v8/test/mjsunit/harmony/proxies-example-membrane.js

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// Copyright 2011 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// Flags: --harmony
// A simple no-op handler. Adapted from:
// http://wiki.ecmascript.org/doku.php?id=harmony:proxies#examplea_no-op_forwarding_proxy
function createHandler(obj) {
return {
getOwnPropertyDescriptor: function(name) {
var desc = Object.getOwnPropertyDescriptor(obj, name);
if (desc !== undefined) desc.configurable = true;
return desc;
},
getPropertyDescriptor: function(name) {
var desc = Object.getOwnPropertyDescriptor(obj, name);
//var desc = Object.getPropertyDescriptor(obj, name); // not in ES5
if (desc !== undefined) desc.configurable = true;
return desc;
},
getOwnPropertyNames: function() {
return Object.getOwnPropertyNames(obj);
},
getPropertyNames: function() {
return Object.getOwnPropertyNames(obj);
//return Object.getPropertyNames(obj); // not in ES5
},
defineProperty: function(name, desc) {
Object.defineProperty(obj, name, desc);
},
delete: function(name) {
return delete obj[name];
},
fix: function() {
if (Object.isFrozen(obj)) {
var result = {};
Object.getOwnPropertyNames(obj).forEach(function(name) {
result[name] = Object.getOwnPropertyDescriptor(obj, name);
});
return result;
}
// As long as obj is not frozen, the proxy won't allow itself to be fixed
return undefined; // will cause a TypeError to be thrown
},
has: function(name) { return name in obj; },
hasOwn: function(name) { return ({}).hasOwnProperty.call(obj, name); },
get: function(receiver, name) { return obj[name]; },
set: function(receiver, name, val) {
obj[name] = val; // bad behavior when set fails in non-strict mode
return true;
},
enumerate: function() {
var result = [];
for (var name in obj) { result.push(name); };
return result;
},
keys: function() { return Object.keys(obj); }
};
}
// Auxiliary definitions enabling tracking of object identity in output.
var objectMap = new WeakMap;
var objectCounter = 0;
function registerObject(x, s) {
if (x === Object(x) && !objectMap.has(x))
objectMap.set(x, ++objectCounter + (s == undefined ? "" : ":" + s));
}
registerObject(this, "global");
registerObject(Object.prototype, "Object.prototype");
function str(x) {
if (x === Object(x)) return "[" + typeof x + " " + objectMap.get(x) + "]";
if (typeof x == "string") return "\"" + x + "\"";
return "" + x;
}
// A simple membrane. Adapted from:
// http://wiki.ecmascript.org/doku.php?id=harmony:proxies#a_simple_membrane
function createSimpleMembrane(target) {
var enabled = true;
function wrap(obj) {
registerObject(obj);
print("wrap enter", str(obj));
try {
var x = wrap2(obj);
registerObject(x, "wrapped");
print("wrap exit", str(obj), "as", str(x));
return x;
} catch(e) {
print("wrap exception", str(e));
throw e;
}
}
function wrap2(obj) {
if (obj !== Object(obj)) {
return obj;
}
function wrapCall(fun, that, args) {
registerObject(that);
print("wrapCall enter", fun, str(that));
try {
var x = wrapCall2(fun, that, args);
print("wrapCall exit", fun, str(that), "returning", str(x));
return x;
} catch(e) {
print("wrapCall exception", fun, str(that), str(e));
throw e;
}
}
function wrapCall2(fun, that, args) {
if (!enabled) { throw new Error("disabled"); }
try {
return wrap(fun.apply(that, Array.prototype.map.call(args, wrap)));
} catch (e) {
throw wrap(e);
}
}
var baseHandler = createHandler(obj);
var handler = Proxy.create(Object.freeze({
get: function(receiver, name) {
return function() {
var arg = (name === "get" || name == "set") ? arguments[1] : "";
print("handler enter", name, arg);
var x = wrapCall(baseHandler[name], baseHandler, arguments);
print("handler exit", name, arg, "returning", str(x));
return x;
}
}
}));
registerObject(baseHandler, "basehandler");
registerObject(handler, "handler");
if (typeof obj === "function") {
function callTrap() {
print("call trap enter", str(obj), str(this));
var x = wrapCall(obj, wrap(this), arguments);
print("call trap exit", str(obj), str(this), "returning", str(x));
return x;
}
function constructTrap() {
if (!enabled) { throw new Error("disabled"); }
try {
function forward(args) { return obj.apply(this, args) }
return wrap(new forward(Array.prototype.map.call(arguments, wrap)));
} catch (e) {
throw wrap(e);
}
}
return Proxy.createFunction(handler, callTrap, constructTrap);
} else {
var prototype = wrap(Object.getPrototypeOf(obj));
return Proxy.create(handler, prototype);
}
}
var gate = Object.freeze({
enable: function() { enabled = true; },
disable: function() { enabled = false; }
});
return Object.freeze({
wrapper: wrap(target),
gate: gate
});
}
var o = {
a: 6,
b: {bb: 8},
f: function(x) { return x },
g: function(x) { return x.a },
h: function(x) { this.q = x }
};
o[2] = {c: 7};
var m = createSimpleMembrane(o);
var w = m.wrapper;
print("o =", str(o))
print("w =", str(w));
var f = w.f;
var x = f(66);
var x = f({a: 1});
var x = w.f({a: 1});
var a = x.a;
assertEquals(6, w.a);
assertEquals(8, w.b.bb);
assertEquals(7, w[2]["c"]);
assertEquals(undefined, w.c);
assertEquals(1, w.f(1));
assertEquals(1, w.f({a: 1}).a);
assertEquals(2, w.g({a: 2}));
assertEquals(3, (w.r = {a: 3}).a);
assertEquals(3, w.r.a);
assertEquals(3, o.r.a);
w.h(3);
assertEquals(3, w.q);
assertEquals(3, o.q);
assertEquals(4, (new w.h(4)).q);
var wb = w.b;
var wr = w.r;
var wf = w.f;
var wf3 = w.f(3);
var wfx = w.f({a: 6});
var wgx = w.g({a: {aa: 7}});
var wh4 = new w.h(4);
m.gate.disable();
assertEquals(3, wf3);
assertThrows(function() { w.a }, Error);
assertThrows(function() { w.r }, Error);
assertThrows(function() { w.r = {a: 4} }, Error);
assertThrows(function() { o.r.a }, Error);
assertEquals("object", typeof o.r);
assertEquals(5, (o.r = {a: 5}).a);
assertEquals(5, o.r.a);
assertThrows(function() { w[1] }, Error);
assertThrows(function() { w.c }, Error);
assertThrows(function() { wb.bb }, Error);
assertThrows(function() { wr.a }, Error);
assertThrows(function() { wf(4) }, Error);
assertThrows(function() { wfx.a }, Error);
assertThrows(function() { wgx.aa }, Error);
assertThrows(function() { wh4.q }, Error);
m.gate.enable();
assertEquals(6, w.a);
assertEquals(5, w.r.a);
assertEquals(5, o.r.a);
assertEquals(7, w.r = 7);
assertEquals(7, w.r);
assertEquals(7, o.r);
assertEquals(8, w.b.bb);
assertEquals(7, w[2]["c"]);
assertEquals(undefined, w.c);
assertEquals(8, wb.bb);
assertEquals(3, wr.a);
assertEquals(4, wf(4));
assertEquals(3, wf3);
assertEquals(6, wfx.a);
assertEquals(7, wgx.aa);
assertEquals(4, wh4.q);
// An identity-preserving membrane. Adapted from:
// http://wiki.ecmascript.org/doku.php?id=harmony:proxies#an_identity-preserving_membrane
function createMembrane(wetTarget) {
var wet2dry = WeakMap();
var dry2wet = WeakMap();
function asDry(obj) {
registerObject(obj)
print("asDry enter", str(obj))
try {
var x = asDry2(obj);
registerObject(x, "dry");
print("asDry exit", str(obj), "as", str(x));
return x;
} catch(e) {
print("asDry exception", str(e));
throw e;
}
}
function asDry2(wet) {
if (wet !== Object(wet)) {
// primitives provide only irrevocable knowledge, so don't
// bother wrapping it.
return wet;
}
var dryResult = wet2dry.get(wet);
if (dryResult) { return dryResult; }
var wetHandler = createHandler(wet);
var dryRevokeHandler = Proxy.create(Object.freeze({
get: function(receiver, name) {
return function() {
var arg = (name === "get" || name == "set") ? arguments[1] : "";
print("dry handler enter", name, arg);
var optWetHandler = dry2wet.get(dryRevokeHandler);
try {
var x = asDry(optWetHandler[name].apply(
optWetHandler, Array.prototype.map.call(arguments, asWet)));
print("dry handler exit", name, arg, "returning", str(x));
return x;
} catch (eWet) {
var x = asDry(eWet);
print("dry handler exception", name, arg, "throwing", str(x));
throw x;
}
};
}
}));
dry2wet.set(dryRevokeHandler, wetHandler);
if (typeof wet === "function") {
function callTrap() {
print("dry call trap enter", str(this));
var x = asDry(wet.apply(
asWet(this), Array.prototype.map.call(arguments, asWet)));
print("dry call trap exit", str(this), "returning", str(x));
return x;
}
function constructTrap() {
function forward(args) { return wet.apply(this, args) }
return asDry(new forward(Array.prototype.map.call(arguments, asWet)));
}
dryResult =
Proxy.createFunction(dryRevokeHandler, callTrap, constructTrap);
} else {
dryResult =
Proxy.create(dryRevokeHandler, asDry(Object.getPrototypeOf(wet)));
}
wet2dry.set(wet, dryResult);
dry2wet.set(dryResult, wet);
return dryResult;
}
function asWet(obj) {
registerObject(obj)
print("asWet enter", str(obj))
try {
var x = asWet2(obj)
registerObject(x, "wet")
print("asWet exit", str(obj), "as", str(x))
return x
} catch(e) {
print("asWet exception", str(e))
throw e
}
}
function asWet2(dry) {
if (dry !== Object(dry)) {
// primitives provide only irrevocable knowledge, so don't
// bother wrapping it.
return dry;
}
var wetResult = dry2wet.get(dry);
if (wetResult) { return wetResult; }
var dryHandler = createHandler(dry);
var wetRevokeHandler = Proxy.create(Object.freeze({
get: function(receiver, name) {
return function() {
var arg = (name === "get" || name == "set") ? arguments[1] : "";
print("wet handler enter", name, arg);
var optDryHandler = wet2dry.get(wetRevokeHandler);
try {
var x = asWet(optDryHandler[name].apply(
optDryHandler, Array.prototype.map.call(arguments, asDry)));
print("wet handler exit", name, arg, "returning", str(x));
return x;
} catch (eDry) {
var x = asWet(eDry);
print("wet handler exception", name, arg, "throwing", str(x));
throw x;
}
};
}
}));
wet2dry.set(wetRevokeHandler, dryHandler);
if (typeof dry === "function") {
function callTrap() {
print("wet call trap enter", str(this));
var x = asWet(dry.apply(
asDry(this), Array.prototype.map.call(arguments, asDry)));
print("wet call trap exit", str(this), "returning", str(x));
return x;
}
function constructTrap() {
function forward(args) { return dry.apply(this, args) }
return asWet(new forward(Array.prototype.map.call(arguments, asDry)));
}
wetResult =
Proxy.createFunction(wetRevokeHandler, callTrap, constructTrap);
} else {
wetResult =
Proxy.create(wetRevokeHandler, asWet(Object.getPrototypeOf(dry)));
}
dry2wet.set(dry, wetResult);
wet2dry.set(wetResult, dry);
return wetResult;
}
var gate = Object.freeze({
revoke: function() {
dry2wet = wet2dry = Object.freeze({
get: function(key) { throw new Error("revoked"); },
set: function(key, val) { throw new Error("revoked"); }
});
}
});
return Object.freeze({ wrapper: asDry(wetTarget), gate: gate });
}
var receiver
var argument
var o = {
a: 6,
b: {bb: 8},
f: function(x) { receiver = this; argument = x; return x },
g: function(x) { receiver = this; argument = x; return x.a },
h: function(x) { receiver = this; argument = x; this.q = x },
s: function(x) { receiver = this; argument = x; this.x = {y: x}; return this }
}
o[2] = {c: 7}
var m = createMembrane(o)
var w = m.wrapper
print("o =", str(o))
print("w =", str(w))
var f = w.f
var x = f(66)
var x = f({a: 1})
var x = w.f({a: 1})
var a = x.a
assertEquals(6, w.a)
assertEquals(8, w.b.bb)
assertEquals(7, w[2]["c"])
assertEquals(undefined, w.c)
assertEquals(1, w.f(1))
assertSame(o, receiver)
assertEquals(1, w.f({a: 1}).a)
assertSame(o, receiver)
assertEquals(2, w.g({a: 2}))
assertSame(o, receiver)
assertSame(w, w.f(w))
assertSame(o, receiver)
assertSame(o, argument)
assertSame(o, w.f(o))
assertSame(o, receiver)
// Note that argument !== o, since o isn't dry, so gets wrapped wet again.
assertEquals(3, (w.r = {a: 3}).a)
assertEquals(3, w.r.a)
assertEquals(3, o.r.a)
w.h(3)
assertEquals(3, w.q)
assertEquals(3, o.q)
assertEquals(4, (new w.h(4)).q)
assertEquals(5, w.s(5).x.y)
assertSame(o, receiver)
var wb = w.b
var wr = w.r
var wf = w.f
var wf3 = w.f(3)
var wfx = w.f({a: 6})
var wgx = w.g({a: {aa: 7}})
var wh4 = new w.h(4)
var ws5 = w.s(5)
var ws5x = ws5.x
m.gate.revoke()
assertEquals(3, wf3)
assertThrows(function() { w.a }, Error)
assertThrows(function() { w.r }, Error)
assertThrows(function() { w.r = {a: 4} }, Error)
assertThrows(function() { o.r.a }, Error)
assertEquals("object", typeof o.r)
assertEquals(5, (o.r = {a: 5}).a)
assertEquals(5, o.r.a)
assertThrows(function() { w[1] }, Error)
assertThrows(function() { w.c }, Error)
assertThrows(function() { wb.bb }, Error)
assertEquals(3, wr.a)
assertThrows(function() { wf(4) }, Error)
assertEquals(6, wfx.a)
assertEquals(7, wgx.aa)
assertThrows(function() { wh4.q }, Error)
assertThrows(function() { ws5.x }, Error)
assertThrows(function() { ws5x.y }, Error)