defr little flow control library to turn callback apis into promises

defr-promise-converter

w = window

w.defr = (fnOrCtx, fnOrUndef) ->
    ctx = if fnOrUndef then fnOrCtx else window
    fn = if fnOrUndef then fnOrUndef else fnOrCtx
    submittedArgs = null
    getDeferredGenerator = (_.find(defr.conversions, (c)->c.canAdapt fn, ctx)?.adapt || defr.defaultConversion)
    getDeferred = _.wrap getDeferredGenerator(fn, ctx), (fn, args...) ->
        submittedArgs = _.toArray args
        fn.apply @, args
    _.compose ((d)-> d.fail (logResults "error", -> console.log this, "fn", fn, "ctx", ctx, "args", submittedArgs)), getDeferred
defr.conversions = [
    {
        canAdapt: (fn, ctx) -> fn instanceof FileReader
        adapt: (reader) -> (startRead) -> 
            $.Deferred (d) ->
                reader.onerror = reader.onabort = d.reject
                reader.onloadend = (e, args...) -> d.resolve.apply @, (_.union [e.target.result], [e], args)
                startRead(reader)
    }
    {
        canAdapt: (fn) -> (_.isArray fn) and _.all fn, (x) -> x.done && x.pipe && x.fail && x.then;
        adapt: (deferreds) -> -> $.when.apply $, deferreds 
    }
]
defr.defaultConversion = (fn, ctx) -> (args...) ->
    $.Deferred (d) ->
        fn.apply ctx, (_.union args, [d.resolve, d.reject] )

logResults = (text, continueWith) -> ->
    w.logResults.last = ctx: @, args: (_.toArray arguments), text: text
    (w.logResults.stack = w.logResults.stack || []).push w.logResults.last
    console.log text||"", this, arguments
    continueWith?.apply @, arguments