Struct MapFold 

pub struct MapFold<L1, L2, S, F, M>
where
    F: Fold<L2, S>,
    M: Fn(&L1) -> L2,
{ /* private fields */ }

Map fold — transform entries before folding.

Implementations

impl<L1, L2, S, F, M> MapFold<L1, L2, S, F, M>

where F: Fold<L2, S>, M: Fn(&L1) -> L2,

pub fn new(inner: F, mapper: M) -> Self

Create a map fold.

Trait Implementations

impl<L1, L2, S, F, M> Fold<L1, S> for MapFold<L1, L2, S, F, M>

where F: Fold<L2, S>, M: Fn(&L1) -> L2,

fn initial(&self, context: &FoldContext) -> S

Get the initial state before any entries are processed.

fn step(&self, state: S, entry: &L1, context: &FoldContext) -> S

Process a single entry and return the new state.

fn finalize(&self, state: S, context: &FoldContext) -> S

Finalize the state after all entries are processed.

fn derive<'a, I>(&self, entries: I, context: &FoldContext) -> FoldOutcome<S>

where Self: Sized, I: IntoIterator<Item = &'a L>, L: 'a,

Derive state from an iterator of entries.

fn derive_filtered<'a, I, F>( &self, entries: I, context: &FoldContext, filter: F, ) -> FoldOutcome<S>

where Self: Sized, I: IntoIterator<Item = &'a L>, L: 'a, F: Fn(&L) -> bool,

Derive state with a filter.