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
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
|
#ifndef VECTOR_H
#define VECTOR_H
#include <stdexcept>
#include <algorithm>
#include <memory>
template<typename T, typename A>
struct vector_base
{
A alloc; // allocator
T *elem; // start of allocation
int sz; // number of elements
int space; // amount of allocated space
vector_base(const A &a, int n)
: alloc{ a }, elem{ alloc.allocate(n) }, sz{ n }, space{ n } {}
vector_base()
: alloc{}, elem{}, sz{}, space{} {}
~vector_base() { alloc.deallocate(elem, space); }
};
// an almost real vector of Ts
template<typename T, typename A = std::allocator<T>>
class vector : private vector_base<T, A> // read "for all types T" (just like in math)
{
/*
invariant:
if 0<=n<sz, elem[n] is element n
sz<=space;
if sz<space there is space for (space-sz) doubles after elem[sz-1]
*/
A alloc; // use allocate to handle memory for elements
int sz; // the size
T *elem; // pointer to the elements (or 0)
int space; // number of elements plus number of free slots
public:
explicit vector(int s)
: sz{ s },
elem{ new T[s] },
space{ s }
{
for (std::size_t i = 0; i < sz; ++i)
{
elem[i] = 0;
}
}
vector(std::initializer_list<T> lst)
: sz{ lst.size() },
elem{ new T[sz] }
{
std::copy(lst.begin(), lst.end(), elem);
}
vector(const vector<T> &arg)
: sz{ arg.size() },
elem{ new T[arg.sz] }
{
std::copy(arg.elem, arg.elem + arg.sz, elem);
}
vector &operator=(const vector &a); // copy assignment
vector(vector &&a) // move constructor: define move
: sz{ a.sz }, elem{ a.elem }
{
a.sz = 0;
a.elem = nullptr;
}
vector &operator=(vector<T> &&a);
vector() : sz{ 0 }, elem{ nullptr }, space{ 0 } {} // default constructor
~vector() { delete[] elem; } // destructor
std::size_t size() const { return sz; } // return current size
std::size_t capacity() const { return space; }
T &at(int n);
const T &at(int n) const;
T &operator[](std::size_t n) { return elem[n]; } // access: return reference
const T operator[](std::size_t n) const { return elem[n]; }
void reserve(const int newalloc); //growth
void resize(int newsize, T val);
void push_back(const T &val);
void push_front(const T &val);
};
#endif
template<typename T, typename A>
vector<T, A> &vector<T, A>::operator=(const vector<T, A> &a)
{
if (this == &a)
{
return *this; // self-assignment; no work needed
}
if (a.sz <= space) // enough space, no need for new allocation
{
for (std::size_t i = 0; i < a.sz; ++i)
{
elem[i] = a.elem[i]; // copy elements
}
sz = a.sz;
return *this;
}
T *p = new T[a.sz]; // allocate new space
for (std::size_t i = 0; i < a.sz; ++i)
{
p[i] = a.elem[i]; // copy elements
}
delete[] elem; // deallocate old space
space = sz = a.sz; // set new size
elem = p; // set new elements
return *this; // return a self-reference
}
template<typename T, typename A>
void vector<T, A>::resize(int newsize, T val)
// make the vector have newsize elements
// initialize each new element with the default value 0.0
{
reserve(newsize);
for (std::size_t i = sz; i < newsize; ++i)
{
alloc.construct(&elem[i], val);
}
for (std::size_t i = newsize; i <sz; ++i)
{
alloc.destroy(&elem[i]);
}
sz = newsize;
}
template<typename T, typename A>
void vector<T, A>::push_back(const T &val)
{
if (space == 0)
{
reserve(8);
}
else if (sz == space)
{
reserve(2 * space); // get more space
}
alloc.construct(&elem[sz], val); // add val at end
++sz; // increase the size
}
template<typename T, typename A>
void vector<T, A>::push_front(const T &val)
{
if (space == 0)
{
reserve(8);
}
else if (sz == space)
{
reserve(2 * space); // get more space
}
alloc.construct(&elem[0], val); // add val at front
++sz; // increase the size
}
template<typename T, typename A>
void vector<T, A>::reserve(const int newalloc)
{
if (newalloc <= this->space)
{
return; // never decrease allocation
}
vector_base<T, A> b{ this->alloc, newalloc }; // allocate new space
std::uninitialized_copy(b.elem, &b.elem[this->sz], this->elem); // copy
for (int i = 0; i < this->sz; ++i)
{
this->alloc.destroy(&this->elem[i]); // destroy old
}
std::swap<vector_base<T, A>>(*this, b); // swap representations
}
template<typename T, typename A>
vector<T, A> &vector<T, A>::operator=(vector<T> &&a)
{
delete[] elem; // deallocate old space
elem = a.elem; // copy a's elem and sz
sz = a.sz;
a.elem = nullptr; // make a the empty vector
a.sz = 0;
return *this;
}
template<typename T, typename A>
T &vector<T, A>::at(int n)
{
if (n < 0 || sz <= n)
{
throw std::out_of_range{ "vector element out of range" };
}
return elem[n];
}
template<typename T, typename A>
const T &vector<T, A>::at(int n) const
{
if (n < 0 || sz <= n)
{
throw std::out_of_range{ "vector element out of range" };
}
return elem[n];
}
|
