Trait Cursor 

pub trait Cursor: LayoutExt {
    type Storage;

    // Required methods
    fn key_valid(&self, storage: &Self::Storage) -> bool;
    fn val_valid(&self, storage: &Self::Storage) -> bool;
    fn key<'a>(&self, storage: &'a Self::Storage) -> Self::Key<'a>;
    fn val<'a>(&self, storage: &'a Self::Storage) -> Self::Val<'a>;
    fn get_key<'a>(&self, storage: &'a Self::Storage) -> Option<Self::Key<'a>>;
    fn get_val<'a>(&self, storage: &'a Self::Storage) -> Option<Self::Val<'a>>;
    fn map_times<L: FnMut(Self::TimeGat<'_>, Self::DiffGat<'_>)>(
        &mut self,
        storage: &Self::Storage,
        logic: L,
    );
    fn step_key(&mut self, storage: &Self::Storage);
    fn seek_key(&mut self, storage: &Self::Storage, key: Self::Key<'_>);
    fn step_val(&mut self, storage: &Self::Storage);
    fn seek_val(&mut self, storage: &Self::Storage, val: Self::Val<'_>);
    fn rewind_keys(&mut self, storage: &Self::Storage);
    fn rewind_vals(&mut self, storage: &Self::Storage);

    // Provided methods
    fn populate_key<'a>(
        &mut self,
        storage: &'a Self::Storage,
        key: Self::Key<'a>,
        meet: Option<&Self::Time>,
        target: &mut EditList<Self::Val<'a>, Self::Time, Self::Diff>,
    ) { ... }
    fn to_vec<K, IK, V, IV>(
        &mut self,
        storage: &Self::Storage,
        into_key: IK,
        into_val: IV,
    ) -> Vec<((K, V), Vec<(Self::Time, Self::Diff)>)>
       where IK: for<'a> Fn(Self::Key<'a>) -> K,
             IV: for<'a> Fn(Self::Val<'a>) -> V { ... }
}

A cursor for navigating ordered (key, val, time, diff) updates.

Required Associated Types

type Storage

Storage required by the cursor.

Required Methods

fn key_valid(&self, storage: &Self::Storage) -> bool

Indicates if the current key is valid.

A value of false indicates that the cursor has exhausted all keys.

fn val_valid(&self, storage: &Self::Storage) -> bool

Indicates if the current value is valid.

A value of false indicates that the cursor has exhausted all values for this key.

fn key<'a>(&self, storage: &'a Self::Storage) -> Self::Key<'a>

A reference to the current key. Asserts if invalid.

fn val<'a>(&self, storage: &'a Self::Storage) -> Self::Val<'a>

A reference to the current value. Asserts if invalid.

fn get_key<'a>(&self, storage: &'a Self::Storage) -> Option<Self::Key<'a>>

Returns a reference to the current key, if valid.

fn get_val<'a>(&self, storage: &'a Self::Storage) -> Option<Self::Val<'a>>

Returns a reference to the current value, if valid.

fn map_times<L: FnMut(Self::TimeGat<'_>, Self::DiffGat<'_>)>( &mut self, storage: &Self::Storage, logic: L, )

Applies logic to each pair of time and difference. Intended for mutation of the closure’s scope.

fn step_key(&mut self, storage: &Self::Storage)

Advances the cursor to the next key.

fn seek_key(&mut self, storage: &Self::Storage, key: Self::Key<'_>)

Advances the cursor to the specified key.

fn step_val(&mut self, storage: &Self::Storage)

Advances the cursor to the next value.

fn seek_val(&mut self, storage: &Self::Storage, val: Self::Val<'_>)

Advances the cursor to the specified value.

fn rewind_keys(&mut self, storage: &Self::Storage)

Rewinds the cursor to the first key.

fn rewind_vals(&mut self, storage: &Self::Storage)

Rewinds the cursor to the first value for current key.

Provided Methods

fn populate_key<'a>( &mut self, storage: &'a Self::Storage, key: Self::Key<'a>, meet: Option<&Self::Time>, target: &mut EditList<Self::Val<'a>, Self::Time, Self::Diff>, )

Loads target with all updates associated with the supplied key.

First target is cleared, and then if we find key we populated it with each of its (val, time, diff) updates. If meet is supplied, the time is joined with each time in the updates, to advance the times before consolidation.

fn to_vec<K, IK, V, IV>( &mut self, storage: &Self::Storage, into_key: IK, into_val: IV, ) -> Vec<((K, V), Vec<(Self::Time, Self::Diff)>)>

where IK: for<'a> Fn(Self::Key<'a>) -> K, IV: for<'a> Fn(Self::Val<'a>) -> V,

Rewinds the cursor and outputs its contents to a Vec

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl<C, TInner> Cursor for differential_dataflow::trace::wrappers::enter::CursorEnter<C, TInner>

where C: Cursor, TInner: Refines<C::Time> + Lattice,

type Storage = <C as Cursor>::Storage

impl<C, TInner, F> Cursor for differential_dataflow::trace::wrappers::enter_at::CursorEnter<C, TInner, F>

where C: Cursor, TInner: Refines<C::Time> + Lattice, F: FnMut(C::Key<'_>, C::Val<'_>, C::TimeGat<'_>) -> TInner,

type Storage = <C as Cursor>::Storage

impl<C: Cursor> Cursor for RcBatchCursor<C>

type Storage = Rc<<C as Cursor>::Storage>

impl<C: Cursor> Cursor for CursorFrontier<C, C::Time>

type Storage = <C as Cursor>::Storage

impl<C: Cursor> Cursor for CursorList<C>

type Storage = Vec<<C as Cursor>::Storage>

impl<C: Cursor<Storage: BatchReader>> Cursor for BatchCursorFrontier<C>

type Storage = BatchFrontier<<C as Cursor>::Storage>

impl<L: Layout> Cursor for OrdValCursor<L>

type Storage = OrdValBatch<L>

impl<L: for<'a> Layout<ValContainer: BatchContainer<Owned: Default>>> Cursor for OrdKeyCursor<L>

type Storage = OrdKeyBatch<L>

impl<TInner, C: Cursor> Cursor for differential_dataflow::trace::wrappers::enter::BatchCursorEnter<C, TInner>

where TInner: Refines<C::Time> + Lattice,

type Storage = BatchEnter<<C as Cursor>::Storage, TInner>

impl<TInner, C: Cursor, F> Cursor for differential_dataflow::trace::wrappers::enter_at::BatchCursorEnter<C, TInner, F>

where TInner: Refines<C::Time> + Lattice, F: FnMut(C::Key<'_>, C::Val<'_>, C::TimeGat<'_>) -> TInner,

type Storage = BatchEnter<<C as Cursor>::Storage, TInner, F>