feat: Add BodyEncoder and BodyDecoder (#29)

Sources/KituraContracts/BodyDecoder.swift

@@ -0,0 +1,27 @@
+/**
+ * Copyright IBM Corporation 2018
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ **/
+
+import Foundation
+
+/**
+ A class that conforms to `BodyDecoder` must be able to decode from `Data` into a `Codable` type.
+ This class can then be used to produce input objects for a Codable route.
+ */
+public protocol BodyDecoder: AnyObject {
+    func decode<T : Decodable>(_ type: T.Type, from data: Data) throws -> T
+}
+
+extension JSONDecoder: BodyDecoder {}

Sources/KituraContracts/BodyEncoder.swift

@@ -0,0 +1,27 @@
+/**
+ * Copyright IBM Corporation 2018
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ **/
+
+import Foundation
+
+/**
+ A class that conforms to `BodyEncoder` must be able to encode a `Codable` type into `Data`.
+ This class can then be used to produce output objects for a Codable route.
+ */
+public protocol BodyEncoder: AnyObject {
+    func encode<T : Encodable>(_ value: T) throws -> Data
+}
+extension JSONEncoder: BodyEncoder {}
+

Sources/KituraContracts/CodableQuery/QueryDecoder.swift

@@ -38,7 +38,7 @@ import LoggerAPI
  - Non-optional `Bool` decodes to `false`
  - All other non-optional types throw a decoding error
  */
-public class QueryDecoder: Coder, Decoder {
+public class QueryDecoder: Coder, Decoder, BodyDecoder {
 
     /**
      The coding key path.

Sources/KituraContracts/CodableQuery/QueryEncoder.swift

@@ -37,7 +37,7 @@ extension CharacterSet {
  }
  ````
  */
-public class QueryEncoder: Coder, Encoder {
+public class QueryEncoder: Coder, Encoder, BodyEncoder {
 
     /**
      A `[String: String]` dictionary.