MapCSS text-offset using way direction

I’m creating a MapCSS style for use in JOSM and I’m attempting to render name:left on the left side of the street and name:right on the right side of the street. I already managed to consistently draw a line on the right side of the street by using a negative value for offset. However, unlike offset, for text-offset, a negative value moves the text upward, regardless of the direction of the way. So how do I get the correct street name on the correct side of the road?

From the wiki page,

text-offset-y (can also be written as text-offset)

The functionality you want would have to be a feature request on JOSM Trac.

(not a direct answer to the question but) is a combination such as “name:left / name:right” an option instead?