | unary-expression '/' multiplicative-binary-expression
				 | unary-expression '%' multiplicative-binary-expression
				 | unary-expression "**" multiplicative-binary-expression

unary-expression		::= prefix-expression | postfix-expression

postfix-expression		::= primary-expression null-join property-access-postifx
				 | primary-expression function-call-postfix
				 | primary-expression null-join "++"
				 | primary-expression null-join "--"
				 | primary-expression null-join template-literal
				 | primary-expression null-join '?'

prefix-expression		::= '+' null-join primary-expression
				 | '-' null-join primary-expression
				 | "++" null-join primary-expression
				 | "--" null-join primary-expression
				 | '!' null-join primary-expression
				 | '~' null-join primary-expression
				 | "..." null-join expression
				 | "typeof" expression
				 | "void" expression
				 | "delete" expression
				 | "await" exprssion
				 | "new" expression

primary-expression		::= lexical-literal
				 | syntactic-literal
				 | paren-enclosed-expression
				 | class-expression
				 | function-expression
				 | arrow-expression
				 | "this"
				 | identifier
				 | typcons-name

arrow-expression		::= [ "async" ] arrow-expression-params "=>" arrow-expression-body

arrow-expression-body		::= compound-statement-block 
				 | expression

arrow-expression-params		::= function-call-expression
				 | identifier

class-expression		::= "class" class-body

function-expression		::= [ "async" ] "function" function-params-postfix compound-statement

paren-enclosed-expression	::= '(' [ expression ] ')'

syntactic-literal		::= template-literal
				 | object-literal
				 | array-literal


template-literal		::= '`' { printable | template-expression } '`'

template-expression		::= "${" [ expression ] '}'

object-literal			::= '{' [ comma-separated-properties ] '}'

comma-separated-properties	::= property { ',' property }

property			::= [ identifier ':' ] expression

array-literal			::= '[' [ comma-separated-expressions ]  ']'

property-access-postfix		::= bracket-notation-property | dot-notation-property

bracket-notation-property	::= { bracket-enclosed-expressions }

bracket-enclosed-expression  	::= '[' expression ']'

dot-notation-property		::= '.' null-join dot-separated-expressions

dot-separated-expressions	::= expression { '.' null-join expression }

function-call-postfix		::= '(' [ comma-separated-expressions ] ')'

comma-separated-expressions 	::= expression { ',' expression }

function-params-postfix		::= '(' [ comma-separated-function-params ] ')'

comma-separated-function-params	::= function-parameter { ',' function-parameter }

function-parameter		::= identifier [ '=' expression ]
				 | object-literal

module-element			::= module-names
				 | curly-enclosed-module-names

paren-enclosed-string		::= '(' string-literal ')'

curly-enclosed-module-name	::= '{' comma-separated-module-names '}'

comma-separated-module-names	::= module-names { ',' module-names }

module-names			::= identifier
				 | identifier-as-another
				 | string-literal

identifier-as-another		::= identifier "as" identifier

# Lexical Grammar for ECMAScript

identifier			::= underscore-fix-ident
				 | asterisk-fix-ident
				 | snakecase-ident
				 | camelcase-ident
				 | mixedcase-ident

asterisk-fix-ident		::= '*' [ identifier ]

underscore-fix-ident		::= '_' [ identifier ]

mixedcase-ident			::= letter { letter | digit | '_' }

snakecase-ident			::= lower { lower | digit | '_' }


camelcase-ident			::= lower { letter | digit | '_' }

pascalcase-ident		::= upper { letter | digit | '_' }

lexical-literal			::= bigint-literal
				 | null-literal
				 | boolean-literal
				 | float-literal
				 | integer-literal
				 | string-literal
				 | regex-literal

regexp-literal			::= '/' regexp-pattern '/' { regex-flags }

regexp-flags			::= 'g' | 'i' | 'm' | 's' | 'u' | 'y' | 'd'

regexp-pattern			::= ? any valid js regexp pattern ?

bigint-literal			::= { digit } 'n'

null-literal			::= "null" 	| "undefined"

boolean-literal			::= "true" 	| "false"

float-literal			::= scientific-notation | rational-number

integer-literal			::= { digit }
				 | bin-prefix { bin-digit }
				 | oct-prefix { oct-digit }
				 | hex-prefix { hex-digit }

string-literal			::= single-quoted-string
				 | double-quoted-string

scientific-notation		::= { digit } ( 'e' 	| 'E' ) [ '-' | '+' ] { digit }

rational-number			::= [ { digit } ] '.' { digit }

single-quoted-string		::= "'" { printable } "'"

double-quoted-string		::= '"' { printable } '"'

printable			::= letter | digit | punctuation | whitespace

oct-prefix			::= '0' ( 'o' | 'O' )

hex-preix			::= '0' ( 'x' | 'X' )

bin-prefix			::= '0' ( 'b' | 'B' )

hex-digit			::= digit | hex-lower | hex-upper

hex-lower			::= 'a' | ... | 'f'

hex-upper			::= 'A' | ... | 'F'

oct-digit			::= '0' | ... | '7'

bin-digit			::= '0' | '1' 

digit				::= '0' | '1' | '2' | ... | '7' | '8' | '9'

punctuation			::= '!'| '"' | '#' | '$' | '%' | '&' | "'" 
		 		 | '(' | ')' | '*' | '+' | ',' | '-' | '.' | '/' 
				 | ':' | ';' | '<' | '=' | '>' | '?' | '@' 
				 | '[' | '\\' | ']' | '^' | '_' | '`' 
				 | '{' | '|' | '}' | '~'

letter				::= uppper | lower

upper				::= 'A' | 'B' | 'C' | ... | 'X' | 'Y' | 'Z' 

lower				::= 'a' | 'b' | 'c' | ... | 'x' | 'y' | 'z'

escape-sequence			::= '\' char-escape
				 | '\' unicode-escape
				 | '\' hex-escape
				 | '\' unicode-point-escape
				 | '\' newline

char-escape			::= "'" | '"' | '\' | 'n' | 'r' | 't' | 'b' | 'f' | 'v' | '0'

unicode-escape			::= 'u' { hex-digit }

hex-escape			::= 'x' { hex-digit }

unicode-point-escape		::= 'u' '{' { hex-digit } '}' 

ignorable			::= whitespace
				 | comment

comment				::= single-line-comment | multi-line-comment

multi-line-comment 		::= "/*" { no-star-slash } "*/"

no-star-slash			::= ? any character except star and forward slash ?

single-line-comment		::= "// " { no-newline } newline

no-newline			::= ? any chacter except newline ?

null-join			::= ? matching nothing, a nil token, used to denote zero-with joins ?

whitespace			::= newline
				 | space
				 | tabulator

space				::= ? literal space character ?

tabulator			::= ? literal horizontal tab character ?

newline				::= ? lietal newline character ?