ValidateAndApplyPropertyDescriptor.js

'use strict';

var GetIntrinsic = require('get-intrinsic');

var $TypeError = GetIntrinsic('%TypeError%');

var DefineOwnProperty = require('../helpers/DefineOwnProperty');
var isPropertyDescriptor = require('../helpers/isPropertyDescriptor');
var isSamePropertyDescriptor = require('../helpers/isSamePropertyDescriptor');

var FromPropertyDescriptor = require('./FromPropertyDescriptor');
var IsAccessorDescriptor = require('./IsAccessorDescriptor');
var IsDataDescriptor = require('./IsDataDescriptor');
var IsGenericDescriptor = require('./IsGenericDescriptor');
var IsPropertyKey = require('./IsPropertyKey');
var SameValue = require('./SameValue');
var Type = require('./Type');

// https://262.ecma-international.org/6.0/#sec-validateandapplypropertydescriptor
// https://262.ecma-international.org/8.0/#sec-validateandapplypropertydescriptor

// eslint-disable-next-line max-lines-per-function, max-statements
module.exports = function ValidateAndApplyPropertyDescriptor(O, P, extensible, Desc, current) {
	// this uses the ES2017+ logic, since it fixes a number of bugs in the ES2015 logic.
	var oType = Type(O);
	if (oType !== 'Undefined' && oType !== 'Object') {
		throw new $TypeError('Assertion failed: O must be undefined or an Object');
	}
	if (Type(extensible) !== 'Boolean') {
		throw new $TypeError('Assertion failed: extensible must be a Boolean');
	}
	if (!isPropertyDescriptor({
		Type: Type,
		IsDataDescriptor: IsDataDescriptor,
		IsAccessorDescriptor: IsAccessorDescriptor
	}, Desc)) {
		throw new $TypeError('Assertion failed: Desc must be a Property Descriptor');
	}
	if (Type(current) !== 'Undefined' && !isPropertyDescriptor({
		Type: Type,
		IsDataDescriptor: IsDataDescriptor,
		IsAccessorDescriptor: IsAccessorDescriptor
	}, current)) {
		throw new $TypeError('Assertion failed: current must be a Property Descriptor, or undefined');
	}
	if (oType !== 'Undefined' && !IsPropertyKey(P)) {
		throw new $TypeError('Assertion failed: if O is not undefined, P must be a Property Key');
	}
	if (Type(current) === 'Undefined') {
		if (!extensible) {
			return false;
		}
		if (IsGenericDescriptor(Desc) || IsDataDescriptor(Desc)) {
			if (oType !== 'Undefined') {
				DefineOwnProperty(
					IsDataDescriptor,
					SameValue,
					FromPropertyDescriptor,
					O,
					P,
					{
						'[[Configurable]]': Desc['[[Configurable]]'],
						'[[Enumerable]]': Desc['[[Enumerable]]'],
						'[[Value]]': Desc['[[Value]]'],
						'[[Writable]]': Desc['[[Writable]]']
					}
				);
			}
		} else {
			if (!IsAccessorDescriptor(Desc)) {
				throw new $TypeError('Assertion failed: Desc is not an accessor descriptor');
			}
			if (oType !== 'Undefined') {
				return DefineOwnProperty(
					IsDataDescriptor,
					SameValue,
					FromPropertyDescriptor,
					O,
					P,
					Desc
				);
			}
		}
		return true;
	}
	if (IsGenericDescriptor(Desc) && !('[[Configurable]]' in Desc) && !('[[Enumerable]]' in Desc)) {
		return true;
	}
	if (isSamePropertyDescriptor({ SameValue: SameValue }, Desc, current)) {
		return true; // removed by ES2017, but should still be correct
	}
	// "if every field in Desc is absent, return true" can't really match the assertion that it's a Property Descriptor
	if (!current['[[Configurable]]']) {
		if (Desc['[[Configurable]]']) {
			return false;
		}
		if ('[[Enumerable]]' in Desc && !Desc['[[Enumerable]]'] === !!current['[[Enumerable]]']) {
			return false;
		}
	}
	if (IsGenericDescriptor(Desc)) {
		// no further validation is required.
	} else if (IsDataDescriptor(current) !== IsDataDescriptor(Desc)) {
		if (!current['[[Configurable]]']) {
			return false;
		}
		if (IsDataDescriptor(current)) {
			if (oType !== 'Undefined') {
				DefineOwnProperty(
					IsDataDescriptor,
					SameValue,
					FromPropertyDescriptor,
					O,
					P,
					{
						'[[Configurable]]': current['[[Configurable]]'],
						'[[Enumerable]]': current['[[Enumerable]]'],
						'[[Get]]': undefined
					}
				);
			}
		} else if (oType !== 'Undefined') {
			DefineOwnProperty(
				IsDataDescriptor,
				SameValue,
				FromPropertyDescriptor,
				O,
				P,
				{
					'[[Configurable]]': current['[[Configurable]]'],
					'[[Enumerable]]': current['[[Enumerable]]'],
					'[[Value]]': undefined
				}
			);
		}
	} else if (IsDataDescriptor(current) && IsDataDescriptor(Desc)) {
		if (!current['[[Configurable]]'] && !current['[[Writable]]']) {
			if ('[[Writable]]' in Desc && Desc['[[Writable]]']) {
				return false;
			}
			if ('[[Value]]' in Desc && !SameValue(Desc['[[Value]]'], current['[[Value]]'])) {
				return false;
			}
			return true;
		}
	} else if (IsAccessorDescriptor(current) && IsAccessorDescriptor(Desc)) {
		if (!current['[[Configurable]]']) {
			if ('[[Set]]' in Desc && !SameValue(Desc['[[Set]]'], current['[[Set]]'])) {
				return false;
			}
			if ('[[Get]]' in Desc && !SameValue(Desc['[[Get]]'], current['[[Get]]'])) {
				return false;
			}
			return true;
		}
	} else {
		throw new $TypeError('Assertion failed: current and Desc are not both data, both accessors, or one accessor and one data.');
	}
	if (oType !== 'Undefined') {
		return DefineOwnProperty(
			IsDataDescriptor,
			SameValue,
			FromPropertyDescriptor,
			O,
			P,
			Desc
		);
	}
	return true;
};