Add DynamicNodeEncoding protocol

DynamicNodeEncoding allows easily adding the ability to choose if iVars should be attribute or element encoded by inheriting DynamicNodeEncoding and implimenting a single static function in any Codable class or struct.

This is simpler than the current method that requires a global dynamic encoding closure for every XMLEncoder instance. This allows changing the encoding where the data models live, rather than the creator of the XMLEncoder instance needing to have knowledge of all the possible structs and classes that the encoder might encounter at init time.

Sources/XMLCoder/Encoder/DynamicNodeEncoding.swift

@@ -0,0 +1,30 @@
+//
+//  DynamicNodeEncoding.swift
+//  XMLCoder
+//
+//  Created by Joseph Mattiello on 1/24/19.
+//
+
+import Foundation
+
+public protocol DynamicNodeEncoding: Encodable {
+    static func nodeEncoding(forKey key: CodingKey) -> XMLEncoder.NodeEncoding
+}
+
+public extension DynamicNodeEncoding {
+    static func nodeEncoding(forKey key: CodingKey) -> XMLEncoder.NodeEncoding {
+        return XMLEncoder.NodeEncoding.default
+    }
+}
+
+extension Array: DynamicNodeEncoding where Element: DynamicNodeEncoding {
+    public static func nodeEncoding(forKey key: CodingKey) -> XMLEncoder.NodeEncoding {
+        return Element.nodeEncoding(forKey: key)
+    }
+}
+
+extension DynamicNodeEncoding where Self: Collection, Self.Iterator.Element: DynamicNodeEncoding {
+    public static func nodeEncoding(forKey key: CodingKey) -> XMLEncoder.NodeEncoding {
+        return Element.nodeEncoding(forKey: key)
+    }
+}

Tests/XMLCoderTests/DynamicNodeEncodingTest.swift

@@ -0,0 +1,160 @@
+//
+//  SOAPSample.swift
+//  XMLCoderTests
+//
+//  Created by Joseph Mattiello on 1/23/19.
+//
+
+import Foundation
+import XCTest
+@testable import XMLCoder
+
+let libraryXML = """
+<?xml version="1.0" encoding="UTF-8"?>
+<library count="2">
+    <book id="123">
+        <id>123</id>
+        <title>Cat in the Hat</title>
+        <category main="Y">Kids</category>
+        <category main="N">Wildlife</category>
+    </book>
+    <book id="456">
+        <id>789</id>
+        <title>1984</title>
+        <category main="Y">Classics</category>
+        <category main="N">News</category>
+    </book>
+</library>
+""".data(using: .utf8)!
+
+private struct Library: Codable, Equatable {
+    let count: Int
+    let books: [Book]
+
+    private enum CodingKeys: String, CodingKey {
+        case count
+        case books = "book"
+    }
+}
+
+private struct Book: Codable, Equatable, DynamicNodeEncoding {
+    let id: UInt
+    let title: String
+    let categories: [Category]
+
+    private enum CodingKeys: String, CodingKey {
+        case id
+        case title
+        case categories = "category"
+    }
+
+    static func nodeEncoding(forKey key: CodingKey) -> XMLEncoder.NodeEncoding {
+        switch key {
+        case Book.CodingKeys.id: return .both
+        default: return .element
+        }
+    }
+}
+
+extension Book {
+    init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        id = try container.decode(UInt.self, forKey: .id)
+        title = try container.decode(String.self, forKey: .title)
+
+        var nested = try container.nestedUnkeyedContainer(forKey: .categories)
+
+        var decoded = [Category]()
+        var finished = false
+
+        while !finished {
+            do {
+                 let another = try nested.decode(Category.self)
+                decoded.append(another)
+            } catch DecodingError.valueNotFound {
+                finished = true
+            } catch {
+                throw error
+            }
+        }
+
+        categories = decoded
+    }
+}
+
+private struct Category: Codable, Equatable, DynamicNodeEncoding {
+    let main: Bool
+    let value: String
+
+    private enum CodingKeys: String, CodingKey {
+        case main
+        case value = ""
+    }
+
+    static func nodeEncoding(forKey key: CodingKey) -> XMLEncoder.NodeEncoding {
+        switch key {
+        case Category.CodingKeys.main:
+            return .attribute
+        default:
+            return .element
+        }
+    }
+}
+
+private func decodeArray<T>(_ decoder: Decoder, decode: (inout UnkeyedDecodingContainer) throws -> T) throws -> [T] {
+    let keyedContainer = try decoder.container(keyedBy: CodingKeys.self)
+    var container = try keyedContainer.nestedUnkeyedContainer(forKey: .value)
+
+    var decoded = [T]()
+    var finished = false
+
+    while !finished {
+        do {
+            decoded.append(try decode(&container))
+        } catch DecodingError.valueNotFound {
+            finished = true
+        } catch {
+            throw error
+        }
+    }
+
+    return decoded
+}
+
+final class IntrinsicTest: XCTestCase {
+
+    func testEncode() {
+        let book1 = Book(id: 123,
+                         title: "Cat in the Hat",
+                         categories: [
+                            Category(main: true, value: "Kids"),
+                            Category(main: false, value: "Wildlife")
+            ])
+
+        let book2 = Book(id: 456,
+                         title: "1984",
+                         categories: [
+                            Category(main: true, value: "Classics"),
+                            Category(main: false, value: "News")
+            ])
+
+        let library = Library(count: 2, books: [book1, book2])
+        let encoder = XMLEncoder()
+        encoder.outputFormatting = [.prettyPrinted]
+
+        let header = XMLHeader(version: 1.0, encoding: "UTF-8")
+        do {
+            let encoded = try encoder.encode(library, withRootKey: "library", header: header)
+            let xmlString = String(data: encoded, encoding: .utf8)
+            XCTAssertNotNil(xmlString)
+            print(xmlString!)
+        } catch {
+            print("Test threw error: " + error.localizedDescription)
+            XCTFail(error.localizedDescription)
+        }
+    }
+
+    static var allTests = [
+        ("testEncode", testEncode),
+        ]
+}

XMLCoder.xcodeproj/project.pbxproj

@@ -24,6 +24,8 @@
 		A61DCCD821DF9CA200C0A19D /* ClassTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = A61DCCD621DF8DB300C0A19D /* ClassTests.swift */; };
 		A61FE03921E4D60B0015D993 /* UnkeyedIntTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = A61FE03721E4D4F10015D993 /* UnkeyedIntTests.swift */; };
 		A61FE03C21E4EAB10015D993 /* KeyedIntTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = A61FE03A21E4EA8B0015D993 /* KeyedIntTests.swift */; };
+		B35157CE21F986DD009CA0CC /* DynamicNodeEncoding.swift in Sources */ = {isa = PBXBuildFile; fileRef = B35157CD21F986DD009CA0CC /* DynamicNodeEncoding.swift */; };
+		B3BE1D612202C1F600259831 /* DynamicNodeEncodingTest.swift in Sources */ = {isa = PBXBuildFile; fileRef = B3BE1D602202C1F600259831 /* DynamicNodeEncodingTest.swift */; };
 		BF63EF0021CCDED2001D38C5 /* XMLStackParserTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = BF63EEFF21CCDED2001D38C5 /* XMLStackParserTests.swift */; };
 		BF63EF0621CD7A74001D38C5 /* URLBox.swift in Sources */ = {isa = PBXBuildFile; fileRef = BF63EF0521CD7A74001D38C5 /* URLBox.swift */; };
 		BF63EF0821CD7AF8001D38C5 /* URLBoxTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = BF63EF0721CD7AF8001D38C5 /* URLBoxTests.swift */; };
@@ -126,6 +128,8 @@
 		A61DCCD621DF8DB300C0A19D /* ClassTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ClassTests.swift; sourceTree = "<group>"; };
 		A61FE03721E4D4F10015D993 /* UnkeyedIntTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UnkeyedIntTests.swift; sourceTree = "<group>"; };
 		A61FE03A21E4EA8B0015D993 /* KeyedIntTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = KeyedIntTests.swift; sourceTree = "<group>"; };
+		B35157CD21F986DD009CA0CC /* DynamicNodeEncoding.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DynamicNodeEncoding.swift; sourceTree = "<group>"; };
+		B3BE1D602202C1F600259831 /* DynamicNodeEncodingTest.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = DynamicNodeEncodingTest.swift; sourceTree = "<group>"; };
 		BF63EEFF21CCDED2001D38C5 /* XMLStackParserTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = XMLStackParserTests.swift; sourceTree = "<group>"; };
 		BF63EF0521CD7A74001D38C5 /* URLBox.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = URLBox.swift; sourceTree = "<group>"; };
 		BF63EF0721CD7AF8001D38C5 /* URLBoxTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = URLBoxTests.swift; sourceTree = "<group>"; };
@@ -329,6 +333,7 @@
 				OBJ_19 /* XMLKeyedEncodingContainer.swift */,
 				OBJ_20 /* XMLReferencingEncoder.swift */,
 				OBJ_21 /* XMLUnkeyedEncodingContainer.swift */,
+				B35157CD21F986DD009CA0CC /* DynamicNodeEncoding.swift */,
 			);
 			path = Encoder;
 			sourceTree = "<group>";
@@ -360,6 +365,7 @@
 				OBJ_38 /* RelationshipsTest.swift */,
 				BF63EF1D21CEC99A001D38C5 /* BenchmarkTests.swift */,
 				D1FC040421C7EF8200065B43 /* RJISample.swift */,
+				B3BE1D602202C1F600259831 /* DynamicNodeEncodingTest.swift */,
 				A61DCCD621DF8DB300C0A19D /* ClassTests.swift */,
 				D14D8A8521F1D6B300B0D31A /* SingleChildTests.swift */,
 			);
@@ -549,6 +555,7 @@
 				OBJ_53 /* EncodingErrorExtension.swift in Sources */,
 				BF9457B921CBB4DB005ACFDE /* XMLStackParser.swift in Sources */,
 				OBJ_54 /* XMLEncoder.swift in Sources */,
+				B35157CE21F986DD009CA0CC /* DynamicNodeEncoding.swift in Sources */,
 				BF9457BA21CBB4DB005ACFDE /* ISO8601DateFormatter.swift in Sources */,
 				OBJ_55 /* XMLEncodingStorage.swift in Sources */,
 				BF9457A921CBB498005ACFDE /* KeyedBox.swift in Sources */,
@@ -611,6 +618,7 @@
 				OBJ_85 /* NodeEncodingStrategyTests.swift in Sources */,
 				OBJ_86 /* NoteTest.swift in Sources */,
 				BF63EF0C21CD7F28001D38C5 /* EmptyTests.swift in Sources */,
+				B3BE1D612202C1F600259831 /* DynamicNodeEncodingTest.swift in Sources */,
 				BF9457F721CBB6BC005ACFDE /* DataTests.swift in Sources */,
 				BF9457EE21CBB6BC005ACFDE /* IntTests.swift in Sources */,
 				BF8171F221D3D03E00901EB0 /* SharedBoxTests.swift in Sources */,