my-idlers/node_modules/d/lazy.js

"use strict";

var isPlainFunction = require("type/plain-function/is")
  , ensureValue     = require("type/value/ensure")
  , isValue         = require("type/value/is")
  , map             = require("es5-ext/object/map")
  , contains        = require("es5-ext/string/#/contains");

var call = Function.prototype.call
  , defineProperty = Object.defineProperty
  , getOwnPropertyDescriptor = Object.getOwnPropertyDescriptor
  , getPrototypeOf = Object.getPrototypeOf
  , hasOwnProperty = Object.prototype.hasOwnProperty
  , cacheDesc = { configurable: false, enumerable: false, writable: false, value: null }
  , define;

define = function (name, options) {
	var value, dgs, cacheName, desc, writable = false, resolvable, flat;
	options = Object(ensureValue(options));
	cacheName = options.cacheName;
	flat = options.flat;
	if (!isValue(cacheName)) cacheName = name;
	delete options.cacheName;
	value = options.value;
	resolvable = isPlainFunction(value);
	delete options.value;
	dgs = { configurable: Boolean(options.configurable), enumerable: Boolean(options.enumerable) };
	if (name !== cacheName) {
		dgs.get = function () {
			if (hasOwnProperty.call(this, cacheName)) return this[cacheName];
			cacheDesc.value = resolvable ? call.call(value, this, options) : value;
			cacheDesc.writable = writable;
			defineProperty(this, cacheName, cacheDesc);
			cacheDesc.value = null;
			if (desc) defineProperty(this, name, desc);
			return this[cacheName];
		};
	} else if (!flat) {
		dgs.get = function self() {
			var ownDesc;
			if (hasOwnProperty.call(this, name)) {
				ownDesc = getOwnPropertyDescriptor(this, name);
				// It happens in Safari, that getter is still called after property
				// was defined with a value, following workarounds that
				// While in IE11 it may happen that here ownDesc is undefined (go figure)
				if (ownDesc) {
					if (ownDesc.hasOwnProperty("value")) return ownDesc.value;
					if (typeof ownDesc.get === "function" && ownDesc.get !== self) {
						return ownDesc.get.call(this);
					}
					return value;
				}
			}
			desc.value = resolvable ? call.call(value, this, options) : value;
			defineProperty(this, name, desc);
			desc.value = null;
			return this[name];
		};
	} else {
		dgs.get = function self() {
			var base = this, ownDesc;
			if (hasOwnProperty.call(this, name)) {
				// It happens in Safari, that getter is still called after property
				// was defined with a value, following workarounds that
				ownDesc = getOwnPropertyDescriptor(this, name);
				if (ownDesc.hasOwnProperty("value")) return ownDesc.value;
				if (typeof ownDesc.get === "function" && ownDesc.get !== self) {
					return ownDesc.get.call(this);
				}
			}
			while (!hasOwnProperty.call(base, name)) base = getPrototypeOf(base);
			desc.value = resolvable ? call.call(value, base, options) : value;
			defineProperty(base, name, desc);
			desc.value = null;
			return base[name];
		};
	}
	dgs.set = function (value) {
		if (hasOwnProperty.call(this, name)) {
			throw new TypeError("Cannot assign to lazy defined '" + name + "' property of " + this);
		}
		dgs.get.call(this);
		this[cacheName] = value;
	};
	if (options.desc) {
		desc = {
			configurable: contains.call(options.desc, "c"),
			enumerable: contains.call(options.desc, "e")
		};
		if (cacheName === name) {
			desc.writable = contains.call(options.desc, "w");
			desc.value = null;
		} else {
			writable = contains.call(options.desc, "w");
			desc.get = dgs.get;
			desc.set = dgs.set;
		}
		delete options.desc;
	} else if (cacheName === name) {
		desc = {
			configurable: Boolean(options.configurable),
			enumerable: Boolean(options.enumerable),
			writable: Boolean(options.writable),
			value: null
		};
	}
	delete options.configurable;
	delete options.enumerable;
	delete options.writable;
	return dgs;
};

module.exports = function (props) {
	return map(props, function (desc, name) { return define(name, desc); });
};