Print arguments of concrete annotations

Author: odersky

compiler/src/dotty/tools/dotc/core/Annotations.scala

@@ -7,14 +7,16 @@ import StdNames._
 import dotty.tools.dotc.ast.tpd
 import scala.util.Try
 import util.Spans.Span
+import printing.{Showable, Printer, Texts}
+import Texts.{Text, Str}
 
 object Annotations {
 
   def annotClass(tree: Tree)(using Context) =
     if (tree.symbol.isConstructor) tree.symbol.owner
     else tree.tpe.typeSymbol
 
-  abstract class Annotation {
+  abstract class Annotation extends Showable {
     def tree(using Context): Tree
 
     def symbol(using Context): Symbol = annotClass(tree)
@@ -44,6 +46,13 @@ object Annotations {
     /** The tree evaluation has finished. */
     def isEvaluated: Boolean = true
 
+    /** A string representation of the annotation.
+     */
+    final def toText(printer: Printer): Text = printer.toText(this)
+
+    /** A text representing thge arguments of this annotation. Overridden in ConcreteAnnotation */
+    def argsText(printer: Printer): Text = ""
+
     def ensureCompleted(using Context): Unit = tree
 
     def sameAnnotation(that: Annotation)(using Context): Boolean =
@@ -52,6 +61,19 @@ object Annotations {
 
   case class ConcreteAnnotation(t: Tree) extends Annotation {
     def tree(using Context): Tree = t
+    override def argsText(printer: Printer): Text =
+      def toTextArg(arg: Tree): Text = arg match
+        case Typed(SeqLiteral(elems, _), _) => printer.toTextGlobal(elems, ", ")
+        case _ => printer.toText(arg)
+      def recur(tree: Tree): Text = tree match
+        case TypeApply(fn, args) =>
+          recur(fn) ~ "[" ~ printer.toTextGlobal(args, ", ") ~ "]"
+        case Apply(fn, args) =>
+          recur(fn)
+          ~ (Str("(") ~ Text(args.map(toTextArg), ", ") ~ ")" provided args.nonEmpty)
+        case _ =>
+          ""
+      recur(t)
   }
 
   abstract class LazyAnnotation extends Annotation {

compiler/src/dotty/tools/dotc/printing/PlainPrinter.scala

@@ -553,7 +553,8 @@ class PlainPrinter(_ctx: Context) extends Printer {
     case _ => literalText(String.valueOf(const.value))
   }
 
-  def toText(annot: Annotation): Text = s"@${annot.symbol.name}" // for now
+  def toText(annot: Annotation): Text =
+    Str(s"@${annot.symbol.name}") ~ annot.argsText(this)
 
   def toText(param: LambdaParam): Text =
     varianceSign(param.paramVariance)