// Copyright 2021 the V8 project authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #ifndef INCLUDE_V8_OBJECT_H_ #define INCLUDE_V8_OBJECT_H_ #include "v8-local-handle.h" // NOLINT(build/include_directory) #include "v8-maybe.h" // NOLINT(build/include_directory) #include "v8-persistent-handle.h" // NOLINT(build/include_directory) #include "v8-primitive.h" // NOLINT(build/include_directory) #include "v8-traced-handle.h" // NOLINT(build/include_directory) #include "v8-value.h" // NOLINT(build/include_directory) #include "v8config.h" // NOLINT(build/include_directory) namespace v8 { class Array; class Function; class FunctionTemplate; template class PropertyCallbackInfo; /** * A private symbol * * This is an experimental feature. Use at your own risk. */ class V8_EXPORT Private : public Data { public: /** * Returns the print name string of the private symbol, or undefined if none. */ Local Name() const; /** * Create a private symbol. If name is not empty, it will be the description. */ static Local New(Isolate* isolate, Local name = Local()); /** * Retrieve a global private symbol. If a symbol with this name has not * been retrieved in the same isolate before, it is created. * Note that private symbols created this way are never collected, so * they should only be used for statically fixed properties. * Also, there is only one global name space for the names used as keys. * To minimize the potential for clashes, use qualified names as keys, * e.g., "Class#property". */ static Local ForApi(Isolate* isolate, Local name); V8_INLINE static Private* Cast(Data* data); private: Private(); static void CheckCast(Data* that); }; /** * An instance of a Property Descriptor, see Ecma-262 6.2.4. * * Properties in a descriptor are present or absent. If you do not set * `enumerable`, `configurable`, and `writable`, they are absent. If `value`, * `get`, or `set` are absent, but you must specify them in the constructor, use * empty handles. * * Accessors `get` and `set` must be callable or undefined if they are present. * * \note Only query properties if they are present, i.e., call `x()` only if * `has_x()` returns true. * * \code * // var desc = {writable: false} * v8::PropertyDescriptor d(Local()), false); * d.value(); // error, value not set * if (d.has_writable()) { * d.writable(); // false * } * * // var desc = {value: undefined} * v8::PropertyDescriptor d(v8::Undefined(isolate)); * * // var desc = {get: undefined} * v8::PropertyDescriptor d(v8::Undefined(isolate), Local())); * \endcode */ class V8_EXPORT PropertyDescriptor { public: // GenericDescriptor PropertyDescriptor(); // DataDescriptor explicit PropertyDescriptor(Local value); // DataDescriptor with writable property PropertyDescriptor(Local value, bool writable); // AccessorDescriptor PropertyDescriptor(Local get, Local set); ~PropertyDescriptor(); Local value() const; bool has_value() const; Local get() const; bool has_get() const; Local set() const; bool has_set() const; void set_enumerable(bool enumerable); bool enumerable() const; bool has_enumerable() const; void set_configurable(bool configurable); bool configurable() const; bool has_configurable() const; bool writable() const; bool has_writable() const; struct PrivateData; PrivateData* get_private() const { return private_; } PropertyDescriptor(const PropertyDescriptor&) = delete; void operator=(const PropertyDescriptor&) = delete; private: PrivateData* private_; }; /** * PropertyAttribute. */ enum PropertyAttribute { /** None. **/ None = 0, /** ReadOnly, i.e., not writable. **/ ReadOnly = 1 << 0, /** DontEnum, i.e., not enumerable. **/ DontEnum = 1 << 1, /** DontDelete, i.e., not configurable. **/ DontDelete = 1 << 2 }; /** * Accessor[Getter|Setter] are used as callback functions when * setting|getting a particular property. See Object and ObjectTemplate's * method SetAccessor. */ using AccessorGetterCallback = void (*)(Local property, const PropertyCallbackInfo& info); using AccessorNameGetterCallback = void (*)(Local property, const PropertyCallbackInfo& info); using AccessorSetterCallback = void (*)(Local property, Local value, const PropertyCallbackInfo& info); using AccessorNameSetterCallback = void (*)(Local property, Local value, const PropertyCallbackInfo& info); /** * Access control specifications. * * Some accessors should be accessible across contexts. These * accessors have an explicit access control parameter which specifies * the kind of cross-context access that should be allowed. * * TODO(dcarney): Remove PROHIBITS_OVERWRITING as it is now unused. */ enum AccessControl { DEFAULT = 0, ALL_CAN_READ = 1, ALL_CAN_WRITE = 1 << 1, PROHIBITS_OVERWRITING = 1 << 2 }; /** * Property filter bits. They can be or'ed to build a composite filter. */ enum PropertyFilter { ALL_PROPERTIES = 0, ONLY_WRITABLE = 1, ONLY_ENUMERABLE = 2, ONLY_CONFIGURABLE = 4, SKIP_STRINGS = 8, SKIP_SYMBOLS = 16 }; /** * Options for marking whether callbacks may trigger JS-observable side effects. * Side-effect-free callbacks are allowlisted during debug evaluation with * throwOnSideEffect. It applies when calling a Function, FunctionTemplate, * or an Accessor callback. For Interceptors, please see * PropertyHandlerFlags's kHasNoSideEffect. * Callbacks that only cause side effects to the receiver are allowlisted if * invoked on receiver objects that are created within the same debug-evaluate * call, as these objects are temporary and the side effect does not escape. */ enum class SideEffectType { kHasSideEffect, kHasNoSideEffect, kHasSideEffectToReceiver }; /** * Keys/Properties filter enums: * * KeyCollectionMode limits the range of collected properties. kOwnOnly limits * the collected properties to the given Object only. kIncludesPrototypes will * include all keys of the objects's prototype chain as well. */ enum class KeyCollectionMode { kOwnOnly, kIncludePrototypes }; /** * kIncludesIndices allows for integer indices to be collected, while * kSkipIndices will exclude integer indices from being collected. */ enum class IndexFilter { kIncludeIndices, kSkipIndices }; /** * kConvertToString will convert integer indices to strings. * kKeepNumbers will return numbers for integer indices. */ enum class KeyConversionMode { kConvertToString, kKeepNumbers, kNoNumbers }; /** * Integrity level for objects. */ enum class IntegrityLevel { kFrozen, kSealed }; /** * A JavaScript object (ECMA-262, 4.3.3) */ class V8_EXPORT Object : public Value { public: /** * Set only return Just(true) or Empty(), so if it should never fail, use * result.Check(). */ V8_WARN_UNUSED_RESULT Maybe Set(Local context, Local key, Local value); V8_WARN_UNUSED_RESULT Maybe Set(Local context, uint32_t index, Local value); /** * Implements CreateDataProperty(O, P, V), see * https://tc39.es/ecma262/#sec-createdataproperty. * * Defines a configurable, writable, enumerable property with the given value * on the object unless the property already exists and is not configurable * or the object is not extensible. * * Returns true on success. */ V8_WARN_UNUSED_RESULT Maybe CreateDataProperty(Local context, Local key, Local value); V8_WARN_UNUSED_RESULT Maybe CreateDataProperty(Local context, uint32_t index, Local value); /** * Implements [[DefineOwnProperty]] for data property case, see * https://tc39.es/ecma262/#table-essential-internal-methods. * * In general, CreateDataProperty will be faster, however, does not allow * for specifying attributes. * * Returns true on success. */ V8_WARN_UNUSED_RESULT Maybe DefineOwnProperty( Local context, Local key, Local value, PropertyAttribute attributes = None); /** * Implements Object.defineProperty(O, P, Attributes), see * https://tc39.es/ecma262/#sec-object.defineproperty. * * The defineProperty function is used to add an own property or * update the attributes of an existing own property of an object. * * Both data and accessor descriptors can be used. * * In general, CreateDataProperty is faster, however, does not allow * for specifying attributes or an accessor descriptor. * * The PropertyDescriptor can change when redefining a property. * * Returns true on success. */ V8_WARN_UNUSED_RESULT Maybe DefineProperty( Local context, Local key, PropertyDescriptor& descriptor); V8_WARN_UNUSED_RESULT MaybeLocal Get(Local context, Local key); V8_WARN_UNUSED_RESULT MaybeLocal Get(Local context, uint32_t index); /** * Gets the property attributes of a property which can be None or * any combination of ReadOnly, DontEnum and DontDelete. Returns * None when the property doesn't exist. */ V8_WARN_UNUSED_RESULT Maybe GetPropertyAttributes( Local context, Local key); /** * Implements Object.getOwnPropertyDescriptor(O, P), see * https://tc39.es/ecma262/#sec-object.getownpropertydescriptor. */ V8_WARN_UNUSED_RESULT MaybeLocal GetOwnPropertyDescriptor( Local context, Local key); /** * Object::Has() calls the abstract operation HasProperty(O, P), see * https://tc39.es/ecma262/#sec-hasproperty. Has() returns * true, if the object has the property, either own or on the prototype chain. * Interceptors, i.e., PropertyQueryCallbacks, are called if present. * * Has() has the same side effects as JavaScript's `variable in object`. * For example, calling Has() on a revoked proxy will throw an exception. * * \note Has() converts the key to a name, which possibly calls back into * JavaScript. * * See also v8::Object::HasOwnProperty() and * v8::Object::HasRealNamedProperty(). */ V8_WARN_UNUSED_RESULT Maybe Has(Local context, Local key); V8_WARN_UNUSED_RESULT Maybe Delete(Local context, Local key); V8_WARN_UNUSED_RESULT Maybe Has(Local context, uint32_t index); V8_WARN_UNUSED_RESULT Maybe Delete(Local context, uint32_t index); /** * Note: SideEffectType affects the getter only, not the setter. */ V8_WARN_UNUSED_RESULT Maybe SetAccessor( Local context, Local name, AccessorNameGetterCallback getter, AccessorNameSetterCallback setter = nullptr, MaybeLocal data = MaybeLocal(), AccessControl settings = DEFAULT, PropertyAttribute attribute = None, SideEffectType getter_side_effect_type = SideEffectType::kHasSideEffect, SideEffectType setter_side_effect_type = SideEffectType::kHasSideEffect); void SetAccessorProperty(Local name, Local getter, Local setter = Local(), PropertyAttribute attributes = None, AccessControl settings = DEFAULT); /** * Sets a native data property like Template::SetNativeDataProperty, but * this method sets on this object directly. */ V8_WARN_UNUSED_RESULT Maybe SetNativeDataProperty( Local context, Local name, AccessorNameGetterCallback getter, AccessorNameSetterCallback setter = nullptr, Local data = Local(), PropertyAttribute attributes = None, SideEffectType getter_side_effect_type = SideEffectType::kHasSideEffect, SideEffectType setter_side_effect_type = SideEffectType::kHasSideEffect); /** * Attempts to create a property with the given name which behaves like a data * property, except that the provided getter is invoked (and provided with the * data value) to supply its value the first time it is read. After the * property is accessed once, it is replaced with an ordinary data property. * * Analogous to Template::SetLazyDataProperty. */ V8_WARN_UNUSED_RESULT Maybe SetLazyDataProperty( Local context, Local name, AccessorNameGetterCallback getter, Local data = Local(), PropertyAttribute attributes = None, SideEffectType getter_side_effect_type = SideEffectType::kHasSideEffect, SideEffectType setter_side_effect_type = SideEffectType::kHasSideEffect); /** * Functionality for private properties. * This is an experimental feature, use at your own risk. * Note: Private properties are not inherited. Do not rely on this, since it * may change. */ Maybe HasPrivate(Local context, Local key); Maybe SetPrivate(Local context, Local key, Local value); Maybe DeletePrivate(Local context, Local key); MaybeLocal GetPrivate(Local context, Local key); /** * Returns an array containing the names of the enumerable properties * of this object, including properties from prototype objects. The * array returned by this method contains the same values as would * be enumerated by a for-in statement over this object. */ V8_WARN_UNUSED_RESULT MaybeLocal GetPropertyNames( Local context); V8_WARN_UNUSED_RESULT MaybeLocal GetPropertyNames( Local context, KeyCollectionMode mode, PropertyFilter property_filter, IndexFilter index_filter, KeyConversionMode key_conversion = KeyConversionMode::kKeepNumbers); /** * This function has the same functionality as GetPropertyNames but * the returned array doesn't contain the names of properties from * prototype objects. */ V8_WARN_UNUSED_RESULT MaybeLocal GetOwnPropertyNames( Local context); /** * Returns an array containing the names of the filtered properties * of this object, including properties from prototype objects. The * array returned by this method contains the same values as would * be enumerated by a for-in statement over this object. */ V8_WARN_UNUSED_RESULT MaybeLocal GetOwnPropertyNames( Local context, PropertyFilter filter, KeyConversionMode key_conversion = KeyConversionMode::kKeepNumbers); /** * Get the prototype object. This does not skip objects marked to * be skipped by __proto__ and it does not consult the security * handler. */ Local GetPrototype(); /** * Set the prototype object. This does not skip objects marked to * be skipped by __proto__ and it does not consult the security * handler. */ V8_WARN_UNUSED_RESULT Maybe SetPrototype(Local context, Local prototype); /** * Finds an instance of the given function template in the prototype * chain. */ Local FindInstanceInPrototypeChain(Local tmpl); /** * Call builtin Object.prototype.toString on this object. * This is different from Value::ToString() that may call * user-defined toString function. This one does not. */ V8_WARN_UNUSED_RESULT MaybeLocal ObjectProtoToString( Local context); /** * Returns the name of the function invoked as a constructor for this object. */ Local GetConstructorName(); /** * Sets the integrity level of the object. */ Maybe SetIntegrityLevel(Local context, IntegrityLevel level); /** Gets the number of internal fields for this Object. */ int InternalFieldCount() const; /** Same as above, but works for PersistentBase. */ V8_INLINE static int InternalFieldCount( const PersistentBase& object) { return object.template value()->InternalFieldCount(); } /** Same as above, but works for BasicTracedReference. */ V8_INLINE static int InternalFieldCount( const BasicTracedReference& object) { return object.template value()->InternalFieldCount(); } /** Gets the value from an internal field. */ V8_INLINE Local GetInternalField(int index); /** Sets the value in an internal field. */ void SetInternalField(int index, Local value); /** * Gets a 2-byte-aligned native pointer from an internal field. This field * must have been set by SetAlignedPointerInInternalField, everything else * leads to undefined behavior. */ V8_INLINE void* GetAlignedPointerFromInternalField(int index); /** Same as above, but works for PersistentBase. */ V8_INLINE static void* GetAlignedPointerFromInternalField( const PersistentBase& object, int index) { return object.template value()->GetAlignedPointerFromInternalField( index); } /** Same as above, but works for TracedReference. */ V8_INLINE static void* GetAlignedPointerFromInternalField( const BasicTracedReference& object, int index) { return object.template value()->GetAlignedPointerFromInternalField( index); } /** * Sets a 2-byte-aligned native pointer in an internal field. To retrieve such * a field, GetAlignedPointerFromInternalField must be used, everything else * leads to undefined behavior. */ void SetAlignedPointerInInternalField(int index, void* value); void SetAlignedPointerInInternalFields(int argc, int indices[], void* values[]); /** * HasOwnProperty() is like JavaScript's Object.prototype.hasOwnProperty(). * * See also v8::Object::Has() and v8::Object::HasRealNamedProperty(). */ V8_WARN_UNUSED_RESULT Maybe HasOwnProperty(Local context, Local key); V8_WARN_UNUSED_RESULT Maybe HasOwnProperty(Local context, uint32_t index); /** * Use HasRealNamedProperty() if you want to check if an object has an own * property without causing side effects, i.e., without calling interceptors. * * This function is similar to v8::Object::HasOwnProperty(), but it does not * call interceptors. * * \note Consider using non-masking interceptors, i.e., the interceptors are * not called if the receiver has the real named property. See * `v8::PropertyHandlerFlags::kNonMasking`. * * See also v8::Object::Has(). */ V8_WARN_UNUSED_RESULT Maybe HasRealNamedProperty(Local context, Local key); V8_WARN_UNUSED_RESULT Maybe HasRealIndexedProperty( Local context, uint32_t index); V8_WARN_UNUSED_RESULT Maybe HasRealNamedCallbackProperty( Local context, Local key); /** * If result.IsEmpty() no real property was located in the prototype chain. * This means interceptors in the prototype chain are not called. */ V8_WARN_UNUSED_RESULT MaybeLocal GetRealNamedPropertyInPrototypeChain( Local context, Local key); /** * Gets the property attributes of a real property in the prototype chain, * which can be None or any combination of ReadOnly, DontEnum and DontDelete. * Interceptors in the prototype chain are not called. */ V8_WARN_UNUSED_RESULT Maybe GetRealNamedPropertyAttributesInPrototypeChain(Local context, Local key); /** * If result.IsEmpty() no real property was located on the object or * in the prototype chain. * This means interceptors in the prototype chain are not called. */ V8_WARN_UNUSED_RESULT MaybeLocal GetRealNamedProperty( Local context, Local key); /** * Gets the property attributes of a real property which can be * None or any combination of ReadOnly, DontEnum and DontDelete. * Interceptors in the prototype chain are not called. */ V8_WARN_UNUSED_RESULT Maybe GetRealNamedPropertyAttributes( Local context, Local key); /** Tests for a named lookup interceptor.*/ bool HasNamedLookupInterceptor() const; /** Tests for an index lookup interceptor.*/ bool HasIndexedLookupInterceptor() const; /** * Returns the identity hash for this object. The current implementation * uses a hidden property on the object to store the identity hash. * * The return value will never be 0. Also, it is not guaranteed to be * unique. */ int GetIdentityHash(); /** * Clone this object with a fast but shallow copy. Values will point * to the same values as the original object. */ // TODO(dcarney): take an isolate and optionally bail out? Local Clone(); /** * Returns the context in which the object was created. */ MaybeLocal GetCreationContext(); /** * Shortcut for GetCreationContext().ToLocalChecked(). **/ Local GetCreationContextChecked(); /** Same as above, but works for Persistents */ V8_INLINE static MaybeLocal GetCreationContext( const PersistentBase& object) { return object.template value()->GetCreationContext(); } /** * Gets the context in which the object was created (see GetCreationContext()) * and if it's available reads respective embedder field value. * If the context can't be obtained nullptr is returned. * Basically it's a shortcut for * obj->GetCreationContext().GetAlignedPointerFromEmbedderData(index) * which doesn't create a handle for Context object on the way and doesn't * try to expand the embedder data attached to the context. * In case the Local is already available because of other reasons, * it's fine to keep using Context::GetAlignedPointerFromEmbedderData(). */ void* GetAlignedPointerFromEmbedderDataInCreationContext(int index); /** * Checks whether a callback is set by the * ObjectTemplate::SetCallAsFunctionHandler method. * When an Object is callable this method returns true. */ bool IsCallable() const; /** * True if this object is a constructor. */ bool IsConstructor() const; /** * True if this object can carry information relevant to the embedder in its * embedder fields, false otherwise. This is generally true for objects * constructed through function templates but also holds for other types where * V8 automatically adds internal fields at compile time, such as e.g. * v8::ArrayBuffer. */ bool IsApiWrapper() const; /** * True if this object was created from an object template which was marked * as undetectable. See v8::ObjectTemplate::MarkAsUndetectable for more * information. */ bool IsUndetectable() const; /** * Call an Object as a function if a callback is set by the * ObjectTemplate::SetCallAsFunctionHandler method. */ V8_WARN_UNUSED_RESULT MaybeLocal CallAsFunction(Local context, Local recv, int argc, Local argv[]); /** * Call an Object as a constructor if a callback is set by the * ObjectTemplate::SetCallAsFunctionHandler method. * Note: This method behaves like the Function::NewInstance method. */ V8_WARN_UNUSED_RESULT MaybeLocal CallAsConstructor( Local context, int argc, Local argv[]); /** * Return the isolate to which the Object belongs to. */ Isolate* GetIsolate(); V8_INLINE static Isolate* GetIsolate(const TracedReference& handle) { return handle.template value()->GetIsolate(); } /** * If this object is a Set, Map, WeakSet or WeakMap, this returns a * representation of the elements of this object as an array. * If this object is a SetIterator or MapIterator, this returns all * elements of the underlying collection, starting at the iterator's current * position. * For other types, this will return an empty MaybeLocal (without * scheduling an exception). */ MaybeLocal PreviewEntries(bool* is_key_value); static Local New(Isolate* isolate); /** * Creates a JavaScript object with the given properties, and * a the given prototype_or_null (which can be any JavaScript * value, and if it's null, the newly created object won't have * a prototype at all). This is similar to Object.create(). * All properties will be created as enumerable, configurable * and writable properties. */ static Local New(Isolate* isolate, Local prototype_or_null, Local* names, Local* values, size_t length); V8_INLINE static Object* Cast(Value* obj); /** * Support for TC39 "dynamic code brand checks" proposal. * * This API allows to query whether an object was constructed from a * "code like" ObjectTemplate. * * See also: v8::ObjectTemplate::SetCodeLike */ bool IsCodeLike(Isolate* isolate) const; private: Object(); static void CheckCast(Value* obj); Local SlowGetInternalField(int index); void* SlowGetAlignedPointerFromInternalField(int index); }; // --- Implementation --- Local Object::GetInternalField(int index) { #ifndef V8_ENABLE_CHECKS using A = internal::Address; using I = internal::Internals; A obj = internal::ValueHelper::ValueAsAddress(this); // Fast path: If the object is a plain JSObject, which is the common case, we // know where to find the internal fields and can return the value directly. int instance_type = I::GetInstanceType(obj); if (I::CanHaveInternalField(instance_type)) { int offset = I::kJSObjectHeaderSize + (I::kEmbedderDataSlotSize * index); A value = I::ReadRawField(obj, offset); #ifdef V8_COMPRESS_POINTERS // We read the full pointer value and then decompress it in order to avoid // dealing with potential endiannes issues. value = I::DecompressTaggedField(obj, static_cast(value)); #endif auto isolate = reinterpret_cast( internal::IsolateFromNeverReadOnlySpaceObject(obj)); return Local::New(isolate, value); } #endif return SlowGetInternalField(index); } void* Object::GetAlignedPointerFromInternalField(int index) { #if !defined(V8_ENABLE_CHECKS) using A = internal::Address; using I = internal::Internals; A obj = internal::ValueHelper::ValueAsAddress(this); // Fast path: If the object is a plain JSObject, which is the common case, we // know where to find the internal fields and can return the value directly. auto instance_type = I::GetInstanceType(obj); if (I::CanHaveInternalField(instance_type)) { int offset = I::kJSObjectHeaderSize + (I::kEmbedderDataSlotSize * index) + I::kEmbedderDataSlotExternalPointerOffset; Isolate* isolate = I::GetIsolateForSandbox(obj); A value = I::ReadExternalPointerField( isolate, obj, offset); return reinterpret_cast(value); } #endif return SlowGetAlignedPointerFromInternalField(index); } Private* Private::Cast(Data* data) { #ifdef V8_ENABLE_CHECKS CheckCast(data); #endif return reinterpret_cast(data); } Object* Object::Cast(v8::Value* value) { #ifdef V8_ENABLE_CHECKS CheckCast(value); #endif return static_cast(value); } } // namespace v8 #endif // INCLUDE_V8_OBJECT_H_