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 ÿØÿà JFIF    ÿÛ „  ( %!1!%*+...983,7(-.- ÿØÿà JFIF    ÿÛ „  ( %!1!%*+...983,7(-.- // 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_VALUE_H_ #define INCLUDE_V8_VALUE_H_ #include "v8-data.h" // NOLINT(build/include_directory) #include "v8-internal.h" // NOLINT(build/include_directory) #include "v8-local-handle.h" // NOLINT(build/include_directory) #include "v8-maybe.h" // NOLINT(build/include_directory) #include "v8config.h" // NOLINT(build/include_directory) /** * The v8 JavaScript engine. */ namespace v8 { class Primitive; class Numeric; class BigInt; class Int32; class Integer; class Number; class Object; class String; class Uint32; /** * The superclass of all JavaScript values and objects. */ class V8_EXPORT Value : public Data { public: /** * Returns true if this value is the undefined value. See ECMA-262 * 4.3.10. * * This is equivalent to `value === undefined` in JS. */ V8_INLINE bool IsUndefined() const; /** * Returns true if this value is the null value. See ECMA-262 * 4.3.11. * * This is equivalent to `value === null` in JS. */ V8_INLINE bool IsNull() const; /** * Returns true if this value is either the null or the undefined value. * See ECMA-262 * 4.3.11. and 4.3.12 * * This is equivalent to `value == null` in JS. */ V8_INLINE bool IsNullOrUndefined() const; /** * Returns true if this value is true. * * This is not the same as `BooleanValue()`. The latter performs a * conversion to boolean, i.e. the result of `Boolean(value)` in JS, whereas * this checks `value === true`. */ V8_INLINE bool IsTrue() const; /** * Returns true if this value is false. * * This is not the same as `!BooleanValue()`. The latter performs a * conversion to boolean, i.e. the result of `!Boolean(value)` in JS, whereas * this checks `value === false`. */ V8_INLINE bool IsFalse() const; /** * Returns true if this value is a symbol or a string. * * This is equivalent to * `typeof value === 'string' || typeof value === 'symbol'` in JS. */ bool IsName() const; /** * Returns true if this value is an instance of the String type. * See ECMA-262 8.4. * * This is equivalent to `typeof value === 'string'` in JS. */ V8_INLINE bool IsString() const; /** * Returns true if this value is a symbol. * * This is equivalent to `typeof value === 'symbol'` in JS. */ bool IsSymbol() const; /** * Returns true if this value is a function. * * This is equivalent to `typeof value === 'function'` in JS. */ bool IsFunction() const; /** * Returns true if this value is an array. Note that it will return false for * an Proxy for an array. */ bool IsArray() const; /** * Returns true if this value is an object. */ bool IsObject() const; /** * Returns true if this value is a bigint. * * This is equivalent to `typeof value === 'bigint'` in JS. */ bool IsBigInt() const; /** * Returns true if this value is boolean. * * This is equivalent to `typeof value === 'boolean'` in JS. */ bool IsBoolean() const; /** * Returns true if this value is a number. * * This is equivalent to `typeof value === 'number'` in JS. */ bool IsNumber() const; /** * Returns true if this value is an `External` object. */ bool IsExternal() const; /** * Returns true if this value is a 32-bit signed integer. */ bool IsInt32() const; /** * Returns true if this value is a 32-bit unsigned integer. */ bool IsUint32() const; /** * Returns true if this value is a Date. */ bool IsDate() const; /** * Returns true if this value is an Arguments object. */ bool IsArgumentsObject() const; /** * Returns true if this value is a BigInt object. */ bool IsBigIntObject() const; /** * Returns true if this value is a Boolean object. */ bool IsBooleanObject() const; /** * Returns true if this value is a Number object. */ bool IsNumberObject() const; /** * Returns true if this value is a String object. */ bool IsStringObject() const; /** * Returns true if this value is a Symbol object. */ bool IsSymbolObject() const; /** * Returns true if this value is a NativeError. */ bool IsNativeError() const; /** * Returns true if this value is a RegExp. */ bool IsRegExp() const; /** * Returns true if this value is an async function. */ bool IsAsyncFunction() const; /** * Returns true if this value is a Generator function. */ bool IsGeneratorFunction() const; /** * Returns true if this value is a Generator object (iterator). */ bool IsGeneratorObject() const; /** * Returns true if this value is a Promise. */ bool IsPromise() const; /** * Returns true if this value is a Map. */ bool IsMap() const; /** * Returns true if this value is a Set. */ bool IsSet() const; /** * Returns true if this value is a Map Iterator. */ bool IsMapIterator() const; /** * Returns true if this value is a Set Iterator. */ bool IsSetIterator() const; /** * Returns true if this value is a WeakMap. */ bool IsWeakMap() const; /** * Returns true if this value is a WeakSet. */ bool IsWeakSet() const; /** * Returns true if this value is a WeakRef. */ bool IsWeakRef() const; /** * Returns true if this value is an ArrayBuffer. */ bool IsArrayBuffer() const; /** * Returns true if this value is an ArrayBufferView. */ bool IsArrayBufferView() const; /** * Returns true if this value is one of TypedArrays. */ bool IsTypedArray() const; /** * Returns true if this value is an Uint8Array. */ bool IsUint8Array() const; /** * Returns true if this value is an Uint8ClampedArray. */ bool IsUint8ClampedArray() const; /** * Returns true if this value is an Int8Array. */ bool IsInt8Array() const; /** * Returns true if this value is an Uint16Array. */ bool IsUint16Array() const; /** * Returns true if this value is an Int16Array. */ bool IsInt16Array() const; /** * Returns true if this value is an Uint32Array. */ bool IsUint32Array() const; /** * Returns true if this value is an Int32Array. */ bool IsInt32Array() const; /** * Returns true if this value is a Float16Array. */ bool IsFloat16Array() const; /** * Returns true if this value is a Float32Array. */ bool IsFloat32Array() const; /** * Returns true if this value is a Float64Array. */ bool IsFloat64Array() const; /** * Returns true if this value is a BigInt64Array. */ bool IsBigInt64Array() const; /** * Returns true if this value is a BigUint64Array. */ bool IsBigUint64Array() const; /** * Returns true if this value is a DataView. */ bool IsDataView() const; /** * Returns true if this value is a SharedArrayBuffer. */ bool IsSharedArrayBuffer() const; /** * Returns true if this value is a JavaScript Proxy. */ bool IsProxy() const; /** * Returns true if this value is a WasmMemoryObject. */ bool IsWasmMemoryObject() const; /** * Returns true if this value is a WasmMemoryMapDescriptor. */ bool IsWasmMemoryMapDescriptor() const; /** * Returns true if this value is a WasmModuleObject. */ bool IsWasmModuleObject() const; /** * Returns true if this value is the WasmNull object. */ bool IsWasmNull() const; /** * Returns true if the value is a Module Namespace Object. */ bool IsModuleNamespaceObject() const; /** * Returns true if the value is a primitive. */ bool IsPrimitive() const; /** * Perform `ToPrimitive(value)` as specified in: * https://tc39.es/ecma262/#sec-toprimitive. */ V8_WARN_UNUSED_RESULT MaybeLocal ToPrimitive( Local context) const; /** * Perform `ToNumeric(value)` as specified in: * https://tc39.es/ecma262/#sec-tonumeric. */ V8_WARN_UNUSED_RESULT MaybeLocal ToNumeric( Local context) const; /** * Perform the equivalent of `BigInt(value)` in JS. */ V8_WARN_UNUSED_RESULT MaybeLocal ToBigInt( Local context) const; /** * Perform the equivalent of `Number(value)` in JS. */ V8_WARN_UNUSED_RESULT MaybeLocal ToNumber( Local context) const; /** * Perform the equivalent of `String(value)` in JS. */ V8_WARN_UNUSED_RESULT MaybeLocal ToString( Local context) const; /** * Provide a string representation of this value usable for debugging. * This operation has no observable side effects and will succeed * unless e.g. execution is being terminated. */ V8_WARN_UNUSED_RESULT MaybeLocal ToDetailString( Local context) const; /** * Perform the equivalent of `Tagged(value)` in JS. */ V8_WARN_UNUSED_RESULT MaybeLocal ToObject( Local context) const; /** * Perform the equivalent of `Number(value)` in JS and convert the result * to an integer. Negative values are rounded up, positive values are rounded * down. NaN is converted to 0. Infinite values yield undefined results. */ V8_WARN_UNUSED_RESULT MaybeLocal ToInteger( Local context) const; /** * Perform the equivalent of `Number(value)` in JS and convert the result * to an unsigned 32-bit integer by performing the steps in * https://tc39.es/ecma262/#sec-touint32. */ V8_WARN_UNUSED_RESULT MaybeLocal ToUint32( Local context) const; /** * Perform the equivalent of `Number(value)` in JS and convert the result * to a signed 32-bit integer by performing the steps in * https://tc39.es/ecma262/#sec-toint32. */ V8_WARN_UNUSED_RESULT MaybeLocal ToInt32(Local context) const; /** * Perform the equivalent of `Boolean(value)` in JS. This can never fail. */ Local ToBoolean(Isolate* isolate) const; /** * Attempts to convert a string to an array index. * Returns an empty handle if the conversion fails. */ V8_WARN_UNUSED_RESULT MaybeLocal ToArrayIndex( Local context) const; /** Returns the equivalent of `ToBoolean()->Value()`. */ bool BooleanValue(Isolate* isolate) const; /** Returns the equivalent of `ToNumber()->Value()`. */ V8_WARN_UNUSED_RESULT Maybe NumberValue(Local context) const; /** Returns the equivalent of `ToInteger()->Value()`. */ V8_WARN_UNUSED_RESULT Maybe IntegerValue( Local context) const; /** Returns the equivalent of `ToUint32()->Value()`. */ V8_WARN_UNUSED_RESULT Maybe Uint32Value( Local context) const; /** Returns the equivalent of `ToInt32()->Value()`. */ V8_WARN_UNUSED_RESULT Maybe Int32Value(Local context) const; /** JS == */ V8_WARN_UNUSED_RESULT Maybe Equals(Local context, Local that) const; bool StrictEquals(Local that) const; bool SameValue(Local that) const; template V8_INLINE static Value* Cast(T* value) { return static_cast(value); } Local TypeOf(Isolate*); Maybe InstanceOf(Local context, Local object); /** * Get the hash of this value. The hash is not guaranteed to be * unique. For |Object| and |Name| instances the result is equal to * |GetIdentityHash|. Hashes are not guaranteed to be stable across * different isolates or processes. */ uint32_t GetHash(); private: V8_INLINE bool QuickIsUndefined() const; V8_INLINE bool QuickIsNull() const; V8_INLINE bool QuickIsNullOrUndefined() const; #if V8_STATIC_ROOTS_BOOL V8_INLINE bool QuickIsTrue() const; V8_INLINE bool QuickIsFalse() const; #endif // V8_STATIC_ROOTS_BOOL V8_INLINE bool QuickIsString() const; bool FullIsUndefined() const; bool FullIsNull() const; bool FullIsTrue() const; bool FullIsFalse() const; bool FullIsString() const; static void CheckCast(Data* that); }; /** * Can be used to avoid repeated expensive type checks for groups of objects * that are expected to be similar (e.g. when Blink converts a bunch of * JavaScript objects to "ScriptWrappable" after a "HasInstance" check) by * making use of V8-internal "hidden classes". An object that has passed the * full check can be remembered via {Update}; further objects can be queried * using {Matches}. * Note that the answer will be conservative/"best-effort": when {Matches} * returns true, then the {candidate} can be relied upon to have the same * shape/constructor/prototype/etc. as the {baseline}. Otherwise, no reliable * statement can be made (the objects might still have indistinguishable shapes * for all intents and purposes, but this mechanism, being optimized for speed, * couldn't determine that quickly). */ class V8_EXPORT TypecheckWitness { public: explicit TypecheckWitness(Isolate* isolate); /** * Checks whether {candidate} can cheaply be identified as being "similar" * to the {baseline} that was passed to {Update} earlier. * It's safe to call this on an uninitialized {TypecheckWitness} instance: * it will then return {false} for any input. */ V8_INLINE bool Matches(Local candidate) const; /** * Remembers a new baseline for future {Matches} queries. */ void Update(Local baseline); private: Local cached_map_; }; template <> V8_INLINE Value* Value::Cast(Data* value) { #ifdef V8_ENABLE_CHECKS CheckCast(value); #endif return static_cast(value); } bool Value::IsUndefined() const { #ifdef V8_ENABLE_CHECKS return FullIsUndefined(); #else return QuickIsUndefined(); #endif } bool Value::QuickIsUndefined() const { using A = internal::Address; using I = internal::Internals; A obj = internal::ValueHelper::ValueAsAddress(this); #if V8_STATIC_ROOTS_BOOL return I::is_identical(obj, I::StaticReadOnlyRoot::kUndefinedValue); #else if (!I::HasHeapObjectTag(obj)) return false; if (I::GetInstanceType(obj) != I::kOddballType) return false; return (I::GetOddballKind(obj) == I::kUndefinedOddballKind); #endif // V8_STATIC_ROOTS_BOOL } bool Value::IsNull() const { #ifdef V8_ENABLE_CHECKS return FullIsNull(); #else return QuickIsNull(); #endif } bool Value::QuickIsNull() const { using A = internal::Address; using I = internal::Internals; A obj = internal::ValueHelper::ValueAsAddress(this); #if V8_STATIC_ROOTS_BOOL return I::is_identical(obj, I::StaticReadOnlyRoot::kNullValue); #else if (!I::HasHeapObjectTag(obj)) return false; if (I::GetInstanceType(obj) != I::kOddballType) return false; return (I::GetOddballKind(obj) == I::kNullOddballKind); #endif // V8_STATIC_ROOTS_BOOL } bool Value::IsNullOrUndefined() const { #ifdef V8_ENABLE_CHECKS return FullIsNull() || FullIsUndefined(); #else return QuickIsNullOrUndefined(); #endif } bool Value::QuickIsNullOrUndefined() const { #if V8_STATIC_ROOTS_BOOL return QuickIsNull() || QuickIsUndefined(); #else using A = internal::Address; using I = internal::Internals; A obj = internal::ValueHelper::ValueAsAddress(this); if (!I::HasHeapObjectTag(obj)) return false; if (I::GetInstanceType(obj) != I::kOddballType) return false; int kind = I::GetOddballKind(obj); return kind == I::kNullOddballKind || kind == I::kUndefinedOddballKind; #endif // V8_STATIC_ROOTS_BOOL } bool Value::IsTrue() const { #if V8_STATIC_ROOTS_BOOL && !defined(V8_ENABLE_CHECKS) return QuickIsTrue(); #else return FullIsTrue(); #endif } #if V8_STATIC_ROOTS_BOOL bool Value::QuickIsTrue() const { using A = internal::Address; using I = internal::Internals; A obj = internal::ValueHelper::ValueAsAddress(this); return I::is_identical(obj, I::StaticReadOnlyRoot::kTrueValue); } #endif // V8_STATIC_ROOTS_BOOL bool Value::IsFalse() const { #if V8_STATIC_ROOTS_BOOL && !defined(V8_ENABLE_CHECKS) return QuickIsFalse(); #else return FullIsFalse(); #endif } #if V8_STATIC_ROOTS_BOOL bool Value::QuickIsFalse() const { using A = internal::Address; using I = internal::Internals; A obj = internal::ValueHelper::ValueAsAddress(this); return I::is_identical(obj, I::StaticReadOnlyRoot::kFalseValue); } #endif // V8_STATIC_ROOTS_BOOL bool Value::IsString() const { #ifdef V8_ENABLE_CHECKS return FullIsString(); #else return QuickIsString(); #endif } bool Value::QuickIsString() const { using A = internal::Address; using I = internal::Internals; A obj = internal::ValueHelper::ValueAsAddress(this); if (!I::HasHeapObjectTag(obj)) return false; #if V8_STATIC_ROOTS_BOOL && !V8_MAP_PACKING return I::CheckInstanceMapRange(obj, I::StaticReadOnlyRoot::kStringMapLowerBound, I::StaticReadOnlyRoot::kStringMapUpperBound); #else return (I::GetInstanceType(obj) < I::kFirstNonstringType); #endif // V8_STATIC_ROOTS_BOOL } bool TypecheckWitness::Matches(Local candidate) const { internal::Address obj = internal::ValueHelper::ValueAsAddress(*candidate); internal::Address obj_map = internal::Internals::LoadMap(obj); internal::Address cached = internal::ValueHelper::ValueAsAddress(*cached_map_); return obj_map == cached; } } // namespace v8 #endif // INCLUDE_V8_VALUE_H_