value.js

// Copyright (c) 2014 Titanium I.T. LLC. All rights reserved. For license, see "README" or "LICENSE" file.
"use strict";

var ensure = require("../util/ensure.js");
var oop = require("../util/oop.js");
var shim = require("../util/shim.js");

var Me = module.exports = function Value() {};
Me.extend = oop.extendFn(Me);
oop.makeAbstract(Me, [
	"diff",
	"toString",
	"compatibility"
]);

Me.safe = function safe(fn) {
	return function() {
		ensureCompatibility(this, this.compatibility(), arguments);
		return fn.apply(this, arguments);
	};
};

Me.prototype.value = function value() {
	ensure.signature(arguments, []);
	return this;
};

Me.prototype.equals = function equals(that) {
	return this.diff(that) === "";
};

function ensureCompatibility(self, compatible, args) {
	var arg;
	for (var i = 0; i < args.length; i++) {   // args is not an Array, can't use forEach
		arg = args[i];
		checkOneArg(self, compatible, arg);
	}
}

function checkOneArg(self, compatible, arg) {
	var type = typeof arg;
	if (arg === null) type = "null";
	if (type !== "object") throwError(type);

	for (var i = 0; i < compatible.length; i++) {
		if (arg instanceof compatible[i]) return;
	}
	throwError(oop.instanceName(arg));

	function throwError(type) {
		throw new Error(oop.instanceName(self) + " isn't compatible with " + type);
	}
}