Function futures_ext::bounded_traversal::bounded_traversal

pub fn bounded_traversal<In, Ins, Out, OutCtx, Unfold, UFut, Fold, FFut>(
    scheduled_max: usize, 
    init: In, 
    unfold: Unfold, 
    fold: Fold
) -> impl Future<Item = Out, Error = UFut::Error> where
    Unfold: FnMut(In) -> UFut,
    UFut: IntoFuture<Item = (OutCtx, Ins)>,
    Ins: IntoIterator<Item = In>,
    Fold: FnMut(OutCtx, Iter<Out>) -> FFut,
    FFut: IntoFuture<Item = Out, Error = UFut::Error>, 

bounded_traversal traverses implicit asynchronous tree specified by init and unfold arguments, and it also does backward pass with fold operation. All unfold and fold operations are executed in parallel if they do not depend on each other (not related by ancestor-descendant relation in implicit tree) with amount of concurrency constrained by scheduled_max.

init: In

Is the root of the implicit tree to be traversed

unfold: FnMut(In) -> impl IntoFuture<Item = (OutCtx, impl IntoIterator<Item = In>)>

Asynchronous function which given input value produces list of its children. And context associated with current node. If this list is empty, it is a leaf of the tree, and fold will be run on this node.

fold: FnMut(OutCtx, impl Iterator<Out>) -> impl IntoFuture<Item=Out>

Aynchronous function which given node context and output of fold for its chidlren should produce new output value.

return value impl Future<Item = Out>

Result of running fold operation on the root of the tree.