Added MacroTransform as a transformer template for macro phases.

1 files changed, 54 insertions, 0 deletions

diff --git a/src/dotty/tools/dotc/transform/MacroTransform.scala b/src/dotty/tools/dotc/transform/MacroTransform.scala
new file mode 100644
index 000000000..4113b2d8e
--- /dev/null
+++ b/src/dotty/tools/dotc/transform/MacroTransform.scala
@@ -0,0 +1,54 @@
+package dotty.tools.dotc
+package transform
+
+import core._
+import typer._
+import Phases._
+import ast.Trees._
+import Contexts._
+import Symbols._
+import Decorators._
+
+/** A base class for transforms.
+ *  A transform contains a compiler phase which applies a tree transformer.
+ */
+abstract class MacroTransform extends Phase {
+
+  import ast.tpd._
+
+  override def run(implicit ctx: Context): Unit = {
+    val unit = ctx.compilationUnit
+    unit.tpdTree = newTransformer.transform(unit.tpdTree)
+  }
+
+  def newTransformer: TransformerMap
+
+  class TransformerMap extends TreeMap {
+
+    def transformStats(trees: List[Tree], exprOwner: Symbol)(implicit ctx: Context): List[Tree] = {
+      val exprCtx = ctx.withOwner(exprOwner)
+      def transformStat(stat: Tree): Tree = stat match {
+        case _: Import | _: DefTree => transform(stat)
+        case Thicket(stats) => cpy.Thicket(stat, stats mapConserve transformStat)
+        case _ => transform(stat)(exprCtx)
+      }
+      flatten(trees.mapconserve(transformStat(_)))
+    }
+
+    override def transform(tree: Tree)(implicit ctx: Context): Tree = {
+      def localCtx = ctx.fresh.setTree(tree).setOwner(tree.symbol)
+      tree match {
+        case _: PackageDef | _: MemberDef =>
+          super.transform(tree)(localCtx)
+        case Template(constr, parents, self, body) =>
+          cpy.Template(tree,
+            transformSub(constr),
+            transform(parents),
+            transformSub(self),
+            transformStats(body, tree.symbol))
+        case _ =>
+          super.transform(tree)
+      }
+    }
+  }
+}