public function add($expression, $subPattern = null, $additionalCharacters = '')
    {
        $this->expression .= $this->addBrackets($expression, $subPattern) . $additionalCharacters;

        return $this;
    }
public function add($expression, $subPattern = null, $additionalCharacters = '')
    {
        $this->expression .= $this->addBrackets($expression, $subPattern) . $additionalCharacters;

        return $this;
    }
public function add ( $ expression , $ subPattern = null , $ additionalCharacters = '' ) { $ this -> expression .= $ this -> addBrackets ( $ expression , $ subPattern ) . $ additionalCharacters ; return $ this ; }
Add a regular expression partial

@param string  $expression           Regular expression partial to add
@param boolean $subPattern           Capture sub patterns?
@param string  $additionalCharacters Additional characters after brackets - e.g. ?

@return $this
Add a regular expression partial