##### LM #####
context undo

	lex
		ignore /( ' ' | '\t')+/
		literal '*', '(', ')', '^', ';', '\n'
		token id /[a-zA-Z_]+/
	end

	Out: parser<out>

	def out_item
		[id]
	|	['(' item* ')']

	def out 
		[out_item*]

	def item 
		[id]
		{
			send Out [r1]
		}
	|	['(' item* ')']
		{
			send Out ['(']
			send Out [r2]
			send Out [')']
		}

	def A1 []
	def A2 []


	def start 
		[A1 item* '^']
	|	[A2 item* ';' '\n']

end # undo

cons Undo: undo[]
Undo.Out = construct parser<undo::out> []

parse Input: undo::start(Undo)[ stdin ]
print( Input )

##### IN #####
a b c;
##### EXP #####
a b c;