String Interpolation, Equatability, Hashability (#48)

* String Interpolation, Equatability, Hashability

* More

* Add default for String

Sources/Html/Node.swift

@@ -20,6 +20,39 @@ public enum Node {
 }
 
 extension Node {
+  /// Default HTML DOCTYPE.
+  public static let doctype: Node = .doctype("html")
+
+  /// A root document node including the default HTML DOCTYPE.
+  public static func document(_ children: Node...) -> Node {
+    return .fragment([doctype] + children)
+  }
+
+  public mutating func append(_ node: Node) {
+    switch (self, node) {
+    case (.fragment(var nodes), .fragment(let moreNodes)):
+      nodes.append(contentsOf: moreNodes)
+      self = .fragment(nodes)
+    case (.fragment(var nodes), let node):
+      nodes.append(node)
+      self = .fragment(nodes)
+    case (let node, .fragment(var nodes)):
+      nodes.insert(node, at: nodes.startIndex)
+      self = .fragment(nodes)
+    case (.comment(var comment), .comment(let anotherComment)):
+      comment.append(contentsOf: anotherComment)
+      self = .comment(comment)
+    case (.raw(var raw), .raw(let anotherRaw)):
+      raw.append(contentsOf: anotherRaw)
+      self = .raw(raw)
+    case (.text(var text), .text(let anotherText)):
+      text.append(contentsOf: anotherText)
+      self = .text(text)
+    default:
+      self = .fragment([self, node])
+    }
+  }
+
   public var isEmpty: Bool {
     switch self {
     case let .comment(string), let .doctype(string), let .raw(string), let .text(string):
@@ -32,6 +65,64 @@ extension Node {
   }
 }
 
+extension Node: Equatable {
+  public static func == (lhs: Node, rhs: Node) -> Bool {
+    switch (lhs, rhs) {
+    case
+    let (.comment(lhs), .comment(rhs)),
+    let (.doctype(lhs), .doctype(rhs)),
+    let (.raw(lhs), .raw(rhs)),
+    let (.text(lhs), .text(rhs)):
+      return lhs == rhs
+    case let (
+      .element(lhsTag, lhsAttributes, lhsChildren),
+      .element(rhsTag, rhsAttributes, rhsChildren)):
+
+      return lhsTag == rhsTag
+        && zip(lhsAttributes, rhsAttributes).allSatisfy { $0 == $1 }
+        && lhsChildren == rhsChildren
+    case let (.fragment(lhs), .fragment(rhs)):
+      return lhs == rhs
+    default:
+      return false
+    }
+  }
+}
+
+extension Node: Hashable {
+  public func hash(into hasher: inout Hasher) {
+    enum HashingTag: String {
+      case comment, doctype, element, fragment, raw, text
+    }
+
+    switch self {
+    case let .comment(comment):
+      hasher.combine(HashingTag.comment)
+      hasher.combine(comment)
+    case let .doctype(doctype):
+      hasher.combine(HashingTag.doctype)
+      hasher.combine(doctype)
+    case let .element(tag, attributes, children):
+      hasher.combine(HashingTag.element)
+      hasher.combine(tag)
+      attributes.forEach {
+        hasher.combine($0)
+        hasher.combine($1)
+      }
+      hasher.combine(children)
+    case let .fragment(nodes):
+      hasher.combine(HashingTag.fragment)
+      hasher.combine(nodes)
+    case let .raw(raw):
+      hasher.combine(HashingTag.raw)
+      hasher.combine(raw)
+    case let .text(text):
+      hasher.combine(HashingTag.text)
+      hasher.combine(text)
+    }
+  }
+}
+
 extension Node: ExpressibleByArrayLiteral {
   public init(arrayLiteral elements: Node...) {
     self = .fragment(elements)
@@ -44,12 +135,40 @@ extension Node: ExpressibleByStringLiteral {
   }
 }
 
-extension Node {
-  /// Default HTML DOCTYPE.
-  public static let doctype: Node = .doctype("html")
+#if swift(>=5.0)
+public struct NodeStringInterpolation: StringInterpolationProtocol {
+  var node: Node
 
-  /// A root document node including the default HTML DOCTYPE.
-  public static func document(_ children: Node...) -> Node {
-    return .fragment([doctype] + children)
+  public init(literalCapacity: Int, interpolationCount: Int) {
+    self.node = .fragment([])
+  }
+
+  public mutating func appendInterpolation(_ value: Node) {
+    self.node.append(value)
+  }
+
+  public mutating func appendInterpolation(_ value: String) {
+    self.node.append(.text(value))
+  }
+
+  public mutating func appendLiteral(_ literal: String) {
+    self.node.append(.text(literal))
+  }
+}
+
+extension Node: ExpressibleByStringInterpolation {
+  public init(stringInterpolation: NodeStringInterpolation) {
+    self = stringInterpolation.node
+  }
+}
+#else
+extension Node: ExpressibleByStringInterpolation {
+  public init(stringInterpolation strings: Node...) {
+    self = .fragment(strings)
+  }
+
+  public init<T>(stringInterpolationSegment expr: T) {
+    self = .text("\(expr)")
   }
 }
+#endif