| //===----------------------------------------------------------------------===// |
| // |
| // This source file is part of the Swift.org open source project |
| // |
| // Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors |
| // Licensed under Apache License v2.0 with Runtime Library Exception |
| // |
| // See https://swift.org/LICENSE.txt for license information |
| // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors |
| // |
| //===----------------------------------------------------------------------===// |
| |
| // Random access for String.UTF16View, only when Foundation is |
| // imported. Making this API dependent on Foundation decouples the |
| // Swift core from a UTF16 representation. |
| extension String.UTF16View.Index : Strideable { |
| /// Construct from an integer offset. |
| public init(_ offset: Int) { |
| _precondition(offset >= 0, "Negative UTF16 index offset not allowed") |
| self.init(_offset: offset) |
| } |
| |
| public func distance(to other: String.UTF16View.Index) -> Int { |
| return _offset.distance(to: other._offset) |
| } |
| |
| public func advanced(by n: Int) -> String.UTF16View.Index { |
| return String.UTF16View.Index(_offset.advanced(by: n)) |
| } |
| } |
| |
| extension String.UTF16View : RandomAccessCollection {} |
| extension String.UTF16View.Indices : RandomAccessCollection {} |
| |
