//
//  CachedValue.swift
//
//  Created by Chris Martin on 6/18/18.
//

import Foundation

class CachedValue<Element> {

    typealias ElementCreator = () -> Element
    private let creator: ElementCreator

    private var cachedValue: Element?

    public var value: Element {

        if let value = cachedValue {
            return value
        }
        else {
            let value = creator()
            cachedValue = value
            return value
        }
    }

    public init(creator: @escaping ElementCreator) {

        self.creator = creator
    }

    public func invalidate() {

        cachedValue = nil
    }
}