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pub const fn is_some_and(self, f: impl ~const FnOnce(T) -> bool) -> boolOption::is_some_and — Returns true if the option is a Some and the value inside of it matches a predicate.
Examples
let x: Option<u32> = Some(2);
assert_eq!(x.is_some_and(|x| x > 1), true);
let x: Option<u32> = Some(0);
assert_eq!(x.is_some_and...
pub const fn is_ok_and<F>(self, f: F) -> boolResult::is_ok_and — Returns true if the result is Ok and the value inside of it matches a predicate.
Examples
let x: Result<u32, &str> = Ok(2);
assert_eq!(x.is_ok_and(|x| x > 1), true);
let x: Result<u32, &str> = Ok(0);
assert_eq!(x.is_ok...
...mpsc::Receiver<
oneshot::Sender<(RequestId, oneshot::Receiver<Response>)>,
>,
) {
loop {
tokio::select! {
usb_response = usb_rx.recv() => match usb_response {
Some((request_id, response)) =>
dispatcher.handle_usb_rx(request_id, response).await,
None => break
},
request = registration_requests.recv() => match request {
Some(reply_to) => dispatcher.register(reply_to).await,
None => break
}
}
}
}
Points...
...let mut connbuilder = SslConnectorBuilder::new(SslMethod::tls()).unwrap();
// https://www.postgresql.org/docs/current/static/libpq-ssl.html describes the modes
match dbssl.to_lowercase().as_ref() {
"require" | "prefer" | "allow" => connbuilder.set_verify(postgres::tls::openssl::openssl::ssl::SSL_VERIFY_NONE),
_ => (), // by default we verify certs: it's like either...
...fill in the match statement below */
/* to make this code compile */
let noise = match animal {
/* Cow and Bull */ => {
"moo".to_string()
}
/* Chicken */ => {
"cluck, cluck!".to_string()
}
/* Dog */ => {
format!("woof, woof! I am {}!", name)
}
/* Worm– or all silent animals?*/ => {
"-- (silence)".to_string()
}
};
/* Bonus task: Give Dogs named Lassie */
/* a different output...
pub struct PrefixComponent<'a>...Instances of this struct can be obtained by matching against the Prefix variant on Component.
Does not occur on Unix.
Examples
use std::path::{Component, Path, Prefix};
use std::ffi::OsStr;
let path = Path::new(r"c:\you\later\");
match path.components().next().unwrap() {
Component::Prefix(prefix_component) => {
assert_eq...
...String,
}
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Now we know we have to match that same error code. Let's find in src/routes/user.rs when we insert a new user:
match user_coll.insert_one(document.to_owned(), None) {
Ok(inserted) => {
match inserted.inserted_id {
Some(id) => { ...},
None...
...At their core, declarative macros allow you to write something similar to a Rust match statement:
match x {
4 => println!("four!"),
5 => println!("five!"),
_ => println!("something else"),
}
With match, x’s structure and value will be evaluated, and the right arm will execute based on what matches. So if x...
...DO NOT USE THIS CODE IN PRODUCTION
let url = match json
.get(0)
.unwrap()
.get("data")
.unwrap()
.get("children")
.unwrap()
.get(0)
.unwrap()
.get("data")
.unwrap()
.get("url")
{
// Parse the youtube url from the string
// "https://www.youtube.com/playlist?list=PLf3u8NhoEikhTC5radGrmmqdkOK-xMDoZ"
// after trimming `"`
Some(url) => match url::Url...
...How to get a compatible version of protoc The protoc binary that you use to generate code needs to have a version that exactly matches the version of the protobuf crate you are using. More specifically, if you are using Rust protobuf x.y.z then you need to use...
pub fn next_if_map<R>(&mut self, f: impl FnOnce(<I as >::Item) -> Result<R, <I as >::Item>) -> Option<R>...let mut iter = "125 GOTO 10".chars().peekable();
let mut line_num = 0_u32;
while let Some(digit) = iter.next_if_map(|c| c.to_digit(10).ok_or(c)) {
line_num = line_num * 10 + digit;
}
assert_eq!(line_num, 125);
assert_eq!(iter.collect::<String>(), " GOTO 10");
Matching custom...
...Next, there is an operation to turn this SIMD mask vector into an integer, resulting in:0b0111
Finally the .trailing_ones method can be used to count how many elements matched before the first one that didn't. For our example it returns 3, and indeed there are 3 matching...
...std::iter::Iterator<Item = <A as std::iter::Iterator>::Item>, { type Item = <A as std::iter::Iterator>::Item; fn next(&mut self) -> Option<Self::Item> { match self { Enum::A(x) => x.next(), Enum::B(x) => x.next(), } } fn size_hint(&self) -> (usize, Option<usize>) { match self { Enum::A(x) => x...
...with Thin Traits, you write virtual methods
whereas with Extensible Enums, you write match statements – and I
think match statements are far more common in Rust today.Still, Thin Traits will be a very good fit for various use cases.
They are a good fit for Servo, for example, where...
...Storing Matching Lines
To finish this function, we need a way to store the matching lines that we want to return. For that, we can make a mutable vector before the for loop and call the push method to store a line in the vector. After the for loop, we...
...let value = rand::thread_rng().gen();
Self { value }
}
}
Match Ergonomics pattern changes §
Lint: rust-2024-incompatible-pat
Rust edition guide: Match ergonomics reservations
I found this change tricky. I was starting off at a disadvantage, because I didn't know what "match ergonomics" or "binding mode" meant. So the warnings...
pub fn div_euclid(self, rhs: f32) -> f32f32::div_euclid — Calculates Euclidean division, the matching method for rem_euclid.
This computes the integer n such that self = n * rhs + self.rem_euclid(rhs). In other words, the result is self / rhs rounded to the integer n such that self >= n * rhs.
Precision
The result of this operation...
pub fn div_euclid(self, rhs: f64) -> f64f64::div_euclid — Calculates Euclidean division, the matching method for rem_euclid.
This computes the integer n such that self = n * rhs + self.rem_euclid(rhs). In other words, the result is self / rhs rounded to the integer n such that self >= n * rhs.
Precision
The result of this operation...
...i32,
) -> Result<Vec<Bytes>> {
let https = HttpsConnector::new()?;
let client = Client::builder().build::<_, hyper::Body>(https);
let group = config.group.as_ref();
let user = config.user.as_ref();
let uri = match group {
Some(v) => format!(
"https://gitlab.com/api/v4/groups/{}/{}?per_page={}",
v, domain, per_page
),
None => match user...
...uint,
callback: &mut |Match|) {
...
}
complete_from_file("foo", "myfile.rs", 3, |match| {
// do something with each match
});
This means the whole search happens regardless of whether you just want the first match. The main reason for doing this is because iterators are somewhat less easy to write for my brain...
"Memory errors are fundamentally state errors, and Rust's move semantics, borrowing, and aliasing XOR mutating help enormously for me to reason about h..."