Trait ProjectionEngine 

pub trait ProjectionEngine<R: GridRow>:
    Send
    + Sync
    + 'static {
    // Required method
    fn rebuild(
        &self,
        snapshot: &StoreSnapshot<R>,
        spec: &ViewSpec<R>,
    ) -> Projection;

    // Provided methods
    fn compact(
        &self,
        previous: &Projection,
        snapshot: &StoreSnapshot<R>,
    ) -> Projection { ... }
    fn aggregate(
        &self,
        previous: &Projection,
        snapshot: &StoreSnapshot<R>,
        spec: &ViewSpec<R>,
    ) -> Projection { ... }
    fn expand(
        &self,
        previous: &Projection,
        snapshot: &StoreSnapshot<R>,
        spec: &ViewSpec<R>,
    ) -> Projection { ... }
}

Builds projections. The default is Rebuild; incremental engines implement the same trait.

Required Methods

fn rebuild(&self, snapshot: &StoreSnapshot<R>, spec: &ViewSpec<R>) -> Projection

Builds the display order of snapshot for spec.

Provided Methods

fn compact( &self, previous: &Projection, snapshot: &StoreSnapshot<R>, ) -> Projection

Drops rows removed since previous was built. Removing rows never reorders the rest and never makes a filtered-out row visible, so this is an O(n) filter, with no sorting. With groups it also recounts them, drops the emptied ones and lays the lines out again with each group’s expansion; the aggregate job (Self::aggregate) refreshes the aggregates.

fn aggregate( &self, previous: &Projection, snapshot: &StoreSnapshot<R>, spec: &ViewSpec<R>, ) -> Projection

The order of previous with fresh aggregates and row counts from snapshot. Neither reorders nor drops rows: Self::compact drops removed ones. Groups combine their subgroups in key order, as a rebuild does, so over the same order the result is the rebuild’s.

fn expand( &self, previous: &Projection, snapshot: &StoreSnapshot<R>, spec: &ViewSpec<R>, ) -> Projection

The order of previous laid out for spec.expansion(). The snapshot resolves the keys of tree rows: a tree is expanded by key.

Implementors

impl<R: GridRow> ProjectionEngine<R> for Rebuild