lol, promise constructor

gistfile1.txt

//
//  Promise.swift
//  Promise
//
//  Created by Benjamin Gruenbaum on 8/12/14.
//  Copyright (c) 2014 Tipranks. All rights reserved.
//

import Foundation


public class Promise<T,E>{
    
    var state:PromiseState<T,E> = PromiseState(state: .Pending, value: nil, error: nil)
    
    var fHandlers:[(T) -> ()] = []
    var rHandlers:[(E) -> ()] = []
    
    init(fn:((T) -> (), reject:(E) -> ()) -> ()) {
        fn({[unowned self] (t:T) in
            for handler in self.fHandlers {
                handler(t)
            }
        } ,
        {[unowned self] (e:E) in
            for handler in self.rHandlers {
                handler(e)
            }
        })
    }
    private init(){

    }
    func then<NT,NE>(onFulfilled:(T) -> Promise<NT,NE>) -> Promise<NT,NE>{
        var p =  Promise<NT,NE>()
        fHandlers.append({ (t:T) in
            let res = onFulfilled(t)
            res.then({ p.fulfill($0) })
            res.catch({ p.reject($0) })
        })
        return p
    }
    
    func then<NT>(onFulfilled:(T) -> NT) -> Promise<NT,E> {
        var p =  Promise<NT,E>()
        fHandlers.append({ (t:T) in
            let res = onFulfilled(t)
            p.fulfill(res)
        })
        return p
    }
    func catch<NT,NE>(onRejected: (E) -> Promise<NT,NE>) -> Promise<NT,NE>{
        var p = Promise<NT,NE>()
        rHandlers.append({ (t:E) in
            let res = onRejected(t)
            res.then({ p.fulfill($0) })
            res.catch({ p.reject($0) })
        })
        return p;
    }
    func catch<NT>(onRejected: (E) -> NT) -> Promise<NT,E> {
        var p =  Promise<NT,E>()
        rHandlers.append({ (t:E) in
            let res = onRejected(t)
            p.fulfill(res)
        })
        return p
    }
    
    private func fulfill(val:T) {
        if state.state != .Pending {
            return
        }
        self.state.state = .Fulfilled
        self.state.value = val
    }
    
    private func reject(err:E) {
        if state.state != .Pending {
            return
        }
        assert(self.state.state != .Rejected)
        self.state.state = .Rejected
        self.state.error = err
    }
    
}

struct PromiseState<T,E> {
    var state:State
    var value:T?
    var error:E?
}

// hack for - unimplemented IR generation feature non-fixed multi-payload enum layout
enum State {
    case Pending
    case Fulfilled
    case Rejected
}