StringBuilder no longer violates the Seq revers...

StringBuilder no longer violates the Seq reverse contract: it returns
a new StringBuilder. The behavior formerly found in reverse (updates
in place) is now available in reverseContents. Migration warning on
reverse. Closes #3327.

Also did some StringBuilder rewriting as per discussion with odersky.
And took a cleaver to parts of the documentation to get to the good
parts a little faster. Review by community.

3 files changed, 17 insertions, 0 deletions

diff --git a/test/files/run/bug3327.check b/test/files/run/bug3327.check
new file mode 100644
index 0000000000..980a0d5f19
--- /dev/null
+++ b/test/files/run/bug3327.check
@@ -0,0 +1 @@
+Hello World!
diff --git a/test/files/run/bug3327.scala b/test/files/run/bug3327.scala
new file mode 100644
index 0000000000..7e6d3fc210
--- /dev/null
+++ b/test/files/run/bug3327.scala
@@ -0,0 +1,8 @@
+object Test {
+  def main (args : Array[String]) {
+    val b = new StringBuilder
+    b.append ("Hello World!")
+    b.lastIndexOf ('e')
+    println (b.toString)
+  }
+}
\ No newline at end of file
diff --git a/test/files/run/stringbuilder.scala b/test/files/run/stringbuilder.scala
index c669f1c3db..28ddc653a5 100644
--- a/test/files/run/stringbuilder.scala
+++ b/test/files/run/stringbuilder.scala
@@ -1,5 +1,7 @@
 object Test extends Application {
   val str = "ABCDEFGHIJKLMABCDEFGHIJKLM"
+  val surrogateStr = "an old Turkic letter: \uD803\uDC22"
+
   type SB = {
     def indexOf(str: String): Int
     def indexOf(str: String, fromIndex: Int): Int
@@ -29,4 +31,10 @@ object Test extends Application {
   sameAnswers(_.lastIndexOf("QZV"))
   sameAnswers(_.lastIndexOf("GHI", 22))
   sameAnswers(_.lastIndexOf("KLM", 22))
+
+  // testing that the "reverse" implementation avoids reversing surrogate pairs
+  val jsb = new JavaStringBuilder(surrogateStr) reverse
+  val ssb = new ScalaStringBuilder(surrogateStr) reverseContents ;
+
+  assert(jsb.toString == ssb.toString)
 }