context undo

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

	Map: map<item, item>

	def item 
		[id]
		{
			Map->insert( lhs, lhs )
		}
	|	[`( item* `)]
		{
			Map->insert( lhs, lhs )
		}

	def no_accum_item 
		[id]
	|	[`( no_accum_item* `)]


	def A1 []
	def A2 []

	def start 
		[A1 item* `^]
	|	[A2 no_accum_item* `; NL]
	{
		for I: item in Map {
			print "map el: [I]
		}
	}

end

Undo: undo = new undo()
Undo->Map = new map<undo::item, undo::item>()

cons I: undo::item "a"
Undo->Map->insert( I, I )

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

###### IN #######
a a a ( a a ) a;
###### EXP #######
map el: a
a a a ( a a ) a;