DocCommentFinder.scala

object DocCommentFinder {

  def findByName[G <: Global](g: G)(rootTree: g.Tree, searchNames: Set[String]): Map[g.Symbol, g.DocComment] = {
    import g.{ Try ⇒ _, _ }
    val searchSymbols: Set[Symbol] = searchNames.map(name ⇒ g.rootMirror.staticModule(name))
    findBySymbol(g)(rootTree, searchSymbols)
  }

  def findBySymbol[G <: Global](g: G)(rootTree: g.Tree, searchSymbols: Set[g.Symbol]): Map[g.Symbol, g.DocComment] = {
    import g._
    class DocCommentSearchTraverser(searchSymbols: Set[Symbol], root: Tree) extends Traverser {
      val remainingItems = collection.mutable.HashSet[Symbol]() ++ searchSymbols
      val found = collection.mutable.HashMap[Symbol, DocComment]()
      def done = remainingItems.isEmpty
      traverse(root)
      override def traverse(tree: Tree) {
        if (!done) {
          tree match {
            case DocDef(comment, subTree) if remainingItems.contains(subTree.symbol) ⇒
              remainingItems -= subTree.symbol
              found += subTree.symbol → comment
              super.traverse(subTree)
            case _ ⇒ super.traverse(tree)
          }
        }
      }
    }
    (new DocCommentSearchTraverser(searchSymbols, rootTree)).found.toMap
  }
  
}