Test + bug fixes

Sources/Engine/FEN.swift

@@ -0,0 +1,76 @@
+public struct Fen: CustomStringConvertible {
+	public enum CastlingAvailibility: String {
+		case Neither = "-"
+		case WhiteKingSide = "K"
+		case WhiteQueenSide = "Q"
+		case BlackKingSide = "k"
+		case BlackQueenSide = "q"
+		case WhiteSide = "KQ"
+		case BlackSide = "kq"
+		case Kings = "Kk"
+		case Queens = "Qq"
+		case WKingBQueen = "Kq"
+		case WQueenBKing = "Qk"
+		case All = "KQkq"
+	}
+	private var _fen: String = ""
+	private var value: String {
+		get {
+			return _fen
+		}
+		set {
+			_fen = newValue
+			let splitted = _fen.split(separator: " ")
+			guard splitted.count == 6 else {
+				return
+			}
+			placement = String(splitted[0])
+			activeColor =
+				switch splitted[1] {
+				case "w": .White
+				case "b": .Black
+				default: .White
+				}
+			castlingAvailibility =
+				CastlingAvailibility(
+					rawValue:
+						String(splitted[2])) ?? .Neither
+			enPassant = String(splitted[3])
+			halfMoveClock =
+				if let c = splitted[4].first, c.isWholeNumber {
+					UInt8(String(c)) ?? 0
+				} else {
+					0
+				}
+			fullMoveClock =
+				if let c = splitted[5].first, c.isWholeNumber {
+					UInt8(String(c)) ?? 1
+				} else {
+					1
+				}
+		}
+	}
+
+	public private(set) var placement: String = ""  // 70 chars
+	public private(set) var activeColor: Color = .White  // 1 char
+	public private(set) var castlingAvailibility: CastlingAvailibility = .All
+	// 1 to 4 chars
+	public private(set) var enPassant: String = "-"  // 1 or 2 chars
+	public private(set) var halfMoveClock: UInt8 = 0
+	public package(set) var fullMoveClock: UInt8 = 1
+
+	public init(fen value: String) {
+		self.value = value
+	}
+
+	public enum FenError: Error {
+		case InvalidCharacter(c: String, column: UInt8)
+		case NumberTooBig(n: UInt8, column: UInt8)
+		case NumberTooSmall(n: UInt8, column: UInt8)
+        case NotAppropriateLength(n: UInt8, column: UInt8)
+	}
+
+	public var description: String {
+		return value
+	}
+}