summaryrefslogtreecommitdiff
path: root/test/files/pos/viewtest2.scala
diff options
context:
space:
mode:
authorGilles Dubochet <gilles.dubochet@epfl.ch>2005-12-16 18:29:42 +0000
committerGilles Dubochet <gilles.dubochet@epfl.ch>2005-12-16 18:29:42 +0000
commitdf50e05006b43b007c2587549030d24b5c154398 (patch)
tree9edfb1fb5b8c04350a00c163cfcdb1fccd79e3aa /test/files/pos/viewtest2.scala
parent17e2b1c2a6f69ba74e79c30d1e44195fe732e3e3 (diff)
downloadscala-df50e05006b43b007c2587549030d24b5c154398.tar.gz
scala-df50e05006b43b007c2587549030d24b5c154398.tar.bz2
scala-df50e05006b43b007c2587549030d24b5c154398.zip
'test-nsc' has been moved to 'test'.
Diffstat (limited to 'test/files/pos/viewtest2.scala')
-rw-r--r--test/files/pos/viewtest2.scala117
1 files changed, 117 insertions, 0 deletions
diff --git a/test/files/pos/viewtest2.scala b/test/files/pos/viewtest2.scala
new file mode 100644
index 0000000000..1958696c1f
--- /dev/null
+++ b/test/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)
+ }
+ }
+}