index.js

/*
prime
 - prototypal inheritance
*/"use strict"

var hasOwn = require("mout/object/hasOwn"),
    mixIn  = require("mout/object/mixIn"),
    create = require("mout/lang/createObject"),
    kindOf = require("mout/lang/kindOf")

var hasDescriptors = true

try {
    Object.defineProperty({}, "~", {})
    Object.getOwnPropertyDescriptor({}, "~")
} catch (e){
    hasDescriptors = false
}

// we only need to be able to implement "toString" and "valueOf" in IE < 9
var hasEnumBug = !({valueOf: 0}).propertyIsEnumerable("valueOf"),
    buggy      = ["toString", "valueOf"]

var verbs = /^constructor|inherits|mixin$/

var implement = function(proto){
    var prototype = this.prototype

    for (var key in proto){
        if (key.match(verbs)) continue
        if (hasDescriptors){
            var descriptor = Object.getOwnPropertyDescriptor(proto, key)
            if (descriptor){
                Object.defineProperty(prototype, key, descriptor)
                continue
            }
        }
        prototype[key] = proto[key]
    }

    if (hasEnumBug) for (var i = 0; (key = buggy[i]); i++){
        var value = proto[key]
        if (value !== Object.prototype[key]) prototype[key] = value
    }

    return this
}

var prime = function(proto){

    if (kindOf(proto) === "Function") proto = {constructor: proto}

    var superprime = proto.inherits

    // if our nice proto object has no own constructor property
    // then we proceed using a ghosting constructor that all it does is
    // call the parent's constructor if it has a superprime, else an empty constructor
    // proto.constructor becomes the effective constructor
    var constructor = (hasOwn(proto, "constructor")) ? proto.constructor : (superprime) ? function(){
        return superprime.apply(this, arguments)
    } : function(){}

    if (superprime){

        mixIn(constructor, superprime)

        var superproto = superprime.prototype
        // inherit from superprime
        var cproto = constructor.prototype = create(superproto)

        // setting constructor.parent to superprime.prototype
        // because it's the shortest possible absolute reference
        constructor.parent = superproto
        cproto.constructor = constructor
    }

    if (!constructor.implement) constructor.implement = implement

    var mixins = proto.mixin
    if (mixins){
        if (kindOf(mixins) !== "Array") mixins = [mixins]
        for (var i = 0; i < mixins.length; i++) constructor.implement(create(mixins[i].prototype))
    }

    // implement proto and return constructor
    return constructor.implement(proto)

}

module.exports = prime