summaryrefslogtreecommitdiff
path: root/include/span.h
blob: 0e8516933c6b13e5c6dcc2c2aa2aa4226a856e72 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
/*****************************************************************************

Copyright (c) 2019, 2020 MariaDB Corporation.

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; version 2 of the License.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA

*****************************************************************************/

#pragma once

#include <cstddef>
#include <iterator>

namespace st_
{

namespace detail
{

template <class T> struct remove_cv
{
  typedef T type;
};
template <class T> struct remove_cv<const T>
{
  typedef T type;
};
template <class T> struct remove_cv<volatile T>
{
  typedef T type;
};
template <class T> struct remove_cv<const volatile T>
{
  typedef T type;
};

} // namespace detail

template <class ElementType> class span
{
public:
  typedef ElementType element_type;
  typedef typename detail::remove_cv<ElementType>::type value_type;
  typedef size_t size_type;
  typedef ptrdiff_t difference_type;
  typedef element_type *pointer;
  typedef const element_type *const_pointer;
  typedef element_type &reference;
  typedef const element_type &const_reference;
  typedef pointer iterator;
  typedef const_pointer const_iterator;
  typedef std::reverse_iterator<iterator> reverse_iterator;

  span() : data_(NULL), size_(0) {}

  span(pointer ptr, size_type count) : data_(ptr), size_(count) {}

  span(pointer first, pointer last) : data_(first), size_(last - first) {}

  template <size_t N> span(element_type (&arr)[N]) : data_(arr), size_(N) {}

  template <class Container>
  span(Container &cont) : data_(cont.data()), size_(cont.size())
  {
  }

  template <class Container>
  span(const Container &cont) : data_(cont.data()), size_(cont.size())
  {
  }

  span(const span &other) : data_(other.data_), size_(other.size_) {}

  ~span(){};

  span &operator=(const span &other)
  {
    data_= other.data();
    size_= other.size();
    return *this;
  }

  template <size_t Count> span<element_type> first() const
  {
    assert(!empty());
    return span(data(), 1);
  }
  template <size_t Count> span<element_type> last() const
  {
    assert(!empty());
    return span(data() + size() - 1, 1);
  }

  span<element_type> first(size_type count) const
  {
    assert(!empty());
    return span(data(), 1);
  }
  span<element_type> last(size_type count) const
  {
    assert(!empty());
    return span(data() + size() - 1, 1);
  }
  span<element_type> subspan(size_type offset, size_type count) const
  {
    assert(!empty());
    assert(size() >= offset + count);
    return span(data() + offset, count);
  }

  size_type size() const { return size_; }
  size_type size_bytes() const { return size() * sizeof(ElementType); }
  bool empty() const __attribute__((warn_unused_result))
  {
    return size() == 0;
  }

  reference operator[](size_type idx) const
  {
    assert(size() > idx);
    return data()[idx];
  }
  reference front() const
  {
    assert(!empty());
    return data()[0];
  }
  reference back() const
  {
    assert(!empty());
    return data()[size() - 1];
  }
  pointer data() const { return data_; }

  iterator begin() const { return data_; }
  iterator end() const { return data_ + size_; }
  reverse_iterator rbegin() const
  {
    return std::reverse_iterator<iterator>(end());
  }
  reverse_iterator rend() const
  {
    return std::reverse_iterator<iterator>(begin());
  }

private:
  pointer data_;
  size_type size_;
};

} // namespace st_