parc.grammar

--
-- This is the complete PARC grammar. It is a PARC grammar that describes the PARC grammar.
--

--
-- Comments start with double hyphen -- and last to the end of line. There are no multi-line comments.
--

"parc" { -- Define package "parc"


	"white-space" "ignore" ; -- The lexical analysis will disregard, all white-space tokens.

	--
	-- Tokens are identifiers that lead with a lower case letter
	--

	globalIdentifier = "A" - "Z" ( "A" - "Z" | "a" - "z" | "0" - "9" ) *
		;

	localIdentifier = "a" - "z" ( "A" - "Z" | "a" - "z" | "0" - "9" ) *
		;

	-- Tokens do not support projections, regex "(\\\\|\\"|[^\\"])*"
	literal = "\"" ( "\\\\" | "\\\"" | ^ "\"" )* "\""
		;

	many = "*" ;

	manyAtLeastOnce = "+" ;

	manyOptional = "?" ;

	--
	-- Productions are identifiers that lead with a upper case letter
	--

	-- The Main production is the entry point to your grammar.
	-- A PARC grammar is not required to define a Main production.
	Main
		= a : Package* => Grammar { PackageList = a }
		;

	Package
		= a : literal "{" b : ( Option | Token | Production ) * "}"
			=> Package{ PackageName = a, Content = b }
		;

	Option
		= a : literal b : literal ";"
			=> Option{ Name = a, Value = b }

	Token
		= a : localIdentifier "=" b : TokenRep Projection? ";"
			=> Token{ id = a, def = b }
		;

	TokenRep
		= TokenDef
		| a : TokenDef b : (many | manyAtLeastOnce | manyOptional)? => TokenRepetition{ Pattern = a, Kind = b }
		;

	TokenDef
		= TokenPrimary
		| a:TokenPrimary ( "|" a:TokenDef )+ => Any{ Left = a }
		| "(" a : TokenDef ")" => Eval{ Expression = a }
		;

	TokenPrimary
		= a : literal => TokenLiteral{ value = a }
		| "^" a : literal => TokenNegative{ value = a }
		| a : literal "-" b : literal => TokenRange{ min = a, max = b }
		;

	Projection
		= "=>" a : globalIdentifier "{" b : InitializerList "}" => Projection{ InitializerList = b }
		| "=>" b : localIdentifier => LocalProjection{ Local = b }
		;

	InitializerList
		= a : Initializer ("," a:Initializer)* => a
		;

	Initializer
		= a : globalIdentifier "=" b : localIdentifier => Initializer{ Member = a, Local = b }
		;

	Production
		= a : globalIdentifier "=" (b : Rule)+ => Production{ Name = a, Rules = b }
		;

	Rule
		= a : localIdentifier ":" b:AnonymousRule => NamedRule{ Name = a, Rule = b }
		| AnonymousRule
		;

	AnonymousRule
		= a:PrimaryRule
		| a:PrimaryRule (b:many | b:manyAtLeastOnce | b:manyOptional) => RepetitionRule{ Rule = a, Kind = b }
		| a:PrimaryRule "|" b:AnonymousRule => ChoiceRule{ Left = a, Right = b }
		;

	PrimaryRule
		= a : literal => LiteralRule{ Literal = a }
		| a : localIdentifier => TokenRule{ Token = a }
		| a : globalIdentifier => ProductionRule{ Production = a }
		| "(" a:AnonymousRule ")" => EvalRule{ Rule = a }
		;
}

-- Notes:
-- There are no reserved keywords.