Improved LinkedList: init from Sequence

Author: timstudt

Linked List/LinkedList.playground/Contents.swift

@@ -272,12 +272,12 @@ extension LinkedList {
     }
 }
 
-// MARK: - Extension to enable initialization from an Array
+// MARK: - Extension to enable initialization from a Sequence
 extension LinkedList {
-    convenience init(array: Array<T>) {
+    convenience init<S>(_ sequence: S) where S: Sequence, S.Element == T {
         self.init()
 
-        array.forEach { append($0) }
+        sequence.forEach { append($0) }
     }
 }
 

Linked List/LinkedList.swift

@@ -266,12 +266,12 @@ extension LinkedList {
     }
 }
 
-// MARK: - Extension to enable initialization from an Array
+// MARK: - Extension to enable initialization from a Sequence
 extension LinkedList {
-    convenience init(array: Array<T>) {
+    convenience init<S>(_ sequence: S) where S: Sequence, S.Element == T {
         self.init()
 
-        array.forEach { append($0) }
+        sequence.forEach { append($0) }
     }
 }
 

Linked List/Tests/LinkedListTests.swift

@@ -307,6 +307,17 @@ class LinkedListTest: XCTestCase {
         XCTAssertEqual(nodeCount, list.count)
     }
 
+    func testSequenceInitTypeInfer() {
+        let arrayInitInfer = LinkedList([1.0, 2.0, 3.0])
+
+        XCTAssertEqual(arrayInitInfer.count, 3)
+        XCTAssertEqual(arrayInitInfer.head?.value, 1.0)
+        XCTAssertEqual(arrayInitInfer.last?.value, 3.0)
+        XCTAssertEqual(arrayInitInfer[1], 2.0)
+        XCTAssertEqual(arrayInitInfer.removeLast(), 3.0)
+        XCTAssertEqual(arrayInitInfer.count, 2)
+    }
+
     func testArrayLiteralInitTypeInfer() {
         let arrayLiteralInitInfer: LinkedList = [1.0, 2.0, 3.0]