1 files changed, 39 insertions, 0 deletions
diff --git a/test/files/macros/Printf.scala b/test/files/macros/Printf.scala
new file mode 100644
index 0000000000..4a88e5b069
--- /dev/null
+++ b/test/files/macros/Printf.scala
@@ -0,0 +1,39 @@
+// macros should be built separately from their clients, so simple "scalac Printf.scala Test.scala" won't work
+// 1) first build this file with "scalac -Xmacros Printf.scala"
+// 2) the build the test with "scalac -cp <output directory of compiling Printf.scala> Test.scala"
+
+object Printf extends App {
+  def macro printf(format: String, params: Any*) : String = {
+    var i = 0
+    def gensym(name: String) = { i += 1; newTermName(name + i) }
+
+    def createTempValDef(value: Tree, clazz: Class[_]): (Option[Tree], Tree) = {
+      val local = gensym("temp")
+      val tpe = if (clazz == classOf[Int]) Ident(newTypeName("Int"))
+        else if (clazz == classOf[String]) Select(Select(Ident(newTermName("java")), newTermName("lang")), newTypeName("String"))
+        else throw new Exception("unknown class " + clazz.toString)
+      (Some(ValDef(Modifiers(), local, tpe, value)), Ident(local))
+    }
+
+    def tree_printf(format: Tree, params: Tree*) = {
+      val Literal(Constant(s_format: String)) = format
+      val paramsStack = scala.collection.mutable.Stack(params: _*)
+      val parsed = s_format.split("(?<=%[\\w%])|(?=%[\\w%])") map {
+        case "%d" => createTempValDef(paramsStack.pop, classOf[Int])
+        case "%s" => createTempValDef(paramsStack.pop, classOf[String])
+        case "%%" => (None, Literal(Constant("%")))
+        case part => (None, Literal(Constant(part)))
+      }
+
+      val evals = for ((Some(eval), _) <- parsed if eval != None) yield eval
+      val prints = for ((_, ref) <- parsed) yield {
+        val print = Select(Select(Ident(newTermName("scala")), newTermName("Predef")), newTermName("print"))
+        Apply(print, List(ref))
+      }
+
+      Block((evals ++ prints).toList, Literal(Constant(())))
+    }
+
+    tree_printf(format, params: _*)
+  }
+}