From 58152c6ee764e2ea66b5ae9a4ed53ba3bae711c3 Mon Sep 17 00:00:00 2001
From: Ben Wetherfield <bwetherfield@gmail.com>
Date: Tue, 30 Jul 2019 23:50:28 -0700
Subject: [PATCH 1/3] Add test for empty struct choice elements

---
 Tests/XMLCoderTests/NestedChoiceTests.swift | 44 +++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/Tests/XMLCoderTests/NestedChoiceTests.swift b/Tests/XMLCoderTests/NestedChoiceTests.swift
index 4810c454..44344c49 100644
--- a/Tests/XMLCoderTests/NestedChoiceTests.swift
+++ b/Tests/XMLCoderTests/NestedChoiceTests.swift
@@ -227,6 +227,50 @@ class NestedChoiceTests: XCTestCase {
         XCTAssertEqual(result, expected)
     }
 
+    func testNestedEnumsWithEmptyStruct() throws {
+        let xml = """
+        <container>
+            <p>
+                <br></br>
+                <run>
+                    <id>1518</id>
+                    <text>I am answering it again.</text>
+                </run>
+                <properties>
+                    <id>431</id>
+                    <title>A Word About Wake Times</title>
+                </properties>
+            </p>
+            <p>
+                <run>
+                    <id>1519</id>
+                    <text>I am answering it again.</text>
+                </run>
+                <br />
+            </p>
+        </container>
+        """
+        let result = try XMLDecoder().decode(Container.self, from: xml.data(using: .utf8)!)
+        let expected = Container(
+            paragraphs: [
+                Paragraph(
+                    entries: [
+                        .br(Break()),
+                        .run(Run(id: 1518, text: "I am answering it again.")),
+                        .properties(Properties(id: 431, title: "A Word About Wake Times")),
+                    ]
+                ),
+                Paragraph(
+                    entries: [
+                        .run(Run(id: 1519, text: "I am answering it again.")),
+                        .br(Break()),
+                    ]
+                ),
+            ]
+        )
+        XCTAssertEqual(result, expected)
+    }
+
     func testNestedEnumsRoundTrip() throws {
         let original = Container(
             paragraphs: [

From c87b068f9fe873b60aef93777b87e53669372778 Mon Sep 17 00:00:00 2001
From: Ben Wetherfield <bwetherfield@gmail.com>
Date: Sat, 20 Jul 2019 23:19:37 -0700
Subject: [PATCH 2/3] Wrap NullBox for decoding

---
 .../XMLCoder/Auxiliaries/KeyedStorage.swift   |  2 +-
 .../Decoder/XMLKeyedDecodingContainer.swift   | 26 ++++++++++++++++---
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/Sources/XMLCoder/Auxiliaries/KeyedStorage.swift b/Sources/XMLCoder/Auxiliaries/KeyedStorage.swift
index 49a82d0d..740455fa 100644
--- a/Sources/XMLCoder/Auxiliaries/KeyedStorage.swift
+++ b/Sources/XMLCoder/Auxiliaries/KeyedStorage.swift
@@ -83,7 +83,7 @@ extension KeyedStorage where Key == String, Value == Box {
         } else if let value = element.value {
             result.append(StringBox(value), at: element.key)
         } else {
-            result.append(NullBox(), at: element.key)
+            result.append(SingleKeyedBox(key: element.key, element: NullBox()), at: element.key)
         }
 
         return result
diff --git a/Sources/XMLCoder/Decoder/XMLKeyedDecodingContainer.swift b/Sources/XMLCoder/Decoder/XMLKeyedDecodingContainer.swift
index cbf42eb2..4380315a 100644
--- a/Sources/XMLCoder/Decoder/XMLKeyedDecodingContainer.swift
+++ b/Sources/XMLCoder/Decoder/XMLKeyedDecodingContainer.swift
@@ -69,8 +69,14 @@ struct XMLKeyedDecodingContainer<K: CodingKey>: KeyedDecodingContainerProtocol {
     }
 
     public func decodeNil(forKey key: Key) throws -> Bool {
-        let elements = container.withShared { keyedBox in
-            keyedBox.elements[key.stringValue]
+        let elements = container.withShared { keyedBox -> [Box] in
+            keyedBox.elements[key.stringValue].map {
+                if let singleKeyed = $0 as? SingleKeyedBox {
+                    return singleKeyed.element
+                } else {
+                    return $0
+                }
+            }
         }
 
         let attributes = container.withShared { keyedBox in
@@ -232,14 +238,26 @@ extension XMLKeyedDecodingContainer {
                     let keyString = key.stringValue.isEmpty ? "value" : key.stringValue
                     let value = keyedBox.elements[keyString]
                     if !value.isEmpty {
-                        return value
+                        return value.map {
+                            if let singleKeyed = $0 as? SingleKeyedBox {
+                                return singleKeyed.element
+                            } else {
+                                return $0
+                            }
+                        }
                     } else if let value = keyedBox.value {
                         return [value]
                     } else {
                         return []
                     }
                 } else {
-                    return keyedBox.elements[key.stringValue]
+                    return keyedBox.elements[key.stringValue].map {
+                        if let singleKeyed = $0 as? SingleKeyedBox {
+                            return singleKeyed.element
+                        } else {
+                            return $0
+                        }
+                    }
                 }
             }
 

From fd0a3a88510d099582b3b0296f0baac186c2ada9 Mon Sep 17 00:00:00 2001
From: Ben Wetherfield <bwetherfield@gmail.com>
Date: Wed, 31 Jul 2019 00:30:05 -0700
Subject: [PATCH 3/3] Refactor needless map

---
 .../Decoder/XMLKeyedDecodingContainer.swift        | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/Sources/XMLCoder/Decoder/XMLKeyedDecodingContainer.swift b/Sources/XMLCoder/Decoder/XMLKeyedDecodingContainer.swift
index 4380315a..e236db91 100644
--- a/Sources/XMLCoder/Decoder/XMLKeyedDecodingContainer.swift
+++ b/Sources/XMLCoder/Decoder/XMLKeyedDecodingContainer.swift
@@ -69,14 +69,8 @@ struct XMLKeyedDecodingContainer<K: CodingKey>: KeyedDecodingContainerProtocol {
     }
 
     public func decodeNil(forKey key: Key) throws -> Bool {
-        let elements = container.withShared { keyedBox -> [Box] in
-            keyedBox.elements[key.stringValue].map {
-                if let singleKeyed = $0 as? SingleKeyedBox {
-                    return singleKeyed.element
-                } else {
-                    return $0
-                }
-            }
+        let elements = container.withShared { keyedBox in
+            keyedBox.elements[key.stringValue]
         }
 
         let attributes = container.withShared { keyedBox in
@@ -85,6 +79,10 @@ struct XMLKeyedDecodingContainer<K: CodingKey>: KeyedDecodingContainerProtocol {
 
         let box = elements.first ?? attributes.first
 
+        if let singleKeyed = box as? SingleKeyedBox {
+            return singleKeyed.element.isNull
+        }
+
         return box?.isNull ?? true
     }