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
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
|
// Note: To prove termination of calls, methods need
// a termination measure, but Dafny does not yet support
// termination measures for methods (but it will in
// the foreseeable future).
// Spec# and Boogie and Chalice: The program will be
// the same, except that these languages do not check
// for any kind of termination.
class Benchmark1 {
method Add(x: int, y: int) returns (r: int)
ensures r == x+y;
{
r := x;
if (y < 0) {
var n := y;
while (n != 0)
invariant r == x+y-n && 0 <= -n;
decreases -n;
{
r := r - 1;
n := n + 1;
}
} else {
var n := y;
while (n != 0)
invariant r == x+y-n && 0 <= n;
decreases n;
{
r := r + 1;
n := n - 1;
}
}
}
method Mul(x: int, y: int) returns (r: int)
ensures r == x*y;
decreases x < 0, x;
{
if (x == 0) {
r := 0;
} else if (x < 0) {
call r := Mul(-x, y);
r := -r;
} else {
call r := Mul(x-1, y);
call r := Add(r, y);
}
}
method Main() {
call TestAdd(3, 180);
call TestAdd(3, -180);
call TestAdd(0, 1);
call TestMul(3, 180);
call TestMul(3, -180);
call TestMul(180, 3);
call TestMul(-180, 3);
call TestMul(0, 1);
call TestMul(1, 0);
}
method TestAdd(x: int, y: int) {
print x, " + ", y, " = ";
call z := Add(x, y);
print z, "\n";
}
method TestMul(x: int, y: int) {
print x, " * ", y, " = ";
call z := Mul(x, y);
print z, "\n";
}
}
|
