MappedRwLockWriteGuard in std::sync - Rust
Description: RAII structure used to release the exclusive write access of a lock when dropped, which can point to a subfield of the protected data.

## MappedRwLockWriteGuard

# Struct MappedRwLockWriteGuard

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    pub struct MappedRwLockWriteGuard<'rwlock, T: ?Sized + 'rwlock> { /* private fields */ }

🔬This is a nightly-only experimental API. (`mapped_lock_guards` #117108)
Expand description

RAII structure used to release the exclusive write access of a lock when dropped, which can point to a subfield of the protected data.

This structure is created by the `map` and `filter_map` methods on `RwLockWriteGuard`.

## Implementations§

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### impl<'rwlock, T: ?Sized> MappedRwLockWriteGuard<'rwlock, T>

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#### pub fn map<U, F>(orig: Self, f: F) -> MappedRwLockWriteGuard<'rwlock, U>
where F: FnOnce(&mut T) -> &mut U, U: ?Sized,

🔬This is a nightly-only experimental API. (`mapped_lock_guards` #117108)

Makes a `MappedRwLockWriteGuard` for a component of the borrowed data, e.g. an enum variant.

The `RwLock` is already locked for writing, so this cannot fail.

This is an associated function that needs to be used as `MappedRwLockWriteGuard::map(...)`. A method would interfere with methods of the same name on the contents of the `MappedRwLockWriteGuard` used through `Deref`.

##### §Panics

If the closure panics, the guard will be dropped (unlocked) and the RwLock will be poisoned.

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#### pub fn filter_map<U, F>( orig: Self, f: F, ) -> Result<MappedRwLockWriteGuard<'rwlock, U>, Self>
where F: FnOnce(&mut T) -> Option<&mut U>, U: ?Sized,

🔬This is a nightly-only experimental API. (`mapped_lock_guards` #117108)

Makes a `MappedRwLockWriteGuard` for a component of the borrowed data. The original guard is returned as an `Err(...)` if the closure returns `None`.

The `RwLock` is already locked for writing, so this cannot fail.

This is an associated function that needs to be used as `MappedRwLockWriteGuard::filter_map(...)`. A method would interfere with methods of the same name on the contents of the `MappedRwLockWriteGuard` used through `Deref`.

##### §Panics

If the closure panics, the guard will be dropped (unlocked) and the RwLock will be poisoned.

## Trait Implementations§

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### impl<T: ?Sized + Debug> Debug for MappedRwLockWriteGuard<'_, T>

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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### impl<T: ?Sized> Deref for MappedRwLockWriteGuard<'_, T>

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#### type Target = T

The resulting type after dereferencing.
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#### fn deref(&self) -> &T

Dereferences the value.
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### impl<T: ?Sized> DerefMut for MappedRwLockWriteGuard<'_, T>

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#### fn deref_mut(&mut self) -> &mut T

Mutably dereferences the value.
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### impl<T: ?Sized + Display> Display for MappedRwLockWriteGuard<'_, T>

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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### impl<T: ?Sized> Drop for MappedRwLockWriteGuard<'_, T>

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#### fn drop(&mut self)

Executes the destructor for this type. Read more
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### impl<T: ?Sized> !Send for MappedRwLockWriteGuard<'_, T>

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### impl<T: ?Sized + Sync> Sync for MappedRwLockWriteGuard<'_, T>

## Auto Trait Implementations§

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### impl<'rwlock, T> Freeze for MappedRwLockWriteGuard<'rwlock, T>
where T: ?Sized,

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### impl<'rwlock, T> !RefUnwindSafe for MappedRwLockWriteGuard<'rwlock, T>

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### impl<'rwlock, T> Unpin for MappedRwLockWriteGuard<'rwlock, T>
where T: ?Sized,

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### impl<'rwlock, T> !UnwindSafe for MappedRwLockWriteGuard<'rwlock, T>

## Blanket Implementations§

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### impl<T> Any for T
where T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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### impl<T> Borrow<T> for T
where T: ?Sized,

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#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for T
where T: ?Sized,

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#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T, U> Into<U> for T
where U: From<T>,

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#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<P, T> Receiver for P
where P: Deref<Target = T> + ?Sized, T: ?Sized,

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#### type Target = T

🔬This is a nightly-only experimental API. (`arbitrary_self_types` #44874)
The target type on which the method may be called.
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### impl<T> ToString for T
where T: Display + ?Sized,

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#### fn to_string(&self) -> String

Converts the given value to a `String`. Read more
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### impl<T, U> TryFrom<U> for T
where U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.