Parsing and rendering macOS shortcuts

Shortcut.swift

import Cocoa

fileprivate let modifierMap = [
    "cmd": "⌘",
    "command": "⌘",
    "shift": "⇧",
    "control": "^",
    "ctrl": "^",
    "opt": "⌥",
    "option": "⌥",
    "alt": "⌥",
    
    "⌘": "⌘",
    "⇧": "⇧",
    "⌥": "⌥",
    "^": "^",
]

fileprivate let virtualKeyMap = [
    "return": "↩", // kVK_Return
    "enter": "↩", // kVK_Return
    "ansi_enter": "⌤", // kVK_ANSI_KeypadEnter
    "clear": "⌧", // kVK_ANSI_KeypadClear
    "tab": "⇥", // kVK_Tab
    "space": "␣", // kVK_Space
    "delete": "⌫", // kVK_Delete
    "del": "⌫", // kVK_Delete
    "escape": "⎋", // kVK_Escape
    "esc": "⎋", // kVK_Escape
    "caps": "⇪", // kVK_CapsLock
    "capslock": "⇪", // kVK_CapsLock
    "function": "fn", // kVK_Function
    "fn": "fn", // kVK_Function
    "f1": "F1", // kVK_F1
    "f2": "F2", // kVK_F2
    "f3": "F3", // kVK_F3
    "f4": "F4", // kVK_F4
    "f5": "F5", // kVK_F5
    "f6": "F6", // kVK_F6
    "f7": "F7", // kVK_F7
    "f8": "F8", // kVK_F8
    "f9": "F9", // kVK_F9
    "f10": "F10", // kVK_F10
    "f11": "F11", // kVK_F11
    "f12": "F12", // kVK_F12
    "f13": "F13", // kVK_F13
    "f14": "F14", // kVK_F14
    "f15": "F15", // kVK_F15
    "f16": "F16", // kVK_F16
    "f17": "F17", // kVK_F17
    "f18": "F18", // kVK_F18
    "f19": "F19", // kVK_F19
    "f20": "F20", // kVK_F20
    "home": "↖", // kVK_Home
    "pageup": "⇞", // kVK_PageUp
    "forwarddelete": "⌦", // kVK_ForwardDelete
    "fdel": "⌦", // kVK_ForwardDelete
    "end": "↘", // kVK_End
    "pagedown": "⇟", // kVK_PageDown
    "left": "◀︎", // kVK_LeftArrow
    "right": "▶︎", // kVK_RightArrow
    "down": "▼", // kVK_DownArrow
    "up": "▲", // kVK_UpArrow
    
    "↩": "↩", // kVK_Return
    "⌤": "⌤", // kVK_ANSI_KeypadEnter
    "⌧": "⌧", // kVK_ANSI_KeypadClear
    "⇥": "⇥", // kVK_Tab
    "␣": "␣", // kVK_Space
    "⌫": "⌫", // kVK_Delete
    "⎋": "⎋", // kVK_Escape
    "⇪": "⇪", // kVK_CapsLock
    "↖": "↖", // kVK_Home
    "⇞": "⇞", // kVK_PageUp
    "⌦": "⌦", // kVK_ForwardDelete
    "↘": "↘", // kVK_End
    "⇟": "⇟", // kVK_PageDown
    "◀︎": "◀︎", // kVK_LeftArrow
    "▶︎": "▶︎", // kVK_RightArrow
    "▼": "▼", // kVK_DownArrow
    "▲": "▲", // kVK_UpArrow
]


fileprivate enum ShortcutToken {
    case text(String)
    case space
}

fileprivate struct ShortcutLexer {
    static func genTokens(_ input: String) -> [ShortcutToken] {
        
        var index = input.startIndex
        var tokens = [ShortcutToken]()
        
        func advance() {
            input.formIndex(after: &index)
        }
        
        func rewind(count: Int) {
            input.formIndex(&index, offsetBy: -count)
        }
        
        var current: Character? {
            return index < input.endIndex ? input[index] : nil
        }
        
        func isSingleMatch(_ c: Character) -> Bool {
            let text = "\(c)"
            return modifierMap[text] == text || virtualKeyMap[text] == text
        }
            
        func nextToken() -> ShortcutToken? {
            guard let c = current else { return nil }
            switch c {
            case let c where c == " ":
                advance()
                return .space
            case let c where isSingleMatch(c):
                advance()
                return .text("\(c)")
            default:
                var text = ""
                while let c = current, c != " ", !isSingleMatch(c) {
                    text.append(c)
                    advance()
                }
                return .text(text)
            }
        }
        
        while let token = nextToken() {
            tokens.append(token)
        }
        
        return tokens
    }
}

ShortcutLexer.genTokens("cmd shift alt p")

struct Shortcut {
    let modifiers: Set<String>
    let virtualKey: String
    let shortcut: String
    
    private var modString: String {
        var result = ""
        for mod in ["^","⌥","⇧","⌘"] where modifiers.contains(mod) {
            result.append(mod)
        }
        return result
    }
    
    var rendered: String {
        var result = ""
        result.append(modString)
        if !virtualKey.isEmpty {
            result.append(virtualKey)
        }
        else {
            result.append(shortcut)
        }
        return result
    }
    
    static func from(_ text: String) -> Shortcut {
        return ShortcutParser.genShortcut(text.lowercased())
    }
}

extension Shortcut : CustomDebugStringConvertible {
    var debugDescription: String {
        var desc = ""
        let mods = modString
        if !mods.isEmpty {
            desc.append("mods(\(mods))")
        }
        if !virtualKey.isEmpty {
            desc.append(desc.isEmpty ? "" : " ")
            desc.append("vkey(\(virtualKey))")
        }
        else if !shortcut.isEmpty {
            desc.append(desc.isEmpty ? "" : " ")
            desc.append("cmd(\(shortcut))")
        }
        return desc
    }
}


fileprivate struct ShortcutParser {
    static func genShortcut(_ text: String) -> Shortcut {
        let tokens = ShortcutLexer.genTokens(text)
        
        var modifiers = Set<String>()
        var virtualKey = ""
        var shortcut = ""
        
        for token in tokens {
            guard case let .text(t) = token else {
                continue
            }
            if let mod = modifierMap[t] {
                modifiers.insert(mod)
            }
            else if let vkey = virtualKeyMap[t] {
                virtualKey = vkey
            }
            else {
                shortcut = t.uppercased()
            }
        }
        
        return .init(
            modifiers: modifiers,
            virtualKey: virtualKey,
            shortcut: shortcut
        )
    }
}

Shortcut.from("cmd tab a").rendered
Shortcut.from("cmd fn q").rendered
Shortcut.from("cmd fn q l s").rendered
Shortcut.from("cmd del 1").rendered
Shortcut.from("cmd space").rendered
Shortcut.from("ctrl space")
Shortcut.from("ctrl up").rendered
Shortcut.from("ctrl shift down").rendered
Shortcut.from("opt cmd shift n").rendered
Shortcut.from("opt cmd shift /").rendered
Shortcut.from("opt cmd shift f1")
Shortcut.from("opt cmd shift f1 q")


enum ShortcutMatch: Int {
    case exact = 2
    case partial = 1
    case none = 0
}

func match(_ shortcut1: Shortcut, _ shortcut2: Shortcut) -> ShortcutMatch {
    let r1 = shortcut1.rendered
    let r2 = shortcut2.rendered
    if r1 == r2 {
        return .exact
    }
    if !shortcut1.modifiers.intersection(shortcut2.modifiers).isEmpty {
        return .partial
    }
    if shortcut1.virtualKey == shortcut2.virtualKey {
        return .partial
    }
    if shortcut1.shortcut == shortcut2.shortcut {
        return .partial
    }
    return .none
}


Shortcut.from("cmd shift q")
Shortcut.from("cmd shift q").rendered
Shortcut.from("alt shift cmd q").rendered
Shortcut.from("shift cmd del")
Shortcut.from("shift del").rendered
Shortcut.from("del").rendered

Shortcut.from("⌫").rendered
Shortcut.from("⌫").rendered
Shortcut.from("Q⌥⇧⌘").rendered == "⌥⇧⌘Q"
Shortcut.from("CONTROL HOME").rendered
Shortcut.from("CONTROL ALT SHIFT HOME").rendered
Shortcut.from("CONTROL ALT SHIFT CAPS").rendered
Shortcut.from("CONTROL ALT TAB").rendered
Shortcut.from("CONTROL ALT enter").rendered


match(Shortcut.from("cmd shift q"), Shortcut.from("cmd q"))
match(Shortcut.from("cmd shift q"), Shortcut.from("cmd q shift"))
match(Shortcut.from("cmd shift q"), Shortcut.from("q shift"))


match(Shortcut.from("⌫"), Shortcut.from("del"))

Shortcut.from("Q⌥⇧⌘")
Shortcut.from("⌫")