Vector
点击查看代码
template <typename T>
class Vector {public:class iterator {public:using value_type = T;using iterator_category = std::random_access_iterator_tag;using difference_type = std::ptrdiff_t;using pointer = T*;using reference = T&;iterator(T *P = nullptr) : p(P) {}iterator& operator ++() {++p;return *this;}iterator& operator --() {--p;return *this;}iterator& operator += (difference_type step) {p += step;return *this;}iterator& operator -= (difference_type step) {p -= step;return *this;}iterator operator + (difference_type step) const {return p + step;} iterator operator - (difference_type step) const {return p - step;}difference_type operator - (const iterator &rhs) const {return p - rhs.p;}reference operator *() const {return *p;}pointer operator ->() const {return p;}bool operator == (const iterator &rhs) const {return p == rhs.p;}bool operator != (const iterator &rhs) const {return p != rhs.p;}bool operator < (const iterator &rhs) const {return p < rhs.p;}bool operator <= (const iterator &rhs) const {return p <= rhs.p;}bool operator > (const iterator &rhs) const {return p > rhs.p;}bool operator >= (const iterator &rhs) const {return p >= rhs.p;}~iterator() = default;private:T *p;};using value_type = T;void reserve(size_t newcap) {if (newcap > MAXSZ) throw std::invalid_argument{"reservation exceeds maximum capacity"};if (newcap <= cap) return;size_t _cap = cap;if (_cap == 0) _cap = 1;for(; _cap < newcap; _cap <<= 1);std::unique_ptr <T[]> tmp_ptr(new T[_cap]);if (ptr != nullptr) {for (size_t i = 0; i < sz; i++) {tmp_ptr[i] = std::move(ptr[i]);} }ptr = std::move(tmp_ptr);cap = _cap;}Vector(size_t S = 0,const T& def = T{}) {if (S > MAXSZ) throw std::invalid_argument{"constructor exceeds maximum size"};reserve(S);sz = S;for (size_t i = 0; i < sz; i++) {ptr[i] = def;} }Vector(std::initializer_list <T> l) : sz(l.size()) {reserve(sz);for (size_t i = 0; i < sz; i++) {ptr[i] = *(l.begin() + i);} }Vector(Vector<T> &rhs) {sz = rhs.sz; cap = rhs.cap;ptr.reset(new T[cap]);for (size_t i = 0; i < sz; i++) prt[i] = rhs.ptr[i]; }Vector& operator = (Vector <T> &rhs) {sz = rhs.sz; cap = rhs.cap;ptr.reset(new T[cap]);for (size_t i = 0; i < sz; i++) ptr[i] = rhs.ptr[i];return *this;}Vector(Vector<T> &&rhs) {sz = rhs.sz; cap = rhs.cap;ptr = std::move(rhs.ptr);rhs.sz = rhs.cap = 0;}Vector& operator = (Vector <T> &&rhs) {sz = rhs.sz; cap = rhs.cap;ptr = std::move(rhs.ptr);rhs.sz = rhs.cap = 0;return *this;}~Vector() = default;size_t size() const {return sz;}size_t capacity() const {return cap;}T& operator [](size_t index) {return ptr[index];}const T& operator [](size_t index) const {return ptr[index];}T& at(size_t index) {if (index >= sz) throw std::out_of_range{"at out of range"};return ptr[index];} const T& at(size_t index) const {if (index >= sz) throw std::out_of_range{"at out of range"};return ptr[index];} void resize(size_t newsz, const T& def = T{}) {if (newsz > MAXSZ) throw std::invalid_argument{"resize exceeds maximum size"};if (newsz > cap) reserve(newsz); if (newsz > sz) {for (size_t i = sz; i < newsz; i++) ptr[i] = def;}sz = newsz;}T& push_back(const T &v) {if (sz == cap) {if (cap == 0) reserve(1);else reserve(cap << 1);}ptr[sz] = v;return ptr[sz++];}T& back() {return ptr[sz - 1];}T& front() {return ptr[0];}void pop_back() {if (sz) sz--;}void clear() {resize(0);}bool empty() {return sz == 0;}iterator begin() {return iterator{ptr.get()};}iterator end() {return iterator{ptr.get() + sz};}private:static constexpr size_t MAXSZ = 134217728;size_t sz = 0, cap = 0;std::unique_ptr <T[]> ptr;
};
