Use BodyAnnot to indicate rhs of inline method

Since fundamental operations such as treeCopy have to know
about inline bodies, it seems better to represent this
information directly in an annotation.

1 files changed, 28 insertions, 0 deletions

diff --git a/src/dotty/tools/dotc/core/Annotations.scala b/src/dotty/tools/dotc/core/Annotations.scala
index 5f96a60e6..fde41ef76 100644
--- a/src/dotty/tools/dotc/core/Annotations.scala
+++ b/src/dotty/tools/dotc/core/Annotations.scala
@@ -42,6 +42,34 @@ object Annotations {
     override def symbol(implicit ctx: Context): Symbol = sym
   }
 
+  /** An annotation indicating the body of a right-hand side,
+   *  typically of an inline method. Treated specially in
+   *  pickling/unpickling and treecopies
+   */
+  abstract class BodyAnnotation extends Annotation {
+    override def symbol(implicit ctx: Context) = defn.BodyAnnot
+    override def derivedAnnotation(tree: Tree)(implicit ctx: Context) =
+      if (tree eq this.tree) this else ConcreteBodyAnnotation(tree)
+    override def arguments(implicit ctx: Context) = Nil
+  }
+
+  case class ConcreteBodyAnnotation(body: Tree) extends BodyAnnotation {
+    def tree(implicit ctx: Context) = body
+  }
+
+  case class LazyBodyAnnotation(bodyExpr: Context => Tree) extends BodyAnnotation {
+    private var evaluated = false
+    private var myBody: Tree = _
+    def tree(implicit ctx: Context) = {
+      if (evaluated) assert(myBody != null)
+      else {
+        evaluated = true
+        myBody = bodyExpr(ctx)
+      }
+      myBody
+    }
+  }
+
   object Annotation {
 
     def apply(tree: Tree) = ConcreteAnnotation(tree)