1 files changed, 46 insertions, 0 deletions
diff --git a/src/compiler/scala/tools/reflect/FastTrack.scala b/src/compiler/scala/tools/reflect/FastTrack.scala
new file mode 100644
index 0000000000..738bcd01a7
--- /dev/null
+++ b/src/compiler/scala/tools/reflect/FastTrack.scala
@@ -0,0 +1,46 @@
+package scala.tools
+package reflect
+
+import scala.reflect.reify.Taggers
+import scala.tools.nsc.typechecker.{Analyzer, Macros}
+
+/** Optimizes system macro expansions by hardwiring them directly to their implementations
+ *  bypassing standard reflective load and invoke to avoid the overhead of Java/Scala reflection.
+ */
+trait FastTrack {
+  self: Macros with Analyzer =>
+
+  import global._
+  import definitions._
+
+  import language.implicitConversions
+  private implicit def context2taggers(c0: MacroContext) : Taggers { val c: c0.type } = new { val c: c0.type = c0 } with Taggers
+
+  implicit def fastTrackEntry2MacroRuntime(entry: FastTrackEntry): MacroRuntime = args => entry.run(args)
+  type FastTrackExpander = PartialFunction[(MacroContext, Tree), Tree]
+  case class FastTrackEntry(sym: Symbol, expander: FastTrackExpander) {
+    def validate(argss: List[List[Any]]): Boolean = {
+      val c = argss.flatten.apply(0).asInstanceOf[MacroContext]
+      val isValid = expander isDefinedAt (c, c.expandee)
+      isValid
+    }
+    def run(args: List[Any]): Any = {
+      val c = args(0).asInstanceOf[MacroContext]
+      val result = expander((c, c.expandee))
+      c.Expr[Nothing](result)(c.TypeTag.Nothing)
+    }
+  }
+
+  lazy val fastTrack: Map[Symbol, FastTrackEntry] = {
+    var registry = Map[Symbol, FastTrackEntry]()
+    implicit class BindTo(sym: Symbol) { def bindTo(expander: FastTrackExpander): Unit = if (sym != NoSymbol) registry += sym -> FastTrackEntry(sym, expander) }
+    MacroInternal_materializeArrayTag bindTo { case (c, Apply(TypeApply(_, List(tt)), List(u))) => c.materializeArrayTag(u, tt.tpe) }
+    MacroInternal_materializeErasureTag bindTo { case (c, Apply(TypeApply(_, List(tt)), List(u))) => c.materializeErasureTag(u, tt.tpe, concrete = false) }
+    MacroInternal_materializeClassTag bindTo { case (c, Apply(TypeApply(_, List(tt)), List(u))) => c.materializeClassTag(u, tt.tpe) }
+    MacroInternal_materializeTypeTag bindTo { case (c, Apply(TypeApply(_, List(tt)), List(u))) => c.materializeTypeTag(u, tt.tpe, concrete = false) }
+    MacroInternal_materializeConcreteTypeTag bindTo { case (c, Apply(TypeApply(_, List(tt)), List(u))) => c.materializeTypeTag(u, tt.tpe, concrete = true) }
+    ApiUniverseReify bindTo { case (c, Apply(TypeApply(_, List(tt)), List(expr))) => c.materializeExpr(c.prefix.tree, expr) }
+    MacroContextReify bindTo { case (c, Apply(TypeApply(_, List(tt)), List(expr))) => c.materializeExpr(c.prefix.tree, expr) }
+    registry
+  }
+}
+\ No newline at end of file