A few yards short of the goal posts attempt at ...

A few yards short of the goal posts attempt at making our usage of
Throwable subclasses more consistent. This patch eliminates a lot of
ad hoc Exception/Error/etc. creation and various arbitrary choices are
rendered slightly less arbitrary. From now on let's try not to use the
word "Exception" or "Error" in the names of Throwable subclasses unless
they actually derive (and make sense to derive) from Exception or Error.
Review by community.

1 files changed, 23 insertions, 25 deletions

diff --git a/src/compiler/scala/tools/nsc/ast/parser/MarkupParsers.scala b/src/compiler/scala/tools/nsc/ast/parser/MarkupParsers.scala
index 53fc6542b2..e918489446 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/MarkupParsers.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/MarkupParsers.scala
@@ -9,7 +9,7 @@ package ast.parser
 
 import scala.collection.mutable
 import mutable.{ Buffer, ArrayBuffer, ListBuffer, HashMap }
-import scala.util.control.ControlException
+import scala.util.control.ControlThrowable
 import scala.tools.nsc.util.{SourceFile,CharArrayReader}
 import scala.xml.{ Text, TextBuffer }
 import scala.xml.Utility.{ isNameStart, isNameChar, isSpace }
@@ -35,15 +35,15 @@ trait MarkupParsers
 {
   self: Parsers =>
 
-  case object MissingEndTagException extends RuntimeException with ControlException {
+  case object MissingEndTagControl extends ControlThrowable {
     override def getMessage = "start tag was here: "
   }
 
-  case object ConfusedAboutBracesException extends RuntimeException with ControlException {
+  case object ConfusedAboutBracesControl extends ControlThrowable {
     override def getMessage = " I encountered a '}' where I didn't expect one, maybe this tag isn't closed <"
   }
 
-  case object TruncatedXML extends RuntimeException with ControlException {
+  case object TruncatedXMLControl extends ControlThrowable {
     override def getMessage = "input ended while parsing XML"
   }
 
@@ -63,9 +63,9 @@ trait MarkupParsers
 
     val eof = false
 
-    def truncatedError(msg: String): Nothing = throw TruncatedXML
+    def truncatedError(msg: String): Nothing = throw TruncatedXMLControl
     def xHandleError(that: Char, msg: String) =
-      if (ch == SU) throw TruncatedXML
+      if (ch == SU) throw TruncatedXMLControl
       else reportSyntaxError(msg)
 
     var input : CharArrayReader = _
@@ -92,11 +92,11 @@ trait MarkupParsers
 
     private def errorBraces() = {
       reportSyntaxError("in XML content, please use '}}' to express '}'")
-      throw ConfusedAboutBracesException
+      throw ConfusedAboutBracesControl
     }
     def errorNoEnd(tag: String) = {
       reportSyntaxError("expected closing tag of " + tag)
-      throw MissingEndTagException
+      throw MissingEndTagControl
     }
 
     /** checks whether next character starts a Scala block, if yes, skip it.
@@ -137,7 +137,7 @@ trait MarkupParsers
             nextch
             xEmbeddedExpr
           case SU =>
-            throw TruncatedXML
+            throw TruncatedXMLControl
           case _ =>
             errorAndResult("' or \" delimited attribute value or '{' scala-expr '}' expected", Literal(Constant("<syntax-error>")))
         }
@@ -307,23 +307,21 @@ trait MarkupParsers
     }
 
     /** Some try/catch/finally logic used by xLiteral and xLiteralPattern.  */
-    private def xLiteralCommon(f: () => Tree, ifTruncated: Exception => Unit): Tree =
-      try f()
+    private def xLiteralCommon(f: () => Tree, ifTruncated: String => Unit): Tree = {
+      try return f()
       catch {
-        case ex: RuntimeException =>
-          ex match {
-            case c @ TruncatedXML =>
-              ifTruncated(c)
-            case c @ (MissingEndTagException | ConfusedAboutBracesException) =>
-              parser.syntaxError(debugLastPos, c.getMessage + debugLastElem + ">")
-            case _: ArrayIndexOutOfBoundsException =>
-              parser.syntaxError(debugLastPos, "missing end tag in XML literal for <%s>" format debugLastElem)
-            case _ => throw ex
-          }
-          EmptyTree
+        case c @ TruncatedXMLControl  =>
+          ifTruncated(c.getMessage)
+        case c @ (MissingEndTagControl | ConfusedAboutBracesControl) =>
+          parser.syntaxError(debugLastPos, c.getMessage + debugLastElem + ">")
+        case _: ArrayIndexOutOfBoundsException =>
+          parser.syntaxError(debugLastPos, "missing end tag in XML literal for <%s>" format debugLastElem)
       }
       finally parser.in resume Tokens.XMLSTART
 
+      EmptyTree
+    }
+
     /** Use a lookahead parser to run speculative body, and return the first char afterward. */
     private def charComingAfter(body: => Unit): Char = {
       input = input.lookaheadReader
@@ -361,7 +359,7 @@ trait MarkupParsers
           ts(0)
         }
       },
-      ex => parser.incompleteInputError(ex.getMessage)
+      msg => parser.incompleteInputError(msg)
     )
 
     /** @see xmlPattern. resynchronizes after successful parse
@@ -377,7 +375,7 @@ trait MarkupParsers
           tree
         }
       },
-      ex => parser.syntaxError(curOffset, ex.getMessage)
+      msg => parser.syntaxError(curOffset, msg)
     )
 
     def escapeToScala[A](op: => A, kind: String) = {
@@ -436,7 +434,7 @@ trait MarkupParsers
               assert(!xEmbeddedBlock, "problem with embedded block")
 
             case SU   =>
-              throw TruncatedXML
+              throw TruncatedXMLControl
 
             case _    => // text
               appendText(r2p(start1, start1, curOffset), ts, xText)