Better positioned regular expression parser, co...

Better positioned regular expression parser, contributed by "asloane"
(#3254). No review.

1 files changed, 19 insertions, 0 deletions

diff --git a/src/library/scala/util/parsing/combinator/RegexParsers.scala b/src/library/scala/util/parsing/combinator/RegexParsers.scala
index 89c5050431..fd8ee60db0 100644
--- a/src/library/scala/util/parsing/combinator/RegexParsers.scala
+++ b/src/library/scala/util/parsing/combinator/RegexParsers.scala
@@ -67,6 +67,25 @@ trait RegexParsers extends Parsers {
     }
   }
 
+  /** `positioned' decorates a parser's result with the start position of the input it consumed.
+   * If whitespace is being skipped, then it is skipped before the start position is recorded.
+   *
+   * @param p a `Parser' whose result conforms to `Positional'.
+   * @return A parser that has the same behaviour as `p', but which marks its result with the
+   *         start position of the input it consumed after whitespace has been skipped, if it
+   *         didn't already have a position.
+   */
+  override def positioned[T <: Positional](p: => Parser[T]): Parser[T] = {
+    val pp = super.positioned(p)
+    new Parser[T] {
+      def apply(in: Input) = {
+        val offset = in.offset
+        val start = handleWhiteSpace(in.source, offset)
+        pp(in.drop (start - offset))
+      }
+    }
+  }
+
   override def phrase[T](p: Parser[T]): Parser[T] =
     super.phrase(p <~ opt("""\z""".r))