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mirror of https://github.com/github/semantic.git synced 2024-12-25 07:55:12 +03:00

Correct the index semantics for keyed explorations.

This commit is contained in:
Rob Rix 2015-11-05 11:31:21 -05:00
parent 07fdfc5abc
commit db616e1dfe

View File

@ -106,16 +106,16 @@ public struct Location<A>: SequenceType {
}
private init?<C: MutableCollectionType, Key where C.Generator.Element == (Key, A), C.Index: BidirectionalIndexType>(_ weave: (A -> Location?) -> A -> Location?, _ up: C -> Location?, _ ts: C) {
func update(index: C.Index)(_ f: C.Index -> C -> Location?)(_ key: Key)(_ a: A) -> Location? {
func update(index: C.Index)(_ f: C -> Location?)(_ key: Key)(_ a: A) -> Location? {
guard ts.indices.contains(index) else { return nil }
var copy = ts
copy[index] = (key, a)
return f(index)(copy)
return f(copy)
}
func into(index: C.Index)(_ ts: C) -> Location? {
guard ts.indices.contains(index) else { return nil }
let (key, value) = ts[index]
return Location(it: value, down: weave(update(index)(into)(key)), up: update(index)(const(up))(key), left: update(index.predecessor())(into)(key), right: update(index.successor())(into)(key))
return Location(it: value, down: weave(update(index)(into(index))(key)), up: update(index)(up)(key), left: update(index)(into(index.predecessor()))(key), right: update(index)(into(index.successor()))(key))
}
guard let location = into(ts.startIndex)(ts) else { return nil }
self = location