Use string interpolation instead of concatenation or format().

It looks like the code predates the introduction of the string interpolation...

(I'd like to replace more uses of the StringBuilder with string interpolation, but binary compatibility is in the way.)

Author: dubinsky

jvm/src/test/scala-2.x/scala/xml/CompilerErrors.scala

@@ -193,7 +193,7 @@ class CompilerTesting {
   // note: `code` should have a | margin
   // the import's needed because toolbox compiler does not accumulate imports like the real one (TODO: verify hypothesis)
   def xmlErrorMessages(msg: String, code: String): List[String] =
-    errorMessages(msg)("import scala.xml.{TopScope => $scope}\n"+ code.stripMargin)
+    errorMessages(msg)("import scala.xml.{TopScope => $scope}\n"+ code.stripMargin) // TODO what is this $scope?
 
   def expectXmlError(msg: String, code: String): Unit = {
     val errors: List[String] = xmlErrorMessages(msg, code)
@@ -203,6 +203,6 @@ class CompilerTesting {
   def expectXmlErrors(msgCount: Int, msg: String, code: String): Unit = {
     val errors: List[String] = xmlErrorMessages(msg, code)
     val errorCount: Int = errors.count(_.contains(msg))
-    assert(errorCount == msgCount, s"$errorCount occurrences of \'$msg\' found -- expected $msgCount in:\n${errors.mkString("\n")}")
+    assert(errorCount == msgCount, s"$errorCount occurrences of '$msg' found -- expected $msgCount in:\n${errors.mkString("\n")}")
   }
 }

shared/src/main/scala/scala/xml/Atom.scala

@@ -24,7 +24,7 @@ import scala.collection.Seq
  */
 class Atom[+A](val data: A) extends SpecialNode with Serializable {
   if (data == null)
-    throw new IllegalArgumentException("cannot construct " + getClass.getSimpleName + " with null")
+    throw new IllegalArgumentException(s"cannot construct ${getClass.getSimpleName} with null")
 
   override protected def basisForHashCode: Seq[Any] = Seq(data)
 

shared/src/main/scala/scala/xml/Attribute.scala

@@ -98,9 +98,9 @@ trait Attribute extends MetaData {
     if (value == null)
       return
     if (isPrefixed)
-      sb.append(pre).append(':')
+      sb.append(s"$pre:")
 
-    sb.append(key).append('=')
+    sb.append(s"$key=")
     val sb2: StringBuilder = new StringBuilder()
     Utility.sequenceToXML(value, TopScope, sb2, stripComments = true)
     Utility.appendQuoted(sb2.toString, sb)

shared/src/main/scala/scala/xml/Comment.scala

@@ -30,7 +30,7 @@ case class Comment(commentText: String) extends SpecialNode {
   final override def doTransform: Boolean = false
 
   if (commentText.contains("--")) {
-    throw new IllegalArgumentException("text contains \"--\"")
+    throw new IllegalArgumentException(s"""text contains "--"""")
   }
   if (commentText.nonEmpty && commentText.charAt(commentText.length - 1) == '-') {
     throw new IllegalArgumentException("The final character of a XML comment may not be '-'. See https://www.w3.org/TR/xml11//#IDA5CES")
@@ -40,5 +40,5 @@ case class Comment(commentText: String) extends SpecialNode {
    * Appends &quot;<!-- text -->&quot; to this string buffer.
    */
   override def buildString(sb: StringBuilder): StringBuilder =
-    sb.append("<!--").append(commentText).append("-->")
+    sb.append(s"<!--$commentText-->")
 }

shared/src/main/scala/scala/xml/EntityRef.scala

@@ -41,5 +41,5 @@ case class EntityRef(entityName: String) extends SpecialNode {
    *  @return the modified string buffer `sb`.
    */
   override def buildString(sb: StringBuilder): StringBuilder =
-    sb.append("&").append(entityName).append(";")
+    sb.append(s"&$entityName;")
 }

shared/src/main/scala/scala/xml/Group.scala

@@ -40,7 +40,7 @@ final case class Group(nodes: Seq[Node]) extends Node {
    * Since Group is very much a hack it throws an exception if you
    *  try to do anything with it.
    */
-  private def fail(msg: String): Nothing = throw new UnsupportedOperationException("class Group does not support method '%s'".format(msg))
+  private def fail(msg: String): Nothing = throw new UnsupportedOperationException(s"class Group does not support method '$msg'")
 
   override def label: Nothing = fail("label")
   override def attributes: Nothing = fail("attributes")

shared/src/main/scala/scala/xml/MetaData.scala

@@ -174,7 +174,7 @@ abstract class MetaData
    *  prefixed, and "key" otherwise.
    */
   def prefixedKey: String = this match {
-    case x: Attribute if x.isPrefixed => x.pre + ":" + key
+    case x: Attribute if x.isPrefixed => s"${x.pre}:$key"
     case _                            => key
   }
 

shared/src/main/scala/scala/xml/NamespaceBinding.scala

@@ -79,10 +79,8 @@ case class NamespaceBinding(prefix: String, uri: String, parent: NamespaceBindin
   private def doBuildString(sb: StringBuilder, stop: NamespaceBinding): Unit = {
     if (List(null, stop, TopScope).contains(this)) return
 
-    val s: String = " xmlns%s=\"%s\"".format(
-      if (prefix != null) ":" + prefix else "",
-      if (uri != null) uri else ""
-    )
-    parent.doBuildString(sb.append(s), stop) // copy(ignore)
+    val prefixStr: String = if (prefix != null) s":$prefix" else ""
+    val uriStr: String = if (uri != null) uri else ""
+    parent.doBuildString(sb.append(s""" xmlns$prefixStr="$uriStr""""), stop) // copy(ignore)
   }
 }

shared/src/main/scala/scala/xml/Node.scala

@@ -184,13 +184,8 @@ abstract class Node extends NodeSeq {
   /**
    * Appends qualified name of this node to `StringBuilder`.
    */
-  def nameToString(sb: StringBuilder): StringBuilder = {
-    if (null != prefix) {
-      sb.append(prefix)
-      sb.append(':')
-    }
-    sb.append(label)
-  }
+  def nameToString(sb: StringBuilder): StringBuilder =
+    sb.append(s"${if (prefix == null) "" else s"$prefix:"}$label")
 
   /**
    * Returns a type symbol (e.g. DTD, XSD), default `'''null'''`.

shared/src/main/scala/scala/xml/NodeSeq.scala

@@ -157,7 +157,7 @@ abstract class NodeSeq extends AbstractSeq[Node] with immutable.Seq[Node] with S
    * Convenience method which returns string text of the named attribute. Use:
    *   - `that \@ "foo"` to get the string text of attribute `"foo"`;
    */
-  def \@(attributeName: String): String = (this \ ("@" + attributeName)).text
+  def \@(attributeName: String): String = (this \ s"@$attributeName").text
 
   override def toString: String = theSeq.mkString