DlistIterator.endpoint: def of bend-collections@1.0.0.0
Import: import bend-collections@1.0.0.0/src/containers/dlist_iterator.bend as DlistIterator
Lines 24-30 of bend-collections@1.0.0.0/src/containers/dlist_iterator.bend: https://jend.leeeet.dev/read.txt?path=bend-collections@1.0.0.0/src/containers/dlist_iterator.bend&start_line=24&end_line=30

import Base
import bend-collections@1.0.0.0/src/containers/doubly_linked_list.bend as D
import bend-collections@1.0.0.0/src/containers/internal/dlist_storage.bend as R

# Cursor links are arena indices plus one; zero is the gap past the end.
# Only this owning iterator can mutate the list until finish. Public handles
# retain their owner and generation; a cursor is never exposed as a handle.
def endpoint(~T: Data, s: D.DList<T>, +front: Bool) -> D.DList<T> & U32:
  D.DL{tag, depth, cap, raw, gens} = s
  R.DL{owner, fresh, free, count, +head, +tail, rd, rc, vals, prevs, nexts} = raw
  (D.DL{tag, depth, cap, R.DL{owner, fresh, free, count, head, tail, rd, rc, vals, prevs, nexts}, gens}, choose(U32, front, head, tail))

Uses (7):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Pair
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Sigma
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/dlist_iterator.bend&name=choose
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/doubly_linked_list.bend&name=DList
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/internal/dlist_storage.bend&name=DList