// Copyright (C) 2011-2012 Software Languages Lab, Vrije Universiteit Brussel
// This code is dual-licensed under both the Apache License and the MPL
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/* Version: MPL 1.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is a shim for the ES-Harmony reflection module
*
* The Initial Developer of the Original Code is
* Tom Van Cutsem, Vrije Universiteit Brussel.
* Portions created by the Initial Developer are Copyright (C) 2011-2012
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
*/
// ----------------------------------------------------------------------------
// This file is a polyfill for the upcoming ECMAScript Reflect API,
// including support for Proxies. See the draft specification at:
// http://wiki.ecmascript.org/doku.php?id=harmony:reflect_api
// http://wiki.ecmascript.org/doku.php?id=harmony:direct_proxies
// For an implementation of the Handler API, see handlers.js, which implements:
// http://wiki.ecmascript.org/doku.php?id=harmony:virtual_object_api
// This implementation supersedes the earlier polyfill at:
// code.google.com/p/es-lab/source/browse/trunk/src/proxies/DirectProxies.js
// This code was tested on tracemonkey / Firefox 12
// (and should run fine on older Firefox versions starting with FF4)
// The code also works correctly on
// v8 --harmony_proxies --harmony_weakmaps (v3.6.5.1)
// Language Dependencies:
// - ECMAScript 5/strict
// - "old" (i.e. non-direct) Harmony Proxies
// - Harmony WeakMaps
// Patches:
// - Object.{freeze,seal,preventExtensions}
// - Object.{isFrozen,isSealed,isExtensible}
// - Object.getPrototypeOf
// - Object.keys
// - Object.prototype.valueOf
// - Object.prototype.isPrototypeOf
// - Object.prototype.toString
// - Object.prototype.hasOwnProperty
// - Object.getOwnPropertyDescriptor
// - Object.defineProperty
// - Object.defineProperties
// - Object.getOwnPropertyNames
// - Object.getOwnPropertySymbols
// - Object.getPrototypeOf
// - Object.setPrototypeOf
// - Object.assign
// - Function.prototype.toString
// - Date.prototype.toString
// - Array.isArray
// - Array.prototype.concat
// - Proxy
// Adds new globals:
// - Reflect
// Direct proxies can be created via Proxy(target, handler)
// ----------------------------------------------------------------------------
(function(global){ // function-as-module pattern
"use strict";
// === Direct Proxies: Invariant Enforcement ===
// Direct proxies build on non-direct proxies by automatically wrapping
// all user-defined proxy handlers in a Validator handler that checks and
// enforces ES5 invariants.
// A direct proxy is a proxy for an existing object called the target object.
// A Validator handler is a wrapper for a target proxy handler H.
// The Validator forwards all operations to H, but additionally
// performs a number of integrity checks on the results of some traps,
// to make sure H does not violate the ES5 invariants w.r.t. non-configurable
// properties and non-extensible, sealed or frozen objects.
// For each property that H exposes as own, non-configurable
// (e.g. by returning a descriptor from a call to getOwnPropertyDescriptor)
// the Validator handler defines those properties on the target object.
// When the proxy becomes non-extensible, also configurable own properties
// are checked against the target.
// We will call properties that are defined on the target object
// "fixed properties".
// We will name fixed non-configurable properties "sealed properties".
// We will name fixed non-configurable non-writable properties "frozen
// properties".
// The Validator handler upholds the following invariants w.r.t. non-configurability:
// - getOwnPropertyDescriptor cannot report sealed properties as non-existent
// - getOwnPropertyDescriptor cannot report incompatible changes to the
// attributes of a sealed property (e.g. reporting a non-configurable
// property as configurable, or reporting a non-configurable, non-writable
// property as writable)
// - getPropertyDescriptor cannot report sealed properties as non-existent
// - getPropertyDescriptor cannot report incompatible changes to the
// attributes of a sealed property. It _can_ report incompatible changes
// to the attributes of non-own, inherited properties.
// - defineProperty cannot make incompatible changes to the attributes of
// sealed properties
// - deleteProperty cannot report a successful deletion of a sealed property
// - hasOwn cannot report a sealed property as non-existent
// - has cannot report a sealed property as non-existent
// - get cannot report inconsistent values for frozen data
// properties, and must report undefined for sealed accessors with an
// undefined getter
// - set cannot report a successful assignment for frozen data
// properties or sealed accessors with an undefined setter.
// - get{Own}PropertyNames lists all sealed properties of the target.
// - keys lists all enumerable sealed properties of the target.
// - enumerate lists all enumerable sealed properties of the target.
// - if a property of a non-extensible proxy is reported as non-existent,
// then it must forever be reported as non-existent. This applies to
// own and inherited properties and is enforced in the
// deleteProperty, get{Own}PropertyDescriptor, has{Own},
// get{Own}PropertyNames, keys and enumerate traps
// Violation of any of these invariants by H will result in TypeError being
// thrown.
// Additionally, once Object.preventExtensions, Object.seal or Object.freeze
// is invoked on the proxy, the set of own property names for the proxy is
// fixed. Any property name that is not fixed is called a 'new' property.
// The Validator upholds the following invariants regarding extensibility:
// - getOwnPropertyDescriptor cannot report new properties as existent
// (it must report them as non-existent by returning undefined)
// - defineProperty cannot successfully add a new property (it must reject)
// - getOwnPropertyNames cannot list new properties
// - hasOwn cannot report true for new properties (it must report false)
// - keys cannot list new properties
// Invariants currently not enforced:
// - getOwnPropertyNames lists only own property names
// - keys lists only enumerable own property names
// Both traps may list more property names than are actually defined on the
// target.
// Invariants with regard to inheritance are currently not enforced.
// - a non-configurable potentially inherited property on a proxy with
// non-mutable ancestry cannot be reported as non-existent
// (An object with non-mutable ancestry is a non-extensible object whose
// [[Prototype]] is either null or an object with non-mutable ancestry.)
// Changes in Handler API compared to previous harmony:proxies, see:
// http://wiki.ecmascript.org/doku.php?id=strawman:direct_proxies
// http://wiki.ecmascript.org/doku.php?id=harmony:direct_proxies
// ----------------------------------------------------------------------------
// ---- WeakMap polyfill ----
// TODO: find a proper WeakMap polyfill
// define an empty WeakMap so that at least the Reflect module code
// will work in the absence of WeakMaps. Proxy emulation depends on
// actual WeakMaps, so will not work with this little shim.
if (typeof WeakMap === "undefined") {
global.WeakMap = function(){};
global.WeakMap.prototype = {
get: function(k) { return undefined; },
set: function(k,v) { throw new Error("WeakMap not supported"); }
};
}
// ---- Normalization functions for property descriptors ----
function isStandardAttribute(name) {
return /^(get|set|value|writable|enumerable|configurable)$/.test(name);
}
// Adapted from ES5 section 8.10.5
function toPropertyDescriptor(obj) {
if (Object(obj) !== obj) {
throw new TypeError("property descriptor should be an Object, given: "+
obj);
}
var desc = {};
if ('enumerable' in obj) { desc.enumerable = !!obj.enumerable; }
if ('configurable' in obj) { desc.configurable = !!obj.configurable; }
if ('value' in obj) { desc.value = obj.value; }
if ('writable' in obj) { desc.writable = !!obj.writable; }
if ('get' in obj) {
var getter = obj.get;
if (getter !== undefined && typeof getter !== "function") {
throw new TypeError("property descriptor 'get' attribute must be "+
"callable or undefined, given: "+getter);
}
desc.get = getter;
}
if ('set' in obj) {
var setter = obj.set;
if (setter !== undefined && typeof setter !== "function") {
throw new TypeError("property descriptor 'set' attribute must be "+
"callable or undefined, given: "+setter);
}
desc.set = setter;
}
if ('get' in desc || 'set' in desc) {
if ('value' in desc || 'writable' in desc) {
throw new TypeError("property descriptor cannot be both a data and an "+
"accessor descriptor: "+obj);
}
}
return desc;
}
function isAccessorDescriptor(desc) {
if (desc === undefined) return false;
return ('get' in desc || 'set' in desc);
}
function isDataDescriptor(desc) {
if (desc === undefined) return false;
return ('value' in desc || 'writable' in desc);
}
function isGenericDescriptor(desc) {
if (desc === undefined) return false;
return !isAccessorDescriptor(desc) && !isDataDescriptor(desc);
}
function toCompletePropertyDescriptor(desc) {
var internalDesc = toPropertyDescriptor(desc);
if (isGenericDescriptor(internalDesc) || isDataDescriptor(internalDesc)) {
if (!('value' in internalDesc)) { internalDesc.value = undefined; }
if (!('writable' in internalDesc)) { internalDesc.writable = false; }
} else {
if (!('get' in internalDesc)) { internalDesc.get = undefined; }
if (!('set' in internalDesc)) { internalDesc.set = undefined; }
}
if (!('enumerable' in internalDesc)) { internalDesc.enumerable = false; }
if (!('configurable' in internalDesc)) { internalDesc.configurable = false; }
return internalDesc;
}
function isEmptyDescriptor(desc) {
return !('get' in desc) &&
!('set' in desc) &&
!('value' in desc) &&
!('writable' in desc) &&
!('enumerable' in desc) &&
!('configurable' in desc);
}
function isEquivalentDescriptor(desc1, desc2) {
return sameValue(desc1.get, desc2.get) &&
sameValue(desc1.set, desc2.set) &&
sameValue(desc1.value, desc2.value) &&
sameValue(desc1.writable, desc2.writable) &&
sameValue(desc1.enumerable, desc2.enumerable) &&
sameValue(desc1.configurable, desc2.configurable);
}
// copied from http://wiki.ecmascript.org/doku.php?id=harmony:egal
function sameValue(x, y) {
if (x === y) {
// 0 === -0, but they are not identical
return x !== 0 || 1 / x === 1 / y;
}
// NaN !== NaN, but they are identical.
// NaNs are the only non-reflexive value, i.e., if x !== x,
// then x is a NaN.
// isNaN is broken: it converts its argument to number, so
// isNaN("foo") => true
return x !== x && y !== y;
}
/**
* Returns a fresh property descriptor that is guaranteed
* to be complete (i.e. contain all the standard attributes).
* Additionally, any non-standard enumerable properties of
* attributes are copied over to the fresh descriptor.
*
* If attributes is undefined, returns undefined.
*
* See also: http://wiki.ecmascript.org/doku.php?id=harmony:proxies_semantics
*/
function normalizeAndCompletePropertyDescriptor(attributes) {
if (attributes === undefined) { return undefined; }
var desc = toCompletePropertyDescriptor(attributes);
// Note: no need to call FromPropertyDescriptor(desc), as we represent
// "internal" property descriptors as proper Objects from the start
for (var name in attributes) {
if (!isStandardAttribute(name)) {
Object.defineProperty(desc, name,
{ value: attributes[name],
writable: true,
enumerable: true,
configurable: true });
}
}
return desc;
}
/**
* Returns a fresh property descriptor whose standard
* attributes are guaranteed to be data properties of the right type.
* Additionally, any non-standard enumerable properties of
* attributes are copied over to the fresh descriptor.
*
* If attributes is undefined, will throw a TypeError.
*
* See also: http://wiki.ecmascript.org/doku.php?id=harmony:proxies_semantics
*/
function normalizePropertyDescriptor(attributes) {
var desc = toPropertyDescriptor(attributes);
// Note: no need to call FromGenericPropertyDescriptor(desc), as we represent
// "internal" property descriptors as proper Objects from the start
for (var name in attributes) {
if (!isStandardAttribute(name)) {
Object.defineProperty(desc, name,
{ value: attributes[name],
writable: true,
enumerable: true,
configurable: true });
}
}
return desc;
}
// store a reference to the real ES5 primitives before patching them later
var prim_preventExtensions = Object.preventExtensions,
prim_seal = Object.seal,
prim_freeze = Object.freeze,
prim_isExtensible = Object.isExtensible,
prim_isSealed = Object.isSealed,
prim_isFrozen = Object.isFrozen,
prim_getPrototypeOf = Object.getPrototypeOf,
prim_getOwnPropertyDescriptor = Object.getOwnPropertyDescriptor,
prim_defineProperty = Object.defineProperty,
prim_defineProperties = Object.defineProperties,
prim_keys = Object.keys,
prim_getOwnPropertyNames = Object.getOwnPropertyNames,
prim_getOwnPropertySymbols = Object.getOwnPropertySymbols,
prim_assign = Object.assign,
prim_isArray = Array.isArray,
prim_concat = Array.prototype.concat,
prim_isPrototypeOf = Object.prototype.isPrototypeOf,
prim_hasOwnProperty = Object.prototype.hasOwnProperty;
// these will point to the patched versions of the respective methods on
// Object. They are used within this module as the "intrinsic" bindings
// of these methods (i.e. the "original" bindings as defined in the spec)
var Object_isFrozen,
Object_isSealed,
Object_isExtensible,
Object_getPrototypeOf,
Object_getOwnPropertyNames;
/**
* A property 'name' is fixed if it is an own property of the target.
*/
function isFixed(name, target) {
return ({}).hasOwnProperty.call(target, name);
}
function isSealed(name, target) {
var desc = Object.getOwnPropertyDescriptor(target, name);
if (desc === undefined) { return false; }
return desc.configurable === false;
}
function isSealedDesc(desc) {
return desc !== undefined && desc.configurable === false;
}
/**
* Performs all validation that Object.defineProperty performs,
* without actually defining the property. Returns a boolean
* indicating whether validation succeeded.
*
* Implementation transliterated from ES5.1 section 8.12.9
*/
function isCompatibleDescriptor(extensible, current, desc) {
if (current === undefined && extensible === false) {
return false;
}
if (current === undefined && extensible === true) {
return true;
}
if (isEmptyDescriptor(desc)) {
return true;
}
if (isEquivalentDescriptor(current, desc)) {
return true;
}
if (current.configurable === false) {
if (desc.configurable === true) {
return false;
}
if ('enumerable' in desc && desc.enumerable !== current.enumerable) {
return false;
}
}
if (isGenericDescriptor(desc)) {
return true;
}
if (isDataDescriptor(current) !== isDataDescriptor(desc)) {
if (current.configurable === false) {
return false;
}
return true;
}
if (isDataDescriptor(current) && isDataDescriptor(desc)) {
if (current.configurable === false) {
if (current.writable === false && desc.writable === true) {
return false;
}
if (current.writable === false) {
if ('value' in desc && !sameValue(desc.value, current.value)) {
return false;
}
}
}
return true;
}
if (isAccessorDescriptor(current) && isAccessorDescriptor(desc)) {
if (current.configurable === false) {
if ('set' in desc && !sameValue(desc.set, current.set)) {
return false;
}
if ('get' in desc && !sameValue(desc.get, current.get)) {
return false;
}
}
}
return true;
}
// ES6 7.3.11 SetIntegrityLevel
// level is one of "sealed" or "frozen"
function setIntegrityLevel(target, level) {
var ownProps = Object_getOwnPropertyNames(target);
var pendingException = undefined;
if (level === "sealed") {
var l = +ownProps.length;
var k;
for (var i = 0; i < l; i++) {
k = String(ownProps[i]);
try {
Object.defineProperty(target, k, { configurable: false });
} catch (e) {
if (pendingException === undefined) {
pendingException = e;
}
}
}
} else {
// level === "frozen"
var l = +ownProps.length;
var k;
for (var i = 0; i < l; i++) {
k = String(ownProps[i]);
try {
var currentDesc = Object.getOwnPropertyDescriptor(target, k);
if (currentDesc !== undefined) {
var desc;
if (isAccessorDescriptor(currentDesc)) {
desc = { configurable: false }
} else {
desc = { configurable: false, writable: false }
}
Object.defineProperty(target, k, desc);
}
} catch (e) {
if (pendingException === undefined) {
pendingException = e;
}
}
}
}
if (pendingException !== undefined) {
throw pendingException;
}
return Reflect.preventExtensions(target);
}
// ES6 7.3.12 TestIntegrityLevel
// level is one of "sealed" or "frozen"
function testIntegrityLevel(target, level) {
var isExtensible = Object_isExtensible(target);
if (isExtensible) return false;
var ownProps = Object_getOwnPropertyNames(target);
var pendingException = undefined;
var configurable = false;
var writable = false;
var l = +ownProps.length;
var k;
var currentDesc;
for (var i = 0; i < l; i++) {
k = String(ownProps[i]);
try {
currentDesc = Object.getOwnPropertyDescriptor(target, k);
configurable = configurable || currentDesc.configurable;
if (isDataDescriptor(currentDesc)) {
writable = writable || currentDesc.writable;
}
} catch (e) {
if (pendingException === undefined) {
pendingException = e;
configurable = true;
}
}
}
if (pendingException !== undefined) {
throw pendingException;
}
if (level === "frozen" && writable === true) {
return false;
}
if (configurable === true) {
return false;
}
return true;
}
// ---- The Validator handler wrapper around user handlers ----
/**
* @param target the object wrapped by this proxy.
* As long as the proxy is extensible, only non-configurable properties
* are checked against the target. Once the proxy becomes non-extensible,
* invariants w.r.t. non-extensibility are also enforced.
*
* @param handler the handler of the direct proxy. The object emulated by
* this handler is validated against the target object of the direct proxy.
* Any violations that the handler makes against the invariants
* of the target will cause a TypeError to be thrown.
*
* Both target and handler must be proper Objects at initialization time.
*/
function Validator(target, handler) {
// for non-revokable proxies, these are const references
// for revokable proxies, on revocation:
// - this.target is set to null
// - this.handler is set to a handler that throws on all traps
this.target = target;
this.handler = handler;
}
Validator.prototype = {
/**
* If getTrap returns undefined, the caller should perform the
* default forwarding behavior.
* If getTrap returns normally otherwise, the return value
* will be a callable trap function. When calling the trap function,
* the caller is responsible for binding its |this| to |this.handler|.
*/
getTrap: function(trapName) {
var trap = this.handler[trapName];
if (trap === undefined) {
// the trap was not defined,
// perform the default forwarding behavior
return undefined;
}
if (typeof trap !== "function") {
throw new TypeError(trapName + " trap is not callable: "+trap);
}
return trap;
},
// === fundamental traps ===
/**
* If name denotes a fixed property, check:
* - whether targetHandler reports it as existent
* - whether the returned descriptor is compatible with the fixed property
* If the proxy is non-extensible, check:
* - whether name is not a new property
* Additionally, the returned descriptor is normalized and completed.
*/
getOwnPropertyDescriptor: function(name) {
"use strict";
var trap = this.getTrap("getOwnPropertyDescriptor");
if (trap === undefined) {
return Reflect.getOwnPropertyDescriptor(this.target, name);
}
name = String(name);
var desc = trap.call(this.handler, this.target, name);
desc = normalizeAndCompletePropertyDescriptor(desc);
var targetDesc = Object.getOwnPropertyDescriptor(this.target, name);
var extensible = Object.isExtensible(this.target);
if (desc === undefined) {
if (isSealedDesc(targetDesc)) {
throw new TypeError("cannot report non-configurable property '"+name+
"' as non-existent");
}
if (!extensible && targetDesc !== undefined) {
// if handler is allowed to return undefined, we cannot guarantee
// that it will not return a descriptor for this property later.
// Once a property has been reported as non-existent on a non-extensible
// object, it should forever be reported as non-existent
throw new TypeError("cannot report existing own property '"+name+
"' as non-existent on a non-extensible object");
}
return undefined;
}
// at this point, we know (desc !== undefined), i.e.
// targetHandler reports 'name' as an existing property
// Note: we could collapse the following two if-tests into a single
// test. Separating out the cases to improve error reporting.
if (!extensible) {
if (targetDesc === undefined) {
throw new TypeError("cannot report a new own property '"+
name + "' on a non-extensible object");
}
}
if (name !== undefined) {
if (!isCompatibleDescriptor(extensible, targetDesc, desc)) {
throw new TypeError("cannot report incompatible property descriptor "+
"for property '"+name+"'");
}
}
if (desc.configurable === false) {
if (targetDesc === undefined || targetDesc.configurable === true) {
// if the property is configurable or non-existent on the target,
// but is reported as a non-configurable property, it may later be
// reported as configurable or non-existent, which violates the
// invariant that if the property might change or disappear, the
// configurable attribute must be true.
throw new TypeError(
"cannot report a non-configurable descriptor " +
"for configurable or non-existent property '" + name + "'");
}
if ('writable' in desc && desc.writable === false) {
if (targetDesc.writable === true) {
// if the property is non-configurable, writable on the target,
// but is reported as non-configurable, non-writable, it may later
// be reported as non-configurable, writable again, which violates
// the invariant that a non-configurable, non-writable property
// may not change state.
throw new TypeError(
"cannot report non-configurable, writable property '" + name +
"' as non-configurable, non-writable");
}
}
}
return desc;
},
/**
* In the direct proxies design with refactored prototype climbing,
* this trap is deprecated. For proxies-as-prototypes, instead
* of calling this trap, the get, set, has or enumerate traps are
* called instead.
*
* In this implementation, we "abuse" getPropertyDescriptor to
* support trapping the get or set traps for proxies-as-prototypes.
* We do this by returning a getter/setter pair that invokes
* the corresponding traps.
*
* While this hack works for inherited property access, it has some
* quirks:
*
* In Firefox, this trap is only called after a prior invocation
* of the 'has' trap has returned true. Hence, expect the following
* behavior:
* <code>
* var child = Object.create(Proxy(target, handler));
* child[name] // triggers handler.has(target, name)
* // if that returns true, triggers handler.get(target, name, child)
* </code>
*
* On v8, the 'in' operator, when applied to an object that inherits
* from a proxy, will call getPropertyDescriptor and walk the proto-chain.
* That calls the below getPropertyDescriptor trap on the proxy. The
* result of the 'in'-operator is then determined by whether this trap
* returns undefined or a property descriptor object. That is why
* we first explicitly trigger the 'has' trap to determine whether
* the property exists.
*
* This has the side-effect that when enumerating properties on
* an object that inherits from a proxy in v8, only properties
* for which 'has' returns true are returned:
*
* <code>
* var child = Object.create(Proxy(target, handler));
* for (var prop in child) {
* // only enumerates prop if (prop in child) returns true
* }
* </code>
*/
getPropertyDescriptor: function(name) {
var handler = this;
if (!handler.has(name)) return undefined;
return {
get: function() {
return handler.get(this, name);
},
set: function(val) {
if (handler.set(this, name, val)) {
return val;
} else {
throw new TypeError("failed assignment to "+name);
}
},
enumerable: true,
configurable: true
};
},
/**
* If name denotes a fixed property, check for incompatible changes.
* If the proxy is non-extensible, check that new properties are rejected.
*/
defineProperty: function(name, desc) {
// TODO(tvcutsem): the current tracemonkey implementation of proxies
// auto-completes 'desc', which is not correct. 'desc' should be
// normalized, but not completed. Consider:
// Object.defineProperty(proxy, 'foo', {enumerable:false})
// This trap will receive desc =
// {value:undefined,writable:false,enumerable:false,configurable:false}
// This will also set all other attributes to their default value,
// which is unexpected and different from [[DefineOwnProperty]].
// Bug filed: https://bugzilla.mozilla.org/show_bug.cgi?id=601329
var trap = this.getTrap("defineProperty");
if (trap === undefined) {
// default forwarding behavior
return Reflect.defineProperty(this.target, name, desc);
}
name = String(name);
var descObj = normalizePropertyDescriptor(desc);
var success = trap.call(this.handler, this.target, name, descObj);
success = !!success; // coerce to Boolean
if (success === true) {
var targetDesc = Object.getOwnPropertyDescriptor(this.target, name);
var extensible = Object.isExtensible(this.target);
// Note: we could collapse the following two if-tests into a single
// test. Separating out the cases to improve error reporting.
if (!extensible) {
if (targetDesc === undefined) {
throw new TypeError("cannot successfully add a new property '"+
name + "' to a non-extensible object");
}
}
if (targetDesc !== undefined) {
if (!isCompatibleDescriptor(extensible, targetDesc, desc)) {
throw new TypeError("cannot define incompatible property "+
"descriptor for property '"+name+"'");
}
if (isDataDescriptor(targetDesc) &&
targetDesc.configurable === false &&
targetDesc.writable === true) {
if (desc.configurable === false && desc.writable === false) {
// if the property is non-configurable, writable on the target
// but was successfully reported to be updated to
// non-configurable, non-writable, it can later be reported
// again as non-configurable, writable, which violates
// the invariant that non-configurable, non-writable properties
// cannot change state
throw new TypeError(
"cannot successfully define non-configurable, writable " +
" property '" + name + "' as non-configurable, non-writable");
}
}
}
if (desc.configurable === false && !isSealedDesc(targetDesc)) {
// if the property is configurable or non-existent on the target,
// but is successfully being redefined as a non-configurable property,
// it may later be reported as configurable or non-existent, which violates
// the invariant that if the property might change or disappear, the
// configurable attribute must be true.
throw new TypeError(
"cannot successfully define a non-configurable " +
"descriptor for configurable or non-existent property '" +
name + "'");
}
}
return success;
},
/**
* On success, check whether the target object is indeed non-extensible.
*/
preventExtensions: function() {
var trap = this.getTrap("preventExtensions");
if (trap === undefined) {
// default forwarding behavior
return Reflect.preventExtensions(this.target);
}
var success = trap.call(this.handler, this.target);
success = !!success; // coerce to Boolean
if (success) {
if (Object_isExtensible(this.target)) {
throw new TypeError("can't report extensible object as non-extensible: "+
this.target);
}
}
return success;
},
/**
* If name denotes a sealed property, check whether handler rejects.
*/
delete: function(name) {
"use strict";
var trap = this.getTrap("deleteProperty");
if (trap === undefined) {
// default forwarding behavior
return Reflect.deleteProperty(this.target, name);
}
name = String(name);
var res = trap.call(this.handler, this.target, name);
res = !!res; // coerce to Boolean
var targetDesc;
if (res === true) {
targetDesc = Object.getOwnPropertyDescriptor(this.target, name);
if (targetDesc !== undefined && targetDesc.configurable === false) {
throw new TypeError("property '" + name + "' is non-configurable "+
"and can't be deleted");
}
if (targetDesc !== undefined && !Object_isExtensible(this.target)) {
// if the property still exists on a non-extensible target but
// is reported as successfully deleted, it may later be reported
// as present, which violates the invariant that an own property,
// deleted from a non-extensible object cannot reappear.
throw new TypeError(
"cannot successfully delete existing property '" + name +
"' on a non-extensible object");
}
}
return res;
},
/**
* The getOwnPropertyNames trap was replaced by the ownKeys trap,
* which now also returns an array (of strings or symbols) and
* which performs the same rigorous invariant checks as getOwnPropertyNames
*
* See issue #48 on how this trap can still get invoked by external libs
* that don't use the patched Object.getOwnPropertyNames function.
*/
getOwnPropertyNames: function() {
// Note: removed deprecation warning to avoid dependency on 'console'
// (and on node, should anyway use util.deprecate). Deprecation warnings
// can also be annoying when they are outside of the user's control, e.g.
// when an external library calls unpatched Object.getOwnPropertyNames.
// Since there is a clean fallback to `ownKeys`, the fact that the
// deprecated method is still called is mostly harmless anyway.
// See also issues #65 and #66.
// console.warn("getOwnPropertyNames trap is deprecated. Use ownKeys instead");
return this.ownKeys();
},
/**
* Checks whether the trap result does not contain any new properties
* if the proxy is non-extensible.
*
* Any own non-configurable properties of the target that are not included
* in the trap result give rise to a TypeError. As such, we check whether the
* returned result contains at least all sealed properties of the target
* object.
*
* Additionally, the trap result is normalized.
* Instead of returning the trap result directly:
* - create and return a fresh Array,
* - of which each element is coerced to a String
*
* This trap is called a.o. by Reflect.ownKeys, Object.getOwnPropertyNames
* and Object.keys (the latter filters out only the enumerable own properties).
*/
ownKeys: function() {
var trap = this.getTrap("ownKeys");
if (trap === undefined) {
// default forwarding behavior
return Reflect.ownKeys(this.target);
}
var trapResult = trap.call(this.handler, this.target);
// propNames is used as a set of strings
var propNames = Object.create(null);
var numProps = +trapResult.length;
var result = new Array(numProps);
for (var i = 0; i < numProps; i++) {
var s = String(trapResult[i]);
if (!Object.isExtensible(this.target) && !isFixed(s, this.target)) {
// non-extensible proxies don't tolerate new own property names
throw new TypeError("ownKeys trap cannot list a new "+
"property '"+s+"' on a non-extensible object");
}
propNames[s] = true;
result[i] = s;
}
var ownProps = Object_getOwnPropertyNames(this.target);
var target = this.target;
ownProps.forEach(function (ownProp) {
if (!propNames[ownProp]) {
if (isSealed(ownProp, target)) {
throw new TypeError("ownKeys trap failed to include "+
"non-configurable property '"+ownProp+"'");
}
if (!Object.isExtensible(target) &&
isFixed(ownProp, target)) {
// if handler is allowed to report ownProp as non-existent,
// we cannot guarantee that it will never later report it as
// existent. Once a property has been reported as non-existent
// on a non-extensible object, it should forever be reported as
// non-existent
throw new TypeError("ownKeys trap cannot report existing own property '"+
ownProp+"' as non-existent on a non-extensible object");
}
}
});
return result;
},
/**
* Checks whether the trap result is consistent with the state of the
* wrapped target.
*/
isExtensible: function() {
var trap = this.getTrap("isExtensible");
if (trap === undefined) {
// default forwarding behavior
return Reflect.isExtensible(this.target);
}
var result = trap.call(this.handler, this.target);
result = !!result; // coerce to Boolean
var state = Object_isExtensible(this.target);
if (result !== state) {
if (result) {
throw new TypeError("cannot report non-extensible object as extensible: "+
this.target);
} else {
throw new TypeError("cannot report extensible object as non-extensible: "+
this.target);
}
}
return state;
},
/**
* Check whether the trap result corresponds to the target's [[Prototype]]
*/
getPrototypeOf: function() {
var trap = this.getTrap("getPrototypeOf");
if (trap === undefined) {
// default forwarding behavior
return Reflect.getPrototypeOf(this.target);
}
var allegedProto = trap.call(this.handler, this.target);
if (!Object_isExtensible(this.target)) {
var actualProto = Object_getPrototypeOf(this.target);
if (!sameValue(allegedProto, actualProto)) {
throw new TypeError("prototype value does not match: " + this.target);
}
}
return allegedProto;
},
/**
* If target is non-extensible and setPrototypeOf trap returns true,
* check whether the trap result corresponds to the target's [[Prototype]]
*/
setPrototypeOf: function(newProto) {
var trap = this.getTrap("setPrototypeOf");
if (trap === undefined) {
// default forwarding behavior
return Reflect.setPrototypeOf(this.target, newProto);
}
var success = trap.call(this.handler, this.target, newProto);
success = !!success;
if (success && !Object_isExtensible(this.target)) {
var actualProto = Object_getPrototypeOf(this.target);
if (!sameValue(newProto, actualProto)) {
throw new TypeError("prototype value does not match: " + this.target);
}
}
return success;
},
/**
* In the direct proxies design with refactored prototype climbing,
* this trap is deprecated. For proxies-as-prototypes, for-in will
* call the enumerate() trap. If that trap is not defined, the
* operation is forwarded to the target, no more fallback on this
* fundamental trap.
*/
getPropertyNames: function() {
throw new TypeError("getPropertyNames trap is deprecated");
},
// === derived traps ===
/**
* If name denotes a fixed property, check whether the trap returns true.
*/
has: function(name) {
var trap = this.getTrap("has");
if (trap === undefined) {
// default forwarding behavior
return Reflect.has(this.target, name);
}
name = String(name);
var res = trap.call(this.handler, this.target, name);
res = !!res; // coerce to Boolean
if (res === false) {
if (isSealed(name, this.target)) {
throw new TypeError("cannot report existing non-configurable own "+
"property '"+ name + "' as a non-existent "+
"property");
}
if (!Object.isExtensible(this.target) &&
isFixed(name, this.target)) {
// if handler is allowed to return false, we cannot guarantee
// that it will not return true for this property later.
// Once a property has been reported as non-existent on a non-extensible
// object, it should forever be reported as non-existent
throw new TypeError("cannot report existing own property '"+name+
"' as non-existent on a non-extensible object");
}
}
// if res === true, we don't need to check for extensibility
// even for a non-extensible proxy that has no own name property,
// the property may have been inherited
return res;
},
/**
* If name denotes a fixed non-configurable, non-writable data property,
* check its return value against the previously asserted value of the
* fixed property.
*/
get: function(receiver, name) {
// experimental support for invoke() trap on platforms that
// support __noSuchMethod__
/*
if (name === '__noSuchMethod__') {
var handler = this;
return function(name, args) {
return handler.invoke(receiver, name, args);
}
}
*/
var trap = this.getTrap("get");
if (trap === undefined) {
// default forwarding behavior
return Reflect.get(this.target, name, receiver);
}
name = String(name);
var res = trap.call(this.handler, this.target, name, receiver);
var fixedDesc = Object.getOwnPropertyDescriptor(this.target, name);
// check consistency of the returned value
if (fixedDesc !== undefined) { // getting an existing property
if (isDataDescriptor(fixedDesc) &&
fixedDesc.configurable === false &&
fixedDesc.writable === false) { // own frozen data property
if (!sameValue(res, fixedDesc.value)) {
throw new TypeError("cannot report inconsistent value for "+
"non-writable, non-configurable property '"+
name+"'");
}
} else { // it's an accessor property
if (isAccessorDescriptor(fixedDesc) &&
fixedDesc.configurable === false &&
fixedDesc.get === undefined) {
if (res !== undefined) {
throw new TypeError("must report undefined for non-configurable "+
"accessor property '"+name+"' without getter");
}
}
}
}
return res;
},
/**
* If name denotes a fixed non-configurable, non-writable data property,
* check that the trap rejects the assignment.
*/
set: function(receiver, name, val) {
var trap = this.getTrap("set");
if (trap === undefined) {
// default forwarding behavior
return Reflect.set(this.target, name, val, receiver);
}
name = String(name);
var res = trap.call(this.handler, this.target, name, val, receiver);
res = !!res; // coerce to Boolean
// if success is reported, check whether property is truly assignable
if (res === true) {
var fixedDesc = Object.getOwnPropertyDescriptor(this.target, name);
if (fixedDesc !== undefined) { // setting an existing property
if (isDataDescriptor(fixedDesc) &&
fixedDesc.configurable === false &&
fixedDesc.writable === false) {
if (!sameValue(val, fixedDesc.value)) {
throw new TypeError("cannot successfully assign to a "+
"non-writable, non-configurable property '"+
name+"'");
}
} else {
if (isAccessorDescriptor(fixedDesc) &&
fixedDesc.configurable === false && // non-configurable
fixedDesc.set === undefined) { // accessor with undefined setter
throw new TypeError("setting a property '"+name+"' that has "+
" only a getter");
}
}
}
}
return res;
},
/**
* Any own enumerable non-configurable properties of the target that are not
* included in the trap result give rise to a TypeError. As such, we check
* whether the returned result contains at least all sealed enumerable properties
* of the target object.
*
* The trap should return an iterator.
*
* However, as implementations of pre-direct proxies still expect enumerate
* to return an array of strings, we convert the iterator into an array.
*/
enumerate: function() {
var trap = this.getTrap("enumerate");
if (trap === undefined) {
// default forwarding behavior
var trapResult = Reflect.enumerate(this.target);
var result = [];
var nxt = trapResult.next();
while (!nxt.done) {
result.push(String(nxt.value));
nxt = trapResult.next();
}
return result;
}
var trapResult = trap.call(this.handler, this.target);
if (trapResult === null ||
trapResult === undefined ||
trapResult.next === undefined) {
throw new TypeError("enumerate trap should return an iterator, got: "+
trapResult);
}
// propNames is used as a set of strings
var propNames = Object.create(null);
// var numProps = +trapResult.length;
var result = []; // new Array(numProps);
// trapResult is supposed to be an iterator
// drain iterator to array as current implementations still expect
// enumerate to return an array of strings
var nxt = trapResult.next();
while (!nxt.done) {
var s = String(nxt.value);
if (propNames[s]) {
throw new TypeError("enumerate trap cannot list a "+
"duplicate property '"+s+"'");
}
propNames[s] = true;
result.push(s);
nxt = trapResult.next();
}
/*for (var i = 0; i < numProps; i++) {
var s = String(trapResult[i]);
if (propNames[s]) {
throw new TypeError("enumerate trap cannot list a "+
"duplicate property '"+s+"'");
}
propNames[s] = true;
result[i] = s;
} */
var ownEnumerableProps = Object.keys(this.target);
var target = this.target;
ownEnumerableProps.forEach(function (ownEnumerableProp) {
if (!propNames[ownEnumerableProp]) {
if (isSealed(ownEnumerableProp, target)) {
throw new TypeError("enumerate trap failed to include "+
"non-configurable enumerable property '"+
ownEnumerableProp+"'");
}
if (!Object.isExtensible(target) &&
isFixed(ownEnumerableProp, target)) {
// if handler is allowed not to report ownEnumerableProp as an own
// property, we cannot guarantee that it will never report it as
// an own property later. Once a property has been reported as
// non-existent on a non-extensible object, it should forever be
// reported as non-existent
throw new TypeError("cannot report existing own property '"+
ownEnumerableProp+"' as non-existent on a "+
"non-extensible object");
}
}
});
return result;
},
/**
* The iterate trap is deprecated by the enumerate trap.
*/
iterate: Validator.prototype.enumerate,
/**
* Any own non-configurable properties of the target that are not included
* in the trap result give rise to a TypeError. As such, we check whether the
* returned result contains at least all sealed properties of the target
* object.
*
* The trap result is normalized.
* The trap result is not returned directly. Instead:
* - create and return a fresh Array,
* - of which each element is coerced to String,
* - which does not contain duplicates
*
* FIXME: keys trap is deprecated
*/
/*
keys: function() {
var trap = this.getTrap("keys");
if (trap === undefined) {
// default forwarding behavior
return Reflect.keys(this.target);
}
var trapResult = trap.call(this.handler, this.target);
// propNames is used as a set of strings
var propNames = Object.create(null);
var numProps = +trapResult.length;
var result = new Array(numProps);
for (var i = 0; i < numProps; i++) {
var s = String(trapResult[i]);
if (propNames[s]) {
throw new TypeError("keys trap cannot list a "+
"duplicate property '"+s+"'");
}
if (!Object.isExtensible(this.target) && !isFixed(s, this.target)) {
// non-extensible proxies don't tolerate new own property names
throw new TypeError("keys trap cannot list a new "+
"property '"+s+"' on a non-extensible object");
}
propNames[s] = true;
result[i] = s;
}
var ownEnumerableProps = Object.keys(this.target);
var target = this.target;
ownEnumerableProps.forEach(function (ownEnumerableProp) {
if (!propNames[ownEnumerableProp]) {
if (isSealed(ownEnumerableProp, target)) {
throw new TypeError("keys trap failed to include "+
"non-configurable enumerable property '"+
ownEnumerableProp+"'");
}
if (!Object.isExtensible(target) &&
isFixed(ownEnumerableProp, target)) {
// if handler is allowed not to report ownEnumerableProp as an own
// property, we cannot guarantee that it will never report it as
// an own property later. Once a property has been reported as
// non-existent on a non-extensible object, it should forever be
// reported as non-existent
throw new TypeError("cannot report existing own property '"+
ownEnumerableProp+"' as non-existent on a "+
"non-extensible object");
}
}
});
return result;
},
*/
/**
* New trap that reifies [[Call]].
* If the target is a function, then a call to
* proxy(...args)
* Triggers this trap
*/
apply: function(target, thisBinding, args) {
var trap = this.getTrap("apply");
if (trap === undefined) {
return Reflect.apply(target, thisBinding, args);
}
if (typeof this.target === "function") {
return trap.call(this.handler, target, thisBinding, args);
} else {
throw new TypeError("apply: "+ target + " is not a function");
}
},
/**
* New trap that reifies [[Construct]].
* If the target is a function, then a call to
* new proxy(...args)
* Triggers this trap
*/
construct: function(target, args, newTarget) {
var trap = this.getTrap("construct");
if (trap === undefined) {
return Reflect.construct(target, args, newTarget);
}
if (typeof target !== "function") {
throw new TypeError("new: "+ target + " is not a function");
}
if (newTarget === undefined) {
newTarget = target;
} else {
if (typeof newTarget !== "function") {
throw new TypeError("new: "+ newTarget + " is not a function");
}
}
return trap.call(this.handler, target, args, newTarget);
}
};
// ---- end of the Validator handler wrapper handler ----
// In what follows, a 'direct proxy' is a proxy
// whose handler is a Validator. Such proxies can be made non-extensible,
// sealed or frozen without losing the ability to trap.
// maps direct proxies to their Validator handlers
var directProxies = new WeakMap();
// patch Object.{preventExtensions,seal,freeze} so that
// they recognize fixable proxies and act accordingly
Object.preventExtensions = function(subject) {
var vhandler = directProxies.get(subject);
if (vhandler !== undefined) {
if (vhandler.preventExtensions()) {
return subject;
} else {
throw new TypeError("preventExtensions on "+subject+" rejected");
}
} else {
return prim_preventExtensions(subject);
}
};
Object.seal = function(subject) {
setIntegrityLevel(subject, "sealed");
return subject;
};
Object.freeze = function(subject) {
setIntegrityLevel(subject, "frozen");
return subject;
};
Object.isExtensible = Object_isExtensible = function(subject) {
var vHandler = directProxies.get(subject);
if (vHandler !== undefined) {
return vHandler.isExtensible();
} else {
return prim_isExtensible(subject);
}
};
Object.isSealed = Object_isSealed = function(subject) {
return testIntegrityLevel(subject, "sealed");
};
Object.isFrozen = Object_isFrozen = function(subject) {
return testIntegrityLevel(subject, "frozen");
};
Object.getPrototypeOf = Object_getPrototypeOf = function(subject) {
var vHandler = directProxies.get(subject);
if (vHandler !== undefined) {
return vHandler.getPrototypeOf();
} else {
return prim_getPrototypeOf(subject);
}
};
// patch Object.getOwnPropertyDescriptor to directly call
// the Validator.prototype.getOwnPropertyDescriptor trap
// This is to circumvent an assertion in the built-in Proxy
// trapping mechanism of v8, which disallows that trap to
// return non-configurable property descriptors (as per the
// old Proxy design)
Object.getOwnPropertyDescriptor = function(subject, name) {
var vhandler = directProxies.get(subject);
if (vhandler !== undefined) {
return vhandler.getOwnPropertyDescriptor(name);
} else {
return prim_getOwnPropertyDescriptor(subject, name);
}
};
// patch Object.defineProperty to directly call
// the Validator.prototype.defineProperty trap
// This is to circumvent two issues with the built-in
// trap mechanism:
// 1) the current tracemonkey implementation of proxies
// auto-completes 'desc', which is not correct. 'desc' should be
// normalized, but not completed. Consider:
// Object.defineProperty(proxy, 'foo', {enumerable:false})
// This trap will receive desc =
// {value:undefined,writable:false,enumerable:false,configurable:false}
// This will also set all other attributes to their default value,
// which is unexpected and different from [[DefineOwnProperty]].
// Bug filed: https://bugzilla.mozilla.org/show_bug.cgi?id=601329
// 2) the current spidermonkey implementation does not
// throw an exception when this trap returns 'false', but instead silently
// ignores the operation (this is regardless of strict-mode)
// 2a) v8 does throw an exception for this case, but includes the rather
// unhelpful error message:
// 'Proxy handler #<Object> returned false from 'defineProperty' trap'
Object.defineProperty = function(subject, name, desc) {
var vhandler = directProxies.get(subject);
if (vhandler !== undefined) {
var normalizedDesc = normalizePropertyDescriptor(desc);
var success = vhandler.defineProperty(name, normalizedDesc);
if (success === false) {
throw new TypeError("can't redefine property '"+name+"'");
}
return subject;
} else {
return prim_defineProperty(subject, name, desc);
}
};
Object.defineProperties = function(subject, descs) {
var vhandler = directProxies.get(subject);
if (vhandler !== undefined) {
var names = Object.keys(descs);
for (var i = 0; i < names.length; i++) {
var name = names[i];
var normalizedDesc = normalizePropertyDescriptor(descs[name]);
var success = vhandler.defineProperty(name, normalizedDesc);
if (success === false) {
throw new TypeError("can't redefine property '"+name+"'");
}
}
return subject;
} else {
return prim_defineProperties(subject, descs);
}
};
Object.keys = function(subject) {
var vHandler = directProxies.get(subject);
if (vHandler !== undefined) {
var ownKeys = vHandler.ownKeys();
var result = [];
for (var i = 0; i < ownKeys.length; i++) {
var k = String(ownKeys[i]);
var desc = Object.getOwnPropertyDescriptor(subject, k);
if (desc !== undefined && desc.enumerable === true) {
result.push(k);
}
}
return result;
} else {
return prim_keys(subject);
}
}
Object.getOwnPropertyNames = Object_getOwnPropertyNames = function(subject) {
var vHandler = directProxies.get(subject);
if (vHandler !== undefined) {
return vHandler.ownKeys();
} else {
return prim_getOwnPropertyNames(subject);
}
}
// fixes issue #71 (Calling Object.getOwnPropertySymbols() on a Proxy
// throws an error)
if (prim_getOwnPropertySymbols !== undefined) {
Object.getOwnPropertySymbols = function(subject) {
var vHandler = directProxies.get(subject);
if (vHandler !== undefined) {
// as this shim does not support symbols, a Proxy never advertises
// any symbol-valued own properties
return [];
} else {
return prim_getOwnPropertySymbols(subject);
}
};
}
// fixes issue #72 ('Illegal access' error when using Object.assign)
// Object.assign polyfill based on a polyfill posted on MDN:
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/\
// Global_Objects/Object/assign
// Note that this polyfill does not support Symbols, but this Proxy Shim
// does not support Symbols anyway.
if (prim_assign !== undefined) {
Object.assign = function (target) {
// check if any argument is a proxy object
var noProxies = true;
for (var i = 0; i < arguments.length; i++) {
var vHandler = directProxies.get(arguments[i]);
if (vHandler !== undefined) {
noProxies = false;
break;
}
}
if (noProxies) {
// not a single argument is a proxy, perform built-in algorithm
return prim_assign.apply(Object, arguments);
}
// there is at least one proxy argument, use the polyfill
if (target === undefined || target === null) {
throw new TypeError('Cannot convert undefined or null to object');
}
var output = Object(target);
for (var index = 1; index < arguments.length; index++) {
var source = arguments[index];
if (source !== undefined && source !== null) {
for (var nextKey in source) {
if (source.hasOwnProperty(nextKey)) {
output[nextKey] = source[nextKey];
}
}
}
}
return output;
};
}
// returns whether an argument is a reference to an object,
// which is legal as a WeakMap key.
function isObject(arg) {
var type = typeof arg;
return (type === 'object' && arg !== null) || (type === 'function');
};
// a wrapper for WeakMap.get which returns the undefined value
// for keys that are not objects (in which case the underlying
// WeakMap would have thrown a TypeError).
function safeWeakMapGet(map, key) {
return isObject(key) ? map.get(key) : undefined;
};
// returns a new function of zero arguments that recursively
// unwraps any proxies specified as the |this|-value.
// The primitive is assumed to be a zero-argument method
// that uses its |this|-binding.
function makeUnwrapping0ArgMethod(primitive) {
return function builtin() {
var vHandler = safeWeakMapGet(directProxies, this);
if (vHandler !== undefined) {
return builtin.call(vHandler.target);
} else {
return primitive.call(this);
}
}
};
// returns a new function of 1 arguments that recursively
// unwraps any proxies specified as the |this|-value.
// The primitive is assumed to be a 1-argument method
// that uses its |this|-binding.
function makeUnwrapping1ArgMethod(primitive) {
return function builtin(arg) {
var vHandler = safeWeakMapGet(directProxies, this);
if (vHandler !== undefined) {
return builtin.call(vHandler.target, arg);
} else {
return primitive.call(this, arg);
}
}
};
Object.prototype.valueOf =
makeUnwrapping0ArgMethod(Object.prototype.valueOf);
Object.prototype.toString =
makeUnwrapping0ArgMethod(Object.prototype.toString);
Function.prototype.toString =
makeUnwrapping0ArgMethod(Function.prototype.toString);
Date.prototype.toString =
makeUnwrapping0ArgMethod(Date.prototype.toString);
Object.prototype.isPrototypeOf = function builtin(arg) {
// bugfix thanks to Bill Mark:
// built-in isPrototypeOf does not unwrap proxies used
// as arguments. So, we implement the builtin ourselves,
// based on the ECMAScript 6 spec. Our encoding will
// make sure that if a proxy is used as an argument,
// its getPrototypeOf trap will be called.
while (true) {
var vHandler2 = safeWeakMapGet(directProxies, arg);
if (vHandler2 !== undefined) {
arg = vHandler2.getPrototypeOf();
if (arg === null) {
return false;
} else if (sameValue(arg, this)) {
return true;
}
} else {
return prim_isPrototypeOf.call(this, arg);
}
}
};
Array.isArray = function(subject) {
var vHandler = safeWeakMapGet(directProxies, subject);
if (vHandler !== undefined) {
return Array.isArray(vHandler.target);
} else {
return prim_isArray(subject);
}
};
function isProxyArray(arg) {
var vHandler = safeWeakMapGet(directProxies, arg);
if (vHandler !== undefined) {
return Array.isArray(vHandler.target);
}
return false;
}
// Array.prototype.concat internally tests whether one of its
// arguments is an Array, by checking whether [[Class]] == "Array"
// As such, it will fail to recognize proxies-for-arrays as arrays.
// We patch Array.prototype.concat so that it "unwraps" proxies-for-arrays
// by making a copy. This will trigger the exact same sequence of
// traps on the proxy-for-array as if we would not have unwrapped it.
// See <https://github.com/tvcutsem/harmony-reflect/issues/19> for more.
Array.prototype.concat = function(/*...args*/) {
var length;
for (var i = 0; i < arguments.length; i++) {
if (isProxyArray(arguments[i])) {
length = arguments[i].length;
arguments[i] = Array.prototype.slice.call(arguments[i], 0, length);
}
}
return prim_concat.apply(this, arguments);
};
// setPrototypeOf support on platforms that support __proto__
var prim_setPrototypeOf = Object.setPrototypeOf;
// patch and extract original __proto__ setter
var __proto__setter = (function() {
var protoDesc = prim_getOwnPropertyDescriptor(Object.prototype,'__proto__');
if (protoDesc === undefined ||
typeof protoDesc.set !== "function") {
return function() {
throw new TypeError("setPrototypeOf not supported on this platform");
}
}
// see if we can actually mutate a prototype with the generic setter
// (e.g. Chrome v28 doesn't allow setting __proto__ via the generic setter)
try {
protoDesc.set.call({},{});
} catch (e) {
return function() {
throw new TypeError("setPrototypeOf not supported on this platform");
}
}
prim_defineProperty(Object.prototype, '__proto__', {
set: function(newProto) {
return Object.setPrototypeOf(this, Object(newProto));
}
});
return protoDesc.set;
}());
Object.setPrototypeOf = function(target, newProto) {
var handler = directProxies.get(target);
if (handler !== undefined) {
if (handler.setPrototypeOf(newProto)) {
return target;
} else {
throw new TypeError("proxy rejected prototype mutation");
}
} else {
if (!Object_isExtensible(target)) {
throw new TypeError("can't set prototype on non-extensible object: " +
target);
}
if (prim_setPrototypeOf)
return prim_setPrototypeOf(target, newProto);
if (Object(newProto) !== newProto || newProto === null) {
throw new TypeError("Object prototype may only be an Object or null: " +
newProto);
// throw new TypeError("prototype must be an object or null")
}
__proto__setter.call(target, newProto);
return target;
}
}
Object.prototype.hasOwnProperty = function(name) {
var handler = safeWeakMapGet(directProxies, this);
if (handler !== undefined) {
var desc = handler.getOwnPropertyDescriptor(name);
return desc !== undefined;
} else {
return prim_hasOwnProperty.call(this, name);
}
}
// ============= Reflection module =============
// see http://wiki.ecmascript.org/doku.php?id=harmony:reflect_api
var Reflect = {
getOwnPropertyDescriptor: function(target, name) {
return Object.getOwnPropertyDescriptor(target, name);
},
defineProperty: function(target, name, desc) {
// if target is a proxy, invoke its "defineProperty" trap
var handler = directProxies.get(target);
if (handler !== undefined) {
return handler.defineProperty(target, name, desc);
}
// Implementation transliterated from [[DefineOwnProperty]]
// see ES5.1 section 8.12.9
// this is the _exact same algorithm_ as the isCompatibleDescriptor
// algorithm defined above, except that at every place it
// returns true, this algorithm actually does define the property.
var current = Object.getOwnPropertyDescriptor(target, name);
var extensible = Object.isExtensible(target);
if (current === undefined && extensible === false) {
return false;
}
if (current === undefined && extensible === true) {
Object.defineProperty(target, name, desc); // should never fail
return true;
}
if (isEmptyDescriptor(desc)) {
return true;
}
if (isEquivalentDescriptor(current, desc)) {
return true;
}
if (current.configurable === false) {
if (desc.configurable === true) {
return false;
}
if ('enumerable' in desc && desc.enumerable !== current.enumerable) {
return false;
}
}
if (isGenericDescriptor(desc)) {
// no further validation necessary
} else if (isDataDescriptor(current) !== isDataDescriptor(desc)) {
if (current.configurable === false) {
return false;
}
} else if (isDataDescriptor(current) && isDataDescriptor(desc)) {
if (current.configurable === false) {
if (current.writable === false && desc.writable === true) {
return false;
}
if (current.writable === false) {
if ('value' in desc && !sameValue(desc.value, current.value)) {
return false;
}
}
}
} else if (isAccessorDescriptor(current) && isAccessorDescriptor(desc)) {
if (current.configurable === false) {
if ('set' in desc && !sameValue(desc.set, current.set)) {
return false;
}
if ('get' in desc && !sameValue(desc.get, current.get)) {
return false;
}
}
}
Object.defineProperty(target, name, desc); // should never fail
return true;
},
deleteProperty: function(target, name) {
var handler = directProxies.get(target);
if (handler !== undefined) {
return handler.delete(name);
}
var desc = Object.getOwnPropertyDescriptor(target, name);
if (desc === undefined) {
return true;
}
if (desc.configurable === true) {
delete target[name];
return true;
}
return false;
},
getPrototypeOf: function(target) {
return Object.getPrototypeOf(target);
},
setPrototypeOf: function(target, newProto) {
var handler = directProxies.get(target);
if (handler !== undefined) {
return handler.setPrototypeOf(newProto);
}
if (Object(newProto) !== newProto || newProto === null) {
throw new TypeError("Object prototype may only be an Object or null: " +
newProto);
}
if (!Object_isExtensible(target)) {
return false;
}
var current = Object.getPrototypeOf(target);
if (sameValue(current, newProto)) {
return true;
}
if (prim_setPrototypeOf) {
try {
prim_setPrototypeOf(target, newProto);
return true;
} catch (e) {
return false;
}
}
__proto__setter.call(target, newProto);
return true;
},
preventExtensions: function(target) {
var handler = directProxies.get(target);
if (handler !== undefined) {
return handler.preventExtensions();
}
prim_preventExtensions(target);
return true;
},
isExtensible: function(target) {
return Object.isExtensible(target);
},
has: function(target, name) {
return name in target;
},
get: function(target, name, receiver) {
receiver = receiver || target;
// if target is a proxy, invoke its "get" trap
var handler = directProxies.get(target);
if (handler !== undefined) {
return handler.get(receiver, name);
}
var desc = Object.getOwnPropertyDescriptor(target, name);
if (desc === undefined) {
var proto = Object.getPrototypeOf(target);
if (proto === null) {
return undefined;
}
return Reflect.get(proto, name, receiver);
}
if (isDataDescriptor(desc)) {
return desc.value;
}
var getter = desc.get;
if (getter === undefined) {
return undefined;
}
return desc.get.call(receiver);
},
// Reflect.set implementation based on latest version of [[SetP]] at
// http://wiki.ecmascript.org/doku.php?id=harmony:proto_climbing_refactoring
set: function(target, name, value, receiver) {
receiver = receiver || target;
// if target is a proxy, invoke its "set" trap
var handler = directProxies.get(target);
if (handler !== undefined) {
return handler.set(receiver, name, value);
}
// first, check whether target has a non-writable property
// shadowing name on receiver
var ownDesc = Object.getOwnPropertyDescriptor(target, name);
if (ownDesc === undefined) {
// name is not defined in target, search target's prototype
var proto = Object.getPrototypeOf(target);
if (proto !== null) {
// continue the search in target's prototype
return Reflect.set(proto, name, value, receiver);
}
// Rev16 change. Cf. https://bugs.ecmascript.org/show_bug.cgi?id=1549
// target was the last prototype, now we know that 'name' is not shadowed
// by an existing (accessor or data) property, so we can add the property
// to the initial receiver object
// (this branch will intentionally fall through to the code below)
ownDesc =
{ value: undefined,
writable: true,
enumerable: true,
configurable: true };
}
// we now know that ownDesc !== undefined
if (isAccessorDescriptor(ownDesc)) {
var setter = ownDesc.set;
if (setter === undefined) return false;
setter.call(receiver, value); // assumes Function.prototype.call
return true;
}
// otherwise, isDataDescriptor(ownDesc) must be true
if (ownDesc.writable === false) return false;
// we found an existing writable data property on the prototype chain.
// Now update or add the data property on the receiver, depending on
// whether the receiver already defines the property or not.
var existingDesc = Object.getOwnPropertyDescriptor(receiver, name);
if (existingDesc !== undefined) {
var updateDesc =
{ value: value,
// FIXME: it should not be necessary to describe the following
// attributes. Added to circumvent a bug in tracemonkey:
// https://bugzilla.mozilla.org/show_bug.cgi?id=601329
writable: existingDesc.writable,
enumerable: existingDesc.enumerable,
configurable: existingDesc.configurable };
Object.defineProperty(receiver, name, updateDesc);
return true;
} else {
if (!Object.isExtensible(receiver)) return false;
var newDesc =
{ value: value,
writable: true,
enumerable: true,
configurable: true };
Object.defineProperty(receiver, name, newDesc);
return true;
}
},
/*invoke: function(target, name, args, receiver) {
receiver = receiver || target;
var handler = directProxies.get(target);
if (handler !== undefined) {
return handler.invoke(receiver, name, args);
}
var fun = Reflect.get(target, name, receiver);
return Function.prototype.apply.call(fun, receiver, args);
},*/
enumerate: function(target) {
var handler = directProxies.get(target);
var result;
if (handler !== undefined) {
// handler.enumerate should return an iterator directly, but the
// iterator gets converted to an array for backward-compat reasons,
// so we must re-iterate over the array
result = handler.enumerate(handler.target);
} else {
result = [];
for (var name in target) { result.push(name); };
}
var l = +result.length;
var idx = 0;
return {
next: function() {
if (idx === l) return { done: true };
return { done: false, value: result[idx++] };
}
};
},
// imperfect ownKeys implementation: in ES6, should also include
// symbol-keyed properties.
ownKeys: function(target) {
return Object_getOwnPropertyNames(target);
},
apply: function(target, receiver, args) {
// target.apply(receiver, args)
return Function.prototype.apply.call(target, receiver, args);
},
construct: function(target, args, newTarget) {
// return new target(...args);
// if target is a proxy, invoke its "construct" trap
var handler = directProxies.get(target);
if (handler !== undefined) {
return handler.construct(handler.target, args, newTarget);
}
if (typeof target !== "function") {
throw new TypeError("target is not a function: " + target);
}
if (newTarget === undefined || newTarget === target) {
// If newTarget is undefined, then newTarget is set to `target` and
// `Reflect.construct(target, ...args)` becomes equivalent to
// `new target(...args)`
// if `target` is an ES2015 Class constructor, it must be called using
// the `new` operator. Hence we use the new operator on a bound function
// to trigger the [[Construct]] internal method. This technique will work
// for both plain constructor functions and ES2015 classes
return new (Function.prototype.bind.apply(target, [null].concat(args)));
} else {
if (typeof newTarget !== "function") {
throw new TypeError("newTarget is not a function: " + target);
}
// if newTarget is a *different* constructor function, we need to
// emulate [[Construct]] by falling back to [[Call]] with a hand-crafted
// new instance inheriting from newTarget.prototype
// Unfortunately this won't work if target is an ES2015 Constructor
// function, whose [[Call]] method throws an error (it must be invoked
// using the `new` operator)
var proto = newTarget.prototype;
var instance = (Object(proto) === proto) ? Object.create(proto) : {};
var result = Function.prototype.apply.call(target, instance, args);
return Object(result) === result ? result : instance;
}
}
};
// feature-test whether the Reflect global exists
if (global.Reflect !== undefined) {
// Reflect exists, add/override the shimmed methods
Object.getOwnPropertyNames(Reflect).forEach(function (key) {
global.Reflect[key] = Reflect[key];
});
} else {
// Reflect doesn't exist, define it as the shimmed Reflect object
global.Reflect = Reflect;
}
// feature-test whether the Proxy global exists, with
// the harmony-era Proxy.create API
if (typeof Proxy !== "undefined" &&
typeof Proxy.create !== "undefined") {
var primCreate = Proxy.create,
primCreateFunction = Proxy.createFunction;
var revokedHandler = primCreate({
get: function() { throw new TypeError("proxy is revoked"); }
});
global.Proxy = function(target, handler) {
// check that target is an Object
if (Object(target) !== target) {
throw new TypeError("Proxy target must be an Object, given "+target);
}
// check that handler is an Object
if (Object(handler) !== handler) {
throw new TypeError("Proxy handler must be an Object, given "+handler);
}
var vHandler = new Validator(target, handler);
var proxy;
if (typeof target === "function") {
proxy = primCreateFunction(vHandler,
// call trap
function() {
var args = Array.prototype.slice.call(arguments);
return vHandler.apply(target, this, args);
},
// construct trap
function() {
var args = Array.prototype.slice.call(arguments);
return vHandler.construct(target, args);
});
} else {
proxy = primCreate(vHandler, Object.getPrototypeOf(target));
}
directProxies.set(proxy, vHandler);
return proxy;
};
global.Proxy.revocable = function(target, handler) {
var proxy = new Proxy(target, handler);
var revoke = function() {
var vHandler = directProxies.get(proxy);
if (vHandler !== null) {
vHandler.target = null;
vHandler.handler = revokedHandler;
}
return undefined;
};
return {proxy: proxy, revoke: revoke};
}
// add the old Proxy.create and Proxy.createFunction methods
// so old code that still depends on the harmony-era Proxy object
// is not broken. Also ensures that multiple versions of this
// library should load fine
global.Proxy.create = primCreate;
global.Proxy.createFunction = primCreateFunction;
} else {
// Proxy global not defined, or old API not available
if (typeof Proxy === "undefined") {
// Proxy global not defined, add a Proxy function stub
global.Proxy = function(_target, _handler) {
throw new Error("proxies not supported on this platform. On v8/node/iojs, make sure to pass the --harmony_proxies flag");
};
}
// Proxy global defined but old API not available
// presumably Proxy global already supports new API, leave untouched
}
// for node.js modules, export every property in the Reflect object
// as part of the module interface
if (typeof exports !== 'undefined') {
Object.keys(Reflect).forEach(function (key) {
exports[key] = Reflect[key];
});
}
// function-as-module pattern
}(typeof exports !== 'undefined' ? global : this));