src/subtitles/xy_circular_array_queue.h

   1 #ifndef __XY_CIRCULAR_ARRAY_QUEUE_HPP_47831C93_EDAA_44B9_94F2_6FF36839D1A6__
   2 #define __XY_CIRCULAR_ARRAY_QUEUE_HPP_47831C93_EDAA_44B9_94F2_6FF36839D1A6__
   3
   4 template <typename ElementType>
   5 class XYCircularArrayQueue
   6 {
   7 public:
   8     typedef ElementType                 value_type;
   9     typedef ElementType&                reference;
  10     typedef const ElementType&          const_reference;
  11 public:
  12     /***
  13      *  @brief  Default constructor creates no elements.
  14      **/
  15     explicit XYCircularArrayQueue()
  16         :_elements(NULL),
  17         _head(0),
  18         _tail(0),
  19         _CAPACITY(0)
  20     {
  21     }
  22
  23     ~XYCircularArrayQueue()
  24     {
  25         delete[]  _elements;
  26     }
  27
  28     inline int init(size_t  capacity)
  29     {
  30         _CAPACITY = capacity;
  31         _elements = new value_type[_CAPACITY];
  32         return _elements ? 0 : -1;
  33     }
  34
  35     inline size_t capacity()
  36     {
  37         return _CAPACITY;
  38     }
  39
  40     inline bool full() const
  41     {
  42         return size() >= (_CAPACITY -1);
  43     }
  44
  45     inline bool empty() const
  46     {
  47         return _head == _tail;
  48     }
  49
  50     /***
  51      * @return: the number of elements in the @queue.
  52      **/
  53     inline size_t size() const
  54     {
  55         return (_CAPACITY -_head+_tail) %_CAPACITY;
  56     }
  57
  58     /***
  59      * @return: the number of free elements in the @queue.
  60      **/
  61     inline size_t free() const
  62     {
  63         return _CAPACITY - (_CAPACITY -_head+_tail) %_CAPACITY;
  64     }
  65
  66     /***
  67      *  @return: a read/write reference to the i-th element.
  68      **/
  69     inline reference get_at(int i)
  70     {
  71         i += _head;
  72         i %= _CAPACITY;
  73         return _elements[i];
  74     }
  75
  76     /***
  77      *  @return: a read-only reference to the i-th element.
  78      **/
  79     inline const_reference get_at(int i) const
  80     {
  81         i += _head;
  82         i %= _CAPACITY;
  83         return _elements[i];
  84     }
  85
  86     /***
  87      *  @return: a read/write reference to the last element
  88      **/
  89     inline reference back()
  90     {
  91         return _elements[(_CAPACITY +_tail -1) % _CAPACITY];
  92     }
  93
  94     /***
  95      *  @return: a read-only reference to the last element
  96      **/
  97     inline const_reference back() const
  98     {
  99         return _elements[(_CAPACITY +_tail -1) % _CAPACITY];
 100     }
 101
 102     /***
 103      *  @return: 0 if succeeded, -1 if failed
 104      **/
 105     inline int push_back(const_reference value)
 106     {
 107         if(size() == (_CAPACITY -1))
 108         {
 109             return -1;
 110         }
 111         else
 112         {
 113             _elements[_tail] = value;
 114             _tail = (_tail+1) % _CAPACITY;
 115             return 0;
 116         }
 117     }
 118
 119     inline reference inc_1_at_tail()
 120     {
 121         _tail++;
 122         _tail += _CAPACITY;
 123         _tail %= _CAPACITY;
 124         return _elements[(_CAPACITY +_tail -1) % _CAPACITY];
 125     }
 126
 127     inline void pop_front()
 128     {
 129         if(empty())
 130         {
 131             return;
 132         }
 133         else
 134         {
 135             _head = (_head + 1) % _CAPACITY;
 136         }
 137     }
 138
 139     inline void pop_back()
 140     {
 141         if(empty())
 142         {
 143             return;
 144         }
 145         else
 146         {
 147             _tail = (_tail - 1 + _CAPACITY) % _CAPACITY;
 148         }
 149     }
 150
 151     inline void pop_last_n(int n)
 152     {
 153         if (size()<n)
 154         {
 155             _head = _tail = 0;
 156         }
 157         else
 158         {
 159             _tail -= n;
 160             _tail += _CAPACITY;
 161             _tail %= _CAPACITY;
 162         }
 163     }
 164 private:
 165     value_type* _elements;
 166     volatile uint32_t _head;
 167     volatile uint32_t _tail;
 168     size_t   _CAPACITY;
 169
 170 };
 171
 172 #endif /* #ifndef __XY_CIRCULAR_ARRAY_QUEUE_HPP_47831C93_EDAA_44B9_94F2_6FF36839D1A6__ */
 173