blob: c681ae706948e822138f4775f8b18f68c596b1b0 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
|
package test
trait Ordered[a] {
def < (x: a): Boolean
}
object O {
implicit def view (x: String): Ordered[String] = new Ordered[String] {
def < (y: String) = x.compareTo(y) < 0
}
}
object Empty extends Tree[Nothing]
case class Node[c <% Ordered[c]](elem: c, l: Tree[c], r: Tree[c]) extends Tree[c]
abstract class Tree[+a <% Ordered[a]] {
def insert[b >: a <% Ordered[b]](x: b): Tree[b] = this match {
case Empty =>
new Node(x, Empty, Empty)
case Node(elem, l, r) =>
if (x == elem) this
else if (x < elem) Node(elem, l insert x, r)
else Node(elem, l, r insert x)
}
def elements: List[a] = this match {
case Empty => List()
case Node(elem, l, r) =>
l.elements ::: List(elem) ::: r.elements
}
}
object Test {
import O.view
def main(args: Array[String]) {
var t: Tree[String] = Empty
for (s <- args) {
t = t insert s
}
println(t.elements)
}
}
|
