104 lines
3.5 KiB
Swift
104 lines
3.5 KiB
Swift
//
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// Copyright (c) 2017 Touch Instinct
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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//
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import RxSwift
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public extension CursorType {
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/// Creates MapCursor with current cursor
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///
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/// - Parameter transform: closure to transform elements
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/// - Returns: new MapCursor instance
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func flatMap<T>(transform: @escaping MapCursor<Self, T>.Transform) -> MapCursor<Self, T> {
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MapCursor(cursor: self, transform: transform)
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}
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/// Creates ResettableMapCursor with current cursor
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///
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/// - Parameter transform: closure to transform elements
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/// - Returns: new ResettableMapCursor instance
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func flatMap<T>(transform: @escaping ResettableMapCursor<Self, T>.Transform)
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-> ResettableMapCursor<Self, T> where Self: ResettableCursorType {
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ResettableMapCursor(cursor: self, transform: transform)
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}
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}
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/// Map cursor implementation with enclosed cursor for fetching results
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public class MapCursor<Cursor: CursorType, T>: CursorType, RxDataSource {
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public typealias ResultType = [Element]
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public typealias Transform = (Cursor.Element) -> T?
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fileprivate let cursor: Cursor
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fileprivate let transform: Transform
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private var elements: [T] = []
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/// Initializer with enclosed cursor
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///
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/// - Parameters:
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/// - cursor: enclosed cursor
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/// - transform: closure to transform elements
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public init(cursor: Cursor, transform: @escaping Transform) {
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self.cursor = cursor
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self.transform = transform
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}
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public var exhausted: Bool {
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cursor.exhausted
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}
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public var count: Int {
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elements.count
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}
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public subscript(index: Int) -> T {
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elements[index]
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}
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public func loadNextBatch() -> Single<[T]> {
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cursor.loadNextBatch().map { newItems in
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let transformedNewItems = newItems.compactMap(self.transform)
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self.elements += transformedNewItems
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return transformedNewItems
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}
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}
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}
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/// MapCursor subclass with implementation of ResettableType
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public class ResettableMapCursor<Cursor: ResettableCursorType, T>: MapCursor<Cursor, T>, ResettableType {
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public typealias ResultType = [Cursor.Element]
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public override init(cursor: Cursor, transform: @escaping Transform) {
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super.init(cursor: cursor, transform: transform)
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}
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public required init(resetFrom other: ResettableMapCursor) {
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super.init(cursor: other.cursor.reset(), transform: other.transform)
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}
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}
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