Grammar re_parser;

Lexer

// A printable character (inside strings)
char = ' ' ...;

// Igndored stufs
blank = ' ';

Parser

Ignored blank;

re =
	{char:} char	|
	{par:} '(' re ')'
Unary
	{ques:} re '?' |
	{star:} re '*' |
	{plus:} re '+'
Left
	{conc:} re re
Left
	{alter:} re '|' re;