Even four years ago I noted in Bug 377320 - QvtOperationalResourceImpl.save() not implemented that QVTo can create models for nearly any EMF meta model you name, besides, ironically, for its own.
While ocasionally this feature is asked for in the forum ("Generate QVTo-file", "Higher-order model transformations with QVTo"), so far nobody found the time to implement this feature. I myself was not able to complete my implementation started in 2012.
Now I have finally completed my implementation and provided it to the Eclipse QVTo Projekt as Git-Patch. I hope the feature will make it into the Neon release.
Der Unparser is a handwritten work of stubborn diligence just recursively converting any possible type of AST node into its textual representation.
I came back to the existing tests for the parser and reused most of the example transformations from it.
The transformations get compiled, unparsed and recompiled. Then the ASTs from the compilation of the original transformation and of the unparsed version are compared.