Generate and parse UUIDs.
Provides support for Universally Unique Identifiers (UUIDs). A UUID is a unique 128-bit number, stored as 16 octets. UUIDs are used to assign unique identifiers to entities without requiring a central allocating authority.
They are particularly useful in distributed systems, though they can be used in disparate areas, such as databases and network protocols. Typically a UUID is displayed in a readable string form as a sequence of hexadecimal digits, separated into groups by hyphens.
The uniqueness property is not strictly guaranteed, however for all practical purposes, it can be assumed that an unintentional collision would be extremely unlikely.
By default, this crate depends on nothing but std
and cannot generate
Uuid
s. You need to enable the following Cargo features to enable
various pieces of functionality:
v1
- adds theUuid::new_v1
function and the ability to create a V1 using an implementation ofuuid::v1::ClockSequence
(usuallyuuid::v1::Context
) and a timestamp fromtime::timespec
.v3
- adds theUuid::new_v3
function and the ability to create a V3 UUID based on the MD5 hash of some data.v4
- adds theUuid::new_v4
function and the ability to randomly generate aUuid
.v5
- adds theUuid::new_v5
function and the ability to create a V5 UUID based on the SHA1 hash of some data.serde
- adds the ability to serialize and deserialize aUuid
using theserde
crate.
You need to enable one of the following Cargo features together with the
v4
feature if you're targeting wasm32-unknown-unknown
target:
js
- enables support for randomness onwasm32-unknown-unknown
via [getrandom
]
Alternatively, you can provide a custom getrandom
implementation yourself
via getrandom::register_custom_getrandom
.
By default, uuid
can be depended on with:
[dependencies]
uuid = "0.8"
To activate various features, use syntax like:
[dependencies]
uuid = { version = "0.8", features = ["serde", "v4"] }
You can disable default features with:
[dependencies]
uuid = { version = "0.8", default-features = false }
Some features are unstable. They may be incomplete or depend on other unstable libraries. These include:
zerocopy-unstable
- adds support for zero-copy deserialization using thezerocopy
library.
Unstable features may break between minor releases.
To allow unstable features, you'll need to enable the Cargo feature as normal, but also pass an additional
flag through your environment to opt-in to unstable uuid
features:
RUSTFLAGS="--cfg uuid_unstable"
To parse a UUID given in the simple format and print it as a urn:
use uuid::Uuid;
fn main() -> Result<(), uuid::Error> {
let my_uuid =
Uuid::parse_str("936DA01F9ABD4d9d80C702AF85C822A8")?;
println!("{}", my_uuid.to_urn());
Ok(())
}
To create a new random (V4) UUID and print it out in hexadecimal form:
// Note that this requires the `v4` feature enabled in the uuid crate.
use uuid::Uuid;
fn main() {
let my_uuid = Uuid::new_v4();
println!("{}", my_uuid);
Ok(())
}
Examples of string representations:
- simple:
936DA01F9ABD4d9d80C702AF85C822A8
- hyphenated:
550e8400-e29b-41d4-a716-446655440000
- urn:
urn:uuid:F9168C5E-CEB2-4faa-B6BF-329BF39FA1E4
- Wikipedia: Universally Unique Identifier
- RFC4122: A Universally Unique IDentifier (UUID) URN Namespace
Licensed under either of
- Apache License, Version 2.0, (LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0)
- MIT license (LICENSE-MIT or https://opensource.org/licenses/MIT)
at your option.
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.