我发现安全数组获取，设置，插入，删除非常有用。我更倾向于记录并忽略错误，因为所有其他错误很快就会变得难以管理。完整代码如下
/**
Safe array get, set, insert and delete.
All action that would cause an error are ignored.
*/
extension Array {
/**
Removes element at index.
Action that would cause an error are ignored.
*/
mutating func remove(safeAt index: Index) {
guard index >= 0 && index < count else {
print("Index out of bounds while deleting item at index \(index) in \(self). This action is ignored.")
return
}
remove(at: index)
}
/**
Inserts element at index.
Action that would cause an error are ignored.
*/
mutating func insert(_ element: Element, safeAt index: Index) {
guard index >= 0 && index <= count else {
print("Index out of bounds while inserting item at index \(index) in \(self). This action is ignored")
return
}
insert(element, at: index)
}
/**
Safe get set subscript.
Action that would cause an error are ignored.
*/
subscript (safe index: Index) -> Element? {
get {
return indices.contains(index) ? self[index] : nil
}
set {
remove(safeAt: index)
if let element = newValue {
insert(element, safeAt: index)
}
}
}
}
测试
import XCTest
class SafeArrayTest: XCTestCase {
func testRemove_Successful() {
var array = [1, 2, 3]
array.remove(safeAt: 1)
XCTAssert(array == [1, 3])
}
func testRemove_Failure() {
var array = [1, 2, 3]
array.remove(safeAt: 3)
XCTAssert(array == [1, 2, 3])
}
func testInsert_Successful() {
var array = [1, 2, 3]
array.insert(4, safeAt: 1)
XCTAssert(array == [1, 4, 2, 3])
}
func testInsert_Successful_AtEnd() {
var array = [1, 2, 3]
array.insert(4, safeAt: 3)
XCTAssert(array == [1, 2, 3, 4])
}
func testInsert_Failure() {
var array = [1, 2, 3]
array.insert(4, safeAt: 5)
XCTAssert(array == [1, 2, 3])
}
func testGet_Successful() {
var array = [1, 2, 3]
let element = array[safe: 1]
XCTAssert(element == 2)
}
func testGet_Failure() {
var array = [1, 2, 3]
let element = array[safe: 4]
XCTAssert(element == nil)
}
func testSet_Successful() {
var array = [1, 2, 3]
array[safe: 1] = 4
XCTAssert(array == [1, 4, 3])
}
func testSet_Successful_AtEnd() {
var array = [1, 2, 3]
array[safe: 3] = 4
XCTAssert(array == [1, 2, 3, 4])
}
func testSet_Failure() {
var array = [1, 2, 3]
array[safe: 4] = 4
XCTAssert(array == [1, 2, 3])
}
}
