include/o3tl/enumarray.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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  19
  20 #ifndef INCLUDED_O3TL_ENUMARRAY_HXX
  21 #define INCLUDED_O3TL_ENUMARRAY_HXX
  22
  23 #include <iterator>
  24 #include <type_traits>
  25 #include <cassert>
  26
  27 namespace o3tl {
  28
  29 template<typename EA>
  30 class enumarray_iterator;
  31 template<typename EA>
  32 class enumarray_const_iterator;
  33
  34 ///
  35 /// This is a container convenience class for arrays indexed by enum values.
  36 ///
  37 /// This assumes that the 'enum class' definition
  38 ///  - starts at zero
  39 ///  - has no holes in its sequence of values
  40 ///  - defines a value called LAST which refers to the greatest constant.
  41 ///
  42 /// \param E the 'enum class' type.
  43 /// \param V the value type to be stored in the array
  44 template<typename E, typename V>
  45 class enumarray final
  46 {
  47 public:
  48     typedef enumarray<E, V> self_type;
  49     typedef enumarray_iterator<self_type> iterator;
  50     typedef enumarray_const_iterator<self_type> const_iterator;
  51
  52     typedef V             value_type;
  53     typedef E             key_type;
  54     typedef size_t        size_type;
  55
  56     static const size_type max_index = static_cast<size_type>(E::LAST);
  57
  58     const V& operator[](E index) const
  59     {
  60         assert(index>=static_cast<E>(0) && index<=E::LAST);
  61         return detail_values[static_cast<size_type>(index)];
  62     }
  63
  64     V& operator[](E index)
  65     {
  66         assert(index>=static_cast<E>(0) && index<=E::LAST);
  67         return detail_values[static_cast<size_type>(index)];
  68     }
  69
  70     void fill(V val)
  71     { for (size_type i=0; i<=max_index; ++i) detail_values[i] = val; }
  72
  73     static size_type size()        { return max_index + 1; }
  74     iterator         begin()       { return iterator(*this, 0); }
  75     iterator         end()         { return iterator(*this, size()); }
  76     const_iterator   begin() const { return const_iterator(*this, 0); }
  77     const_iterator   end() const   { return const_iterator(*this, size()); }
  78
  79     V*               data()       { return detail_values; }
  80
  81 //private:
  82     V detail_values[max_index + 1];
  83 };
  84
  85
  86 template<typename EA>
  87 class enumarray_iterator {
  88     EA&         m_buf;
  89     size_t      m_pos;
  90 public:
  91     typedef enumarray_iterator<EA>  self_type;
  92     typedef typename EA::value_type value_type;
  93     typedef typename EA::key_type   key_type;
  94     typedef std::bidirectional_iterator_tag iterator_category; //should be random access, but that would require define subtraction operators on the enums
  95     typedef
  96         typename std::make_signed<
  97             typename std::underlying_type<typename EA::key_type>::type>::type
  98         difference_type;
  99     typedef typename EA::value_type*   pointer;
 100     typedef typename EA::value_type&   reference;
 101
 102     enumarray_iterator(EA& b, size_t start_pos)
 103          : m_buf(b), m_pos(start_pos) {}
 104     value_type& operator*()  const { return m_buf[static_cast<key_type>(m_pos)]; }
 105     value_type* operator->() const { return &(operator*()); }
 106     self_type&  operator++() { ++m_pos; return *this; }
 107     bool        operator!=(self_type const & other) const { return &m_buf != &other.m_buf || m_pos != other.m_pos; }
 108     bool        operator==(self_type const & other) const { return &m_buf == &other.m_buf && m_pos == other.m_pos; }
 109     enumarray_iterator&
 110                 operator=(self_type const & other) { m_buf = other.m_buf; m_pos = other.m_pos; return *this; }
 111 };
 112
 113 template<typename EA>
 114 class enumarray_const_iterator {
 115     EA const &  m_buf;
 116     size_t      m_pos;
 117 public:
 118     typedef enumarray_const_iterator<EA>    self_type;
 119     typedef typename EA::value_type const   value_type;
 120     typedef typename EA::key_type           key_type;
 121     typedef std::bidirectional_iterator_tag iterator_category; //should be random access, but that would require define subtraction operators on the enums
 122     typedef
 123         typename std::make_signed<
 124             typename std::underlying_type<typename EA::key_type>::type>::type
 125                                             difference_type;
 126     typedef typename EA::value_type const * pointer;
 127     typedef typename EA::value_type const & reference;
 128
 129     enumarray_const_iterator(EA const & b, size_t start_pos)
 130          : m_buf(b), m_pos(start_pos) {}
 131     value_type& operator*()  const { return m_buf[static_cast<key_type>(m_pos)]; }
 132     value_type* operator->() const { return &(operator*()); }
 133     self_type&  operator++() { ++m_pos; return *this; }
 134     bool        operator!=(self_type const & other) const { return &m_buf != &other.m_buf || m_pos != other.m_pos; }
 135     bool        operator==(self_type const & other) const { return &m_buf == &other.m_buf && m_pos == other.m_pos; }
 136     enumarray_const_iterator&
 137                 operator=(self_type const & other) { m_buf = other.m_buf; m_pos = other.m_pos; return *this; }
 138 };
 139
 140 }; // namespace o3tl
 141
 142 #endif /* INCLUDED_O3TL_ENUMARRAY_HXX */
 143
 144 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */