oddball.h

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// Copyright 2018 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 V8_OBJECTS_ODDBALL_H_
#define V8_OBJECTS_ODDBALL_H_
 
#include "src/objects/primitive-heap-object.h"
 
// Has to be the last include (doesn't have include guards):
#include "src/objects/object-macros.h"
 
namespace v8 {
namespace internal {
 
// The Oddball describes objects null, undefined, true, and false.
V8_OBJECT class Oddball : public PrimitiveHeapObject {
 public:
  // [to_number_raw]: Cached raw to_number computed at startup.
  DECL_PRIMITIVE_ACCESSORS(to_number_raw, double)
  inline void set_to_number_raw_as_bits(uint64_t bits);
 
  // [to_string]: Cached to_string computed at startup.
  inline Tagged<String> to_string() const;
  inline void set_to_string(Tagged<String> value,
                            WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
 
  // [to_number]: Cached to_number computed at startup.
  inline Tagged<Number> to_number() const;
  inline void set_to_number(Tagged<Number> value,
                            WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
 
  // [typeof]: Cached type_of computed at startup.
  inline Tagged<String> type_of() const;
  inline void set_type_of(Tagged<String> value,
                          WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
 
  inline uint8_t kind() const;
  inline void set_kind(uint8_t kind);
 
  // ES6 section 7.1.3 ToNumber for Boolean, Null, Undefined.
  V8_WARN_UNUSED_RESULT static inline Handle<Number> ToNumber(
      Isolate* isolate, DirectHandle<Oddball> input);
 
  // Dispatched behavior.
  DECL_VERIFIER(Oddball)
 
  // Initialize the fields.
  static void Initialize(Isolate* isolate, DirectHandle<Oddball> oddball,
                         const char* to_string, DirectHandle<Number> to_number,
                         const char* type_of, uint8_t kind);
 
  static constexpr uint8_t kFalse = 0;
  static constexpr uint8_t kTrue = 1;
  static constexpr uint8_t kNotBooleanMask = static_cast<uint8_t>(~1);
  static constexpr uint8_t kNull = 3;
  static constexpr uint8_t kUndefined = 4;
 
  DECL_PRINTER(Oddball)
 
 private:
  friend struct ObjectTraits<Oddball>;
  friend struct OffsetsForDebug;
  friend class CodeStubAssembler;
  friend class maglev::MaglevAssembler;
  friend class compiler::AccessBuilder;
  friend class TorqueGeneratedOddballAsserts;
 
  UnalignedDoubleMember to_number_raw_;
  TaggedMember<String> to_string_;
  TaggedMember<Number> to_number_;
  TaggedMember<String> type_of_;
  TaggedMember<Smi> kind_;
} V8_OBJECT_END;
 
template <>
struct ObjectTraits<Oddball> {
  using BodyDescriptor =
      FixedBodyDescriptor<offsetof(Oddball, to_string_),
                          offsetof(Oddball, kind_), sizeof(Oddball)>;
 
  static_assert(offsetof(Oddball, kind_) == Internals::kOddballKindOffset);
  static_assert(Oddball::kNull == Internals::kNullOddballKind);
  static_assert(Oddball::kUndefined == Internals::kUndefinedOddballKind);
};
 
V8_OBJECT class Null : public Oddball {
} V8_OBJECT_END;
 
V8_OBJECT class Undefined : public Oddball {
} V8_OBJECT_END;
 
V8_OBJECT class Boolean : public Oddball {
 public:
  V8_INLINE bool ToBool(Isolate* isolate) const;
} V8_OBJECT_END;
 
V8_OBJECT class True : public Boolean {
} V8_OBJECT_END;
 
V8_OBJECT class False : public Boolean {
} V8_OBJECT_END;
 
}  // namespace internal
}  // namespace v8
 
#include "src/objects/object-macros-undef.h"
 
#endif  // V8_OBJECTS_ODDBALL_H_