ZMapTable.swift

// ZMapTable.swift
//
// Copyright (c) 2016 Kaz Yoshikawa. Released under MIT License.

enum ZMapTableOption {
    case StrongToWeak
    case WeakToStrong
    case WeakToWeak
    case StrongToStrong
    
    var creator: () -> NSMapTable {
        switch self {
        case .StrongToWeak:   return NSMapTable.strongToWeakObjectsMapTable
        case .WeakToStrong:   return NSMapTable.weakToStrongObjectsMapTable
        case .WeakToWeak:     return NSMapTable.weakToWeakObjectsMapTable
        case .StrongToStrong: return NSMapTable.strongToStrongObjectsMapTable
        }
    }
}

class ZMapTable<K: AnyObject, V: AnyObject>: CustomStringConvertible {
    
    let mapTable: NSMapTable
    
    init(option: ZMapTableOption) {
        mapTable = option.creator()
    }
    
    subscript(key: K) -> V? {
        get { return self.mapTable.objectForKey(key) as? V }
        set { self.mapTable.setObject(newValue, forKey: key) }
    }
    
    var description: String {
        return self.mapTable.description
    }
}