[mafribe]

I'm not sure what a token tree is. Usually compilers feed a token list to the parser, which then generates an AST. The AST is what compile-time meta-programming such as macro expansion works on.

In fully-blown compile-time meta-programming systems such as Converge or Template Haskell, the "AST expansion plugin" can and typically does itself invoke the compiler to compile arbitrary code which in turn outputs a new AST for further compilation.

I'm not fully sure what macro-by-example is.