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// 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 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;
/**
* Perform `ToPrimitive(value)` as specified in:
* https://tc39.es/ecma262/#sec-toprimitive.
*/
V8_WARN_UNUSED_RESULT MaybeLocal<Primitive> ToPrimitive(
Local<Context> context) const;
/**
* Perform `ToNumeric(value)` as specified in:
* https://tc39.es/ecma262/#sec-tonumeric.
*/
V8_WARN_UNUSED_RESULT MaybeLocal<Numeric> ToNumeric(
Local<Context> context) const;
/**
* Perform the equivalent of `BigInt(value)` in JS.
*/
V8_WARN_UNUSED_RESULT MaybeLocal<BigInt> ToBigInt(
Local<Context> context) const;
/**
* Perform the equivalent of `Number(value)` in JS.
*/
V8_WARN_UNUSED_RESULT MaybeLocal<Number> ToNumber(
Local<Context> context) const;
/**
* Perform the equivalent of `String(value)` in JS.
*/
V8_WARN_UNUSED_RESULT MaybeLocal<String> ToString(
Local<Context> 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<String> ToDetailString(
Local<Context> context) const;
/**
* Perform the equivalent of `Tagged<Object>(value)` in JS.
*/
V8_WARN_UNUSED_RESULT MaybeLocal<Object> ToObject(
Local<Context> 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<Integer> ToInteger(
Local<Context> 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<Uint32> ToUint32(
Local<Context> 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<Int32> ToInt32(Local<Context> context) const;
/**
* Perform the equivalent of `Boolean(value)` in JS. This can never fail.
*/
Local<Boolean> 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<Uint32> ToArrayIndex(
Local<Context> context) const;
/** Returns the equivalent of `ToBoolean()->Value()`. */
bool BooleanValue(Isolate* isolate) const;
/** Returns the equivalent of `ToNumber()->Value()`. */
V8_WARN_UNUSED_RESULT Maybe<double> NumberValue(Local<Context> context) const;
/** Returns the equivalent of `ToInteger()->Value()`. */
V8_WARN_UNUSED_RESULT Maybe<int64_t> IntegerValue(
Local<Context> context) const;
/** Returns the equivalent of `ToUint32()->Value()`. */
V8_WARN_UNUSED_RESULT Maybe<uint32_t> Uint32Value(
Local<Context> context) const;
/** Returns the equivalent of `ToInt32()->Value()`. */
V8_WARN_UNUSED_RESULT Maybe<int32_t> Int32Value(Local<Context> context) const;
/** JS == */
V8_WARN_UNUSED_RESULT Maybe<bool> Equals(Local<Context> context,
Local<Value> that) const;
bool StrictEquals(Local<Value> that) const;
bool SameValue(Local<Value> that) const;
template <class T>
V8_INLINE static Value* Cast(T* value) {
return static_cast<Value*>(value);
}
Local<String> TypeOf(Isolate*);
Maybe<bool> InstanceOf(Local<Context> context, Local<Object> object);
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<Value> candidate) const;
/**
* Remembers a new baseline for future {Matches} queries.
*/
void Update(Local<Value> baseline);
private:
Local<Data> cached_map_;
};
template <>
V8_INLINE Value* Value::Cast(Data* value) {
#ifdef V8_ENABLE_CHECKS
CheckCast(value);
#endif
return static_cast<Value*>(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::kFirstStringMap,
I::StaticReadOnlyRoot::kLastStringMap);
#else
return (I::GetInstanceType(obj) < I::kFirstNonstringType);
#endif // V8_STATIC_ROOTS_BOOL
}
bool TypecheckWitness::Matches(Local<Value> 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_