protected function convertComparison($expr1, $operator, $expr2)
	{
		return $this->convert($expr1) . $operator . $this->convert($expr2);
	}
protected function convertComparison($expr1, $operator, $expr2)
	{
		return $this->convert($expr1) . $operator . $this->convert($expr2);
	}
protected function convertComparison ( $ expr1 , $ operator , $ expr2 ) { return $ this -> convert ( $ expr1 ) . $ operator . $ this -> convert ( $ expr2 ) ; }
Convert a comparison

@param  string $expr1
@param  string $operator
@param  string $expr2
@return string
Convert a comparison