const-struct-version 0.2.0

A trait plus proc-macro to generate a hash based on the fields of a struct. Useful for intelligently expiring a cache when the stored object changes.
Documentation 
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
76
77
78
79
80
81
82
83
84
85
86
87
88
89

#![cfg_attr(rustfmt, rustfmt_skip)]
#![allow(dead_code)]
use const_struct_version::StructVersion;
struct GenericContainer<T> {
    value: T,
    items: Vec<T>,
}
#[doc(hidden)]
const _: () = {
    extern crate const_struct_version as _const_struct_version;
    use _const_struct_version::__private::sha1::Digest as _;
    /// Automatically derived implementation of StructVersion
    #[automatically_derived]
    impl<T: StructVersion> _const_struct_version::StructVersion for GenericContainer<T> {
        fn version() -> String {
            let mut hasher = _const_struct_version::__private::sha1::Sha1::new();
            hasher.update("value");
            hasher
                .update(
                    <T as _const_struct_version::StructVersion>::version().as_bytes(),
                );
            hasher.update("items");
            hasher
                .update(
                    <Vec<T> as _const_struct_version::StructVersion>::version()
                        .as_bytes(),
                );
            ::alloc::__export::must_use({
                let res = ::alloc::fmt::format(format_args!("{0:x}", hasher.finalize()));
                res
            })
        }
    }
};
impl<T: StructVersion> GenericContainer<T> {
    /// Returns a cached version of the structure's hash
    /// This is computed once and stored in a OnceLock for efficient access
    fn version_cached() -> &'static str {
        extern crate const_struct_version as _const_struct_version;
        static VERSION: ::std::sync::OnceLock<String> = ::std::sync::OnceLock::new();
        VERSION.get_or_init(|| <Self as _const_struct_version::StructVersion>::version())
    }
}
struct ConcreteType {
    data: GenericContainer<u32>,
}
#[doc(hidden)]
const _: () = {
    extern crate const_struct_version as _const_struct_version;
    use _const_struct_version::__private::sha1::Digest as _;
    /// Automatically derived implementation of StructVersion
    #[automatically_derived]
    impl _const_struct_version::StructVersion for ConcreteType {
        fn version() -> String {
            let mut hasher = _const_struct_version::__private::sha1::Sha1::new();
            hasher.update("data");
            hasher
                .update(
                    <GenericContainer<
                        u32,
                    > as _const_struct_version::StructVersion>::version()
                        .as_bytes(),
                );
            ::alloc::__export::must_use({
                let res = ::alloc::fmt::format(format_args!("{0:x}", hasher.finalize()));
                res
            })
        }
    }
};
impl ConcreteType {
    /// Returns a cached version of the structure's hash
    /// This is computed once and stored in a OnceLock for efficient access
    fn version_cached() -> &'static str {
        extern crate const_struct_version as _const_struct_version;
        static VERSION: ::std::sync::OnceLock<String> = ::std::sync::OnceLock::new();
        VERSION.get_or_init(|| <Self as _const_struct_version::StructVersion>::version())
    }
}
fn test_generic_struct() {
    let version = <ConcreteType as StructVersion>::version();
}
#[rustc_main]
#[coverage(off)]
#[doc(hidden)]
pub fn main() -> () {
    extern crate test;
    test::test_main_static(&[])
}