[Assorted-commits] SF.net SVN: assorted:[1829] sandbox/trunk/src/scala/EnrichCollections.scala

[<yan...@us...>]

Revision: 1829
          http://assorted.svn.sourceforge.net/assorted/?rev=1829&view=rev
Author:   yangzhang
Date:     2012-05-17 19:30:43 +0000 (Thu, 17 May 2012)
Log Message:
-----------
Add enrich-collections sandbox

Added Paths:
-----------
    sandbox/trunk/src/scala/EnrichCollections.scala

Added: sandbox/trunk/src/scala/EnrichCollections.scala
===================================================================
--- sandbox/trunk/src/scala/EnrichCollections.scala	                        (rev 0)
+++ sandbox/trunk/src/scala/EnrichCollections.scala	2012-05-17 19:30:43 UTC (rev 1829)
@@ -0,0 +1,44 @@
+// For playing with Miles Sabin's 2.10 commit in 2.9.
+// https://github.com/scala/scala/commit/25d1f6d0cb720129b5ac647542cfca3d18304ae2
+
+import scala.collection._
+import scala.collection.generic._
+
+object GenTraversableLike {
+  type HasElem[Repr, A] = Repr => GenTraversableLike[A, Repr]
+  trait FromRepr[Repr] {
+    type A
+    val hasElem: HasElem[Repr, A]
+  }
+  /** Manufacture a conversion from collection representation type `Repr` to
+   *  its corresponding `GenTraversableLike` given an implicitly available
+   *  instance of `FromRepr[Repr]`.
+   *  @see [[scala.collection.generic.FromRepr]]
+   */
+  implicit def fromRepr[Repr](implicit fr : FromRepr[Repr]) = fr.hasElem
+
+  implicit val stringFromRepr : FromRepr[String] { type A = Char } = new FromRepr[String] {
+    type A = Char
+    val hasElem = implicitly[HasElem[String, Char]]
+  }
+
+  implicit def genTraversableLikeFromRepr[C[_], A0]
+    (implicit hasElem0: HasElem[C[A0], A0]) : FromRepr[C[A0]] { type A = A0 } = new FromRepr[C[A0]] {
+      type A = A0
+      val hasElem = hasElem0
+    }
+
+
+  def typed[T](t : => T) {}
+
+  class FilterMapImpl[A, Repr](val r : Repr)(implicit hasElem : HasElem[Repr, A]) {
+    def filterMap[B, That](f : A => Option[B])(implicit cbf : CanBuildFrom[Repr, B, That]) : That = r.flatMap(f(_).toSeq)
+  }
+
+  implicit def filterMap[Repr : FromRepr](r : Repr) = new FilterMapImpl(r)
+
+  val s = "Hello World"
+  val fms1 = s.filterMap(c => if(c >= 'A' && c <= 'Z') Some(c) else None)
+  typed[String](fms1)
+  println(fms1)
+}

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