/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ #include "builtin/SymbolObject.h" #include "vm/StringBuffer.h" #include "vm/Symbol.h" #include "jsobjinlines.h" #include "vm/NativeObject-inl.h" using JS::Symbol; using namespace js; const Class SymbolObject::class_ = { "Symbol", JSCLASS_HAS_RESERVED_SLOTS(RESERVED_SLOTS) | JSCLASS_HAS_CACHED_PROTO(JSProto_Symbol) }; SymbolObject* SymbolObject::create(JSContext* cx, JS::HandleSymbol symbol) { JSObject* obj = NewBuiltinClassInstance(cx, &class_); if (!obj) return nullptr; SymbolObject& symobj = obj->as(); symobj.setPrimitiveValue(symbol); return &symobj; } const JSPropertySpec SymbolObject::properties[] = { JS_PSG("description", descriptionGetter, 0), JS_PS_END }; const JSFunctionSpec SymbolObject::methods[] = { JS_FN(js_toString_str, toString, 0, 0), JS_FN(js_valueOf_str, valueOf, 0, 0), JS_SYM_FN(toPrimitive, toPrimitive, 1, JSPROP_READONLY), JS_FS_END }; const JSFunctionSpec SymbolObject::staticMethods[] = { JS_FN("for", for_, 1, 0), JS_FN("keyFor", keyFor, 1, 0), JS_FS_END }; JSObject* SymbolObject::initClass(JSContext* cx, HandleObject obj) { Handle global = obj.as(); // This uses &JSObject::class_ because: "The Symbol prototype object is an // ordinary object. It is not a Symbol instance and does not have a // [[SymbolData]] internal slot." (ES6 rev 24, 19.4.3) RootedObject proto(cx, GlobalObject::createBlankPrototype(cx, global)); if (!proto) return nullptr; RootedFunction ctor(cx, GlobalObject::createConstructor(cx, construct, ClassName(JSProto_Symbol, cx), 0)); if (!ctor) return nullptr; // Define the well-known symbol properties, such as Symbol.iterator. ImmutablePropertyNamePtr* names = cx->names().wellKnownSymbolNames(); RootedValue value(cx); unsigned attrs = JSPROP_READONLY | JSPROP_PERMANENT; WellKnownSymbols* wks = cx->runtime()->wellKnownSymbols; for (size_t i = 0; i < JS::WellKnownSymbolLimit; i++) { value.setSymbol(wks->get(i)); if (!NativeDefineProperty(cx, ctor, names[i], value, nullptr, nullptr, attrs)) return nullptr; } if (!LinkConstructorAndPrototype(cx, ctor, proto) || !DefinePropertiesAndFunctions(cx, proto, properties, methods) || !DefineToStringTag(cx, proto, cx->names().Symbol) || !DefinePropertiesAndFunctions(cx, ctor, nullptr, staticMethods) || !GlobalObject::initBuiltinConstructor(cx, global, JSProto_Symbol, ctor, proto)) { return nullptr; } return proto; } // ES6 rev 24 (2014 Apr 27) 19.4.1.1 and 19.4.1.2 bool SymbolObject::construct(JSContext* cx, unsigned argc, Value* vp) { // According to a note in the draft standard, "Symbol has ordinary // [[Construct]] behaviour but the definition of its @@create method causes // `new Symbol` to throw a TypeError exception." We do not support @@create // yet, so just throw a TypeError. CallArgs args = CallArgsFromVp(argc, vp); if (args.isConstructing()) { JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_NOT_CONSTRUCTOR, "Symbol"); return false; } // steps 1-3 RootedString desc(cx); if (!args.get(0).isUndefined()) { desc = ToString(cx, args.get(0)); if (!desc) return false; } // step 4 RootedSymbol symbol(cx, JS::Symbol::new_(cx, JS::SymbolCode::UniqueSymbol, desc)); if (!symbol) return false; args.rval().setSymbol(symbol); return true; } // ES6 rev 24 (2014 Apr 27) 19.4.2.2 bool SymbolObject::for_(JSContext* cx, unsigned argc, Value* vp) { CallArgs args = CallArgsFromVp(argc, vp); // steps 1-2 RootedString stringKey(cx, ToString(cx, args.get(0))); if (!stringKey) return false; // steps 3-7 JS::Symbol* symbol = JS::Symbol::for_(cx, stringKey); if (!symbol) return false; args.rval().setSymbol(symbol); return true; } // ES6 rev 25 (2014 May 22) 19.4.2.7 bool SymbolObject::keyFor(JSContext* cx, unsigned argc, Value* vp) { CallArgs args = CallArgsFromVp(argc, vp); // step 1 HandleValue arg = args.get(0); if (!arg.isSymbol()) { ReportValueErrorFlags(cx, JSREPORT_ERROR, JSMSG_UNEXPECTED_TYPE, JSDVG_SEARCH_STACK, arg, nullptr, "not a symbol", nullptr); return false; } // step 2 if (arg.toSymbol()->code() == JS::SymbolCode::InSymbolRegistry) { #ifdef DEBUG RootedString desc(cx, arg.toSymbol()->description()); MOZ_ASSERT(Symbol::for_(cx, desc) == arg.toSymbol()); #endif args.rval().setString(arg.toSymbol()->description()); return true; } // step 3: omitted // step 4 args.rval().setUndefined(); return true; } MOZ_ALWAYS_INLINE bool IsSymbol(HandleValue v) { return v.isSymbol() || (v.isObject() && v.toObject().is()); } // ES6 rev 27 (2014 Aug 24) 19.4.3.2 bool SymbolObject::toString_impl(JSContext* cx, const CallArgs& args) { // steps 1-3 HandleValue thisv = args.thisv(); MOZ_ASSERT(IsSymbol(thisv)); Rooted sym(cx, thisv.isSymbol() ? thisv.toSymbol() : thisv.toObject().as().unbox()); // step 4 return SymbolDescriptiveString(cx, sym, args.rval()); } bool SymbolObject::toString(JSContext* cx, unsigned argc, Value* vp) { CallArgs args = CallArgsFromVp(argc, vp); return CallNonGenericMethod(cx, args); } //ES6 rev 24 (2014 Apr 27) 19.4.3.3 bool SymbolObject::valueOf_impl(JSContext* cx, const CallArgs& args) { // Step 3, the error case, is handled by CallNonGenericMethod. HandleValue thisv = args.thisv(); MOZ_ASSERT(IsSymbol(thisv)); if (thisv.isSymbol()) args.rval().set(thisv); else args.rval().setSymbol(thisv.toObject().as().unbox()); return true; } bool SymbolObject::valueOf(JSContext* cx, unsigned argc, Value* vp) { CallArgs args = CallArgsFromVp(argc, vp); return CallNonGenericMethod(cx, args); } // ES6 19.4.3.4 bool SymbolObject::toPrimitive(JSContext* cx, unsigned argc, Value* vp) { CallArgs args = CallArgsFromVp(argc, vp); // The specification gives exactly the same algorithm for @@toPrimitive as // for valueOf, so reuse the valueOf implementation. return CallNonGenericMethod(cx, args); } // ES2019 Stage 4 Draft / November 28, 2018 // Symbol description accessor // See: https://tc39.github.io/proposal-Symbol-description/ bool SymbolObject::descriptionGetter_impl(JSContext* cx, const CallArgs& args) { // Get symbol object pointer. HandleValue thisv = args.thisv(); MOZ_ASSERT(IsSymbol(thisv)); Rooted sym(cx, thisv.isSymbol() ? thisv.toSymbol() : thisv.toObject().as().unbox()); // Return the symbol's description if present, otherwise return undefined. if (JSString* str = sym->description()) args.rval().setString(str); else args.rval().setUndefined(); return true; } bool SymbolObject::descriptionGetter(JSContext* cx, unsigned argc, Value* vp) { CallArgs args = CallArgsFromVp(argc, vp); return CallNonGenericMethod(cx, args); } JSObject* js::InitSymbolClass(JSContext* cx, HandleObject obj) { return SymbolObject::initClass(cx, obj); }