Add Array/appending(_:) and Array/appending(contentsOf:)

Author: SplittyDev

Sources/Extensions/Array/Array+Selectors.swift

@@ -44,6 +44,32 @@ public extension Array where Element: Equatable {
         let erasedObject = object as AnyObject?
         return self.filter { $0 as AnyObject? !== erasedObject }
     }
+
+    /// Returns a new array with the specified element appended to the end.
+    ///
+    /// - Parameter element: The element to append.
+    /// - Returns: A new array containing all elements of the original array followed by the appended element.
+    /// - Complexity: `O(n + 1)`, where n is the length of the original array.
+    func appending(_ element: Element) -> [Element] {
+        var arr = [Element]()
+        arr.reserveCapacity(self.count + 1)
+        arr.append(contentsOf: self)
+        arr.append(element)
+        return arr
+    }
+
+    /// Returns a new array with the specified elements appended to the end.
+    ///
+    /// - Parameter element: The element to append.
+    /// - Returns: A new array containing all elements of the original array followed by the appended elements.
+    /// - Complexity: `O(n + m)`, where n is the length of the original array and m is the length of the contents array.
+    func appending(contentsOf contents: [Element]) -> [Element] {
+        var arr = [Element]()
+        arr.reserveCapacity(self.count + contents.count)
+        arr.append(contentsOf: self)
+        arr.append(contentsOf: contents)
+        return arr
+    }
 }
 
 public extension Array where Element: Hashable {

Tests/Extensions/ArrayTests.swift

@@ -228,4 +228,16 @@ final class ArrayTests: XCTestCase {
         subject.move(fromOffset: 0, toOffset: 0)
         XCTAssertEqual(subject, [0])
     }
+
+    func testAppendingElement() {
+        XCTAssertEqual([Int]().appending(1).appending(2), [1, 2])
+        XCTAssertEqual([1].appending(2).appending(3), [1, 2, 3])
+    }
+
+    func testAppendingElements() {
+        XCTAssertEqual([Int]().appending(contentsOf: [Int]()), [Int]())
+        XCTAssertEqual([Int]().appending(contentsOf: [1, 2]), [1, 2])
+        XCTAssertEqual([1].appending(contentsOf: [2, 3]), [1, 2, 3])
+        XCTAssertEqual([1, 2].appending(contentsOf: [Int]()), [1, 2])
+    }
 }