Chalice/tests/predicates/setset.chalice


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
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57

class Node {
  var value: int;

  method init(v: int)
    requires acc(value)
    ensures valid
  {
    value := v
    fold this.valid
  }
  
  function get():int requires valid { unfolding valid in value }
  
  method set(v: int)
    requires valid
    ensures valid && get() == v
  {
    unfold valid
    value := v
    fold valid
  }
  
  predicate valid {
    acc(value)
  }
  
  method main(x: Node, y: Node)
    requires x != null && y != null
    requires x.valid && y.valid
  {
    call x.set(3)
    call y.set(3)
    call x.set(3)
    call y.set(3)
    call x.set(3)
    call y.set(3)
    call x.set(3)
    unfold x.valid
    x.value := 3
    fold x.valid
    call y.set(3)
    call x.set(3)
    call y.set(3)
    unfold x.valid
    x.value := 3
    fold x.valid
    unfold x.valid
    x.value := 3
    fold x.valid
    call x.set(3)
    call y.set(3)
    call x.set(4)
    
    assert y.get() == 3
    assert x.get() == 3 // error: should fail
  }
}