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

Adds a margin stripping string interpolator.

13 files changed, 148 insertions, 55 deletions

diff --git a/src/compiler/scala/reflect/reify/Errors.scala b/src/compiler/scala/reflect/reify/Errors.scala
index 3d7cb95792..7c66d5b9eb 100644
--- a/src/compiler/scala/reflect/reify/Errors.scala
+++ b/src/compiler/scala/reflect/reify/Errors.scala
@@ -33,10 +33,10 @@ trait Errors {
   }
 
   def CannotConvertManifestToTagWithoutScalaReflect(tpe: Type, manifestInScope: Tree) = {
-    val msg = s"""
-      |to create a type tag here, it is necessary to interoperate with the manifest `$manifestInScope` in scope.
-      |however manifest -> typetag conversion requires Scala reflection, which is not present on the classpath.
-      |to proceed put scala-reflect.jar on your compilation classpath and recompile.""".trim.stripMargin
+    val msg =
+      sm"""to create a type tag here, it is necessary to interoperate with the manifest `$manifestInScope` in scope.
+          |however manifest -> typetag conversion requires Scala reflection, which is not present on the classpath.
+          |to proceed put scala-reflect.jar on your compilation classpath and recompile."""
     throw new ReificationException(defaultErrorPosition, msg)
   }
 
diff --git a/src/compiler/scala/tools/nsc/transform/Erasure.scala b/src/compiler/scala/tools/nsc/transform/Erasure.scala
index bba5fd4e5e..7b9b13ae1c 100644
--- a/src/compiler/scala/tools/nsc/transform/Erasure.scala
+++ b/src/compiler/scala/tools/nsc/transform/Erasure.scala
@@ -437,19 +437,19 @@ abstract class Erasure extends AddInterfaces
         noclash = false
         unit.error(
           if (member.owner == root) member.pos else root.pos,
-          s"""bridge generated for member ${fulldef(member)}
-             |which overrides ${fulldef(other)}
-             |clashes with definition of $what;
-             |both have erased type ${afterPostErasure(bridge.tpe)}""".stripMargin)
+          sm"""bridge generated for member ${fulldef(member)}
+              |which overrides ${fulldef(other)}
+              |clashes with definition of $what;
+              |both have erased type ${afterPostErasure(bridge.tpe)}""")
       }
       for (bc <- root.baseClasses) {
         if (settings.debug.value)
           afterPostErasure(println(
-            s"""check bridge overrides in $bc
-            ${bc.info.nonPrivateDecl(bridge.name)}
-            ${site.memberType(bridge)}
-            ${site.memberType(bc.info.nonPrivateDecl(bridge.name) orElse IntClass)}
-            ${(bridge.matchingSymbol(bc, site))}""".stripMargin))
+            sm"""check bridge overrides in $bc
+                |${bc.info.nonPrivateDecl(bridge.name)}
+                |${site.memberType(bridge)}
+                |${site.memberType(bc.info.nonPrivateDecl(bridge.name) orElse IntClass)}
+                |${(bridge.matchingSymbol(bc, site))}"""))
 
         def overriddenBy(sym: Symbol) =
           sym.matchingSymbol(bc, site).alternatives filter (sym => !sym.isBridge)
diff --git a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
index 9e9b8b995b..faacb60d75 100644
--- a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
@@ -107,9 +107,9 @@ trait ContextErrors {
         s"$name extends Any, not AnyRef"
     )
     if (isPrimitiveValueType(found) || isTrivialTopType(tp)) "" else "\n" +
-       s"""|Note that $what.
-           |Such types can participate in value classes, but instances
-           |cannot appear in singleton types or in reference comparisons.""".stripMargin
+       sm"""|Note that $what.
+            |Such types can participate in value classes, but instances
+            |cannot appear in singleton types or in reference comparisons."""
   }
 
   import ErrorUtils._
@@ -1128,9 +1128,9 @@ trait ContextErrors {
                                (isView: Boolean, pt: Type, tree: Tree)(implicit context0: Context) = {
       if (!info1.tpe.isErroneous && !info2.tpe.isErroneous) {
         def coreMsg =
-           s"""| $pre1 ${info1.sym.fullLocationString} of type ${info1.tpe}
-               | $pre2 ${info2.sym.fullLocationString} of type ${info2.tpe}
-               | $trailer""".stripMargin
+           sm"""| $pre1 ${info1.sym.fullLocationString} of type ${info1.tpe}
+                | $pre2 ${info2.sym.fullLocationString} of type ${info2.tpe}
+                | $trailer"""
         def viewMsg = {
           val found :: req :: _ = pt.typeArgs
           def explanation = {
@@ -1141,19 +1141,19 @@ trait ContextErrors {
             // involving Any, are further explained from foundReqMsg.
             if (AnyRefClass.tpe <:< req) (
               if (sym == AnyClass || sym == UnitClass) (
-                 s"""|Note: ${sym.name} is not implicitly converted to AnyRef.  You can safely
-                     |pattern match `x: AnyRef` or cast `x.asInstanceOf[AnyRef]` to do so.""".stripMargin
+                 sm"""|Note: ${sym.name} is not implicitly converted to AnyRef.  You can safely
+                      |pattern match `x: AnyRef` or cast `x.asInstanceOf[AnyRef]` to do so."""
               )
               else boxedClass get sym map (boxed =>
-                 s"""|Note: an implicit exists from ${sym.fullName} => ${boxed.fullName}, but
-                     |methods inherited from Object are rendered ambiguous.  This is to avoid
-                     |a blanket implicit which would convert any ${sym.fullName} to any AnyRef.
-                     |You may wish to use a type ascription: `x: ${boxed.fullName}`.""".stripMargin
+                 sm"""|Note: an implicit exists from ${sym.fullName} => ${boxed.fullName}, but
+                      |methods inherited from Object are rendered ambiguous.  This is to avoid
+                      |a blanket implicit which would convert any ${sym.fullName} to any AnyRef.
+                      |You may wish to use a type ascription: `x: ${boxed.fullName}`."""
               ) getOrElse ""
             )
             else
-               s"""|Note that implicit conversions are not applicable because they are ambiguous:
-                   |${coreMsg}are possible conversion functions from $found to $req""".stripMargin
+               sm"""|Note that implicit conversions are not applicable because they are ambiguous:
+                    |${coreMsg}are possible conversion functions from $found to $req"""
           }
           typeErrorMsg(found, req, infer.isPossiblyMissingArgs(found, req)) + (
             if (explanation == "") "" else "\n" + explanation
diff --git a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
index 547d756888..fc10f68454 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
@@ -1306,17 +1306,17 @@ trait Implicits {
         else {
           if (ReflectRuntimeUniverse == NoSymbol) {
             // todo. write a test for this
-            context.error(pos, s"""
-              |to create a manifest here, it is necessary to interoperate with the type tag `$tagInScope` in scope.
-              |however typetag -> manifest conversion requires Scala reflection, which is not present on the classpath.
-              |to proceed put scala-reflect.jar on your compilation classpath and recompile.""".trim.stripMargin)
+            context.error(pos,
+              sm"""to create a manifest here, it is necessary to interoperate with the type tag `$tagInScope` in scope.
+                  |however typetag -> manifest conversion requires Scala reflection, which is not present on the classpath.
+                  |to proceed put scala-reflect.jar on your compilation classpath and recompile.""")
             return SearchFailure
           }
           if (resolveClassTag(pos, tp, allowMaterialization = true) == EmptyTree) {
-            context.error(pos, s"""
-              |to create a manifest here, it is necessary to interoperate with the type tag `$tagInScope` in scope.
-              |however typetag -> manifest conversion requires a class tag for the corresponding type to be present.
-              |to proceed add a class tag to the type `$tp` (e.g. by introducing a context bound) and recompile.""".trim.stripMargin)
+            context.error(pos,
+              sm"""to create a manifest here, it is necessary to interoperate with the type tag `$tagInScope` in scope.
+                  |however typetag -> manifest conversion requires a class tag for the corresponding type to be present.
+                  |to proceed add a class tag to the type `$tp` (e.g. by introducing a context bound) and recompile.""")
             return SearchFailure
           }
           val cm = typed(Ident(ReflectRuntimeCurrentMirror))
diff --git a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
index ee7805cb3d..78ec6508ed 100644
--- a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
@@ -1379,8 +1379,8 @@ abstract class RefChecks extends InfoTransform with scala.reflect.internal.trans
     private def checkCompileTimeOnly(sym: Symbol, pos: Position) = {
       if (sym.isCompileTimeOnly) {
         def defaultMsg =
-          s"""|Reference to ${sym.fullLocationString} should not have survived past type checking,
-              |it should have been processed and eliminated during expansion of an enclosing macro.""".stripMargin
+          sm"""Reference to ${sym.fullLocationString} should not have survived past type checking,
+              |it should have been processed and eliminated during expansion of an enclosing macro."""
         // The getOrElse part should never happen, it's just here as a backstop.
         unit.error(pos, sym.compileTimeOnlyMessage getOrElse defaultMsg)
       }
diff --git a/src/compiler/scala/tools/nsc/typechecker/SuperAccessors.scala b/src/compiler/scala/tools/nsc/typechecker/SuperAccessors.scala
index c9e45b6348..fb8a111da1 100644
--- a/src/compiler/scala/tools/nsc/typechecker/SuperAccessors.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/SuperAccessors.scala
@@ -527,8 +527,8 @@ abstract class SuperAccessors extends transform.Transform with transform.TypingT
       }
       def isJavaProtected = host.isTrait && sym.isJavaDefined && {
         restrictionError(pos, unit,
-          s"""|$clazz accesses protected $sym inside a concrete trait method.
-              |Add an accessor in a class extending ${sym.enclClass} as a workaround.""".stripMargin
+          sm"""$clazz accesses protected $sym inside a concrete trait method.
+              |Add an accessor in a class extending ${sym.enclClass} as a workaround."""
         )
         true
       }
diff --git a/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala b/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala
index b4cdad70e2..48a5a36b00 100644
--- a/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala
@@ -280,11 +280,9 @@ abstract class TreeCheckers extends Analyzer {
               if (sym.owner != currentOwner) {
                 val expected = currentOwner.ownerChain find (x => cond(x)) getOrElse fail("DefTree can't find owner: ")
                 if (sym.owner != expected)
-                  fail("""|
-                          | currentOwner chain: %s
-                          |       symbol chain: %s""".stripMargin.format(
-                            currentOwner.ownerChain take 3 mkString " -> ",
-                            sym.ownerChain mkString " -> ")
+                  fail(sm"""|
+                            | currentOwner chain: ${currentOwner.ownerChain take 3 mkString " -> "}
+                            |       symbol chain: ${sym.ownerChain mkString " -> "}"""
                       )
               }
           }
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index a2aca45e8f..5714c2c109 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -4870,12 +4870,12 @@ trait Typers extends Modes with Adaptations with Tags {
                 defSym = pre.member(defEntry.sym.name)
                 if (defSym ne defEntry.sym) {
                   qual = gen.mkAttributedQualifier(pre)
-                  log(s"""
+                  log(sm"""
                     |  !!! Overloaded package object member resolved incorrectly.
                     |        prefix: $pre
                     |     Discarded: ${defEntry.sym.defString}
                     |         Using: ${defSym.defString}
-                    """.stripMargin)
+                    """)
                 }
               }
               else
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
       }
diff --git a/test/files/run/sm-interpolator.scala b/test/files/run/sm-interpolator.scala
new file mode 100644
index 0000000000..7f7b9f061a
--- /dev/null
+++ b/test/files/run/sm-interpolator.scala
@@ -0,0 +1,41 @@
+object Test extends App {
+  import scala.reflect.internal.util.StringContextStripMarginOps
+  def check(actual: Any, expected: Any) = if (actual != expected) sys.error(s"expected: [$expected], actual: [$actual])")
+
+  val bar = "|\n ||"
+
+  check(
+    sm"""|ab  
+         |de
+         |${bar} | ${1}""",
+      "ab  \nde\n|\n || | 1")
+
+  check(
+    sm"|",
+      "")
+
+  check(
+    sm"${0}",
+      "0")
+
+  check(
+    sm"${0}",
+    "0")
+
+  check(
+    sm"""${0}|${1}
+     |""",
+      "0|1\n")
+
+  check(
+    sm"""   ||""",
+      "|")
+
+  check(
+    sm""" ${" "} ||""",
+      "   ||")
+
+  check(
+      sm"\n",
+     raw"\n".stripMargin)
+}