* [Convergent and Commutative Replicated Data Types][crdt]

* [LSEQ, an Adaptive Structure for Sequences in Distributed Collaborative Editing][lseq]

[lseq]: https://hal.archives-ouvertes.fr/hal-00921633/document

// Copyright 2019 Bryant Luk

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

// http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

public protocol LSEQ: Collection {

associatedtype PositionType

associatedtype Element

associatedtype Index

associatedtype ElementContainer where ElementContainer: LSEQElementContainer,

ElementContainer.PositionType == PositionType, ElementContainer.Element == Element

associatedtype Operation where Operation: LSEQOperation,

Operation.PositionType == PositionType, Operation.Element == Element

var boundary: PositionType.Segment.Identifier { get }

var source: PositionType.Segment.Source { get }

var startPosition: PositionType { get }

var endPosition: PositionType { get }

var clock: PositionType.Clock { get }

var storage: [ElementContainer] { get }

mutating func reserveCapacity(_ minimumCapacity: Int)

mutating func insert(_ newElement: Element, at index: Index)

mutating func insertAndMakeOperation(_ newElement: Element, at index: Index) -> Operation

@discardableResult

mutating func remove(at index: Index) -> Element

@discardableResult

mutating func removeAndMakeOperation(at index: Index) -> (Element, Operation)

mutating func apply(_ operation: Operation)

func makeDifferenceOperations(from other: Self) -> [Operation]

public protocol LSEQOperation {

associatedtype Kind

associatedtype PositionType where PositionType: Position

associatedtype Element

var kind: Kind { get }

var position: PositionType { get }

var element: Element? { get }

public protocol LSEQElementContainer {

associatedtype PositionType where PositionType: Position

associatedtype Element

var position: PositionType { get }

var element: Element { get }

internal extension RandomAccessCollection {

func insertionIndex(for predicate: (Element) -> Bool) -> Index {

var slice: SubSequence = self[...]

while !slice.isEmpty {

let middle = slice.index(slice.startIndex, offsetBy: slice.count / 2)

if predicate(slice[middle]) {

slice = slice[index(after: middle)...]

} else {

slice = slice[..<middle]

}

}

return slice.startIndex

}