##### LM #####
context accum_bt

lex
	ignore /[ \t\n]+/
	token id1 /[a-zA-Z_][a-zA-Z_0-9]*/

	def one [ id1* ]
end

OneParser: accum<one>

lex
	ignore /[ \t]+/
	token id2 /[a-zA-Z_][a-zA-Z_0-9]*/
	literal `! `;
	token NL /'\n'/

	def A1 []
		{ print( "A1\n" ) }

	def A2 []
		{ print( "A2\n" ) }

	def item2
		[id2]
		{
			send OneParser [' extra ']
			send OneParser [$r1]
		}

	def two 
		[A1 item2* `! NL]
	|	[A2 item2* `; NL]
end

end # accum_bt

AccumBt: accum_bt = cons accum_bt[]
AccumBt.OneParser = cons parser<accum_bt::one>[]

parse Two: accum_bt::two(AccumBt)[ stdin ]

send AccumBt.OneParser ['\n'] eos

print( ^Two )
print( ^( AccumBt.OneParser.tree ) '\n' )
##### IN #####
a b c d e ;
##### EXP #####
A1
A2
a b c d e ;
extra a extra b extra c extra d extra e