diff options
Diffstat (limited to 'vendor/lazy_static/src/inline_lazy.rs')
-rw-r--r-- | vendor/lazy_static/src/inline_lazy.rs | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/vendor/lazy_static/src/inline_lazy.rs b/vendor/lazy_static/src/inline_lazy.rs new file mode 100644 index 0000000..219ce9c --- /dev/null +++ b/vendor/lazy_static/src/inline_lazy.rs @@ -0,0 +1,57 @@ +// Copyright 2016 lazy-static.rs Developers +// +// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or +// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or +// http://opensource.org/licenses/MIT>, at your option. This file may not be +// copied, modified, or distributed except according to those terms. + +extern crate core; +extern crate std; + +use self::std::prelude::v1::*; +use self::std::cell::Cell; +use self::std::hint::unreachable_unchecked; +use self::std::sync::Once; +#[allow(deprecated)] +pub use self::std::sync::ONCE_INIT; + +// FIXME: Replace Option<T> with MaybeUninit<T> (stable since 1.36.0) +pub struct Lazy<T: Sync>(Cell<Option<T>>, Once); + +impl<T: Sync> Lazy<T> { + #[allow(deprecated)] + pub const INIT: Self = Lazy(Cell::new(None), ONCE_INIT); + + #[inline(always)] + pub fn get<F>(&'static self, f: F) -> &T + where + F: FnOnce() -> T, + { + self.1.call_once(|| { + self.0.set(Some(f())); + }); + + // `self.0` is guaranteed to be `Some` by this point + // The `Once` will catch and propagate panics + unsafe { + match *self.0.as_ptr() { + Some(ref x) => x, + None => { + debug_assert!(false, "attempted to derefence an uninitialized lazy static. This is a bug"); + + unreachable_unchecked() + }, + } + } + } +} + +unsafe impl<T: Sync> Sync for Lazy<T> {} + +#[macro_export] +#[doc(hidden)] +macro_rules! __lazy_static_create { + ($NAME:ident, $T:ty) => { + static $NAME: $crate::lazy::Lazy<$T> = $crate::lazy::Lazy::INIT; + }; +} |