STL的vector的源码实现
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// Filename: stl_vector.h /* * * Copyright (c) 1994 * Hewlett-Packard Company * * Permission to use, copy, modify, distribute and sell this software * and its documentation for any purpose is hereby granted without fee, * provided that the above copyright notice appear in all copies and * that both that copyright notice and this permission notice appear * in supporting documentation. Hewlett-Packard Company makes no * representations about the suitability of this software for any * purpose. It is provided "as is" without express or implied warranty. * * * Copyright (c) 1996 * Silicon Graphics Computer Systems, Inc. * * Permission to use, copy, modify, distribute and sell this software * and its documentation for any purpose is hereby granted without fee, * provided that the above copyright notice appear in all copies and * that both that copyright notice and this permission notice appear * in supporting documentation. Silicon Graphics makes no * representations about the suitability of this software for any * purpose. It is provided "as is" without express or implied warranty. */ /* NOTE: This is an internal header file, included by other STL headers. * You should not attempt to use it directly. */ #ifndef __SGI_STL_INTERNAL_VECTOR_H #define __SGI_STL_INTERNAL_VECTOR_H __STL_BEGIN_NAMESPACE #if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32) #pragma set woff 1174 #endif //////////////////////////////////////////////////////////////////////////////// // //////////////////////////////////////////////////////////////////////////////// // 默认allocator为alloc, 其具体使用版本请参照<stl_alloc.h> template <class T, class Alloc = alloc> class vector { public: // 标记为'STL标准强制要求'的typedefs用于提供iterator_traits<I>支持 typedef T value_type; // STL标准强制要求 typedef value_type* pointer; // STL标准强制要求 typedef const value_type* const_pointer; // 由于vector的特性, 一般我们实作的时候都分配给其连续的内存空间, // 所以其迭代器只需要定义成原生指针即可满足需要 typedef value_type* iterator; // STL标准强制要求 typedef const value_type* const_iterator; typedef value_type& reference; // STL标准强制要求 typedef const value_type& const_reference; typedef size_t size_type; typedef ptrdiff_t difference_type; // STL标准强制要求 #ifdef __STL_CLASS_PARTIAL_SPECIALIZATION typedef reverse_iterator<const_iterator> const_reverse_iterator; typedef reverse_iterator<iterator> reverse_iterator; #else /* __STL_CLASS_PARTIAL_SPECIALIZATION */ typedef reverse_iterator<const_iterator, value_type, const_reference, difference_type> const_reverse_iterator; typedef reverse_iterator<iterator, value_type, reference, difference_type> reverse_iterator; #endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */ protected: // 这个提供STL标准的allocator接口 typedef simple_alloc<value_type, Alloc> data_allocator; iterator start; // 内存空间起始点 iterator finish; // 当前使用的内存空间结束点 iterator end_of_storage; // 实际分配内存空间的结束点 void insert_aux(iterator position, const T& x); // 释放分配的内存空间 void deallocate() { // 由于使用的是data_allocator进行内存空间的分配, // 所以需要同样嗲用data_allocator::deallocate()进行释放 // 如果直接释放, 对于data_allocator内部使用内存池的版本 // 就会发生错误 if (start) data_allocator::deallocate(start, end_of_storage - start); } void fill_initialize(size_type n, const T& value) { start = allocate_and_fill(n, value); finish = start + n; // 设置当前使用内存空间的结束点 // 构造阶段, 此实作不多分配内存, // 所以要设置内存空间结束点和, 已经使用的内存空间结束点相同 end_of_storage = finish; } public: // 获取几种迭代器 iterator begin() { return start; } const_iterator begin() const { return start; } iterator end() { return finish; } const_iterator end() const { return finish; } reverse_iterator rbegin() { return reverse_iterator(end()); } const_reverse_iterator rbegin() const { return const_reverse_iterator(end()); } reverse_iterator rend() { return reverse_iterator(begin()); } const_reverse_iterator rend() const { return const_reverse_iterator(begin()); } // 返回当前对象个数 size_type size() const { return size_type(end() - begin()); } size_type max_size() const { return size_type(-1) / sizeof(T); } // 返回重新分配内存前最多能存储的对象个数 size_type capacity() const { return size_type(end_of_storage - begin()); } bool empty() const { return begin() == end(); } reference operator[](size_type n) { return *(begin() + n); } const_reference operator[](size_type n) const { return *(begin() + n); } // 本实作中默认构造出的vector不分配内存空间 vector() : start(0), finish(0), end_of_storage(0) {} //////////////////////////////////////////////////////////////////////////////// // 本实作中给定个数和对象, 则只分配所需内存, 不会多分配 //////////////////////////////////////////////////////////////////////////////// // vector(size_type n, const T& value) // ↓ // fill_initialize(n, value) // ↓ // allocate_and_fill(n, value) // ↓ // data_allocator::allocate(n) <stl_alloc.h> // uninitialized_fill_n(result, n, x) <stl_uninitialized.h> //////////////////////////////////////////////////////////////////////////////// vector(size_type n, const T& value) { fill_initialize(n, value); } vector(int n, const T& value) { fill_initialize(n, value); } vector(long n, const T& value) { fill_initialize(n, value); } // 需要对象提供默认构造函数 explicit vector(size_type n) { fill_initialize(n, T()); } //////////////////////////////////////////////////////////////////////////////// // 复制构造, 同样不会多分配内存 //////////////////////////////////////////////////////////////////////////////// // vector(const vector<T, Alloc>& x) // ↓ // allocate_and_copy(x.end() - x.begin(), x.begin(), x.end()); // ↓ // data_allocator::allocate(n) <stl_alloc.h> // uninitialized_copy(first, last, result); <stl_uninitialized.h> //////////////////////////////////////////////////////////////////////////////// vector(const vector<T, Alloc>& x) { start = allocate_and_copy(x.end() - x.begin(), x.begin(), x.end()); finish = start + (x.end() - x.begin()); end_of_storage = finish; } // 复制指定区间的元素, 同样不多分配内存 #ifdef __STL_MEMBER_TEMPLATES //////////////////////////////////////////////////////////////////////////////// // 复制一个区间进行构造, 可能会导致多分配内存 //////////////////////////////////////////////////////////////////////////////// // vector(InputIterator first, InputIterator last) // ↓ // range_initialize(first, last, iterator_category(first)); // ↓ // for ( ; first != last; ++first) // push_back(*first); // 由于使用push_back()操作, 可能导致多次重复分配内存,个人感觉应该先 // data_allocator::allocate((last - first) * sizeof(T)); // 然后uninitialized_copy(first, last, result); // 这样不会多分配内存， 也不会导致多次重新分配内存问题 //////////////////////////////////////////////////////////////////////////////// template <class InputIterator> vector(InputIterator first, InputIterator last) : start(0), finish(0), end_of_storage(0) { range_initialize(first, last, iterator_category(first)); } #else /* __STL_MEMBER_TEMPLATES */ //////////////////////////////////////////////////////////////////////////////// // 复制一个区间进行构造, 可能会导致多分配内存 //////////////////////////////////////////////////////////////////////////////// // vector(const_iterator first, const_iterator last) // ↓ // distance(first, last, n); // ↓ // allocate_and_copy(n, first, last); // ↓ // data_allocator::allocate(n) <stl_alloc.h> // uninitialized_copy(first, last, result); <stl_uninitialized.h> //////////////////////////////////////////////////////////////////////////////// vector(const_iterator first, const_iterator last) { size_type n = 0; distance(first, last, n); start = allocate_and_copy(n, first, last); finish = start + n; end_of_storage = finish; } #endif /* __STL_MEMBER_TEMPLATES */ ~vector() { // 析构对象 destroy(start, finish); // 释放内存 deallocate(); } vector<T, Alloc>& operator=(const vector<T, Alloc>& x); void reserve(size_type n) { if (capacity() < n) { const size_type old_size = size(); iterator tmp = allocate_and_copy(n, start, finish); destroy(start, finish); deallocate(); start = tmp; finish = tmp + old_size; end_of_storage = start + n; } } // 提供访问函数 reference front() { return *begin(); } const_reference front() const { return *begin(); } reference back() { return *(end() - 1); } const_reference back() const { return *(end() - 1); } //////////////////////////////////////////////////////////////////////////////// // 向容器尾追加一个元素, 可能导致内存重新分配 //////////////////////////////////////////////////////////////////////////////// // push_back(const T& x) // | // |---------------- 容量已满? // | // ---------------------------- // No | | Yes // | | // ↓ ↓ // construct(finish, x); insert_aux(end(), x); // ++finish; | // |------ 内存不足, 重新分配 // | 大小为原来的2倍 // new_finish = data_allocator::allocate(len); <stl_alloc.h> // uninitialized_copy(start, position, new_start); <stl_uninitialized.h> // construct(new_finish, x); <stl_construct.h> // ++new_finish; // uninitialized_copy(position, finish, new_finish); <stl_uninitialized.h> //////////////////////////////////////////////////////////////////////////////// void push_back(const T& x) { // 内存满足条件则直接追加元素, 否则需要重新分配内存空间 if (finish != end_of_storage) { construct(finish, x); ++finish; } else insert_aux(end(), x); } // 交换两个vector, 实际上是交换内部的状态指针 void swap(vector<T, Alloc>& x) { __STD::swap(start, x.start); __STD::swap(finish, x.finish); __STD::swap(end_of_storage, x.end_of_storage); } iterator insert(iterator position, const T& x) { size_type n = position - begin(); if (finish != end_of_storage && position == end()) { construct(finish, x); ++finish; } else insert_aux(position, x); return begin() + n; } iterator insert(iterator position) { return insert(position, T()); } #ifdef __STL_MEMBER_TEMPLATES //////////////////////////////////////////////////////////////////////////////// // 在指定位置插入一个区间 //////////////////////////////////////////////////////////////////////////////// // insert(iterator position, InputIterator first, InputIterator last) // ↓ // range_insert(position, first, last, iterator_category(first)); // ↓ // for ( ; first != last; ++first) { // pos = insert(pos, *first); // ++pos; // } //////////////////////////////////////////////////////////////////////////////// template <class InputIterator> void insert(iterator position, InputIterator first, InputIterator last) { range_insert(position, first, last, iterator_category(first)); } #else /* __STL_MEMBER_TEMPLATES */ void insert(iterator position, const_iterator first, const_iterator last); #endif /* __STL_MEMBER_TEMPLATES */ void insert (iterator pos, size_type n, const T& x); void insert (iterator pos, int n, const T& x) { insert(pos, (size_type) n, x); } void insert (iterator pos, long n, const T& x) { insert(pos, (size_type) n, x); } void pop_back() { --finish; destroy(finish); } iterator erase(iterator position) { if (position + 1 != end()) copy(position + 1, finish, position); --finish; destroy(finish); return position; } iterator erase(iterator first, iterator last) { iterator i = copy(last, finish, first); // 析构掉需要析构的元素 destroy(i, finish); finish = finish - (last - first); return first; } // 调整size, 但是并不会重新分配内存空间 void resize(size_type new_size, const T& x) { if (new_size < size()) erase(begin() + new_size, end()); else insert(end(), new_size - size(), x); } void resize(size_type new_size) { resize(new_size, T()); } void clear() { erase(begin(), end()); } protected: // 分配空间, 并且复制对象到分配的空间处 iterator allocate_and_fill(size_type n, const T& x) { iterator result = data_allocator::allocate(n); __STL_TRY { uninitialized_fill_n(result, n, x); return result; } __STL_UNWIND(data_allocator::deallocate(result, n)); } // 分配空间并且拷贝一个区间的元素到新分配空间处 #ifdef __STL_MEMBER_TEMPLATES template <class ForwardIterator> iterator allocate_and_copy(size_type n, ForwardIterator first, ForwardIterator last) { iterator result = data_allocator::allocate(n); __STL_TRY { uninitialized_copy(first, last, result); return result; } __STL_UNWIND(data_allocator::deallocate(result, n)); } #else /* __STL_MEMBER_TEMPLATES */ iterator allocate_and_copy(size_type n, const_iterator first, const_iterator last) { iterator result = data_allocator::allocate(n); __STL_TRY { uninitialized_copy(first, last, result); return result; } __STL_UNWIND(data_allocator::deallocate(result, n)); } #endif /* __STL_MEMBER_TEMPLATES */ #ifdef __STL_MEMBER_TEMPLATES // 初始化一个区间, 使用push_back()操作, 可能引发内存多次重新分配 // 解决方案见 // template <class InputIterator> // vector(InputIterator first, InputIterator last) // 我评注部分 template <class InputIterator> void range_initialize(InputIterator first, InputIterator last, input_iterator_tag) { for ( ; first != last; ++first) push_back(*first); } // This function is only called by the constructor. We have to worry // about resource leaks, but not about maintaining invariants. template <class ForwardIterator> void range_initialize(ForwardIterator first, ForwardIterator last, forward_iterator_tag) { size_type n = 0; distance(first, last, n); start = allocate_and_copy(n, first, last); finish = start + n; end_of_storage = finish; } template <class InputIterator> void range_insert(iterator pos, InputIterator first, InputIterator last, input_iterator_tag); template <class ForwardIterator> void range_insert(iterator pos, ForwardIterator first, ForwardIterator last, forward_iterator_tag); #endif /* __STL_MEMBER_TEMPLATES */ }; //////////////////////////////////////////////////////////////////////////////// // vector实现部分 //////////////////////////////////////////////////////////////////////////////// template <class T, class Alloc> inline bool operator==(const vector<T, Alloc>& x, const vector<T, Alloc>& y) { return x.size() == y.size() && equal(x.begin(), x.end(), y.begin()); } // 字典序比较 template <class T, class Alloc> inline bool operator<(const vector<T, Alloc>& x, const vector<T, Alloc>& y) { return lexicographical_compare(x.begin(), x.end(), y.begin(), y.end()); } #ifdef __STL_FUNCTION_TMPL_PARTIAL_ORDER template <class T, class Alloc> inline void swap(vector<T, Alloc>& x, vector<T, Alloc>& y) { x.swap(y); } #endif /* __STL_FUNCTION_TMPL_PARTIAL_ORDER */ //////////////////////////////////////////////////////////////////////////////// // 重载赋值运算符 //////////////////////////////////////////////////////////////////////////////// // operator=(const vector<T, Alloc>& x) // | // |---------------- 是否是自赋值? // ↓ // ----------------------------------------- // No | | Yes // | | // ↓ |------- 容量判断 // return *this; | // ↓ // ----------------------------------------------------------------- // |x.size() > capacity() | size() >= x.size() | other // | | | // ↓ ↓ | // 容量不足, 需要重新分配 容量足够, 只需要析构掉多余的对象 | // allocate_and_copy( copy(x.begin(), x.end(), begin()); | // x.end() - x.begin(), destroy(i, finish); | // x.begin(), x.end()); | // destroy(start, finish); | // deallocate(); ↓ // copy(x.begin(), x.begin() + size(), start); // uninitialized_copy(x.begin() + size(), x.end(), finish); //////////////////////////////////////////////////////////////////////////////// template <class T, class Alloc> vector<T, Alloc>& vector<T, Alloc>::operator=(const vector<T, Alloc>& x) { if (&x != this) { // 如果x.size() > capacity()那么就需要重新分配内存 // 首先分配内存, 并将容器内原来的元素拷贝到新分配内存中 // 然后析构原容器中元素, 调整内存状态变量 if (x.size() > capacity()) { iterator tmp = allocate_and_copy(x.end() - x.begin(), x.begin(), x.end()); destroy(start, finish); deallocate(); start = tmp; end_of_storage = start + (x.end() - x.begin()); } else if (size() >= x.size()) { iterator i = copy(x.begin(), x.end(), begin()); destroy(i, finish); } else { copy(x.begin(), x.begin() + size(), start); uninitialized_copy(x.begin() + size(), x.end(), finish); } finish = start + x.size(); } return *this; } //////////////////////////////////////////////////////////////////////////////// // 提供插入操作 //////////////////////////////////////////////////////////////////////////////// // insert_aux(iterator position, const T& x) // | // |---------------- 容量是否足够? // ↓ // ----------------------------------------- // Yes | | No // | | // ↓ | // 从opsition开始, 整体向后移动一个位置 | // construct(finish, *(finish - 1)); | // ++finish; | // T x_copy = x; | // copy_backward(position, finish - 2, finish - 1); | // *position = x_copy; | // ↓ // data_allocator::allocate(len); // uninitialized_copy(start, position, new_start); // construct(new_finish, x); // ++new_finish; // uninitialized_copy(position, finish, new_finish); // destroy(begin(), end()); // deallocate(); //////////////////////////////////////////////////////////////////////////////// template <class T, class Alloc> void vector<T, Alloc>::insert_aux(iterator position, const T& x) { if (finish != end_of_storage) { // 还有剩余内存 construct(finish, *(finish - 1)); ++finish; T x_copy = x; copy_backward(position, finish - 2, finish - 1); *position = x_copy; } else { // 内存不足, 需要重新分配 // 本实作中是按原内存2倍进行重新分配 const size_type old_size = size(); const size_type len = old_size != 0 ? 2 * old_size : 1; iterator new_start = data_allocator::allocate(len); iterator new_finish = new_start; // 将内存重新配置 __STL_TRY { new_finish = uninitialized_copy(start, position, new_start); construct(new_finish, x); ++new_finish; new_finish = uninitialized_copy(position, finish, new_finish); } // 分配失败则抛出异常 # ifdef __STL_USE_EXCEPTIONS catch(...) { destroy(new_start, new_finish); data_allocator::deallocate(new_start, len); throw; } # endif /* __STL_USE_EXCEPTIONS */ // 析构原容器中的对象 destroy(begin(), end()); // 释放原容器分配的内存 deallocate(); // 调整内存指针状态 start = new_start; finish = new_finish; end_of_storage = new_start + len; } } template <class T, class Alloc> void vector<T, Alloc>::insert(iterator position, size_type n, const T& x) { // 如果n为0则不进行任何操作 if (n != 0) { if (size_type(end_of_storage - finish) >= n) { // 剩下的内存够分配 T x_copy = x; const size_type elems_after = finish - position; iterator old_finish = finish; if (elems_after > n) { uninitialized_copy(finish - n, finish, finish); finish += n; copy_backward(position, old_finish - n, old_finish); fill(position, position + n, x_copy); } else { uninitialized_fill_n(finish, n - elems_after, x_copy); finish += n - elems_after; uninitialized_copy(position, old_finish, finish); finish += elems_after; fill(position, old_finish, x_copy); } } else { // 剩下的内存不够分配, 需要重新分配 const size_type old_size = size(); const size_type len = old_size + max(old_size, n); iterator new_start = data_allocator::allocate(len); iterator new_finish = new_start; __STL_TRY { new_finish = uninitialized_copy(start, position, new_start); new_finish = uninitialized_fill_n(new_finish, n, x); new_finish = uninitialized_copy(position, finish, new_finish); } # ifdef __STL_USE_EXCEPTIONS catch(...) { destroy(new_start, new_finish); data_allocator::deallocate(new_start, len); throw; } # endif /* __STL_USE_EXCEPTIONS */ destroy(start, finish); deallocate(); start = new_start; finish = new_finish; end_of_storage = new_start + len; } } } #ifdef __STL_MEMBER_TEMPLATES // 在指定位置插入指定区间的对象 template <class T, class Alloc> template <class InputIterator> void vector<T, Alloc>::range_insert(iterator pos, InputIterator first, InputIterator last, input_iterator_tag) { for ( ; first != last; ++first) { pos = insert(pos, *first); ++pos; } } template <class T, class Alloc> template <class ForwardIterator> void vector<T, Alloc>::range_insert(iterator position, ForwardIterator first, ForwardIterator last, forward_iterator_tag) { if (first != last) { size_type n = 0; distance(first, last, n); if (size_type(end_of_storage - finish) >= n) { const size_type elems_after = finish - position; iterator old_finish = finish; if (elems_after > n) { uninitialized_copy(finish - n, finish, finish); finish += n; copy_backward(position, old_finish - n, old_finish); copy(first, last, position); } else { ForwardIterator mid = first; advance(mid, elems_after); uninitialized_copy(mid, last, finish); finish += n - elems_after; uninitialized_copy(position, old_finish, finish); finish += elems_after; copy(first, mid, position); } } else { const size_type old_size = size(); const size_type len = old_size + max(old_size, n); iterator new_start = data_allocator::allocate(len); iterator new_finish = new_start; __STL_TRY { new_finish = uninitialized_copy(start, position, new_start); new_finish = uninitialized_copy(first, last, new_finish); new_finish = uninitialized_copy(position, finish, new_finish); } # ifdef __STL_USE_EXCEPTIONS catch(...) { destroy(new_start, new_finish); data_allocator::deallocate(new_start, len); throw; } # endif /* __STL_USE_EXCEPTIONS */ destroy(start, finish); deallocate(); start = new_start; finish = new_finish; end_of_storage = new_start + len; } } } #else /* __STL_MEMBER_TEMPLATES */ template <class T, class Alloc> void vector<T, Alloc>::insert(iterator position, const_iterator first, const_iterator last) { if (first != last) { size_type n = 0; distance(first, last, n); if (size_type(end_of_storage - finish) >= n) { const size_type elems_after = finish - position; iterator old_finish = finish; if (elems_after > n) { uninitialized_copy(finish - n, finish, finish); finish += n; copy_backward(position, old_finish - n, old_finish); copy(first, last, position); } else { uninitialized_copy(first + elems_after, last, finish); finish += n - elems_after; uninitialized_copy(position, old_finish, finish); finish += elems_after; copy(first, first + elems_after, position); } } else { const size_type old_size = size(); const size_type len = old_size + max(old_size, n); iterator new_start = data_allocator::allocate(len); iterator new_finish = new_start; __STL_TRY { new_finish = uninitialized_copy(start, position, new_start); new_finish = uninitialized_copy(first, last, new_finish); new_finish = uninitialized_copy(position, finish, new_finish); } # ifdef __STL_USE_EXCEPTIONS catch(...) { destroy(new_start, new_finish); data_allocator::deallocate(new_start, len); throw; } # endif /* __STL_USE_EXCEPTIONS */ destroy(start, finish); deallocate(); start = new_start; finish = new_finish; end_of_storage = new_start + len; } } } #endif /* __STL_MEMBER_TEMPLATES */ #if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32) #pragma reset woff 1174 #endif __STL_END_NAMESPACE #endif /* __SGI_STL_INTERNAL_VECTOR_H */ // Local Variables: // mode:C++ // End: 0 0
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