src/gromacs/utility/flags.h

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  35 /*! \file
  36  * \brief
  37  * Declares gmx::FlagsTemplate.
  38  *
  39  * \author Teemu Murtola <teemu.murtola@gmail.com>
  40  * \inlibraryapi
  41  * \ingroup module_utility
  42  */
  43 #ifndef GMX_UTILITY_FLAGS_H
  44 #define GMX_UTILITY_FLAGS_H
  45
  46 namespace gmx
  47 {
  48
  49 /*! \brief
  50  * Template class for typesafe handling of combination of flags.
  51  *
  52  * \tparam FlagType An enumerated type that holds the possible single flags. The enum
  53  * must be of unsigned underlying type.
  54  *
  55  * This class is not used publicly, but is present in an installed header
  56  * because it is used internally in public template classes.
  57  *
  58  * Currently, it is not completely transparent, since or'ing together two
  59  * \p FlagType flags does not automatically create a FlagsTemplate object.
  60  * Also, some operators and more complex operations (like testing for multiple
  61  * flags at the same time) are missing, but can be added if the need arises.
  62  *
  63  * \inlibraryapi
  64  * \ingroup module_utility
  65  */
  66 template<typename FlagType>
  67 class FlagsTemplate
  68 {
  69 public:
  70     static_assert(std::is_enum_v<FlagType> && std::is_unsigned_v<std::underlying_type_t<FlagType>>,
  71                   "Flags must be an unsigned enum type.");
  72     //! Creates a flags object with no flags set.
  73     FlagsTemplate() : flags_(0) {}
  74     //! Creates a flags object from a single flag.
  75     FlagsTemplate(FlagType flag) : flags_(flag) {}
  76
  77     /*! \brief
  78      * Tests if the given flag is set.
  79      *
  80      * Note that if \p flag has more than a single bit set, then returns
  81      * true if any of them is set.
  82      */
  83     bool test(FlagType flag) const { return (flags_ & flag) != 0; }
  84     //! Clears all flags.
  85     void clearAll() { flags_ = 0; }
  86     //! Sets the given flag.
  87     void set(FlagType flag) { flags_ |= flag; }
  88     //! Clears the given flag.
  89     void clear(FlagType flag) { flags_ &= ~flag; }
  90     //! Sets or clears the given flag.
  91     void set(FlagType flag, bool bSet)
  92     {
  93         if (bSet)
  94         {
  95             set(flag);
  96         }
  97         else
  98         {
  99             clear(flag);
 100         }
 101     }
 102
 103     //! Combines flags from two flags objects.
 104     FlagsTemplate<FlagType> operator|(const FlagsTemplate<FlagType>& other) const
 105     {
 106         return FlagsTemplate<FlagType>(flags_ | other.flags_);
 107     }
 108     //! Combines flags from another flag object.
 109     FlagsTemplate<FlagType>& operator|=(const FlagsTemplate<FlagType>& other)
 110     {
 111         flags_ |= other.flags_;
 112         return *this;
 113     }
 114     //! Combined flags from two flags objects.
 115     FlagsTemplate<FlagType> operator&(const FlagsTemplate<FlagType>& other) const
 116     {
 117         return FlagsTemplate<FlagType>(flags_ & other.flags_);
 118     }
 119     //! Returns an object with all flags flipped.
 120     FlagsTemplate<FlagType> operator~() const { return FlagsTemplate<FlagType>(~flags_); }
 121
 122 private:
 123     //! Creates a flags object with the given flags.
 124     explicit FlagsTemplate(unsigned long flags) : flags_(flags) {}
 125
 126     uint64_t flags_;
 127 };
 128
 129 } // namespace gmx
 130
 131 #endif