##### LM #####
lex
	ignore /[\t\n ]+/
	literal `^ `| `- `, `: `! `? `.
	literal `( `) `{ `} `* `& `+

	literal `-- `:> `:>> `<: `-> `**

	token word /[a-zA-Z_][a-zA-Z0-9_]*/
	token uint /[0-9]+/
end


def start 
	[expression]
	{
		print_xml( lhs )
	}

def expression [term expression_op*]

def expression_op
	[`| term]
|	[`& term]
|	[`- term]
|	[`-- term]

def term [factor_rep term_op_list_short]

# This list is done manually to get shortest match.
def term_op_list_short
	[]
|	[term_op term_op_list_short]

def term_op
	[factor_rep]
|	[`. factor_rep]
|	[`:> factor_rep]
|	[`:>> factor_rep]
|	[`<: factor_rep]

def factor_rep 
	[factor_neg factor_rep_op*]

def factor_rep_op
	[`*]
|	[`**]
|	[`?]
|	[`+]
|	[`{ factor_rep_num `}]
|	[`{ `, factor_rep_num `}]
|	[`{ factor_rep_num `, `}]
|	[`{ factor_rep_num `, factor_rep_num `}]

def factor_rep_num [uint]

def factor_neg 
	[`! factor_neg]
|	[`^ factor_neg]
|	[factor]

def factor 
	[alphabet_num]
|	[word]
|	[`( expression `)]

def alphabet_num 
	[uint]
|	[`- uint]

parse start[ stdin ]
print( '\n' )
##### IN #####
1 - 1
##### EXP #####
<start><expression><term><factor_rep><factor_neg><factor><alphabet_num><uint>1</uint></alphabet_num></factor></factor_neg><_repeat_factor_rep_op></_repeat_factor_rep_op></factor_rep><term_op_list_short></term_op_list_short></term><_repeat_expression_op><expression_op><_literal_0007>-</_literal_0007><term><factor_rep><factor_neg><factor><alphabet_num><uint>1</uint></alphabet_num></factor></factor_neg><_repeat_factor_rep_op></_repeat_factor_rep_op></factor_rep><term_op_list_short></term_op_list_short></term></expression_op></_repeat_expression_op></expression></start>