Dactyloidae iOS initial commit

mobile/ios/Storage/Cursor.swift

@@ -0,0 +1,124 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+import Foundation
+
+/**
+ * Status results for a Cursor
+ */
+public enum CursorStatus {
+    case success
+    case failure
+    case closed
+}
+
+public protocol TypedCursor: Sequence {
+    associatedtype T
+    var count: Int { get }
+    var status: CursorStatus { get }
+    var statusMessage: String { get }
+    subscript(index: Int) -> T? { get }
+    func asArray() -> [T]
+}
+
+/**
+ * Provides a generic method of returning some data and status information about a request.
+ */
+open class Cursor<T>: TypedCursor {
+    open var count: Int {
+        get { return 0 }
+    }
+
+    // Extra status information
+    open var status: CursorStatus
+    public var statusMessage: String
+
+    init(err: NSError) {
+        self.status = .failure
+        self.statusMessage = err.description
+    }
+
+    public init(status: CursorStatus = .success, msg: String = "") {
+        self.statusMessage = msg
+        self.status = status
+    }
+
+    // Collection iteration and access functions
+    open subscript(index: Int) -> T? {
+        get { return nil }
+    }
+
+    open func asArray() -> [T] {
+        var acc = [T]()
+        acc.reserveCapacity(self.count)
+        for row in self {
+            // Shouldn't ever be nil -- that's to allow the generator or subscript to be
+            // out of range.
+            if let row = row {
+                acc.append(row)
+            }
+        }
+        return acc
+    }
+
+    open func makeIterator() -> AnyIterator<T?> {
+        var nextIndex = 0
+        return AnyIterator() {
+            if nextIndex >= self.count || self.status != CursorStatus.success {
+                return nil
+            }
+
+            defer { nextIndex += 1 }
+            return self[nextIndex]
+        }
+    }
+
+    open func close() {
+        status = .closed
+        statusMessage = "Closed"
+    }
+
+    deinit {
+        if status != CursorStatus.closed {
+            close()
+        }
+    }
+}
+
+/*
+ * A cursor implementation that wraps an array.
+ */
+open class ArrayCursor<T> : Cursor<T> {
+    fileprivate var data: [T]
+
+    open override var count: Int {
+        if status != .success {
+            return 0
+        }
+        return data.count
+    }
+
+    public init(data: [T], status: CursorStatus, statusMessage: String) {
+        self.data = data
+        super.init(status: status, msg: statusMessage)
+    }
+
+    public convenience init(data: [T]) {
+        self.init(data: data, status: CursorStatus.success, statusMessage: "Success")
+    }
+
+    open override subscript(index: Int) -> T? {
+        get {
+            if index >= data.count || index < 0 || status != .success {
+                return nil
+            }
+            return data[index]
+        }
+    }
+
+    override open func close() {
+        data = [T]()
+        super.close()
+    }
+}