make Range and ClosedRange conditionally Codable

stdlib/public/core/ClosedRange.swift

@@ -456,3 +456,22 @@ extension ClosedRange {
 // shorthand. TODO: Add documentation
 public typealias CountableClosedRange<Bound: Strideable> = ClosedRange<Bound>
   where Bound.Stride : SignedInteger
+
+extension ClosedRange : Codable where Bound : Codable {
+    private enum CodingKeys : String, CodingKey {
+        case lowerBound = "lowerBound", upperBound = "upperBound"
+    }
+
+    public init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        let lowerBound = try container.decode(Bound.self, forKey: .lowerBound)
+        let upperBound = try container.decode(Bound.self, forKey: .upperBound)
+        self = lowerBound...upperBound
+    }
+
+    public func encode(to encoder: Encoder) throws {
+        var container = encoder.container(keyedBy: CodingKeys.self)
+        try container.encode(lowerBound, forKey: .lowerBound)
+        try container.encode(upperBound, forKey: .upperBound)
+    }
+}

stdlib/public/core/Range.swift

@@ -898,3 +898,22 @@ public typealias CountableRange<Bound: Strideable> = Range<Bound>
 // shorthand. TODO: Add documentation
 public typealias CountablePartialRangeFrom<Bound: Strideable> = PartialRangeFrom<Bound>
   where Bound.Stride : SignedInteger
+
+extension Range : Codable where Bound : Codable {
+    private enum CodingKeys : String, CodingKey {
+        case lowerBound = "lowerBound", upperBound = "upperBound"
+    }
+
+    public init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        let lowerBound = try container.decode(Bound.self, forKey: .lowerBound)
+        let upperBound = try container.decode(Bound.self, forKey: .upperBound)
+        self = lowerBound..<upperBound
+    }
+
+    public func encode(to encoder: Encoder) throws {
+        var container = encoder.container(keyedBy: CodingKeys.self)
+        try container.encode(lowerBound, forKey: .lowerBound)
+        try container.encode(upperBound, forKey: .upperBound)
+    }
+}