155 lines
3.8 KiB
Rust
155 lines
3.8 KiB
Rust
use core::{
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cell::Cell,
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sync::atomic::{AtomicUsize, Ordering::SeqCst},
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};
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use once_cell::unsync::OnceCell;
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#[test]
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fn once_cell() {
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let c = OnceCell::new();
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assert!(c.get().is_none());
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c.get_or_init(|| 92);
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assert_eq!(c.get(), Some(&92));
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c.get_or_init(|| panic!("Kabom!"));
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assert_eq!(c.get(), Some(&92));
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}
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#[test]
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fn once_cell_with_value() {
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const CELL: OnceCell<i32> = OnceCell::with_value(12);
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let cell = CELL;
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assert_eq!(cell.get(), Some(&12));
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}
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#[test]
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fn once_cell_get_mut() {
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let mut c = OnceCell::new();
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assert!(c.get_mut().is_none());
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c.set(90).unwrap();
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*c.get_mut().unwrap() += 2;
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assert_eq!(c.get_mut(), Some(&mut 92));
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}
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#[test]
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fn once_cell_drop() {
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static DROP_CNT: AtomicUsize = AtomicUsize::new(0);
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struct Dropper;
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impl Drop for Dropper {
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fn drop(&mut self) {
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DROP_CNT.fetch_add(1, SeqCst);
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}
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}
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let x = OnceCell::new();
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x.get_or_init(|| Dropper);
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assert_eq!(DROP_CNT.load(SeqCst), 0);
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drop(x);
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assert_eq!(DROP_CNT.load(SeqCst), 1);
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}
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#[test]
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fn once_cell_drop_empty() {
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let x = OnceCell::<String>::new();
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drop(x);
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}
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#[test]
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fn clone() {
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let s = OnceCell::new();
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let c = s.clone();
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assert!(c.get().is_none());
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s.set("hello".to_string()).unwrap();
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let c = s.clone();
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assert_eq!(c.get().map(String::as_str), Some("hello"));
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}
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#[test]
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fn get_or_try_init() {
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let cell: OnceCell<String> = OnceCell::new();
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assert!(cell.get().is_none());
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let res = std::panic::catch_unwind(|| cell.get_or_try_init(|| -> Result<_, ()> { panic!() }));
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assert!(res.is_err());
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assert!(cell.get().is_none());
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assert_eq!(cell.get_or_try_init(|| Err(())), Err(()));
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assert_eq!(cell.get_or_try_init(|| Ok::<_, ()>("hello".to_string())), Ok(&"hello".to_string()));
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assert_eq!(cell.get(), Some(&"hello".to_string()));
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}
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#[test]
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fn from_impl() {
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assert_eq!(OnceCell::from("value").get(), Some(&"value"));
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assert_ne!(OnceCell::from("foo").get(), Some(&"bar"));
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}
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#[test]
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fn partialeq_impl() {
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assert!(OnceCell::from("value") == OnceCell::from("value"));
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assert!(OnceCell::from("foo") != OnceCell::from("bar"));
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assert!(OnceCell::<String>::new() == OnceCell::new());
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assert!(OnceCell::<String>::new() != OnceCell::from("value".to_owned()));
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}
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#[test]
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fn into_inner() {
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let cell: OnceCell<String> = OnceCell::new();
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assert_eq!(cell.into_inner(), None);
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let cell = OnceCell::new();
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cell.set("hello".to_string()).unwrap();
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assert_eq!(cell.into_inner(), Some("hello".to_string()));
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}
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#[test]
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fn debug_impl() {
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let cell = OnceCell::new();
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assert_eq!(format!("{:#?}", cell), "OnceCell(Uninit)");
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cell.set(vec!["hello", "world"]).unwrap();
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assert_eq!(
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format!("{:#?}", cell),
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r#"OnceCell(
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[
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"hello",
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"world",
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],
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)"#
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);
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}
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#[test]
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#[should_panic(expected = "reentrant init")]
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fn reentrant_init() {
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let x: OnceCell<Box<i32>> = OnceCell::new();
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let dangling_ref: Cell<Option<&i32>> = Cell::new(None);
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x.get_or_init(|| {
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let r = x.get_or_init(|| Box::new(92));
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dangling_ref.set(Some(r));
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Box::new(62)
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});
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eprintln!("use after free: {:?}", dangling_ref.get().unwrap());
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}
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#[test]
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fn aliasing_in_get() {
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let x = OnceCell::new();
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x.set(42).unwrap();
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let at_x = x.get().unwrap(); // --- (shared) borrow of inner `Option<T>` --+
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let _ = x.set(27); // <-- temporary (unique) borrow of inner `Option<T>` |
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println!("{}", at_x); // <------- up until here ---------------------------+
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}
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#[test]
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// https://github.com/rust-lang/rust/issues/34761#issuecomment-256320669
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fn arrrrrrrrrrrrrrrrrrrrrr() {
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let cell = OnceCell::new();
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{
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let s = String::new();
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cell.set(&s).unwrap();
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}
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}
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