# Struct rustc_data_structures::undo_log::VecLog

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    pub struct VecLog<T> {
        log: Vec<T>,
        num_open_snapshots: usize,
    }

Expand description

A basic undo log.

## Fields§

§`log: Vec<T>`§`num_open_snapshots: usize`

## Trait Implementations§

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### impl<T> Clone for VecLog<T>
where T: Clone,

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#### fn clone(&self) -> VecLog<T>

Returns a copy of the value. Read more
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#### fn clone_from(&mut self, source: &Self)

Performs copy-assignment from `source`. Read more
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### impl<T> Debug for VecLog<T>
where T: Debug,

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

Formats the value using the given formatter. Read more
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### impl<T> Default for VecLog<T>

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#### fn default() -> VecLog<T>

Returns the “default value” for a type. Read more
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### impl<T> Index<usize> for VecLog<T>

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#### type Output = T

The returned type after indexing.
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#### fn index(&self, key: usize) -> &T

Performs the indexing (`container[index]`) operation. Read more
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### impl<T> Snapshots<T> for VecLog<T>

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#### type Snapshot = Snapshot

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#### fn has_changes(&self, snapshot: &Snapshot) -> bool

Returns true if `self` has made any changes since snapshot started.
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#### fn actions_since_snapshot(&self, snapshot: &Snapshot) -> &[T]

Returns the slice of actions that were taken since the snapshot began.
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#### fn start_snapshot(&mut self) -> Snapshot

Starts a new snapshot. That snapshot must eventually either be committed via a call to commit or rollback via rollback_to. Snapshots can be nested (i.e., you can start a snapshot whilst another snapshot is in progress) but you must then commit or rollback the inner snapshot before attempting to commit or rollback the outer snapshot.
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#### fn rollback_to<R>(&mut self, values: impl FnOnce() -> R, snapshot: Snapshot)
where R: Rollback<T>,

Rollback (undo) the changes made to `storage` since the snapshot.
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#### fn commit(&mut self, snapshot: Snapshot)

Commit: keep the changes that have been made since the snapshot began
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### impl<T> UndoLogs<T> for VecLog<T>

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#### fn num_open_snapshots(&self) -> usize

How many open snapshots this undo log currently has
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#### fn push(&mut self, undo: T)

Pushes a new “undo item” onto the undo log. This method is invoked when some action is taken (e.g., a variable is unified). It records the info needed to reverse that action should an enclosing snapshot be rolleod back.
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#### fn clear(&mut self)

Removes all items from the undo log.
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#### fn in_snapshot(&self) -> bool

True if a snapshot has started, false otherwise
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#### fn extend<I>(&mut self, undos: I)
where Self: Sized, I: IntoIterator<Item = T>,

Extends the undo log with many undos.

## Auto Trait Implementations§

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### impl<T> DynSend for VecLog<T>
where T: DynSend,

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### impl<T> DynSync for VecLog<T>
where T: DynSync,

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### impl<T> Freeze for VecLog<T>

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### impl<T> RefUnwindSafe for VecLog<T>
where T: RefUnwindSafe,

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### impl<T> Send for VecLog<T>
where T: Send,

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### impl<T> Sync for VecLog<T>
where T: Sync,

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### impl<T> Unpin for VecLog<T>
where T: Unpin,

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### impl<T> UnwindSafe for VecLog<T>
where T: UnwindSafe,

## Blanket Implementations§

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### impl<T> Aligned for T

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#### const ALIGN: Alignment = const ALIGN: Alignment = Alignment::of::<Self>();

Alignment of `Self`.
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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> Instrument for T

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#### fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided `Span`, returning an `Instrumented` wrapper. Read more
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#### fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current `Span`, returning an `Instrumented` wrapper. Read more
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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<T> Pointable for T

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#### const ALIGN: usize = _

The alignment of pointer.
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#### type Init = T

The type for initializers.
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#### unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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#### unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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#### unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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#### unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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### impl<T> ToOwned for T
where T: Clone,

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#### type Owned = T

The resulting type after obtaining ownership.
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#### fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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#### fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. 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.
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### impl<T> WithSubscriber for T

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#### fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided `Subscriber` to this type, returning a `WithDispatch` wrapper. Read more
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#### fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default `Subscriber` to this type, returning a `WithDispatch` wrapper. Read more
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### impl<'a, T> Captures<'a> for T
where T: ?Sized,

## Layout§

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain `repr(...)` attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 32 bytes