Real time transformation

Hi,

I'm aware of the UltiSnips transformation feature.

I would like to do it in real time on one tab stop, is it possible? To be clearer, is it possible to type and to directly apply the regex?

For example, I would like to define a snippet like so:

    echo "${1/\"/\\"/g}";

To automatically escape the " present in the string.

For the moment, I implement it like so:

    echo "${1/\"/\\"/g}"; //$1

Have you an idea?