blob: 9f7d474db06634b2776e8daeafe94a15233ab658 (
plain)
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
|
class Node {
var n: Node
predicate P { acc(n) && (n != null ==> acc(n.P)) }
function length(): int
requires rd(P)
ensures result >= 1
{ unfolding rd(P) in 1 + (n == null ? 0 : n.length()) }
}
class Test {
method test(node: Node)
requires node != null
requires acc(node.P)
{
assert node.length() >= 1
assert (unfolding rd(node.P) in node.n == null) ==> (node.length() == 1) /* Holds in Chalice and Syxc */
//assert (unfolding rd(node.P) in node.n != null) ==> (unfolding rd(node.P) in node.n.length() >= 1) /* Holds in Chalice and Syxc */
assert (unfolding rd(node.P) in node.n != null) ==> (node.length() > 1) /* Holds in Chalice and Syxc */
assert (node.length() == 1) ==> (unfolding rd(node.P) in node.n == null) /* Fails in Chalice and Syxc */
assert (node.length() == 1) <==> (unfolding rd(node.P) in node.n == null)
// assert n.length() > 1 <==> unfolding rd(n.P) in n.n != null /* Fails in Chalice and Syxc */
}
}
|