auto_array/
lib.rs

1#![no_std]
2
3/// # Examples
4/// ```rust
5/// use auto_array::auto_array;
6/// auto_array! {
7///     // Additional attributes, docs, and visibility are supported.
8///     /// A const array.
9///     #[allow(unused)]
10///     const A: [u8; _] = [3, 3, 3];
11///     /// A static array with conditional compilation and pub(crate) visibility.
12///     pub(crate) static B: [u8; _] = [1, #[cfg(unix)] 2];
13/// }
14/// assert_eq!(A, [3, 3, 3]);
15/// assert_eq!(B, [1, #[cfg(unix)] 2]);
16/// ```
17#[macro_export]
18macro_rules! auto_array {
19    ($($(#[$attr:meta])* $vis:vis $const_or_static:ident $name:ident: [$ty:ty; _] = $array:expr;)*) => {
20        $($(#[$attr])* $vis $const_or_static $name: [$ty; <[$ty]>::len(<[$ty; _]>::as_slice(&$array))] = $array;)*
21    };
22}
23
24#[cfg(test)]
25mod tests {
26    macro_rules! assert_type_and_value {
27        ($($lhs:path: $ty:ty = $rhs:expr;)*) => {
28            $(let _: $ty = $lhs;
29            assert_eq!($lhs, $rhs);)*
30        };
31    }
32
33    #[test]
34    fn single_arrays() {
35        auto_array!(
36            pub const A: [i32; _] = [1, 2, 3];
37        );
38        auto_array!(
39            pub(super) static B: [i8; _] = [4, 4, 4, 4];
40        );
41        assert_type_and_value!(
42            A: [i32; 3] = [1, 2, 3];
43            B: [i8; 4] = [4, 4, 4, 4];
44        );
45    }
46
47    #[test]
48    fn multiple_arrays() {
49        auto_array!(
50            const A: [i8; _] = [1, 2, 3];
51            const B: [i16; _] = [];
52            const C: [i32; _] = [4, 4, 4, 4];
53            const D: [i64; _] = [6, 6, 6, 6, 6, 6];
54        );
55        assert_type_and_value!(
56            A: [i8; 3] = [1, 2, 3];
57            B: [i16; 0] = [];
58            C: [i32; 4] = [4, 4, 4, 4];
59            D: [i64; 6] = [6, 6, 6, 6, 6, 6];
60        );
61
62        auto_array!(
63            static E: [u32; _] = [1];
64            static F: [u64; _] = [2, 2];
65        );
66        assert_type_and_value!(
67            E: [u32; 1] = [1];
68            F: [u64; 2] = [2, 2];
69        );
70    }
71
72    #[test]
73    fn mix_const_and_static() {
74        auto_array!(
75            const A: [u8; _] = [2, 2];
76            static B: [u8; _] = [3, 3, 3];
77        );
78        assert_type_and_value!(
79            A: [u8; 2] = [2, 2];
80            B: [u8; 3] = [3, 3, 3];
81        );
82    }
83
84    #[test]
85    #[deny(dead_code, clippy::approx_constant)]
86    fn attributes() {
87        auto_array!(
88            #[expect(dead_code)]
89            #[expect(clippy::approx_constant)]
90            pub(crate) const UNUSED: [f32; _] = [3.14];
91        );
92    }
93
94    #[test]
95    fn empty_invocation() {
96        auto_array!();
97    }
98}
auto_array/lib.rs

auto_array/
lib.rs
