From 25a98964b5109aa55b71a8a26886c59903193548 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Thu, 6 Oct 2005 13:14:33 +0000
Subject: *** empty log message ***

---
 test-nsc/files/pos/viewtest2.scala | 117 +++++++++++++++++++++++++++++++++++++
 1 file changed, 117 insertions(+)
 create mode 100755 test-nsc/files/pos/viewtest2.scala

(limited to 'test-nsc/files/pos/viewtest2.scala')

diff --git a/test-nsc/files/pos/viewtest2.scala b/test-nsc/files/pos/viewtest2.scala
new file mode 100755
index 0000000000..1958696c1f
--- /dev/null
+++ b/test-nsc/files/pos/viewtest2.scala
@@ -0,0 +1,117 @@
+package test;
+
+/** A trait for totally ordered data.
+ */
+trait Ordered[+a] {
+
+  /** Result of comparing `this' with operand `that'.
+   *  returns `x' where
+   *  x < 0    iff    this < that
+   *  x == 0   iff    this == that
+   *  x > 0    iff    this > that
+   */
+  def compareTo [b >: a <% Ordered[b]](that: b): int;
+
+  def <  [b >: a <% Ordered[b]](that: b): boolean = (this compareTo that) <  0;
+
+  def >  [b >: a <% Ordered[b]](that: b): boolean = (this compareTo that) >  0;
+
+  def <= [b >: a <% Ordered[b]](that: b): boolean = (this compareTo that) <= 0;
+
+  def >= [b >: a <% Ordered[b]](that: b): boolean = (this compareTo that) >= 0;
+}
+
+
+object O {
+
+  implicit def view1(x: String): Ordered[String] = new Ordered[String] {
+    def compareTo [b >: String <% Ordered[b]](y: b): int = y match {
+      case y1: String => x compareTo y1;
+      case _ => -(y compareTo x)
+    }
+  }
+  implicit def view2(x: char): Ordered[char] = new Ordered[char] {
+    def compareTo [b >: char <% Ordered[b]](y: b): int = y match {
+      case y1: char => x - y1;
+      case _ => -(y compareTo x)
+    }
+  }
+
+  implicit def view3[a <% Ordered[a]](x: List[a]): Ordered[List[a]] =
+    new Ordered[List[a]] {
+      def compareTo [b >: List[a] <% Ordered[b]](y: b): int = y match {
+	case y1: List[a] => compareLists(x, y1);
+	case _ => -(y compareTo x)
+      }
+      private def compareLists(xs: List[a], ys: List[a]): int = {
+	if (xs.isEmpty && ys.isEmpty) 0
+	else if (xs.isEmpty) -1
+	else if (ys.isEmpty) 1
+	else {
+	  val s = xs.head compareTo ys.head;
+	  if (s != 0) s
+	  else compareLists(xs.tail, ys.tail)
+	}
+      }
+    }
+
+  implicit def view4[a](x: a): a = x;
+}
+
+trait Tree[+a <% Ordered[a]] {
+  def insert[b >: a <% Ordered[b]](x: b): Tree[b];
+  def elements: List[a]
+}
+
+object Empty extends Tree[All] {
+  def insert[b >: All <% Ordered[b]](x: b): Tree[b] = new Node(x, Empty, Empty);
+  def elements: List[All] = List();
+}
+
+class Node[a <% Ordered[a]](elem: a, l: Tree[a], r: Tree[a]) extends Tree[a] {
+  def insert[b >: a <% Ordered[b]](x: b): Tree[b] =
+    if (x == elem) this
+    else if (x < elem) new Node(elem, l insert x, r)
+    else new Node(elem, l, r insert x);
+  def elements: List[a] =
+    l.elements ::: List(elem) ::: r.elements
+}
+
+case class Str(elem: String) extends Ordered[Str] {
+  def compareTo[b >: Str <% Ordered[b]](that: b): int = that match {
+    case that1: Str => this.elem compareTo that1.elem
+    case _ => -(that compareTo this)
+  }
+}
+
+object Test {
+  import O._;
+
+  private def toCharList(s: String): List[Char] =
+    if (s.length() == 0) List()
+    else s.charAt(0) :: toCharList(s.substring(1));
+
+  def main(args: Array[String]) = {
+    {
+      var t: Tree[String] = Empty;
+      for (val s <- args) {
+	t = t insert s
+      }
+      System.out.println(t.elements)
+    }
+    {
+      var t: Tree[Str] = Empty;
+      for (val s <- args) {
+	t = t insert Str(s)
+      }
+      System.out.println(t.elements)
+    }
+    {
+      var t: Tree[List[char]] = Empty;
+      for (val s <- args) {
+	t = t insert toCharList(s)
+      }
+      System.out.println(t.elements)
+    }
+  }
+}
-- 
cgit v1.2.3