1 #pragma warning(disable:4996) 2 #include<iostream> 3 #include<string> 4 #include<vector> 5 #include<algorithm> 6 #include<cstdio> 7 #include<complex> 8 #include<new> 9 #include<memory> 10 #include<exception> 11 #include<cstdlib> 12 #include<iterator> 13 #include<initializer_list> 14 using namespace std; 15 //template<typename t> class alloc 16 //{public: 17 // alloc():a(),s(){ //成员变量默认初始化 18 // } 19 // t* allocate(size_t n){ 20 // return a.allocate(n); 21 // } 22 ////变长模板参数，allocator的第二个参数是变长的，要调用它，外层的construct也要有变长参数 23 //template<typename...Args> void construct(t* p, const Args&...rest){ 24 // a.construct(p,rest... ); 25 // } 26 // void deallocate(t* p, size_t n) 27 // { 28 // a.deallocate(p, n); 29 // } 30 // void destory(t* p) 31 // { 32 // a.destory(p); 33 // } 34 // 35 // 36 //private: 37 // allocator<t> a; 38 // string s; 39 // 40 //}; 41 //vector为空，capacity=0,否则预分配空间为16，当空间不足时，扩大两倍增长， 42 template<typename T, class Allocator = std::allocator<T> > 43 class Vector{ 44 private: 45 T* start; 46 T* finish; 47 T* end_of_storage; 48 size_t length; 49 size_t capacity; 50 public: 51 typedef T* iterator; 52 typedef const T* const_iterator; 53 Vector():start(NULL),finish(0){ 54 end_of_storage = NULL; 55 length = 0; 56 capacity = 0; 57 } 58 Vector(const std::initializer_list<T> &lst) 59 { 60 for (auto it = lst.begin(); it != lst.end();it++) 61 { 62 this->push_back(*it); 63 } 64 65 } 66 Vector(size_t n, const T&value = T()){ 67 Allocator a; 68 T*p = NULL; 69 if (n <= 16){ p = a.allocate(16); 70 capacity = 16; 71 } 72 else { 73 p = a.allocate(static_cast<int>(1.5 * n)); 74 capacity = static_cast<size_t>(1.5*n); 75 } 76 start = p; 77 finish=uninitialized_fill_n(p, n, value); 78 if (n <= 16) end_of_storage = start + 15; 79 else end_of_storage = p + static_cast<int>(1.5*n)-1; 80 length = n; 81 } 82 /*Vector(size_t n, const T&value){ Vector(n, value); }*/ 83 Vector(const Vector& rhs){ 84 capacity = rhs.capacity; 85 length = rhs.length; 86 Allocator a; 87 start=a.allocate(capacity); 88 end_of_storage = start + capacity - 1; 89 finish = start + length ; 90 91 for (T* p = start,*q = rhs.start; p != finish; p++, q++){ 92 a.construct(p, *q); 93 } 94 } 95 void push_back(const T& value){ 96 if (capacity == 0){ //为空容器时需要申请新空间 97 Allocator a; 98 start = a.allocate(16); 99 a.construct(start, value); 100 finish = start + 1; 101 end_of_storage = start + 15; 102 length = 1; 103 capacity = 16; 104 } 105 else if (length < capacity){ 106 Allocator a; 107 a.construct(finish++, value); 108 length += 1; 109 } 110 else { //空间不足时1.5倍扩大空间 111 Allocator a; 112 auto old_capacity = capacity; 113 auto new_start = a.allocate(static_cast<size_t>(1.5*capacity)); 114 auto new_finish = uninitialized_copy(this->begin(), this->begin()+length, new_start); //没有使用迭代器形式 115 new_finish = uninitialized_fill_n(new_finish, 1, value); 116 //释放掉旧空间 117 capacity = static_cast<size_t>(1.5*capacity); 118 length += 1; 119 120 auto temp = start; 121 while (temp != finish) 122 { 123 a.destroy(temp++); 124 } 125 a.deallocate(start, old_capacity); 126 start = new_start; 127 finish = new_finish; 128 end_of_storage = start + capacity - 1; 129 } 130 } 131 void pop_back(){//弹出的意义是不在含有该对象 132 Allocator a; 133 a.destroy(--finish); //finish指向尾后位置，自减后销毁了对象，不存在了 134 length -= 1; 135 136 } 137 iterator insert(const_iterator position, const T&value); 138 T& operator[](size_t n){return *(start + n); } //如果index out of bound or Vector为空 ,让用户自己去处理 139 const T& operator[](size_t n)const { return *(start + n); } 140 T& front(){ return *start; } 141 const T&front()const{ return *start; } 142 T& back(){ return *(finish-1); } 143 const T&back()const{ return *(finish - 1); } 144 size_t size(){ return length; } 145 size_t volume(){ return capacity; } 146 iterator begin(){ return start; } 147 const_iterator cbegin()const { return start; } 148 iterator end(){ return finish; } 149 const_iterator cend(){ return finish; } 150 Vector& operator=(const Vector&rhs){ 151 if (this->start ==rhs.start) return *this; //两个相等，两个相同 152 //释放掉原有的内存空间，allocator分配的空间如果不deallocate,会造成内存泄漏 153 auto old_start = this->start; 154 auto old_finish = this->finish; 155 size_t old_capacity = this->capacity; 156 capacity = rhs.capacity; 157 length = rhs.length; 158 Allocator a; 159 start = a.allocate(capacity); 160 end_of_storage = start + capacity - 1; 161 finish = start + length; 162 163 for (T* p = start, *q = rhs.start; p != finish; p++, q++){ 164 a.construct(p, *q); 165 } 166 Allocator b;//是需要重新创建b，还是用前面的a就可以完成下面的动作 167 T* p = old_start; 168 while (p!=old_finish) 169 { 170 b.destroy(p++); 171 } 172 b.deallocate(old_start, old_capacity); 173 return *this; 174 175 }; 176 ~Vector(){ 177 Allocator a; 178 T* p = start; 179 while (p!= finish) 180 { 181 a.destroy(p++); 182 } 183 a.deallocate(start, capacity); 184 start = finish = end_of_storage = NULL; //是否多余语句 185 cout << " dectr completed"; 186 } 187 188 }; 189 template<typename T> 190 class demo{ 191 public: 192 demo():d(){} 193 T size(); 194 private: 195 T d; 196 }; 197 class foo{ 198 public: 199 foo() :a(5), s("dka"){} 200 private: 201 int a; string s; 202 203 }; 204 205 int main() 206 { 207 Vector<string> v1; 208 cout << v1.volume() << " " << v1.size() << "\n"; 209 Vector<string> v2(10);//10个空串，调用了string的default ctr 210 cout << v2.size() << " " << v2.volume() << endl; 211 cout << "the first item of v2: " << v2[0] << " or " << v2.front() << endl; 212 //Vector<string> v3(10, 'c'); no instance of parameters (int,char) 213 Vector<string> v4(10, "c"); 214 Vector<string> v5(v4); 215 cout << v5.back() << " " << v5.size() << v5.volume() << endl; 216 v5 = v1; 217 for (auto it = v5.begin(); it!= v5.end();it++) 218 { 219 cout << *it; 220 } 221 /*cout << v5[0] << endl;*/ 222 223 Vector<string> v6(v1); //用空vector初始化另一个vector ;这两个vector都应该表现正常 224 for (auto it = v6.cbegin(); it != v6.cend();it++) 225 { 226 cout << *it << endl; 227 } 228 v1 = v4;//v1原本为空，用含10个元素的v4赋值，并用push_back添加尾元素 229 for (auto x : v1) cout << x << endl; 230 v1.push_back("hdwa"); 231 cout << v1.size() << v1[10] << endl; 232 v1.pop_back(); 233 cout << v1.back() << endl; 234 string s; 235 Vector<int> iv(10); 236 for (auto y:iv) 237 { 238 printf("%d", y); 239 } 240 Vector<string> v7={ "dak", "dj" }; 241 cout << v7.volume() << " " << v7.size() << v7[0] << " " << v7[1] << endl; 242 243 244 }
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转载于:https://www.cnblogs.com/hchacha/p/7286430.html