rune_alloc/btree/
mem.rs

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1use core::mem;
2
3use crate::ptr;
4
5/// This replaces the value behind the `v` unique reference by calling the
6/// relevant function.
7///
8/// If a panic occurs in the `change` closure, the entire process will be aborted.
9#[allow(dead_code)] // keep as illustration and for future use
10#[inline]
11pub(crate) fn take_mut<T, E>(v: &mut T, change: impl FnOnce(T) -> Result<T, E>) -> Result<(), E> {
12    replace(v, |value| Ok((change(value)?, ())))
13}
14
15/// This replaces the value behind the `v` unique reference by calling the
16/// relevant function, and returns a result obtained along the way.
17///
18/// If a panic occurs in the `change` closure, the entire process will be aborted.
19#[inline]
20pub(crate) fn replace<T, R, E>(
21    v: &mut T,
22    change: impl FnOnce(T) -> Result<(T, R), E>,
23) -> Result<R, E> {
24    struct PanicGuard;
25
26    impl Drop for PanicGuard {
27        fn drop(&mut self) {
28            crate::abort()
29        }
30    }
31
32    let guard = PanicGuard;
33    let value = unsafe { ptr::read(v) };
34    let (new_value, ret) = change(value)?;
35    unsafe {
36        ptr::write(v, new_value);
37    }
38    mem::forget(guard);
39    Ok(ret)
40}
rune_alloc/btree/mem.rs

rune_alloc/btree/
mem.rs
