mirror of
https://github.com/pezkuwichain/pezkuwi-subxt.git
synced 2026-05-07 06:08:03 +00:00
Sergey Pepyakin
70 lines
2.2 KiB
Rust
70 lines
2.2 KiB
Rust
// Copyright 2018 Parity Technologies (UK) Ltd.
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// This file is part of Polkadot.
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// Polkadot is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// Polkadot is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Polkadot. If not, see <http://www.gnu.org/licenses/>.
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#[doc(hidden)]
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pub mod imp {
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pub use core::cell::RefCell;
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pub use core::mem::transmute;
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pub use core::mem::replace;
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// This code is a simplified version of [`LocalKey`] and it's wasm32 specialization: [`statik::Key`].
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// [`LocalKey`]: https://github.com/alexcrichton/rust/blob/98931165a23a1c2860d99759385f45d6807c8982/src/libstd/thread/local.rs#L89
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// [`statik::Key`]: https://github.com/alexcrichton/rust/blob/98931165a23a1c2860d99759385f45d6807c8982/src/libstd/thread/local.rs#L310-L312
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pub struct LocalKey<T: 'static> {
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pub init: fn() -> T,
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pub inner: RefCell<Option<T>>,
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}
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// This is safe as long there is no threads in wasm32.
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unsafe impl<T: 'static> ::core::marker::Sync for LocalKey<T> { }
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impl<T: 'static> LocalKey<T> {
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pub const fn new(init: fn() -> T) -> LocalKey<T> {
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LocalKey {
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init,
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inner: RefCell::new(None),
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}
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}
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pub fn with<F, R>(&'static self, f: F) -> R
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where F: FnOnce(&T) -> R
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{
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if self.inner.borrow().is_none() {
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let v = (self.init)();
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*self.inner.borrow_mut() = Some(v);
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}
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// This code can't panic because:
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// 1. `inner` can be borrowed mutably only once at the initialization time.
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// 2. After the initialization `inner` is always `Some`.
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f(&*self.inner.borrow().as_ref().unwrap())
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}
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}
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}
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#[doc(hidden)]
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#[macro_export]
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macro_rules! thread_local_impl {
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($(#[$attr:meta])* static $name:ident: $t:ty = $init:expr) => (
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$(#[$attr])*
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static $name: $crate::imp::LocalKey<$t> = {
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fn __init() -> $t { $init }
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$crate::imp::LocalKey::new(__init)
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};
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);
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}
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