Regular Expression Grammer (JS)

Pattern :: 
	Disjunction

Disjunction :: 
	Alternative
	Alternative | Disjunction

Alternative ::
	[empty]
	Alternative Term

Term ::
	Assertion
	Atom
	Atom Quantifier

Assertion ::
	^
	$
	\ b
	\ B

Quantifier ::
	QuantifierPrefix
	QuantifierPrefix ?
	
QuantifierPrefix ::
	*
	+
	?
	{ DecimalDigits }
	{ DecimalDigits , }
	{ DecimalDigits , DecimalDigits }

Atom ::
	PatternCharacter
	.
	\ AtomEscape
	CharacterClass
	( Disjunction )
	( ? : Disjunction )
	( ? = Disjunction )
	( ? ! Disjunction )

PatternCharacter :: SourceCharacter but not any of:
	^ $ \ . * + ? ( ) [ ] { } |
	
AtomEscape ::
	DecimalEscape
	CharacterEscape
	CharacterClassEscape

CharacterEscape ::
	ControlEscape
	c ControlLetter
	HexEscapeSequence
	UnicodeEscapeSequence
	IdentityEscape
	
ControlEscape :: one of
	f n r t v
	
ControlLetter :: one of
	a b c d e f g h i j k l m n o p q r s t u v w x y z
	A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
	
IdentityEscape ::
	SourceCharacter but not IdentifierPart

DecimalEscape ::
	DecimalIntegerLiteral [lookahead ? DecimalDigit]

CharacterClassEscape :: one of
	d D s S w W

CharacterClass ::
	[ [lookahead ? {^}] ClassRanges ]
	[ ^ ClassRanges ]
	
ClassRanges ::
	[empty]
	NonemptyClassRanges

NonemptyClassRanges ::
	ClassAtom
	ClassAtom NonemptyClassRangesNoDash
	ClassAtom - ClassAtom ClassRanges

NonemptyClassRangesNoDash ::
	ClassAtom
	ClassAtomNoDash NonemptyClassRangesNoDash
	ClassAtomNoDash - ClassAtom ClassRanges

ClassAtom ::
	-
	ClassAtomNoDash

ClassAtomNoDash ::
	SourceCharacter but not one of\ ] -
	\ ClassEscape

ClassEscape ::
	DecimalEscape
	b
	CharacterEscape
	CharacterClassEscape

* Source: ECMA-262