def split_walk.go

unified-nsga-iii@0.2.2.0 · non_dominated_sort.bend:209

import Base
import unified-nsga-iii@0.2.2.0/util.bend as Util

209# Per-candidate split is independent given `all`. Mid-split then
210# concatenate fronts / leftovers so order matches the tail-first walk.
211def split_walk.go(+all: List<&2, Row>, +fuel: Nat, cand: List<&2, Row>) -> Split:
212  match fuel cand:
213    case 0n Nil{}:
214      Split{Nil{}, Nil{}}
215    case 0n +r <> rest:
216      split_put(r, split_walk.go(all, 0n, rest), row_dom(all, r))
217    case 1n+p Nil{}:
218      Split{Nil{}, Nil{}}
219    case 1n+p +r <> Nil{}:
220      split_put(r, Split{Nil{}, Nil{}}, row_dom(all, r))
221    case 1n+p h <> t:
222      +xs = {h <> t : List<&2, Row>}
223      +mid = Nat.div(Util.list_len(Row, xs), 2n)
224      lo hi = split_walk.go(all, p, List.take(&2, Row, xs, mid)) split_walk.go(all, p, List.drop(&2, Row, xs, mid))
225      split_cat(lo, hi)