Dynamic node encoding + new formatters + various fixes

Sources/XMLCoder/Auxiliaries/Box/BoolBox.swift

@@ -17,9 +17,9 @@ struct BoolBox: Equatable {
     }
 
     init?(xmlString: String) {
-        switch xmlString {
-        case "false", "0": self.init(false)
-        case "true", "1": self.init(true)
+        switch xmlString.lowercased() {
+        case "false", "0", "n", "no": self.init(false)
+        case "true", "1", "y", "yes": self.init(true)
         case _: return nil
         }
     }

Sources/XMLCoder/Auxiliaries/Box/Box.swift

@@ -17,6 +17,17 @@ protocol SimpleBox: Box {
     // A simple tagging protocol, for now.
 }
 
-protocol SharedBoxProtocol {
-    func unbox() -> Box
+protocol TypeErasedSharedBoxProtocol {
+    func typeErasedUnbox() -> Box
+}
+
+protocol SharedBoxProtocol: TypeErasedSharedBoxProtocol {
+    associatedtype B: Box
+    func unbox() -> B
+}
+
+extension SharedBoxProtocol {
+    func typeErasedUnbox() -> Box {
+        return unbox()
+    }
 }

Sources/XMLCoder/Auxiliaries/Box/KeyedBox.swift

@@ -47,9 +47,7 @@ struct KeyedStorage<Key: Hashable & Comparable, Value> {
 }
 
 extension KeyedStorage: Sequence {
-    typealias Iterator = Buffer.Iterator
-
-    func makeIterator() -> Iterator {
+    func makeIterator() -> Buffer.Iterator {
         return buffer.makeIterator()
     }
 }
@@ -74,30 +72,27 @@ struct KeyedBox {
     typealias Attributes = KeyedStorage<Key, Attribute>
     typealias Elements = KeyedStorage<Key, Element>
 
-    var attributes: Attributes = [:]
     var elements: Elements = [:]
+    var attributes: Attributes = [:]
 
-    init() {
-        attributes = [:]
-        elements = [:]
+    func unbox() -> (elements: Elements, attributes: Attributes) {
+        return (
+            elements: elements,
+            attributes: attributes
+        )
     }
+}
 
+extension KeyedBox {
     init<E, A>(elements: E, attributes: A)
         where E: Sequence, E.Element == (Key, Element), A: Sequence, A.Element == (Key, Attribute) {
-        self.elements = Elements(Dictionary(uniqueKeysWithValues: elements))
-        self.attributes = Attributes(Dictionary(uniqueKeysWithValues: attributes))
+        let elements = Elements(Dictionary(uniqueKeysWithValues: elements))
+        let attributes = Attributes(Dictionary(uniqueKeysWithValues: attributes))
+        self.init(elements: elements, attributes: attributes)
     }
 
     init(elements: [Key: Element], attributes: [Key: Attribute]) {
-        self.elements = Elements(elements)
-        self.attributes = Attributes(attributes)
-    }
-
-    func unbox() -> (elements: Elements, attributes: Attributes) {
-        return (
-            elements: elements,
-            attributes: attributes
-        )
+        self.init(elements: Elements(elements), attributes: Attributes(attributes))
     }
 }
 

Sources/XMLCoder/Auxiliaries/Box/SharedBox.swift

@@ -30,7 +30,7 @@ extension SharedBox: Box {
 }
 
 extension SharedBox: SharedBoxProtocol {
-    func unbox() -> Box {
+    func unbox() -> Unboxed {
         return unboxed
     }
 }

Sources/XMLCoder/Auxiliaries/String+Extensions.swift

@@ -7,9 +7,9 @@
 
 import Foundation
 
-extension String {
+extension StringProtocol where Self.Index == String.Index {
     func escape(_ characterSet: [(character: String, escapedCharacter: String)]) -> String {
-        var string = self
+        var string = String(self)
 
         for set in characterSet {
             string = string.replacingOccurrences(of: set.character, with: set.escapedCharacter, options: .literal)
@@ -18,3 +18,28 @@ extension String {
         return string
     }
 }
+
+extension StringProtocol {
+    func capitalizingFirstLetter() -> Self {
+        guard count > 1 else {
+            return self
+        }
+        return Self(prefix(1).uppercased() + dropFirst())!
+    }
+
+    mutating func capitalizeFirstLetter() {
+        self = capitalizingFirstLetter()
+    }
+
+    func lowercasingFirstLetter() -> Self {
+        // avoid lowercasing single letters (I), or capitalized multiples (AThing ! to aThing, leave as AThing)
+        guard count > 1, !(String(prefix(2)) == prefix(2).lowercased()) else {
+            return self
+        }
+        return Self(prefix(1).lowercased() + dropFirst())!
+    }
+
+    mutating func lowercaseFirstLetter() {
+        self = lowercasingFirstLetter()
+    }
+}