// Copyright 2014 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef V8_BASE_FLAGS_H_
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#define V8_BASE_FLAGS_H_
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#include <cstddef>
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#include "src/base/compiler-specific.h"
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namespace v8 {
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namespace base {
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// The Flags class provides a type-safe way of storing OR-combinations of enum
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// values. The Flags<T, S> class is a template class, where T is an enum type,
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// and S is the underlying storage type (usually int).
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//
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// The traditional C++ approach for storing OR-combinations of enum values is to
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// use an int or unsigned int variable. The inconvenience with this approach is
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// that there's no type checking at all; any enum value can be OR'd with any
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// other enum value and passed on to a function that takes an int or unsigned
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// int.
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template <typename T, typename S = int>
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class Flags final {
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public:
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typedef T flag_type;
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typedef S mask_type;
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constexpr Flags() : mask_(0) {}
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constexpr Flags(flag_type flag) // NOLINT(runtime/explicit)
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: mask_(static_cast<S>(flag)) {}
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constexpr explicit Flags(mask_type mask) : mask_(static_cast<S>(mask)) {}
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constexpr bool operator==(flag_type flag) const {
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return mask_ == static_cast<S>(flag);
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}
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constexpr bool operator!=(flag_type flag) const {
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return mask_ != static_cast<S>(flag);
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}
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Flags& operator&=(const Flags& flags) {
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mask_ &= flags.mask_;
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return *this;
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}
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Flags& operator|=(const Flags& flags) {
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mask_ |= flags.mask_;
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return *this;
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}
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Flags& operator^=(const Flags& flags) {
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mask_ ^= flags.mask_;
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return *this;
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}
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constexpr Flags operator&(const Flags& flags) const {
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return Flags(*this) &= flags;
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}
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constexpr Flags operator|(const Flags& flags) const {
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return Flags(*this) |= flags;
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}
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constexpr Flags operator^(const Flags& flags) const {
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return Flags(*this) ^= flags;
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}
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Flags& operator&=(flag_type flag) { return operator&=(Flags(flag)); }
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Flags& operator|=(flag_type flag) { return operator|=(Flags(flag)); }
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Flags& operator^=(flag_type flag) { return operator^=(Flags(flag)); }
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constexpr Flags operator&(flag_type flag) const {
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return operator&(Flags(flag));
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}
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constexpr Flags operator|(flag_type flag) const {
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return operator|(Flags(flag));
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}
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constexpr Flags operator^(flag_type flag) const {
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return operator^(Flags(flag));
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}
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constexpr Flags operator~() const { return Flags(~mask_); }
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constexpr operator mask_type() const { return mask_; }
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constexpr bool operator!() const { return !mask_; }
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friend size_t hash_value(const Flags& flags) { return flags.mask_; }
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private:
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mask_type mask_;
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};
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#define DEFINE_OPERATORS_FOR_FLAGS(Type) \
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inline Type operator&( \
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Type::flag_type lhs, \
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Type::flag_type rhs)ALLOW_UNUSED_TYPE V8_WARN_UNUSED_RESULT; \
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inline Type operator&(Type::flag_type lhs, Type::flag_type rhs) { \
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return Type(lhs) & rhs; \
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} \
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inline Type operator&( \
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Type::flag_type lhs, \
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const Type& rhs)ALLOW_UNUSED_TYPE V8_WARN_UNUSED_RESULT; \
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inline Type operator&(Type::flag_type lhs, const Type& rhs) { \
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return rhs & lhs; \
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} \
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inline void operator&(Type::flag_type lhs, \
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Type::mask_type rhs)ALLOW_UNUSED_TYPE; \
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inline void operator&(Type::flag_type lhs, Type::mask_type rhs) {} \
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inline Type operator|(Type::flag_type lhs, Type::flag_type rhs) \
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ALLOW_UNUSED_TYPE V8_WARN_UNUSED_RESULT; \
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inline Type operator|(Type::flag_type lhs, Type::flag_type rhs) { \
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return Type(lhs) | rhs; \
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} \
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inline Type operator|(Type::flag_type lhs, const Type& rhs) \
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ALLOW_UNUSED_TYPE V8_WARN_UNUSED_RESULT; \
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inline Type operator|(Type::flag_type lhs, const Type& rhs) { \
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return rhs | lhs; \
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} \
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inline void operator|(Type::flag_type lhs, Type::mask_type rhs) \
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ALLOW_UNUSED_TYPE; \
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inline void operator|(Type::flag_type lhs, Type::mask_type rhs) {} \
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inline Type operator^(Type::flag_type lhs, Type::flag_type rhs) \
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ALLOW_UNUSED_TYPE V8_WARN_UNUSED_RESULT; \
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inline Type operator^(Type::flag_type lhs, Type::flag_type rhs) { \
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return Type(lhs) ^ rhs; \
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} \
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inline Type operator^(Type::flag_type lhs, const Type& rhs) \
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ALLOW_UNUSED_TYPE V8_WARN_UNUSED_RESULT; \
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inline Type operator^(Type::flag_type lhs, const Type& rhs) { \
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return rhs ^ lhs; \
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} \
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inline void operator^(Type::flag_type lhs, Type::mask_type rhs) \
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ALLOW_UNUSED_TYPE; \
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inline void operator^(Type::flag_type lhs, Type::mask_type rhs) {} \
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inline Type operator~(Type::flag_type val)ALLOW_UNUSED_TYPE; \
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inline Type operator~(Type::flag_type val) { return ~Type(val); }
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} // namespace base
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} // namespace v8
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#endif // V8_BASE_FLAGS_H_
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