STL 源码剖析 deque实现源码
#ifndef _HJSTL_DEQUE_H_
#define _HJSTL_DEQUE_H_
/*
* Author:hujian
* Time:2016/4/28
* discription:this file is about deque structure.
*
*/
#include "hjstl_alloc.h"
#include "hjstl_construct.h"
#include "hjstl_iterator.h"
#include "hjstl_uninitialized.h"
#define _HJSTL_DEQUE_PUBLIC_ public
#define _HJSTL_DEQUE_PRIVATE_ private
#define _HJSTL_DEQUE_PROTECTED_ protected
//deque buffer size
inline size_t __HJSTL_deque_buf_size(size_t n, size_t sz){
return n != 0 ? n : (sz < 512 ? size_t(512 / sz) : size_t(1));
}
//the deque iterator.this is very complex.
template iterator;
typedef __HJSTL_deque_iterator const_iterator;
static size_t buffer_size(){
//you want to set the buffer size
return __HJSTL_deque_buf_size(BufSize, sizeof(Type));
}
typedef hjstl_random_access_iterator_tag hjstl_iterator_category;
typedef Type hjstl_value_type;
typedef Ptr hjstl_pointer;
typedef Ref hjstl_reference;
typedef size_t size_type;
typedef ptrdiff_t hjstl_difference_type;
typedef Type** map_pointer;
typedef __HJSTL_deque_iterator self;
Type* cur; //the iterator's buffer's current element.
Type* first;//the iterator's buffer's head element
Type* last;//the iterator's buffer's tail element
map_pointer node;//this node pointer to the controller.
//constructor
__HJSTL_deque_iterator(Type* x,map_pointer y)
:cur(x), first(*y), last(*y + buffer_size(), node(y)){}
__HJSTL_deque_iterator()
:cur(0), first(0), last(0), node(0){}
__HJSTL_deque_iterator(const iterator& x)
:cur(x.cur), first(x.first), last(x.last), node(x.node){}
hjstl_reference operator*() const { return *cur; }
hjstl_pointer operator->() const { return &(operator*()); }
hjstl_difference_type operator -(const self&x) const {
return hjstl_difference_type(buffer_size())*(node - x.node - 1) +
(cur - first) + (x.last - x.cur);
}
self& operator ++(){ //++iterator
++cur;
if (cur == last){
set_node(node + 1);
cur = first;
}
return *this;
}
self operator++(int) {//iterator++
self tmp = *this;
++*this;
return tmp;
}
self& operator --(){//--iterator
if (cur == first){
set_node(node - 1);
cur = last;
}
--cur;
return *this;
}
self operator --(int){//iterator--
self tmp = *this;
--*this;
return tmp;
}
self& operator +=(hjstl_difference_type n){//iterator += n
hjstl_difference_type offset = n + (cur - first);
//ok,aim index is at the same buffer,just pointer to..
if (offset >= 0 && offset < hjstl_difference_type(buffer_size)){
cur += n;
}
else{//difference buffer.so,we need to do more thing
hjstl_difference_type node_offset = offset>0/*forward*/ ?
offset / hjstl_difference_type(buffer_size) :
-hjstl_difference_type(-offset - 1) - 1;
//goto the node.
set_node(node + node_offset);
//goto the cur we should.
cur = first + (offset - node_offset*hjstl_difference_type(buffer_size()));
}
return *this;
}
//ok,we have implemented the +=,then the + is so easy to implement
self operator +(hjstl_difference_type n) const {
self tmp = *this;
return tmp += n;
}
//yeah,do you know we can use add to implement minus..?
self & operator -=(hjstl_difference_type n){
return *this += -n;
}
//:>
self operator -(hjstl_difference_type n) const {
self tmp = *this;
return tmp -= n;
}
//random put/get
hjstl_reference operator[](hjstl_difference_type n) const
{
return *(*this + n);
}
bool operator ==(const self& x) const { return cur == x.cur; }
bool operator !=(const self& x) const { return cur != x.cur; }
bool operator<(const self&x)const {
return (node == x.node) ? (cur < x.cur) : (node < x.node);
}
//set node.goto..
void set_node(map_pointer new_node)
{
node = new_node;
first = *new_node;
last = first + hjstl_difference_type(buffer_size());
}
};
template
inline hjstl_random_access_iterator_tag
hjstl_iterator_category(const __HJSTL_deque_iterator&){
return hjstl_random_access_iterator_tag();
}
template
inline Type* hjstl_value_type(const __HJSTL_deque_iterator&){
return 0;
}
template
inline ptrdiff_t* hjstl_distance_type(const __HJSTL_deque_iterator&){
return 0;
}
//the follow codes is about the deque.
//you can set the block's size,the default block size is 512 bytes
template
class _HJSTL_deque{
_HJSTL_DEQUE_PUBLIC_:
typedef Type value_type;
typedef value_type* pointer;
typedef const value_type* const_pointer;
typedef value_type& reference;
typedef const value_type& const_reference;
typedef size_t size_type;
typedef ptrdiff_t difference_type;
//the deque's iterator.
typedef __HJSTL_deque_iterator iterator;
typedef __HJSTL_deque_iterator const_iterator;
_HJSTL_DEQUE_PROTECTED_:
//pointer of pointer of Type.
typedef pointer* map_pointer;
//the data allocator.
typedef _HJSTL_simple_alloc data_allocator;
//map node allocator
typedef _HJSTL_simple_alloc map_allocator;
//get the buffer size
static size_type buffer_size(){
return __HJSTL_deque_buf_size(BufSize, sizeof(value_type));
}
//the initialze map size(the nodes of the map in the beginning)
static size_type initial_map_size(){
return 8;//you can change here to adjust your map nodes.
}
//the data member.
iterator start;//the first node of map.
iterator finish;//the last node of map
//the map.this is an array.stored the node pointer.
//and the node is pointer too.
map_pointer map;
//the map size
size_type map_size;
_HJSTL_DEQUE_PUBLIC_://get member.
iterator begin(){ return start; }
iterator end(){ return finish; }
const iterator begin() const { return start; }
const iterator end() const { return finish; }
reference operator[](size_type n){
return start[difference_type(n)];
}
const reference operator[](size_type n) const{
return start[difference_type(n)];
}
reference front(){
return *start;//the first node's first element.
}
reference back(){
iterator tmp = finish;
//the finish is empry.
--tmp;
return *tmp;
}
const reference front() const{
return *start;//the first node's first element.
}
const reference back() const{
const_iterator tmp = finish;
//the finish is empry.
--tmp;
return *tmp;
}
//the size of this eque
//NOTICE:the operator '-' is not so simple.you need to know that.
size_type size()const{ return finish - start; }
//-1 is max number...
size_type max_size()const { return size_type(-1); }
//is empty?
bool empty(){ return start == finish; }
_HJSTL_DEQUE_PUBLIC_://the follow is constructor
_HJSTL_deque() : start(), finish(), map(0){
//just set up an default deque for user.
create_map_and_nodes(0);
}
_HJSTL_deque(const _HJSTL_deque&x)
:start(), finish, map(0), map_size(0)
{
create_map_and_nodes(x.size());
try{
uninitialized_copy(x.begin(), x.end(), start);
}
catch (...){
//error
destroy_map_and_nodes();
}
}
_HJSTL_deque(size_type n, const value_type& value)
:start(), finish(), map(0), map_size(0)
{
fill_initialze(n, value);
}
_HJSTL_deque(int n, const value_type& value)
:start(), finish(), map(0), map_size(0)
{
fill_initialze(n, value);
}
_HJSTL_deque(long n, const value_type& value)
:start(), finish(), map(0), map_size(0)
{
fill_initialze(n, value);
}
explicit _HJSTL_deque(size_type n)
:start(), finish(), map(0), map_size(0)
{
fill_initialze(n, value_type());
}
template
_HJSTL_deque(InputIterator first, InputIterator last)
: start(), finish(), map(0), map_size(0)
{
range_initialze(first, last, hjstl_iterator_category(first));
}
_HJSTL_deque(const value_type* first, const value_type* last)
:start(), finish(), map(0), map_size(0)
{
create_map_and_nodes(last-first);
try{
uninitialized_copy(first, last, start);
}
catch (...){
destroy_map_and_nodes();
}
}
_HJSTL_deque(const_iterator first, const_iterator last)
:start(), finish(), map(0), map_size(0)
{
create_map_and_nodes(last - first);
try{
uninitialized_copy(first, last, start);
}
catch (...){
destroy_map_and_nodes();
}
}
//deconstructor
~_HJSTL_deque(){
destroy(start, finish);
destroy_map_and_nodes();
}
//function.
_HJSTL_deque& operator =(const _HJSTL_deque& x)
{
const size_type len = size();
if (&x != this){//difference deque
earse(copy(x.begin(), x.end(), start), finish);
}
else{
const_iterator mid = x.begin() + difference_type(len);
copy(x.begin(), mid, start);
insert(finish, mid, x.end());
}
return *this;
}
//erase an iterator
iterator erase(iterator pos)
{
iterator next = pos;
++next;
difference_type index = pos - start; //the length of before remove element.
if (index < (size() >> 1/*just like size()/2*/)){//less
copy_backward(start, pos, next);
pop_front();//delete the pos's value
}
else{//more.
copy(next, finish, pos);
pop_back();//delete the pos'value
}
//return the pos's value
return start + index;
}
//erase the range [first,last)
iterator erase(iterator first, iterator last)
{
//if you want to clear the deque.just use clear
if (first == start&&last == finish){
clear();
return finish;
}
else{
difference_type len = last - first;
difference_type elements_before = first - start;
if (elements_before < (size() - len) / 2)//the before elements less
{
copy_backward(start, first, last);
//the new start
iterator new_start = start + len;
//destructor the elemenst we do not want to left
destroy(start, new_start);
//back the memory to the memeory pool
for (map_pointer cur = start.node; cur < new_start.node; ++cur){
data_allocator::deallocate(*cur, buffer_size());
}
//set the start
start = new_start;
}
else{//the length of range [first,last) ->before>after
copy(last, finish, first);
iterator new_finish = finish - len;
destroy(new_finish, finish);
for (map_pointer cur = new_finish.node + 1; cur <= finish.node; ++cur){
data_allocator::deallocate(*cur, buffer_size());
}
//set the new finish
finish = new_finish;
}
return start + elements_before;
}
}
//insert an item into the deque.
//this is the insert aux
iterator insert_aux(iterator pos, const value_type& value)
{
difference_type index = pos - start;
value_type copy_v = value;
if (index < size() / 2){//before=after
push_back(back());
iterator back_1 = finish;
--back_1;
iterator back_2 = back_1;
--back_2;
pos = start + index;
copy(pos, back_2, back_1);
}
//assignment.
*pos = copy_v;
return pos;
}
//this is the insert
iterator insert(iterator position, const value_type& value)
{
//front or back?
if (position.cur == start.cur){
push_front(value);
return start;
}
else if (position.cur == finish.cur){
push_back(value);
iterator tmp = finish;
--tmp;
return tmp;
}
else{
return insert_aux(position, value);
}
}
//insert
iterator insert(iterator position){
//empty initialze
return insert(position, value_type());
}
//realloc the map
void reallocate_map(size_type nodes_to_add, bool add_at_front/*opt*/)
{
size_type old_num_nodes = finish - start + 1;
size_type new_num_nodes = old_num_nodes + nodes_to_add;
map_pointer new_nstart;
if (map_size > 2 * new_num_nodes){
new_nstart = map + (map_size - new_num_nodes) / 2 +
(add_at_front ? nodes_to_add : 0);
if (new_nstart < start.node){
copy(start.node, finish.node + 1, new_nstart);
}
else{
copy_backward(start.node, finish.node + 1,new_nstart+ old_num_nodes);
}
}
else{
size_type new_map_size = map_size + (map_size > nodes_to_add ? map_size : nodes_to_add) + 1;
map_pointer new_map = map_allocator::allocate(new_map_size);
new_nstart = new_map + (new_map_size - new_num_nodes) / 2 +
(add_at_front ? nodes_to_add : 0);
copy(start.node, finish.node + 1, new_nstart);
map_allocator::deallocate(map, map_size);
//set the new map.attr
map = new_map;
map_size = new_map_size;
}
start.set_node(new_nstart);
finish.set_node(new_nstart + old_num_nodes + 1);
}
//reserve map at back
//default add 1 node
void reserver_map_at_back(size_type nodes_to_add = 1)
{
if (nodes_to_add + 1 > map_size - (finish.node - map)){
reallocate_map(nodes_to_add, false);
}
}
void reserver_map_at_front(size_type nodes_to_add = 1)
{
if (nodes_to_add > start.node - map){
reallocate_map(nodes_to_add, true);
}
}
//just swap
void swap(_HJSTL_deque& x)
{
std::swap(start, x.start);
std::swap(finish, x.finish);
std::swap(map, x.map);
std::swap(map_size, x.map_size);
}
//push_back
void push_back(const value_type& value)
{
if (finish.cur != finish.last - 1){
construct(finish.cur, value);
++finish.cur;
}
else{//i let the another function do this
push_back_aux(value);
}
}
//push_back_aux
void push_back_aux(const value_type& value)
{
value_type copy_v = value;
reserver_map_at_back();
//alloc an new node
*(finish.node + 1) = allocate_node();
try{
construct(finish.cur, copy_v);
finish.set_node(finish.node + 1);
finish.cur = finish.first;
}
catch (...){
//if error,just deallocate the alloc-ed memory.
deallocate_node(*(finish.node + 1));
}
}
//push_front_aux
void push_front_aux(const value_type& value)
{
value_type copy_v = value;
reserver_map_at_front();
//allocate an new node
*(start.node-1)=allocate_node();
try{
start.set_node(start.node - 1);
start.cur = start.last - 1;
construct(start.cur, copy_v);
}
catch (...){
//error
start.set_node(start.node + 1);
start.cur = start.first;
deallocate_node(*(start.node - 1));
}
}
//push_front
void push_front(const value_type& value)
{
if (start.cur != start.first){
construct(start.cur, value);
--start.cur;
}
else{
push_front_aux(value);
}
}
//pop_front_aux
//edge...
void pop_front_aux()
{
destroy(start.cur);
deallocate_node(start.first);
start.set_node(start.node + 1);
start.cur = start.first;
}
//pop_back_aux
//edge
void pop_back_aux()
{
deallocate_node(finish.first);
finish.set_node(finish.node - 1);
finish.cur = finish.last - 1;
destroy(finish.cur);
}
//pop_back
void pop_back()
{
if (finish.cur != finish.first){
--finish.cur;
destroy(finish.cur);
}
else{
pop_back_aux();
}
}
//pop_front
void pop_front()
{
if (start.cur != start.last - 1){
destroy(start.cur);
++start.cur;
}
else
{
pop_front_aux();
}
}
_HJSTL_DEQUE_PROTECTED_://some useful function
//allocate an node
pointer allocate_node(){
return data_allocator::allocate(buffer_size());
}
//deallocate an node
void deallocate_node(pointer ptr){
data_allocator::deallocate(ptr, buffer_size());
}
//set up a deque with num_elements.
void create_map_and_nodes(size_type num_elements)
{
//the needed nodes
size_type num_nodes = num_elements / buffer_size() + 1;
//get the map size
map_size = initial_map_size()> (num_nodes+2) ? initial_map_size() : num_nodes+2;
//alloc map_size's nodes for map.
map = map_allocator::allocate(map_size);
//in the mid.
map_pointer nstart, nfinish;
nstart = map + (map_size - num_nodes) / 2;
nfinish = nstart + num_nodes - 1;
map_pointer cur;
try{
//alloc for each node
for (cur = nstart; cur<=nfinish; cur++){
*cur = allocate_node();
}
}
catch (...){
//deallocate.
for (map_pointer n = nstart; n < cur; n++){
deallocate_node(*n);
}
map_allocator::deallocate(map, map_size);
}
//set the start and finish
start.set_node(nstart);
finish.set_node(nfinish);
start.cur = start.first;
//make sure you can understand the follow code.
finish.cur = finish.first + num_elements%buffer_size();
}
//destroy map and nodes
void destroy_map_and_nodes(){
for (map_pointer cur = start.node; cur <= finish.node; ++cur){
deallocate_node(*cur);
}
map_allocator::deallocate(map, map_size);
}
//fill initialze
void fill_initialze(size_type n, const value_type& value)
{
create_map_and_nodes(n);
map_pointer cur;
try{
for (cur = start.node; cur < finish.node; ++cur){
uninitialized_fill(*cur, *cur + buffer_size(), value);
}
//finish node initialze
uninitialized_fill(finish.first, finish.cur, value);
}
catch (...){
//if not succeed,destory the old..
for (map_pointer n = start.node; n < cur; ++n){
destroy(*n, *n + buffer_size());
}
destroy_map_and_nodes();
}
}
//range initialze
template
void range_initialze(InputIterator first, InputIterator last, hjstl_input_iterator_tag)
{
create_map_and_nodes(0);
while (first != last){
push_back(*first++);
}
}
template
void range_initialze(ForwardIterator first, ForwardIterator last, hjstl_forward_iterator_tag)
{
size_type n = 0;
hjstl_distance(first, last, n);
create_map_and_nodes(n);
try{
uninitialized_copy(first, last, start);
}
catch (...){
destroy_map_and_nodes();
}
}
_HJSTL_DEQUE_PUBLIC_:
//clear this deque
//we need to left one buffer for this empty deque.
//
void clear()
{
for (map_pointer node = start.node + 1; node < finish.node; ++node){
destroy(*node, *node + buffer_size());
data_allocator::deallocate(*node, buffer_size());
}
//if we have at least 2 buffer left,just left the head buffer
if (start.node != finish.node){
destroy(start.cur, start.last);
destroy(finish.first, finish.cur);
data_allocator::deallocate(finish.first, buffer_size());
}
//else,just one buffer left now.
//NOTICE:do not back the memory to memory pool.
//this is the must-left buffer in an empty deue.
else{
destroy(start.cur, finish.cur);
}
//set the finish
finish = start;//means this is an empty deque,you can look up the
//function empty() to check the algorithm
}
};//end of hjstl deque
///<2016/4/28 hujian deque>
#endif //end of _HJSTL_DEQUE_H_ 拖了很久，前面写vector和list的时候因为有些地方需要重新改动，比如要去修改（增加特性支持）迭代器部分或者内存管理部分。写完vector之后应该说整个流程都打通了，接下来就是填代码了。
在写list的时候，主要是为了强化对链表这种数据结构的认识。确实，如果能把list里面的链表操作搞明白了，我觉得对于链表可以说是掌握了。
特别是，list实现时采用的是循环双链表，所以只要你明白了他的运行原理及结构，那么什么单向链表，双向链表，循环链表都不在话下。
那如果说重写list最大的收获是加深了对链表的理解，重写deque带来了什么呢？
看了源码之后，你会发现deque是所有容器中代码量最多的。这也从一个侧面反映出了deque的复杂性。
但是，deque不是采用链表，而是线性表。和vector很像，只是vector只能单方向操作，而deque支持头尾操作，而且效率很高。
deque的复杂性在于他的迭代器设计和内存管理，特别是迭代器设计，是整个deque设计过程中的重点和难点。因为deque是一段一段的空间组成的
“连续”空间，所以，对于接口来说，需要实现像vector一样的自然操作，那vector用的是线性表，没什么复杂的，但是deque不是线性表，deque一方面解决了
vector内存生长时的复杂度之外，还加深了存取操作，但随之而来的是加大了设计迭代器的复杂性。
关于deque如何设计迭代器与如何管理内存，可以在我自己整理的文件中看到，关于整个文件，我将把从开始到现在实现的所有文件和说明文档都发到
github，下一步有兴趣的同学可以下载来看看......
因为大家可能在windows下看的，直接编译SGI的STL需要花很大的功夫，还不一定能成功，我写的你不仅可以在windows下编译，还可以在linux下编译，不仅
平台无关，还编译器无关~~~(对于需要做少量修改的地方，大家自行处理)
ok，下面是源码，我会在下一篇文章中贴出github地址，大家可以下载。