stylesheet
  : [ [ ruleset ] [S]* ]*
  ;
combinator
  : PLUS | GREATER
  ;
unary_operator
  : '-' | PLUS
  ;
property
  : IDENT
  ;
ruleset
  : selector [ COMMA selector ]*
    LBRACE declaration [ ';' declaration ]* '}'
  ;
selector
  : simple_selector [ combinator simple_selector ]*
  ;
simple_selector
  : element_name [ HASH | class | attrib | pseudo ]*
  | [ HASH | class | attrib | pseudo ]+
  ;
class
  : '.' IDENT
  ;
element_name
  : IDENT | '*'
  ;
attrib
  : '[' IDENT [ [ '=' | INCLUDES | DASHMATCH ]
    [ IDENT | STRING ] ]? ']'
  ;
pseudo
  : ':' [ IDENT | FUNCTION IDENT? ')' ]
  ;
declaration
  : property ':' expr
  ;
expr
  : term [ COMMA term ]*
  ;
term
  : unary_operator?
    [ NUMBER | PERCENTAGE | LENGTH | EMS | EXS | ANGLE |
      TIME | FREQ ]
  | STRING | IDENT | URI | hexcolor | function
  ;
function
  : FUNCTION expr ')'
  ;
hexcolor
  : HASH S*
  ;

%option case-insensitive

nmstart		[_a-z]
nmchar		[_a-z0-9-]
string1		\"([^\n\r\f\\"]|\\{nl})*\"
string2		\'([^\n\r\f\\']|\\{nl})*\'
invalid1	\"([^\n\r\f\\"]|\\{nl})*
invalid2	\'([^\n\r\f\\']|\\{nl})*

comment		\/\*[^*]*\*+([^/*][^*]*\*+)*\/
ident		-?{nmstart}{nmchar}*
name		{nmchar}+
num		[0-9]+|[0-9]*"."[0-9]+
string		{string1}|{string2}
invalid		{invalid1}|{invalid2}
url		([!#$%&*-~])*
s		[ \t\r\n\f]+
w		{s}?
nl		\n|\r\n|\r|\f

%%

{s}			{return S;}

\/\*[^*]*\*+([^/*][^*]*\*+)*\/		/* ignore comments */
{s}+\/\*[^*]*\*+([^/*][^*]*\*+)*\/	{unput(' '); /*replace by space*/}

"~="			{return INCLUDES;}
"|="			{return DASHMATCH;}

{w}"{"			{return LBRACE;}
{w}"+"			{return PLUS;}
{w}">"			{return GREATER;}
{w}","			{return COMMA;}

{string}		{return STRING;}
{invalid}		{return INVALID; /* unclosed string */}

{ident}			{return IDENT;}

"#"{name}		{return HASH;}

{num}"em"		{return EMS;}
{num}"ex"		{return EXS;}
{num}"px"		{return LENGTH;}
{num}"cm"		{return LENGTH;}
{num}"mm"		{return LENGTH;}
{num}"in"		{return LENGTH;}
{num}"pt"		{return LENGTH;}
{num}"pc"		{return LENGTH;}
{num}{ident}	{return DIMENSION;}

{num}%			{return PERCENTAGE;}
{num}			{return NUMBER;}

"url("{w}{string}{w}")"	{return URI;}
"url("{w}{url}{w}")"	{return URI;}
{ident}"("		{return FUNCTION;}

.