Various cleanups and utility additions

- Some new functionality in tpd and in Symbols.
- Added `sm` interpolator to print nicely.
- Make use of nestedMap where possible.
- Add IdentityDenotTransformer as a convencience class

1 files changed, 34 insertions, 2 deletions

diff --git a/src/dotty/tools/dotc/core/Decorators.scala b/src/dotty/tools/dotc/core/Decorators.scala
index 155ea87e0..cd7b46896 100644
--- a/src/dotty/tools/dotc/core/Decorators.scala
+++ b/src/dotty/tools/dotc/core/Decorators.scala
@@ -143,7 +143,7 @@ object Decorators {
    *  2) Lists can be formatted using the desired separator between two `%` signs,
    *     eg `i"myList = (${myList}%, %)"`
    */
-  implicit class InfoString(val sc: StringContext) extends AnyVal {
+  implicit class StringInterpolators(val sc: StringContext) extends AnyVal {
 
     def i(args: Any*)(implicit ctx: Context): String = {
 
@@ -166,7 +166,39 @@ object Decorators {
       val (args1, suffixes1) = (args, suffixes).zipped.map(treatArg(_, _)).unzip
       new StringContext(prefix :: suffixes1.toList: _*).s(args1: _*)
     }
-  }
 
+    /** Lifted from scala.reflect.internal.util
+     *  A safe combination of [[scala.collection.immutable.StringLike#stripMargin]]
+     *  and [[scala.StringContext#raw]].
+     *
+     *  The margin of each line is defined by whitespace leading up to a '|' character.
+     *  This margin is stripped '''before''' the arguments are interpolated into to string.
+     *
+     *  String escape sequences are '''not''' processed; this interpolater is designed to
+     *  be used with triple quoted Strings.
+     *
+     *  {{{
+     *  scala> val foo = "f|o|o"
+     *  foo: String = f|o|o
+     *  scala> sm"""|${foo}
+     *             |"""
+     *  res0: String =
+     *  "f|o|o
+     *  "
+     *  }}}
+     */
+    final def sm(args: Any*): String = {
+      def isLineBreak(c: Char) = c == '\n' || c == '\f' // compatible with StringLike#isLineBreak
+      def stripTrailingPart(s: String) = {
+        val (pre, post) = s.span(c => !isLineBreak(c))
+        pre + post.stripMargin
+      }
+      val stripped: List[String] = sc.parts.toList match {
+        case head :: tail => head.stripMargin :: (tail map stripTrailingPart)
+        case Nil => Nil
+      }
+      new StringContext(stripped: _*).raw(args: _*)
+    }
+  }
 }