protected function factor()
    {
        $combinator = null;

        if ($combinator = $this->is("combinator")) {
            if (!$element = $this->is("element")) {
                throw new TextParserException("Invalid expression", $this);
            }
        } elseif ($element = $this->is("element")) {
            // 'descendant' is the default combinator
            $combinator = CssParserCombinatorFactory::getInstance(
                "CssParserCombinatorDescendant"
            );
        } else {
            return false;
        }

        return new CssParserModelFactor($combinator, $element);
    }
protected function factor()
    {
        $combinator = null;

        if ($combinator = $this->is("combinator")) {
            if (!$element = $this->is("element")) {
                throw new TextParserException("Invalid expression", $this);
            }
        } elseif ($element = $this->is("element")) {
            // 'descendant' is the default combinator
            $combinator = CssParserCombinatorFactory::getInstance(
                "CssParserCombinatorDescendant"
            );
        } else {
            return false;
        }

        return new CssParserModelFactor($combinator, $element);
    }
protected function factor ( ) { $ combinator = null ; if ( $ combinator = $ this -> is ( "combinator" ) ) { if ( ! $ element = $ this -> is ( "element" ) ) { throw new TextParserException ( "Invalid expression" , $ this ) ; } } elseif ( $ element = $ this -> is ( "element" ) ) { // 'descendant' is the default combinator $ combinator = CssParserCombinatorFactory :: getInstance ( "CssParserCombinatorDescendant" ) ; } else { return false ; } return new CssParserModelFactor ( $ combinator , $ element ) ; }
Is the next thing a factor?

The following example is a factor:
```
> div.my-class[title = hello]
```

In the above example, ">" is an combinator and
"div.my-class[title = hello]" is an element.

@return false|CssParserModelFactor
Is the next thing a factor?