Merge pull request #1676 from retronym/topic/sm-interpolator

Adds a margin stripping string interpolator.

4 files changed, 63 insertions, 9 deletions

diff --git a/src/reflect/scala/reflect/internal/SymbolTable.scala b/src/reflect/scala/reflect/internal/SymbolTable.scala
index 554acf9c0b..02ac59a461 100644
--- a/src/reflect/scala/reflect/internal/SymbolTable.scala
+++ b/src/reflect/scala/reflect/internal/SymbolTable.scala
@@ -345,6 +345,12 @@ abstract class SymbolTable extends macros.Universe
   /** Is this symbol table a part of a compiler universe?
    */
   def isCompilerUniverse = false
+
+  /**
+   * Adds the `sm` String interpolator to a [[scala.StringContext]].
+   */
+  implicit val StringContextStripMarginOps: StringContext => StringContextStripMarginOps = util.StringContextStripMarginOps
+
 }
 
 object SymbolTableStats {
diff --git a/src/reflect/scala/reflect/internal/util/StripMarginInterpolator.scala b/src/reflect/scala/reflect/internal/util/StripMarginInterpolator.scala
new file mode 100644
index 0000000000..e7579229b2
--- /dev/null
+++ b/src/reflect/scala/reflect/internal/util/StripMarginInterpolator.scala
@@ -0,0 +1,40 @@
+package scala.reflect
+package internal
+package util
+
+trait StripMarginInterpolator {
+  def stringContext: StringContext
+
+  /**
+   * 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"""|${foo}
+   *             |"""
+   * res0: String =
+   * "f|o|o
+   * "
+   * }}}
+   */
+  final def sm(args: Any*): String = {
+    def isLineBreak(c: Char) = c == '\n' || c == '\f' // compatible with StringLike#isLineBreak
+    def stripTrailingPart(s: String) = {
+      val (pre, post) = s.span(c => !isLineBreak(c))
+      pre + post.stripMargin
+    }
+    val stripped: List[String] = stringContext.parts.toList match {
+      case head :: tail => head.stripMargin :: (tail map stripTrailingPart)
+      case Nil => Nil
+    }
+    new StringContext(stripped: _*).raw(args: _*)
+  }
+}
diff --git a/src/reflect/scala/reflect/internal/util/package.scala b/src/reflect/scala/reflect/internal/util/package.scala
new file mode 100644
index 0000000000..6d77235db6
--- /dev/null
+++ b/src/reflect/scala/reflect/internal/util/package.scala
@@ -0,0 +1,9 @@
+package scala.reflect
+package internal
+
+package object util {
+  /**
+   * Adds the `sm` String interpolator to a [[scala.StringContext]].
+   */
+  implicit class StringContextStripMarginOps(val stringContext: StringContext) extends StripMarginInterpolator
+}
diff --git a/src/reflect/scala/reflect/runtime/JavaMirrors.scala b/src/reflect/scala/reflect/runtime/JavaMirrors.scala
index 2d08cd887b..ab93d7033a 100644
--- a/src/reflect/scala/reflect/runtime/JavaMirrors.scala
+++ b/src/reflect/scala/reflect/runtime/JavaMirrors.scala
@@ -129,11 +129,10 @@ private[reflect] trait JavaMirrors extends internal.SymbolTable with api.JavaUni
     private def ErrorStaticModule(sym: Symbol) = throw new ScalaReflectionException(s"$sym is a static module, use reflectModule on a RuntimeMirror to obtain its ModuleMirror")
     private def ErrorNotMember(sym: Symbol, owner: Symbol) = throw new ScalaReflectionException(s"expected a member of $owner, you provided ${sym.kindString} ${sym.fullName}")
     private def ErrorNotField(sym: Symbol) = throw new ScalaReflectionException(s"expected a field or an accessor method symbol, you provided $sym")
-    private def ErrorNonExistentField(sym: Symbol) = throw new ScalaReflectionException(s"""
-      |Scala field ${sym.name} isn't represented as a Java field, neither it has a Java accessor method
-      |note that private parameters of class constructors don't get mapped onto fields and/or accessors,
-      |unless they are used outside of their declaring constructors.
-    """.trim.stripMargin)
+    private def ErrorNonExistentField(sym: Symbol) = throw new ScalaReflectionException(
+      sm"""Scala field ${sym.name} isn't represented as a Java field, neither it has a Java accessor method
+          |note that private parameters of class constructors don't get mapped onto fields and/or accessors,
+          |unless they are used outside of their declaring constructors.""")
     private def ErrorSetImmutableField(sym: Symbol) = throw new ScalaReflectionException(s"cannot set an immutable field ${sym.name}")
     private def ErrorNotConstructor(sym: Symbol, owner: Symbol) = throw new ScalaReflectionException(s"expected a constructor of $owner, you provided $sym")
     private def ErrorFree(member: Symbol, freeType: Symbol) = throw new ScalaReflectionException(s"cannot reflect ${member.kindString} ${member.name}, because it's a member of a weak type ${freeType.name}")
@@ -541,8 +540,8 @@ private[reflect] trait JavaMirrors extends internal.SymbolTable with api.JavaUni
           val result = anns find (_.annotationType == annotClass)
           if (result.isEmpty && (anns exists (_.annotationType.getName == name)))
             throw new ClassNotFoundException(
-              s"""Mirror classloader mismatch: $jclazz (loaded by ${ReflectionUtils.show(jclazz.getClassLoader)})
-              |is unrelated to the mirror's classloader: (${ReflectionUtils.show(classLoader)})""".stripMargin)
+              sm"""Mirror classloader mismatch: $jclazz (loaded by ${ReflectionUtils.show(jclazz.getClassLoader)})
+                  |is unrelated to the mirror's classloader: (${ReflectionUtils.show(classLoader)})""")
           result
         }
       def loadBytes[T: ClassTag](name: String): Option[T] =
@@ -955,8 +954,8 @@ private[reflect] trait JavaMirrors extends internal.SymbolTable with api.JavaUni
             javaTypeToValueClass(jclazz) orElse lookupClass
 
         assert (cls.isType,
-          s"""${if (cls == NoSymbol) "not a type: symbol" else "no symbol could be"}
-             | loaded from $jclazz in $owner with name $simpleName and classloader $classLoader""".stripMargin)
+          sm"""${if (cls == NoSymbol) "not a type: symbol" else "no symbol could be"}
+              | loaded from $jclazz in $owner with name $simpleName and classloader $classLoader""")
 
         cls.asClass
       }