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circular_buffer.h
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1 /* +---------------------------------------------------------------------------+
2  | The Mobile Robot Programming Toolkit (MRPT) C++ library |
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10  | Contact: Jose-Luis Blanco <jlblanco@ctima.uma.es> |
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27  +---------------------------------------------------------------------------+ */
28 #ifndef circular_buffer_H
29 #define circular_buffer_H
30 
31 // Note: This file is included from "stl_extensions.h"
32 
33 #include <mrpt/utils/utils_defs.h>
34 #include <vector>
35 
36 namespace mrpt
37 {
38  namespace utils
39  {
40  /** A circular buffer of fixed size (defined at construction-time), implemented with a std::vector as the underlying storage.
41  * \ingroup stlext_grp
42  */
43  template <typename T>
44  class circular_buffer
45  {
46  private:
47  std::vector<T> m_data;
48  const size_t m_size;
49  size_t m_next_read,m_next_write;
50 
51  public:
52  circular_buffer(const size_t size) :
53  m_data(size),
54  m_size(size),
55  m_next_read(0),
56  m_next_write(0)
57  {
58  if (m_size<=2) throw std::invalid_argument("size must be >2");
59  }
60  //virtual ~circular_buffer() { }
61 
62  /** Insert a copy of the given element in the buffer.
63  * \exception std::out_of_range If the buffer run out of space.
64  */
65  void push(T d) {
66  m_data[m_next_write++]=d;
67  if (m_next_write==m_size) m_next_write=0;
68 
69  if (m_next_write==m_next_read)
70  throw std::out_of_range("push: circular_buffer is full");
71  }
72 
73  /** Insert a reference of the given element in the buffer.
74  * \exception std::out_of_range If the buffer run out of space.
75  */
76  void push_ref(const T &d) {
77  m_data[m_next_write++]=d;
78  if (m_next_write==m_size) m_next_write=0;
79 
80  if (m_next_write==m_next_read)
81  throw std::out_of_range("push: circular_buffer is full");
82  }
83 
84  /** Insert an array of elements in the buffer.
85  * \exception std::out_of_range If the buffer run out of space.
86  */
87  void push_many(T *array_elements, size_t count) {
88  while (count--)
89  push(*array_elements++);
90  }
91 
92  /** Retrieve an element from the buffer.
93  * \exception std::out_of_range If the buffer is empty.
94  */
95  T pop() {
96  if (m_next_read==m_next_write)
97  throw std::out_of_range("pop: circular_buffer is empty");
98 
99  const size_t i = m_next_read++;
100  if (m_next_read==m_size) m_next_read=0;
101  return m_data[i];
102  }
103 
104  /** Retrieve an element from the buffer.
105  * \exception std::out_of_range If the buffer is empty.
106  */
107  void pop(T &out_val) {
108  if (m_next_read==m_next_write)
109  throw std::out_of_range("pop: circular_buffer is empty");
110 
111  out_val=m_data[m_next_read++];
112  if (m_next_read==m_size) m_next_read=0;
113  }
114 
115  /** Pop a number of elements into a user-provided array.
116  * \exception std::out_of_range If the buffer has less elements than requested.
117  */
118  void pop_many(T *out_array, size_t count) {
119  while (count--)
120  pop(*out_array++);
121  }
122 
123  /** Return the number of elements available for read ("pop") in the buffer (this is NOT the maximum size of the internal buffer)
124  * \sa capacity
125  */
126  size_t size() const {
127  if (m_next_write>=m_next_read)
128  return m_next_write-m_next_read;
129  else return m_next_write + (m_size-m_next_read);
130  }
131 
132  /** Return the maximum capacity of the buffer.
133  * \sa size
134  */
135  size_t capacity() const {
136  return m_size;
137  }
138 
139  /** The maximum number of elements that can be written ("push") without rising an overflow error.
140  */
141  size_t available() const {
142  return (capacity()-size())-1;
143  }
144 
145  /** Delete all the stored data, if any. */
146  void clear() {
147  m_next_write = m_next_read = 0;
148  }
149 
150  }; // end class circular_buffer
151 
152  } // End of namespace
153 } // End of namespace
154 #endif


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