vector源码

成员变量

//迭代器

//对应begin()iterator start；

//对应end(), 指向可⽤空间下⼀个位置iterator finish；

//指向整个容量的⼀下个位置iterator end_of_storage;

push_back，

将新元素插⼊vector尾端时，先检查是有还有备⽤空间，如果有就直接在备⽤空间上构造元素，并调整迭代器finish。 如果没有备⽤空间，就要扩充空间（重新配置，移动数据，释放原空间）

void push_back(const T& x){

if(finish != end_of_storage) {

construct(finish, x); ++finish; } else

insert_aux(end(), x);}

insert_aux，单个元素插⼊指定位置

template

void MVector::insert_aux(iterator position, const T& x){

// 空间⾜够

if (finish != end_of_storage) {

construct(finish, *(finish - 1)); ++finish; T x_copy = x;

//

copy_backward(position, finish - 2, finish - 1); *position = x_copy; } else {

// 空间不⾜，重新分配空间 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;

try {

// 前段拷贝

new_finish = uninitialized_copy(start, position, new_start); // 构造插⼊的元素 construct(new_finish, x); ++new_finish;

// 后段拷贝

uninitialized_copy(position, finish, new_finish); }

catch (...) {

// 回滚

destroy(new_start, new_finish);

data_allocator::deallocate(new_start, len); throw; }

// 释放⽼内存 destroy(begin(), end()); deallocate(); start = new_start;

finish = new_finish;

end_of_storage = new_start + len; }}