start = g:greg {return "<pre>"+g+"</pre>";}

greg = p:preg _ g:greg _ / preg _

preg
	= nonterminal seta terminal  nonterminal
    / nonterminal seta terminal
    / nonterminal seta "%"

grammar = p:production _ g:grammar _ 
{return p+"<br>"+g } / production _

production = pre: nonterminal seta pos: char* 

seta="->" {return "-&gt;";}

nonterminal = capital

terminal = letter

word = char+ {return text();}

char = letter / capital

capital = [A-Z]

letter = [a-z]

_ "whitespace"
  = [ \t\n\r]*