compiler plugin - insert code after typer

[Matías Toro Ipinza]

Hello,

I'm new to writing a compiler plugin and I need to insert some simple code into the AST. 

For simplicity lets suppose I wan't to insert 'println("2")' before some arbitrary tree

So far I've managed to make it to work this way:

def transform(tree: Tree) = {

    /* some selection code for the tree */

    val newTree = reify{println("2")}.tree

    val newTreeTyped = typer.typed(Block(List(x), tree))

    super.transform(newTreeTyped)

}

But the problem is that the real code that I wan't to insert is dynamic. For example, the message to print can be variable.

For this reason (without using splice) I wan't to create the tree manually.

I've replace the reify code with this:

val newTree = Apply(Ident(newTermName("println")), List(Literal(Constant(2))))

Wich works if I use reflection, but if I compile this plugin, it give me the following error:

Exception in thread "main" scala.reflect.internal.Types$TypeError: not found: object println

at scala.tools.nsc.typechecker.Contexts$Context.issue(Contexts.scala:401)

at scala.tools.nsc.typechecker.Infer$Inferencer.issue(Infer.scala:312)

at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$normalTypedApply$1$1.apply(Typers.scala:4613)

at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$normalTypedApply$1$1.apply(Typers.scala:4613)

at scala.tools.nsc.typechecker.Typers$Typer.onError$3(Typers.scala:4571)

at scala.tools.nsc.typechecker.Typers$Typer.normalTypedApply$1(Typers.scala:4613)

at scala.tools.nsc.typechecker.Typers$Typer.typedApply$1(Typers.scala:4625)

at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:5530)

at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5608)

at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedStat$1(Typers.scala:2927)

at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$60.apply(Typers.scala:3031)

at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$60.apply(Typers.scala:3031)

at scala.collection.immutable.List.loop$1(List.scala:170)

       .....

The other way that has worked for me is like this:

val newTree = Apply(Select(Ident(reify{scala.Predef}.tree.symbol), newTermName("println")), List(Literal(Constant("2"))))

But the problem here is the same problem with the first solution, I can't make the content of reify dynamic

What is the way to do it using only strings?

Thanks in advance for your help!