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use std::convert::TryFrom;
use std::fmt;
use std::iter::repeat_with;
use std::time::{SystemTime, UNIX_EPOCH};
/// A D-Bus server GUID.
///
/// See the D-Bus specification [UUIDs chapter] for details.
///
/// You can create a `Guid` from an existing string with [`Guid::try_from::<&str>`][TryFrom].
///
/// [UUIDs chapter]: https://dbus.freedesktop.org/doc/dbus-specification.html#uuids
/// [TryFrom]: #impl-TryFrom%3C%26%27_%20str%3E
#[derive(Clone, Debug, PartialEq, Hash)]
pub struct Guid(String);
impl Guid {
/// Generate a D-Bus GUID that can be used with e.g. [`Connection::new_unix_server`].
///
/// [`Connection::new_unix_server`]: struct.Connection.html#method.new_unix_server
pub fn generate() -> Self {
let r: Vec<u32> = repeat_with(|| fastrand::u32(..)).take(3).collect();
let r3 = match SystemTime::now().duration_since(UNIX_EPOCH) {
Ok(n) => n.as_secs() as u32,
Err(_) => fastrand::u32(..),
};
let s = format!("{:08x}{:08x}{:08x}{:08x}", r[0], r[1], r[2], r3);
Self(s)
}
/// Returns a string slice for the GUID.
pub fn as_str(&self) -> &str {
self.0.as_str()
}
}
impl fmt::Display for Guid {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{}", self.as_str())
}
}
impl TryFrom<&str> for Guid {
type Error = crate::Error;
/// Creates a GUID from a string with 32 hex digits.
///
/// Returns `Err(`[`Error::InvalidGUID`]`)` if the provided string is not a well-formed GUID.
///
/// [`Error::InvalidGUID`]: enum.Error.html#variant.InvalidGUID
fn try_from(value: &str) -> std::result::Result<Self, Self::Error> {
if value.as_bytes().len() != 32 || !value.chars().all(|c| char::is_ascii_hexdigit(&c)) {
Err(crate::Error::InvalidGUID)
} else {
Ok(Guid(value.to_string()))
}
}
}
#[cfg(test)]
mod tests {
use crate::Guid;
#[test]
fn generate() {
let u1 = Guid::generate();
let u2 = Guid::generate();
assert_eq!(u1.as_str().len(), 32);
assert_eq!(u2.as_str().len(), 32);
assert_ne!(u1, u2);
assert_ne!(u1.as_str(), u2.as_str());
}
}