src/base/flags.hh

   1 /*
   2  * Copyright (c) 2020 Daniel R. Carvalho
   3  * Copyright (c) 2008 The Hewlett-Packard Development Company
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions are
   8  * met: redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer;
  10  * redistributions in binary form must reproduce the above copyright
  11  * notice, this list of conditions and the following disclaimer in the
  12  * documentation and/or other materials provided with the distribution;
  13  * neither the name of the copyright holders nor the names of its
  14  * contributors may be used to endorse or promote products derived from
  15  * this software without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  18  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  19  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  20  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  21  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  22  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  23  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  27  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28  */
  29
  30 #ifndef __BASE_FLAGS_HH__
  31 #define __BASE_FLAGS_HH__
  32
  33 #include <type_traits>
  34
  35 /**
  36  * Wrapper that groups a few flag bits under the same undelying container.
  37  *
  38  * @tparam T The type of the underlying container. Must be an unsigned integer.
  39  */
  40 template <typename T>
  41 class Flags
  42 {
  43   private:
  44     static_assert(std::is_unsigned<T>::value, "Flag type must be unsigned");
  45
  46     /** The undelying container of the flags' bits. */
  47     T _flags;
  48
  49   public:
  50     typedef T Type;
  51
  52     /**
  53      * @ingroup api_flags
  54      * @{
  55      */
  56
  57     /**
  58      * Initialize flags with a given value. If no value is provided, the
  59      * flag bits are initialized cleared.
  60      *
  61      * @param flags The value to initialize the flags with.
  62      */
  63     Flags(Type flags=0) : _flags(flags) {}
  64
  65     operator const Type() const { return _flags; }
  66
  67     const Flags<T> &
  68     operator=(T flags)
  69     {
  70         _flags = flags;
  71         return *this;
  72     }
  73
  74     /**
  75      * Verifies whether any bit matching the given mask is set.
  76      *
  77      * @param mask The mask containing the bits to verify.
  78      * @return True if any matching bit is set; false otherwise.
  79      */
  80     bool isSet(Type mask) const { return (_flags & mask); }
  81
  82     /**
  83      * Verifies whether no bits matching the given mask are set.
  84      *
  85      * @param mask The mask containing the bits to verify.
  86      * @return True if matching bits are set; false otherwise.
  87      */
  88     bool allSet(Type mask) const { return (_flags & mask) == mask; }
  89
  90     /**
  91      * Verifies whether no bits matching the given mask are set.
  92      *
  93      * @param mask The mask containing the bits to verify.
  94      * @return True if matching bits are cleared; false otherwise.
  95      */
  96     bool noneSet(Type mask) const { return (_flags & mask) == 0; }
  97
  98     /** Clear all flag's bits. */
  99     void clear() { _flags = 0; }
 100
 101     /**
 102      * Clear all flag's bits matching the given mask.
 103      *
 104      * @param mask The mask containing the bits to be cleared.
 105      */
 106     void clear(Type mask) { _flags &= ~mask; }
 107
 108     /**
 109      * Set all flag's bits matching the given mask.
 110      *
 111      * @param mask The mask containing the bits to be set.
 112      */
 113     void set(Type mask) { _flags |= mask; }
 114
 115     /**
 116      * Conditionally set or clear some bits of the flag, given a mask.
 117      *
 118      * @param mask The mask containing the bits to be modified.
 119      * @param condition If true, set masked bits; otherwise, clear them.
 120      */
 121     void
 122     set(Type mask, bool condition)
 123     {
 124         condition ? set(mask) : clear(mask);
 125     }
 126
 127     /**
 128      * Replace the contents of the bits matching the mask with the
 129      * corresponding bits in the provided flags.
 130      *
 131      * This is equivalent to:
 132      *     flags.clear(mask); flags.set(flags & mask);
 133      *
 134      * @param flags Flags to extract new bits from.
 135      * @param mask Mask used to determine which bits are replaced.
 136      */
 137     void
 138     update(Type flags, Type mask)
 139     {
 140         _flags = (_flags & ~mask) | (flags & mask);
 141     }
 142     /** @} */ // end of api_flags
 143 };
 144
 145 #endif // __BASE_FLAGS_HH__