Package dssl;

Helpers
	all = [0 .. 127];
	digit = ['0' .. '9'];
	letter = [['a' .. 'z'] + ['A' .. 'Z']];
	name = letter (digit | letter | '_')*;
	sign = '+' | '-';

	tab = 9;
	lf = 10;
	cr = 13;
	eol = cr | lf | cr lf;
	separator = ' ' | tab | eol;

	apostrophe = 39;
	quote = 34;
	not_eol = [all - [cr + lf]];
	escape_char = '\' not_eol;

	c_char = [all - [apostrophe + ['\' + [lf + cr]]]] | escape_char;
	c_char_sequence = c_char+;
	s_char = [all - [quote + ['\' + [lf + cr]]]] | escape_char;
	s_char_sequence = s_char*;

	not_star = [all - '*'];
	not_star_slash = [not_star - '/'];

	double_slash = '//';
	slash_star = '/*';

	line_comment = double_slash not_eol* eol;
	block_comment = slash_star not_star* '*'+ (not_star_slash not_star* '*'+)* '/';

Tokens
	blank = separator+;
	comment = line_comment | block_comment;

	l_brace = '{';
	r_brace = '}';

	def = 'def';

	exch = 'exch';
	pop = 'pop';
	dup = 'dup';

	roll = 'roll';
	clear = 'clear';
	copy = 'copy';

	count = 'count';
	countto = 'countto';

	read = 'read';
	print = 'print';
	interpret = 'interpret';

	int = 'int';
	bool = 'bool';
	float = 'float';
	char = 'char';
	string = 'string';

	exec = 'exec';

	halt = 'halt';
	break = 'break';

	equals = '=';

	plus_equals = '+=';
	and_equals = '&=';
	or_equals = '|=';
	xor_equals = '^=';
	minus_equals = '-=';
	concat_equals = '~=';

	arithmetic_left_shift_equals = '<<=';
	arithmetic_right_shift_equals = '>>=';
	logical_right_shift_equals = '>>>=';

	multiply_equals = '*=';
	divide_equals = '/=';
	remainder_equals = '%=';
	idivide_equals = '//=';
	modulo_equals = '%%=';

	equal_to = '==';
	not_equal_to = '!=';

	less_than = '<';
	less_or_equal = '<=';
	more_than = '>';
	more_or_equal = '>=';

	plus = '+';
	and = '&';
	or = '|';
	xor = '^';
	minus = '-';
	concat = '~';

	arithmetic_left_shift = '<<';
	arithmetic_right_shift = '>>';
	logical_right_shift = '>>>';

	multiply = '*';
	divide = '/';
	remainder = '%';
	idivide = '//';
	modulo = '%%';

	not = 'not';
	neg = 'neg';
	inv = 'inv';

	int_value = sign? digit+;
	bool_value = 'true' | 'false';
	float_value = sign? (digit+ ('.' digit*)? | '.' digit+);
	char_value = apostrophe c_char apostrophe;
	string_value = quote s_char_sequence quote;

	label = '/' name;
	identifier = name;