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-

// Copyright 2019 Developers of the Rand project.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-#![allow(dead_code)]
-use core::sync::atomic::{AtomicUsize, Ordering::Relaxed};
-
-// This structure represents a lazily initialized static usize value. Useful
-// when it is preferable to just rerun initialization instead of locking.
-// Both unsync_init and sync_init will invoke an init() function until it
-// succeeds, then return the cached value for future calls.
-//
-// Both methods support init() "failing". If the init() method returns UNINIT,
-// that value will be returned as normal, but will not be cached.
-//
-// Users should only depend on the _value_ returned by init() functions.
-// Specifically, for the following init() function:
-//      fn init() -> usize {
-//          a();
-//          let v = b();
-//          c();
-//          v
-//      }
-// the effects of c() or writes to shared memory will not necessarily be
-// observed and additional synchronization methods with be needed.
-pub struct LazyUsize(AtomicUsize);
-
-impl LazyUsize {
-    pub const fn new() -> Self {
-        Self(AtomicUsize::new(Self::UNINIT))
-    }
-
-    // The initialization is not completed.
-    pub const UNINIT: usize = usize::max_value();
-
-    // Runs the init() function at least once, returning the value of some run
-    // of init(). Multiple callers can run their init() functions in parallel.
-    // init() should always return the same value, if it succeeds.
-    pub fn unsync_init(&self, init: impl FnOnce() -> usize) -> usize {
-        // Relaxed ordering is fine, as we only have a single atomic variable.
-        let mut val = self.0.load(Relaxed);
-        if val == Self::UNINIT {
-            val = init();
-            self.0.store(val, Relaxed);
-        }
-        val
-    }
-}
-
-// Identical to LazyUsize except with bool instead of usize.
-pub struct LazyBool(LazyUsize);
-
-impl LazyBool {
-    pub const fn new() -> Self {
-        Self(LazyUsize::new())
-    }
-
-    pub fn unsync_init(&self, init: impl FnOnce() -> bool) -> bool {
-        self.0.unsync_init(|| init() as usize) != 0
-    }
-}
-

-