src/main/java/com/bazaarvoice/jless/parser/Parser.java
Rule ExpressionFunction() {
        return Sequence(
                Sequence(
                        "expression(",
                        ZeroOrMore(
                                TestNot(
                                        ')',
                                        Ws0(),
                                        AnyOf(";}")
                                ),
                                ANY
                        ),
                        ')'
                ),
                push(new SimpleNode(match()))
        );
    }
Rule ExpressionFunction() {
        return Sequence(
                Sequence(
                        "expression(",
                        ZeroOrMore(
                                TestNot(
                                        ')',
                                        Ws0(),
                                        AnyOf(";}")
                                ),
                                ANY
                        ),
                        ')'
                ),
                push(new SimpleNode(match()))
        );
    }
Rule ExpressionFunction ( ) { return Sequence ( Sequence ( "expression(" , ZeroOrMore ( TestNot ( ' ' , Ws0 ( ) , AnyOf ( ";}" ) ) , ANY ) , ' ' ) , push ( new SimpleNode ( match ( ) ) ) ) ; }
'expression(' (!(')' Ws0 [;}]) .)* ');'
expression ( ( ! ( ) Ws0 [ ; } ] ) . ) * ) ;