uuid/
macros.rs

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1macro_rules! define_uuid_macro {
2    {$(#[$doc:meta])*} => {
3        $(#[$doc])*
4        #[cfg(feature = "macro-diagnostics")]
5        #[macro_export]
6        macro_rules! uuid {
7            ($uuid:literal) => {{
8                $crate::Uuid::from_bytes($crate::private_uuid_macro_internal::parse_lit!($uuid))
9            }};
10        }
11
12        $(#[$doc])*
13        #[cfg(not(feature = "macro-diagnostics"))]
14        #[macro_export]
15        macro_rules! uuid {
16            ($uuid:literal) => {{
17                const OUTPUT: $crate::Uuid = match $crate::Uuid::try_parse($uuid) {
18                    Ok(u) => u,
19                    Err(_) => {
20                        // here triggers const_err
21                        // const_panic requires 1.57
22                        #[allow(unconditional_panic)]
23                        let _ = ["invalid uuid representation"][1];
24
25                        loop {} // -> never type
26                    }
27                };
28                OUTPUT
29            }};
30        }
31    }
32}
33
34define_uuid_macro! {
35/// Parse [`Uuid`][uuid::Uuid]s from string literals at compile time.
36///
37/// ## Usage
38///
39/// This macro transforms the string literal representation of a
40/// [`Uuid`][uuid::Uuid] into the bytes representation, raising a compilation
41/// error if it cannot properly be parsed.
42///
43/// ## Examples
44///
45/// Setting a global constant:
46///
47/// ```
48/// # use uuid::{uuid, Uuid};
49/// pub const SCHEMA_ATTR_CLASS: Uuid = uuid!("00000000-0000-0000-0000-ffff00000000");
50/// pub const SCHEMA_ATTR_UUID: Uuid = uuid!("00000000-0000-0000-0000-ffff00000001");
51/// pub const SCHEMA_ATTR_NAME: Uuid = uuid!("00000000-0000-0000-0000-ffff00000002");
52/// ```
53///
54/// Defining a local variable:
55///
56/// ```
57/// # use uuid::uuid;
58/// let uuid = uuid!("urn:uuid:F9168C5E-CEB2-4faa-B6BF-329BF39FA1E4");
59/// ```
60///
61/// ## Compilation Failures
62///
63/// Invalid UUIDs are rejected:
64///
65/// ```compile_fail
66/// # use uuid::uuid;
67/// let uuid = uuid!("F9168C5E-ZEB2-4FAA-B6BF-329BF39FA1E4");
68/// ```
69///
70/// Enable the feature `macro-diagnostics` to see the error messages below.
71///
72/// Provides the following compilation error:
73///
74/// ```txt
75/// error: invalid character: expected an optional prefix of `urn:uuid:` followed by 0123456789abcdefABCDEF-, found Z at 9
76///     |
77///     |     let id = uuid!("F9168C5E-ZEB2-4FAA-B6BF-329BF39FA1E4");
78///     |                              ^
79/// ```
80///
81/// Tokens that aren't string literals are also rejected:
82///
83/// ```compile_fail
84/// # use uuid::uuid;
85/// let uuid_str: &str = "550e8400e29b41d4a716446655440000";
86/// let uuid = uuid!(uuid_str);
87/// ```
88///
89/// Provides the following compilation error:
90///
91/// ```txt
92/// error: expected string literal
93///   |
94///   |     let uuid = uuid!(uuid_str);
95///   |                      ^^^^^^^^
96/// ```
97///
98/// [uuid::Uuid]: https://docs.rs/uuid/*/uuid/struct.Uuid.html
99}
uuid/macros.rs

uuid/
macros.rs
