There's a tree widget with Salt:
++++ New York
With this in mind, would it be sufficient to have a script that translates `tree` output to the correct Salt input? From the top of my head I came up with this:
tree --noreport | sed -e 's/├── \|└── /+ /g' -e 's/│ \| /+/g' -e 's/^/+/'
You need to fix a space in the 1st line manually, though.