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//
// File.swift
// Sage
//
// Copyright 2016-2017 Nikolai Vazquez
// Modified by SuperGeroy
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
/// A chess board file.
///
/// Files refer to the eight columns of a chess board, beginning with A and ending with H from left to right.
public enum File: Int, Comparable, CustomStringConvertible {
/// A direction in file.
public enum Direction {
/// Left direction.
case left
/// Right direction.
case right
}
/// File "A".
case a = 1
/// File "B".
case b = 2
/// File "C".
case c = 3
/// File "D".
case d = 4
/// File "E".
case e = 5
/// File "F".
case f = 6
/// File "G".
case g = 7
/// File "H".
case h = 8
/// A regardless of Swift version.
internal static let _a = File.a
/// B regardless of Swift version.
internal static let _b = File.b
/// C regardless of Swift version.
internal static let _c = File.c
/// D regardless of Swift version.
internal static let _d = File.d
/// E regardless of Swift version.
internal static let _e = File.e
/// F regardless of Swift version.
internal static let _f = File.f
/// G regardless of Swift version.
internal static let _g = File.g
/// H regardless of Swift version.
internal static let _h = File.h
}
extension File {
/// An array of all files.
public static let all: [File] = [.a, .b, .c, .d, .e, .f, .g, .h]
/// The column index of `self`.
public var index: Int {
return rawValue - 1
}
/// A textual representation of `self`.
public var description: String {
return String(character)
}
/// The character value of `self`.
public var character: Character {
switch self {
case .a: return "a"
case .b: return "b"
case .c: return "c"
case .d: return "d"
case .e: return "e"
case .f: return "f"
case .g: return "g"
case .h: return "h"
}
}
/// Create an instance from a character value.
public init?(_ character: Character) {
switch character {
case "A", "a": self = .a
case "B", "b": self = .b
case "C", "c": self = .c
case "D", "d": self = .d
case "E", "e": self = .e
case "F", "f": self = .f
case "G", "g": self = .g
case "H", "h": self = .h
default: return nil
}
}
/// Create a `File` from a zero-based column index.
public init?(index: Int) {
self.init(rawValue: index + 1)
}
/// Returns a rank from advancing `self` by `value`.
public func advanced(by value: Int) -> File? {
return File(rawValue: rawValue + value)
}
/// The next file after `self`.
public func next() -> File? {
return File(rawValue: (rawValue + 1))
}
/// The previous file to `self`.
public func previous() -> File? {
return File(rawValue: (rawValue - 1))
}
/// The opposite file of `self`.
public func opposite() -> File {
return File(rawValue: 9 - rawValue)!
}
/// The files from `self` to `other`.
public func to(_ other: File) -> [File] {
return _to(other)
}
/// The files between `self` and `other`.
public func between(_ other: File) -> [File] {
return _between(other)
}
}
extension File: ExpressibleByExtendedGraphemeClusterLiteral { }
extension File {
/// Create an instance initialized to `value`.
public init(unicodeScalarLiteral value: Character) {
guard let file = File(value) else {
fatalError("File value not within \"A\" and \"H\" or \"a\" and \"h\", inclusive")
}
self = file
}
/// Create an instance initialized to `value`.
public init(extendedGraphemeClusterLiteral value: Character) {
self.init(unicodeScalarLiteral: value)
}
}
/// Returns `true` if one file is further left than the other.
public func < (lhs: File, rhs: File) -> Bool {
return lhs.rawValue < rhs.rawValue
}
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