将闭包传递给Scala编译器插件

// User code. This represents some function that might take some args
// and outputs an abstract syntax tree.
def createFooTree(...): scala.reflect.runtime.universe.Tree = ...

// Later user code (maybe separate compilation?). Here the user generates
// code programmatically using the function call to |createFooTree| and inserts
// the code using insertTree.
insertTree(createFooTree(...))

重要的插件代码可能如下所示(基于this)：

class InsertTreeComponent(val global: Global)
  extends PluginComponent
  with TypingTransformers {
  import global._
  import definitions._

  override val phaseName = "insertTree"

  override val runsRightAfter = Some("parser")
  override val runsAfter = runsRightAfter.toList
  override val runsBefore = List[String]("typer")

  def newPhase(prev: Phase): StdPhase = new StdPhase(prev) {
    def apply(unit: CompilationUnit) {
      val onTransformer = new TypingTransformer(unit) {
        override def transform(tree: Tree): Tree = tree match {
          case orig @ Apply(
            function,// |treeClosure| is the closure we passed,which should
            // evaluate to a Tree (albeit a runtime Tree).
            // The function.toString bit matches anything that looks like a
            // function call with a function called |insertTree|.
            treeClosure) if (function.toString == "insertTree") => {
            // This function evaluates and returns the Tree,inserting it
            // into the call site as automatically-generated code.
            // Unfortunately,the following line isn't valid.
            eval(treeClosure): Tree
          }   
  ...

知道怎么做吗？请不要说“只使用宏”;至少在2.10,它们不够通用.

顺便说一句,我看到了我概述的方法存在两个问题：1)编译器插件采用AST,而不是闭包.它需要一些创建闭包的方法,可能会在用户代码上添加构建依赖项. 2)用户无法访问scala.reflect.internal.Trees.Tree,只能访问scala.reflect.runtime.universe.Tree,因此插件需要在两者之间进行转换.