Pattern matching on Array types, working for re...

Pattern matching on Array types, working for reals.

  def f[T](a: Array[T]) = a match {
    case x: Array[Int]      => x(0)
    case x: Array[Double]   => 2
    // etc.
  }

I'd also like to thank "instantiateTypeVar" for displacing the
mechanical spiders and giant squid beings which used to fill my
nightmares. Now that I know true horror, I welcome the squid.

Closes #2755, review by odersky.

1 files changed, 58 insertions, 0 deletions

diff --git a/test/files/run/bug2755.scala b/test/files/run/bug2755.scala
new file mode 100644
index 0000000000..8d10b56734
--- /dev/null
+++ b/test/files/run/bug2755.scala
@@ -0,0 +1,58 @@
+// Test cases: the only place we can cut and paste without crying
+// ourself to sleep.
+object Test {
+  def f1(a: Any)  = a match {
+    case x: Array[Int]      => x(0)
+    case x: Array[Double]   => 2
+    case x: Array[Float]    => x.sum.toInt
+    case x: Array[String]   => x.size
+    case x: Array[AnyRef]   => 5
+    case x: Array[_]        => 6
+    case _                  => 7
+  }
+  def f2(a: Array[_])  = a match {
+    case x: Array[Int]      => x(0)
+    case x: Array[Double]   => 2
+    case x: Array[Float]    => x.sum.toInt
+    case x: Array[String]   => x.size
+    case x: Array[AnyRef]   => 5
+    case x: Array[_]        => 6
+    case _                  => 7
+  }
+  def f3[T](a: Array[T]) = a match {
+    case x: Array[Int]      => x(0)
+    case x: Array[Double]   => 2
+    case x: Array[Float]    => x.sum.toInt
+    case x: Array[String]   => x.size
+    case x: Array[AnyRef]   => 5
+    case x: Array[_]        => 6
+    case _                  => 7
+  }
+
+
+  def main(args: Array[String]): Unit = {
+    println(f1(Array(1, 2, 3)))
+    println(f1(Array(1.0, -2.0, 3.0, 1.0)))
+    println(f1(Array(1.0f, 2.0f, 3.0f, -3.0f)))
+    println(f1((1 to 4).toArray map (_.toString)))
+    println(f1(new Array[Any](10)))    // should match as Array[AnyRef]
+    println(f1(Array(1L)))
+    println(f1(null))
+
+    println(f2(Array(1, 2, 3)))
+    println(f2(Array(1.0, -2.0, 3.0, 1.0)))
+    println(f2(Array(1.0f, 2.0f, 3.0f, -3.0f)))
+    println(f2((1 to 4).toArray map (_.toString)))
+    println(f2(new Array[Any](10)))    // should match as Array[AnyRef]
+    println(f2(Array(1L)))
+    println(f2(null))
+
+    println(f3(Array(1, 2, 3)))
+    println(f3(Array(1.0, -2.0, 3.0, 1.0)))
+    println(f3(Array(1.0f, 2.0f, 3.0f, -3.0f)))
+    println(f3((1 to 4).toArray map (_.toString)))
+    println(f3(new Array[Any](10)))    // should match as Array[AnyRef]
+    println(f3(Array(1L)))
+    println(f3(null))
+  }
+}