1const std = @import("std");
2const builtin = @import("builtin");
3const expectEqual = std.testing.expectEqual;
4
5test "switch simple" {
6 const a: u64 = 10;
7 const zz: u64 = 103;
8
9 // All branches of a switch expression must be able to be coerced to a
10 // common type.
11 //
12 // Branches cannot fallthrough. If fallthrough behavior is desired, combine
13 // the cases and use an if.
14 const b = switch (a) {
15 // Multiple cases can be combined via a ','
16 1, 2, 3 => 0,
17
18 // Ranges can be specified using the ... syntax. These are inclusive
19 // of both ends.
20 5...100 => 1,
21
22 // Branches can be arbitrarily complex.
23 101 => blk: {
24 const c: u64 = 5;
25 break :blk c * 2 + 1;
26 },
27
28 // Switching on arbitrary expressions is allowed as long as the
29 // expression is known at compile-time.
30 zz => zz,
31 blk: {
32 const d: u32 = 5;
33 const e: u32 = 100;
34 break :blk d + e;
35 } => 107,
36
37 // The else branch catches everything not already captured.
38 // Else branches are mandatory unless the entire range of values
39 // is handled.
40 else => 9,
41 };
42
43 try expectEqual(1, b);
44}
45
46// Switch expressions can be used outside a function:
47const os_msg = switch (builtin.target.os.tag) {
48 .linux => "we found a linux user",
49 else => "not a linux user",
50};
51
52// Inside a function, switch statements implicitly are compile-time
53// evaluated if the target expression is compile-time known.
54test "switch inside function" {
55 switch (builtin.target.os.tag) {
56 .fuchsia => {
57 // On an OS other than fuchsia, block is not even analyzed,
58 // so this compile error is not triggered.
59 // On fuchsia this compile error would be triggered.
60 @compileError("fuchsia not supported");
61 },
62 else => {},
63 }
64}
65
66// test