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《STL源码剖析》---stl_deque.h阅读笔记(2)
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G++ 2.91.57，cygnus\cygwin-b20\include\g++\stl_deque.h 完整列表
/*
*
* 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) 1997
* 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_DEQUE_H
#define __SGI_STL_INTERNAL_DEQUE_H
/* Class 的恆長特性（invariants）:
* 對於任何 nonsingular iterator I：
* i.node 是 map array 中的某個元素的位址。
* i.node 所指內容則是一個指標，指向某個節點（緩衝區）的頭。
* i.first == *(i.node)
* i.last == i.first + node_size（也就是 buffer_size()）
* i.cur 是一個指標，指向範圍 [i.first, i.last) 之間。注意：
* 這意味 i.cur 永遠是一個 dereferenceable pointer,
* 縱使 i 是一個 past-the-end iterator.
* Start 和 Finish 總是 nonsingular iterators。注意：這意味
* empty deque 一定會有一個node，而一個具有N個元素的deque，
* （N 表示緩衝區大小），一定會有兩個nodes。
* 對於start.node 和finish.node 以外的每一個node，其中的每一個元素
* 都是一個經過初始化的物件。如果 start.node == finish.node，
* 那麼 [start.cur, finish.cur) 都是經過初始化的物件，而該範圍以外
* 元素則是未經初始化的空間。否則，[start.cur, start.last) 和
* [finish.first, finish.cur) 是經過初始化的物件，而
* [start.first, start.cur) 和 [finish.cur, finish.last)
* 則是未經初始化的空間
* [map, map + map_size) 是一個有效的，non-empty 的範圍。
* [start.node, finish.node] 是一個有效的範圍，內含於
* [map, map + map_size) 之內。
* 範圍 [map, map + map_size) 內的任何一個指標會指向一個經過配置的
* node — 若且唯若該指標在範圍 [start.node, finish.node] 之內。
*/
/*
* 在前一版的deque中，node_size 由編譯器定死。這個版本允許使用者選擇節點
* （node）的大小。Deque 有三個 template 參數，其中第三個是一個型別為 size_t
* 的數值，代表每個節點（node）內含的元素個數。如果第三個 template 參數為0
* （那是預設值），deque 就使用預設的節點大小。
*
* 使用不同的節點大小的唯一理由是，或許你的程式需要不同的效率並願意付出其他方
* 面的代價。例如，假設你的程式內含許多deques，每一個都只內含一些元素，那麼
* 你可以使用較小的 nodes 來節省記憶體（或許會因此犧牲速度）。
*
* 不幸的是，某些編譯器面對 non-type template 參數會有問題。stl_config.h 之
* 中為此定義了一個 __STL_NON_TYPE_TMPL_PARAM_BUG。如果你的編譯器正是如
* 此，你就無法使用不同的節點大小，你必須使用預設大小。
*/
__STL_BEGIN_NAMESPACE
#if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32)
#pragma set woff 1174
#endif
/*
此函数用来计算缓冲区的大小
如果n不等于0，那么返回n，开发者自己决定
否则：如果sz小于512，返回512/sz
如果sz大于512，返回1
*/
inline size_t __deque_buf_size(size_t n, size_t sz)
{
return n != 0 ? n : (sz < 512 ? size_t(512 / sz) : size_t(1));
}
//deque的迭代器，它没有继承std::iterator
#ifndef __STL_NON_TYPE_TMPL_PARAM_BUG
template <class T, class Ref, class Ptr, size_t BufSiz>
struct __deque_iterator {
typedef __deque_iterator<T, T&, T*, BufSiz> iterator;
typedef __deque_iterator<T, const T&, const T*, BufSiz> const_iterator;
static size_t buffer_size() {return __deque_buf_size(BufSiz, sizeof(T)); }
#else /* __STL_NON_TYPE_TMPL_PARAM_BUG */
template <class T, class Ref, class Ptr>
struct __deque_iterator {
typedef __deque_iterator<T, T&, T*> iterator;
typedef __deque_iterator<T, const T&, const T*> const_iterator;
static size_t buffer_size() {return __deque_buf_size(0, sizeof(T)); }
#endif
//没有继承std::iterator，自己定义5个迭代器相应的类型。
//其占用内存连续（部分连续）迭代器类型是random_access_iterator_tag
typedef random_access_iterator_tag iterator_category; // (1)
typedef T value_type; // (2)
typedef Ptr pointer; // (3)
typedef Ref reference; // (4)
typedef size_t size_type;
typedef ptrdiff_t difference_type; // (5)
typedef T** map_pointer; //注意，是指针的指针
//map_pointer指向中控器，中控器的存储的是指针，指向node-buf结点缓冲区
typedef __deque_iterator self;
/*
关于下面4个元素的意义以及和map中控器、缓冲区buffer的关系，见图（2）
*/
T* cur; // 迭代器所指元素
T* first; // 迭代器所指元素所在缓冲区的开头
T* last; // 迭代器所指元素所在缓冲区的结尾（结尾包含在缓冲区内）
map_pointer node;//指向中控器的结点，这个结点指向迭代器所指元素所在的缓冲区
//迭代器的构造函数
//x是迭代器所指结点，y为中控器中的结点的值，指向x所指缓冲区
__deque_iterator(T* x, map_pointer y)
: cur(x), first(*y), last(*y + buffer_size()), node(y) {}
//默认构造函数
__deque_iterator() : cur(0), first(0), last(0), node(0) {}
//用一个迭代器x初始化本迭代器
__deque_iterator(const iterator& x)
: cur(x.cur), first(x.first), last(x.last), node(x.node) {}
//迭代器需要重载的运算符
reference operator*() const { return *cur; }
#ifndef __SGI_STL_NO_ARROW_OPERATOR
//重载箭头是返回地址
pointer operator->() const { return &(operator*()); }
#endif /* __SGI_STL_NO_ARROW_OPERATOR */
/*
两个迭代器之间的距离。这两个迭代器可能不在同一个buffer上。
*/
difference_type operator-(const self& x) const {
return difference_type(buffer_size()) * (node - x.node - 1) +
(cur - first) + (x.last - x.cur);
}
// 參考 More Effective C++, item6: Distinguish between prefix and
// postfix forms of increment and decrement operators.
/*
迭代器前进一步。
先++cur，再判断cur==last。说明cur不会指向last的。last所指空间不存内容
*/
self& operator++() {
++cur; // 前进一步
if (cur == last) { // 到了所在缓冲区的尾端了
set_node(node + 1); // 切换到下一个缓冲区
cur = first; // 的第一个元素
}
return *this;
}
self operator++(int) {
self tmp = *this;
++*this;
return tmp;
}
//迭代器往回走一步。
self& operator--() {
if (cur == first) { // 如果在所在缓冲区的头部
set_node(node - 1); // 切换到前一个缓冲区
cur = last; // 的最后一个元素
}
--cur; // 直接往回走一步
return *this;
}
self operator--(int) {
self tmp = *this;
--*this;
return tmp;
}
/*
迭代器向前进或后退n步（取决于n的正负）。这是支持random access iterator 所必须的操作。
如果这个操作不会是迭代器走出当前所在缓冲区，直接更改cur即可。
如果这个操作使迭代器走出当前所在缓冲区，要计算出操作后在哪个缓冲区的哪个位置。
*/
self& operator+=(difference_type n) {
difference_type offset = n + (cur - first);
if (offset >= 0 && offset < difference_type(buffer_size()))
// 不会走出当前所在缓冲区
cur += n;
else {
// 走出了当前所在缓冲区
difference_type node_offset =
offset > 0 ? offset / difference_type(buffer_size())
: -difference_type((-offset - 1) / buffer_size()) - 1;
// 切换缓冲区
set_node(node + node_offset);
// 找到切换缓冲区后，迭代器所指向的元素
cur = first + (offset - node_offset * difference_type(buffer_size()));
}
return *this;
}
self operator+(difference_type n) const {
self tmp = *this;
return tmp += n; // 调用operator+=
}
//调用operator+=
self& operator-=(difference_type n) { return *this += -n; }
self operator-(difference_type n) const {
self tmp = *this;
return tmp -= n; // 调用operator-=
}
reference operator[](difference_type n) const { return *(*this + n); }
// 以上调用了operator*, operator+
/*迭代器关于比较的运算符的重载*/
bool operator==(const self& x) const { return cur == x.cur; }
bool operator!=(const self& x) const { return !(*this == x); }
bool operator<(const self& x) const {
return (node == x.node) ? (cur < x.cur) : (node < x.node);
}
//切换缓冲区，更改了first和last，但是未更改cur
void set_node(map_pointer new_node) {
node = new_node;
first = *new_node;
last = first + difference_type(buffer_size());
}
};
//编译器不支持片特性话partial specialization
#ifndef __STL_CLASS_PARTIAL_SPECIALIZATION
#ifndef __STL_NON_TYPE_TMPL_PARAM_BUG
template <class T, class Ref, class Ptr, size_t BufSiz>
inline random_access_iterator_tag
iterator_category(const __deque_iterator<T, Ref, Ptr, BufSiz>&) {
return random_access_iterator_tag();
}
template <class T, class Ref, class Ptr, size_t BufSiz>
inline T* value_type(const __deque_iterator<T, Ref, Ptr, BufSiz>&) {
return 0;
}
template <class T, class Ref, class Ptr, size_t BufSiz>
inline ptrdiff_t* distance_type(const __deque_iterator<T, Ref, Ptr, BufSiz>&) {
return 0;
}
#else /* __STL_NON_TYPE_TMPL_PARAM_BUG */
template <class T, class Ref, class Ptr>
inline random_access_iterator_tag
iterator_category(const __deque_iterator<T, Ref, Ptr>&) {
return random_access_iterator_tag();
}
template <class T, class Ref, class Ptr>
inline T* value_type(const __deque_iterator<T, Ref, Ptr>&) { return 0; }
template <class T, class Ref, class Ptr>
inline ptrdiff_t* distance_type(const __deque_iterator<T, Ref, Ptr>&) {
return 0;
}
#endif /* __STL_NON_TYPE_TMPL_PARAM_BUG */
#endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */
/*
deque的定义，默认使用alloc配置器
*/
template <class T, class Alloc = alloc, size_t BufSiz = 0>
class deque {
public: // Basic types
typedef T 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;
public: // 迭代器
#ifndef __STL_NON_TYPE_TMPL_PARAM_BUG
typedef __deque_iterator<T, T&, T*, BufSiz> iterator;
typedef __deque_iterator<T, const T&, const T&, BufSiz> const_iterator;
#else /* __STL_NON_TYPE_TMPL_PARAM_BUG */
typedef __deque_iterator<T, T&, T*> iterator;
typedef __deque_iterator<T, const T&, const T*> const_iterator;
#endif /* __STL_NON_TYPE_TMPL_PARAM_BUG */
#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: // Internal typedefs
// 指向中控器，是指针的指针（pointer of pointer of T）
typedef pointer* map_pointer;
// 空间配置器，用来配置缓冲区
typedef simple_alloc<value_type, Alloc> data_allocator;
// 空间配置器，用来配置中控器
typedef simple_alloc<pointer, Alloc> map_allocator;
static size_type buffer_size() {
return __deque_buf_size(BufSiz, sizeof(value_type));
}
//默认中控器大小为8
static size_type initial_map_size() { return 8; }
protected: // Data members
iterator start; // start.cur指向deque的第一个结点
iterator finish; // finish.cur指向迭代器deque的最后一个结点的后一个元素
map_pointer map; // 指向中控器。其实是指向中控器的第一个结点。
// 中控器是连续的，map_size定义了中控器的大小。
size_type map_size; // 中控器的大小。
public: // 对外的接口
iterator begin() { return start; }
iterator end() { return finish; }
const_iterator begin() const { return start; }
const_iterator end() const { return finish; }
reverse_iterator rbegin() { return reverse_iterator(finish); }
reverse_iterator rend() { return reverse_iterator(start); }
const_reverse_iterator rbegin() const {
return const_reverse_iterator(finish);
}
const_reverse_iterator rend() const {
return const_reverse_iterator(start);
}
reference operator[](size_type n) {
return start[difference_type(n)]; // 调用 __deque_iterator<>::operator[]
}
const_reference operator[](size_type n) const {
return start[difference_type(n)];
}
reference front() { return *start; } // 调用 __deque_iterator<>::operator*
//取出最后一个元素
reference back() {
iterator tmp = finish;
--tmp; // 调用 __deque_iterator<>::operator--
return *tmp; // 调用 __deque_iterator<>::operator*
}
//返回第一个元素，并不删除
const_reference front() const { return *start; }
const_reference back() const {
const_iterator tmp = finish;
--tmp;
return *tmp;
}
//deque中元素个数。后面有两个分号。迭代器调用了iterator::operator-
size_type size() const { return finish - start;; }
//deque最大容量。
size_type max_size() const { return size_type(-1); }
//下面调用了operator::iterator==
bool empty() const { return finish == start; }
public:
// Constructor, destructor.
//默认构造函数
deque()
: start(), finish(), map(0), map_size(0)
// 以上 start() 和 finish() 调用 iterator（亦即 __deque_iterator）
// 的 default constructor，令 cur, first, last, node 都为0。
{
create_map_and_nodes(0);
}
//用一个deque构建新的deque
deque(const deque& x)
: start(), finish(), map(0), map_size(0)
{
create_map_and_nodes(x.size());
__STL_TRY {
uninitialized_copy(x.begin(), x.end(), start);
}
//commit or rollback
__STL_UNWIND(destroy_map_and_nodes());
}
//构建大小为n，元素值为value的deque
deque(size_type n, const value_type& value)
: start(), finish(), map(0), map_size(0)
{
fill_initialize(n, value);
}
deque(int n, const value_type& value)
: start(), finish(), map(0), map_size(0)
{
fill_initialize(n, value);
}
deque(long n, const value_type& value)
: start(), finish(), map(0), map_size(0)
{
fill_initialize(n, value);
}
//构建大小为n的deque，默认值为T(),说明deque容器的元素要有默认构造函数
explicit deque(size_type n)
: start(), finish(), map(0), map_size(0)
{
fill_initialize(n, value_type());
}
/*用一段元素构建的确 */
#ifdef __STL_MEMBER_TEMPLATES
template <class InputIterator>
deque(InputIterator first, InputIterator last)
: start(), finish(), map(0), map_size(0)
{
range_initialize(first, last, iterator_category(first));
}
#else /* __STL_MEMBER_TEMPLATES */
deque(const value_type* first, const value_type* last)
: start(), finish(), map(0), map_size(0)
{
create_map_and_nodes(last - first);
__STL_TRY {
uninitialized_copy(first, last, start);
}
__STL_UNWIND(destroy_map_and_nodes());
}
deque(const_iterator first, const_iterator last)
: start(), finish(), map(0), map_size(0)
{
create_map_and_nodes(last - first);
__STL_TRY {
uninitialized_copy(first, last, start);
}
__STL_UNWIND(destroy_map_and_nodes());
}
#endif /* __STL_MEMBER_TEMPLATES */
~deque() {
destroy(start, finish);
destroy_map_and_nodes();
}
deque& operator= (const deque& x) {
const size_type len = size();
if (&x != this) {
if (len >= x.size())
erase(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;
}
void swap(deque& x) {
__STD::swap(start, x.start);
__STD::swap(finish, x.finish);
__STD::swap(map, x.map);
__STD::swap(map_size, x.map_size);
}
public: // push_* and pop_*
//在deque末尾添加元素
void push_back(const value_type& t) {
if (finish.cur != finish.last - 1) {
// 当前缓冲区还有空间
construct(finish.cur, t); // 直接在可用空间构建
++finish.cur; // 调整finish迭代器
}
else // 当前缓冲区无可用空间（last不能存储元素用）
push_back_aux(t);
}
//在deque头添加元素
void push_front(const value_type& t) {
if (start.cur != start.first) { // 当前缓冲区还有空间
construct(start.cur - 1, t);
--start.cur;
}
else // 当前缓冲区无空间可用了
push_front_aux(t);
}
//删掉末尾元素
void pop_back() {
if (finish.cur != finish.first) {//最后一个缓冲区（finish指的缓冲区）有多于一个元素（含一个）
--finish.cur;
destroy(finish.cur);
}
else
// 最后一个缓冲区无元素
pop_back_aux(); // 这里会进行缓冲区的释放工作
}
//在deque头删除元素
void pop_front() {
if (start.cur != start.last - 1) {
// start.node所指缓冲区有多余一个元素（不含一个）
destroy(start.cur);
++start.cur;
}
else
// start.node所指缓冲区只有一个元素
pop_front_aux(); // 这里会进行缓冲区释放工作
}
public: // Insert
/*在position处插入一个元素
如果position是deque的最前端，则调用push_front()。
如果position是deque的最末端，则调用push_back()。
在两个元素之间插入的话，就调用insert_aux。
*/
// 在position 处安插一個元素，其值为 x
iterator insert(iterator position, const value_type& x) {
if (position.cur == start.cur) {
push_front(x);
return start;
}
else if (position.cur == finish.cur) {
push_back(x);
iterator tmp = finish;
--tmp;
return tmp;
}
else {
return insert_aux(position, x); // 交给insert_aux 去做
}
}
// 在position 处安插一個元素，其值为T()
iterator insert(iterator position) { return insert(position, value_type()); }
void insert(iterator pos, size_type n, const value_type& x);
void insert(iterator pos, int n, const value_type& x) {
insert(pos, (size_type) n, x);
}
void insert(iterator pos, long n, const value_type& x) {
insert(pos, (size_type) n, x);
}
#ifdef __STL_MEMBER_TEMPLATES
template <class InputIterator>
void insert(iterator pos, InputIterator first, InputIterator last) {
insert(pos, first, last, iterator_category(first));
}
#else /* __STL_MEMBER_TEMPLATES */
void insert(iterator pos, const value_type* first, const value_type* last);
void insert(iterator pos, const_iterator first, const_iterator last);
#endif /* __STL_MEMBER_TEMPLATES */
/*
调整deque的大小。
如果deque变小，直接擦除掉多余的元素。
如果deque变大，则在deque后面插入元素补充，元素值为x/T()
*/
void resize(size_type new_size, const value_type& x) {
const size_type len = size();
if (new_size < len)
erase(start + new_size, finish);
else
insert(finish, new_size - len, x);
}
void resize(size_type new_size) { resize(new_size, value_type()); }
public:
// 清除 pos 所指的元素。
/*判断pos距离头近还是距离尾近，距离那个位置近就移动那个位置的元素，保证移动元素个数最少*/
iterator erase(iterator pos) {
iterator next = pos;
++next;
difference_type index = pos - start; // pos和deque开头元素的个数
if (index < (size() >> 1)) { // size() >> 1为size()/2。
//如果pos距离deque头比较近的话，deque的开头到pos元素向后移
copy_backward(start, pos, next);
pop_front(); // 移动后，删除第一个元素
}
else { // 否则pos+1到结尾元素向前移，
copy(next, finish, pos);
pop_back();
}
return start + index;
}
iterator erase(iterator first, iterator last);
void clear();
protected: // Internal construction/destruction
void create_map_and_nodes(size_type num_elements);
void destroy_map_and_nodes();
void fill_initialize(size_type n, const value_type& value);
#ifdef __STL_MEMBER_TEMPLATES
template <class InputIterator>
void range_initialize(InputIterator first, InputIterator last,
input_iterator_tag);
template <class ForwardIterator>
void range_initialize(ForwardIterator first, ForwardIterator last,
forward_iterator_tag);
#endif /* __STL_MEMBER_TEMPLATES */
protected: // Internal push_* and pop_*
void push_back_aux(const value_type& t);
void push_front_aux(const value_type& t);
void pop_back_aux();
void pop_front_aux();
protected: // Internal insert functions
#ifdef __STL_MEMBER_TEMPLATES
template <class InputIterator>
void insert(iterator pos, InputIterator first, InputIterator last,
input_iterator_tag);
template <class ForwardIterator>
void insert(iterator pos, ForwardIterator first, ForwardIterator last,
forward_iterator_tag);
#endif /* __STL_MEMBER_TEMPLATES */
iterator insert_aux(iterator pos, const value_type& x);
void insert_aux(iterator pos, size_type n, const value_type& x);
#ifdef __STL_MEMBER_TEMPLATES
template <class ForwardIterator>
void insert_aux(iterator pos, ForwardIterator first, ForwardIterator last,
size_type n);
#else /* __STL_MEMBER_TEMPLATES */
void insert_aux(iterator pos,
const value_type* first, const value_type* last,
size_type n);
void insert_aux(iterator pos, const_iterator first, const_iterator last,
size_type n);
#endif /* __STL_MEMBER_TEMPLATES */
//在队列头或者尾预留n个位置，如果缓冲区不够则开辟新缓冲区。
iterator reserve_elements_at_front(size_type n) {
size_type vacancies = start.cur - start.first;
if (n > vacancies)
new_elements_at_front(n - vacancies);
return start - difference_type(n);
}
iterator reserve_elements_at_back(size_type n) {
size_type vacancies = (finish.last - finish.cur) - 1;
if (n > vacancies)
new_elements_at_back(n - vacancies);
return finish + difference_type(n);
}
void new_elements_at_front(size_type new_elements);
void new_elements_at_back(size_type new_elements);
void destroy_nodes_at_front(iterator before_start);
void destroy_nodes_at_back(iterator after_finish);
protected: // Allocation of map and nodes
// Makes sure the map has space for new nodes. Does not actually
// add the nodes. Can invalidate map pointers. (And consequently,
// deque iterators.)
//在map尾添加缓冲区
void reserve_map_at_back (size_type nodes_to_add = 1) {
if (nodes_to_add + 1 > map_size - (finish.node - map))
//map空间不够用，则开辟新的map空间，把原来map内容拷贝过来。释放原来的
reallocate_map(nodes_to_add, false);
}
//在map头添加缓冲区
void reserve_map_at_front (size_type nodes_to_add = 1) {
if (nodes_to_add > start.node - map)
reallocate_map(nodes_to_add, true);
}
void reallocate_map(size_type nodes_to_add, bool add_at_front);
//配置新的缓冲区
pointer allocate_node() { return data_allocator::allocate(buffer_size()); }
//释放缓冲区
void deallocate_node(pointer n) {
data_allocator::deallocate(n, buffer_size());
}
//重载比较运算符
#ifdef __STL_NON_TYPE_TMPL_PARAM_BUG
public:
bool operator==(const deque<T, Alloc, 0>& x) const {
return size() == x.size() && equal(begin(), end(), x.begin());
}
bool operator!=(const deque<T, Alloc, 0>& x) const {
return size() != x.size() || !equal(begin(), end(), x.begin());
}
bool operator<(const deque<T, Alloc, 0>& x) const {
return lexicographical_compare(begin(), end(), x.begin(), x.end());
}
#endif /* __STL_NON_TYPE_TMPL_PARAM_BUG */
};
// Non-inline member functions
//不是内联函数
//在pos处插入n个元素，元素值为n
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::insert(iterator pos,
size_type n, const value_type& x) {
if (pos.cur == start.cur) {//pos是deque的头
iterator new_start = reserve_elements_at_front(n);
uninitialized_fill(new_start, start, x);
start = new_start;
}
else if (pos.cur == finish.cur) {//pos是deque的尾
iterator new_finish = reserve_elements_at_back(n);
uninitialized_fill(finish, new_finish, x);
finish = new_finish;
}
else //中间位置
insert_aux(pos, n, x);
}
#ifndef __STL_MEMBER_TEMPLATES
//两个迭代器之间的元素插入到pos处
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::insert(iterator pos,
const value_type* first,
const value_type* last) {
size_type n = last - first;
if (pos.cur == start.cur) {//deque的头
//先预留好位置
iterator new_start = reserve_elements_at_front(n);
__STL_TRY {
//在未初始化内存上直接构造
uninitialized_copy(first, last, new_start);
start = new_start;
}
__STL_UNWIND(destroy_nodes_at_front(new_start));
}
else if (pos.cur == finish.cur) {
iterator new_finish = reserve_elements_at_back(n);
__STL_TRY {
uninitialized_copy(first, last, finish);
finish = new_finish;
}
//commi or rollback
__STL_UNWIND(destroy_nodes_at_back(new_finish));
}
else
insert_aux(pos, first, last, n);
}
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::insert(iterator pos,
const_iterator first,
const_iterator last)
{
size_type n = last - first;
if (pos.cur == start.cur) {
iterator new_start = reserve_elements_at_front(n);
__STL_TRY {
uninitialized_copy(first, last, new_start);
start = new_start;
}
__STL_UNWIND(destroy_nodes_at_front(new_start));
}
else if (pos.cur == finish.cur) {
iterator new_finish = reserve_elements_at_back(n);
__STL_TRY {
uninitialized_copy(first, last, finish);
finish = new_finish;
}
__STL_UNWIND(destroy_nodes_at_back(new_finish));
}
else
insert_aux(pos, first, last, n);
}
#endif /* __STL_MEMBER_TEMPLATES */
//擦除两个迭代器之间的元素
template <class T, class Alloc, size_t BufSize>
deque<T, Alloc, BufSize>::iterator
deque<T, Alloc, BufSize>::erase(iterator first, iterator last) {
if (first == start && last == finish) { // 如果是清除整个 deque
clear(); // 直接调用 clear() 即可
return finish;
}
else {
difference_type n = last - first; // 擦除区间长度
difference_type elems_before = first - start; // 擦除区间前方元素的个数
if (elems_before < (size() - n) / 2) { // 如果前方的元素比更少，
copy_backward(start, first, last); // 前方元素向后移（覆盖擦除区间）
iterator new_start = start + n; // deque 的新起点
destroy(start, new_start); // 多于元素析构
// 释放多于元素所占内存
for (map_pointer cur = start.node; cur < new_start.node; ++cur)
data_allocator::deallocate(*cur, buffer_size());
start = new_start;
}
else { // 后方元素更少
copy(last, finish, first);
iterator new_finish = finish - n;
destroy(new_finish, finish);
for (map_pointer cur = new_finish.node + 1; cur <= finish.node; ++cur)
data_allocator::deallocate(*cur, buffer_size());
finish = new_finish;
}
return start + elems_before;
}
}
//清空deque。最后保留了一个缓冲区，这是deque的策略，也是其初始状态
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::clear() {
//下面针对头尾以外的缓冲区，它们肯定是满的。
for (map_pointer node = start.node + 1; node < finish.node; ++node) {
// 先析构
destroy(*node, *node + buffer_size());
// 再释放
data_allocator::deallocate(*node, buffer_size());
}
if (start.node != finish.node) { // 至少有2个以上（含）缓冲区
destroy(start.cur, start.last); // 头缓冲区元素析构
destroy(finish.first, finish.cur); // 尾缓冲区元素析构
// 释放尾缓冲区，保留了头缓冲区
data_allocator::deallocate(finish.first, buffer_size());
}
else // 只有一个缓冲区
destroy(start.cur, finish.cur); // 析构，但是不释放
finish = start; // 调整迭代器，deque为空
}
//创建map，num_elements为元素个数
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::create_map_and_nodes(size_type num_elements) {
//需要多少个缓冲区，即对应多少个map_node，如果刚好整除，会多出一个来
size_type num_nodes = num_elements / buffer_size() + 1;
//创建map结构，（如果少于8个）要多出2个来，前后各预留一个备用
map_size = max(initial_map_size(), num_nodes + 2);
map = map_allocator::allocate(map_size);
/*下面是nstart和nfinish指向map结构的最中间，这样可以使前后添加能力一样大。*/
map_pointer nstart = map + (map_size - num_nodes) / 2;
map_pointer nfinish = nstart + num_nodes - 1;
map_pointer cur;
__STL_TRY {
//为map内已用结点配置缓冲区。
for (cur = nstart; cur <= nfinish; ++cur)
*cur = allocate_node();
}
# ifdef __STL_USE_EXCEPTIONS
catch(...) {
// "commit or rollback"
for (map_pointer n = nstart; n < cur; ++n)
deallocate_node(*n);
map_allocator::deallocate(map, map_size);
throw;
}
# endif /* __STL_USE_EXCEPTIONS */
//为deque的迭代器start和end设定正确内容
start.set_node(nstart);
finish.set_node(nfinish);
start.cur = start.first; // first, cur都是public
finish.cur = finish.first + num_elements % buffer_size();
//正如前面所说，如果刚好整除会多出一个map_node。此时cur指向多出的这个缓冲区的起始位置。
}
// This is only used as a cleanup function in catch clauses.
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::destroy_map_and_nodes() {
for (map_pointer cur = start.node; cur <= finish.node; ++cur)
deallocate_node(*cur);
map_allocator::deallocate(map, map_size);
}
//分配n个结点，用value初始化
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::fill_initialize(size_type n,
const value_type& value) {
create_map_and_nodes(n); // 把deque的结构都安排好
map_pointer cur;
__STL_TRY {
// 每个结点缓冲区设定初始值。
for (cur = start.node; cur < finish.node; ++cur)
uninitialized_fill(*cur, *cur + buffer_size(), value);
//最后一个结点有点不一样，因为尾端可能有未用空间，不必设置初始值
uninitialized_fill(finish.first, finish.cur, value);
}
# ifdef __STL_USE_EXCEPTIONS
catch(...) {
// "commit or rollback"
for (map_pointer n = start.node; n < cur; ++n)
destroy(*n, *n + buffer_size());
destroy_map_and_nodes();
throw;
}
# endif /* __STL_USE_EXCEPTIONS */
}
//用两个迭代器之间的元素初始化。迭代器类型不同，实现方法不同。
//input_iterator_tag类型迭代器一个一个初始化
//forward_iterator_tag(含其派生类型）内存处理工具初始化。
#ifdef __STL_MEMBER_TEMPLATES
template <class T, class Alloc, size_t BufSize>
template <class InputIterator>
void deque<T, Alloc, BufSize>::range_initialize(InputIterator first,
InputIterator last,
input_iterator_tag) {
create_map_and_nodes(0);//不分配结点
for ( ; first != last; ++first)//一个一个初始化
push_back(*first);
}
template <class T, class Alloc, size_t BufSize>
template <class ForwardIterator>
void deque<T, Alloc, BufSize>::range_initialize(ForwardIterator first,
ForwardIterator last,
forward_iterator_tag) {
size_type n = 0;
distance(first, last, n);
create_map_and_nodes(n);//分配好结点
__STL_TRY {
uninitialized_copy(first, last, start);
}
//commit or rollback
__STL_UNWIND(destroy_map_and_nodes());
}
#endif /* __STL_MEMBER_TEMPLATES */
//只有当finish.cur == finish.last – 1才有调用。
//只有当最后一个缓冲区只剩一个未用空间时才调用
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::push_back_aux(const value_type& t) {
value_type t_copy = t;
reserve_map_at_back(); // 若符合某重条件则必须重换一个map
*(finish.node + 1) = allocate_node(); // 配置一个新结点（缓冲区）
__STL_TRY {
construct(finish.cur, t_copy); // 设置值
finish.set_node(finish.node + 1); // 改变finish，令其指向新结点
finish.cur = finish.first; // 设置 finish 的状态
}
__STL_UNWIND(deallocate_node(*(finish.node + 1)));
}
// 只有当start.cur == start.first才会调用。
// 第一个缓冲区没有未用空间时才会调用。和上面实现类似
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::push_front_aux(const value_type& t) {
value_type t_copy = t;
reserve_map_at_front();
*(start.node - 1) = allocate_node();
__STL_TRY {
start.set_node(start.node - 1);
start.cur = start.last - 1;
construct(start.cur, t_copy);
}
# ifdef __STL_USE_EXCEPTIONS
catch(...) {
// "commit or rollback"
start.set_node(start.node + 1);
start.cur = start.first;
deallocate_node(*(start.node - 1));
throw;
}
# endif /* __STL_USE_EXCEPTIONS */
}
// 只有当finish.cur == finish.first才会调用
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::pop_back_aux() {
deallocate_node(finish.first);
finish.set_node(finish.node - 1);
finish.cur = finish.last - 1;
destroy(finish.cur);
}
// 只有当start.cur == start.last - 1时才会调用
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::pop_front_aux() {
destroy(start.cur);
deallocate_node(start.first);
start.set_node(start.node + 1);
start.cur = start.first;
}
#ifdef __STL_MEMBER_TEMPLATES
template <class T, class Alloc, size_t BufSize>
template <class InputIterator>
void deque<T, Alloc, BufSize>::insert(iterator pos,
InputIterator first, InputIterator last,
input_iterator_tag) {
copy(first, last, inserter(*this, pos));
}
//在pos处插入[first last)元素，对应迭代器类型为forward_iterator_tag(含派生)
template <class T, class Alloc, size_t BufSize>
template <class ForwardIterator>
void deque<T, Alloc, BufSize>::insert(iterator pos,
ForwardIterator first,
ForwardIterator last,
forward_iterator_tag) {
size_type n = 0;
distance(first, last, n);
if (pos.cur == start.cur) {
iterator new_start = reserve_elements_at_front(n);
__STL_TRY {
uninitialized_copy(first, last, new_start);
start = new_start;
}
__STL_UNWIND(destroy_nodes_at_front(new_start));
}
else if (pos.cur == finish.cur) {
iterator new_finish = reserve_elements_at_back(n);
__STL_TRY {
uninitialized_copy(first, last, finish);
finish = new_finish;
}
__STL_UNWIND(destroy_nodes_at_back(new_finish));
}
else
insert_aux(pos, first, last, n);
}
#endif /* __STL_MEMBER_TEMPLATES */
//在pos处插入一个元素，值为x。要判断插入点距头更近还是尾更近……
template <class T, class Alloc, size_t BufSize>
typename deque<T, Alloc, BufSize>::iterator
deque<T, Alloc, BufSize>::insert_aux(iterator pos, const value_type& x) {
difference_type index = pos - start;
value_type x_copy = x;
if (index < size() / 2) {
push_front(front());
iterator front1 = start;
++front1;
iterator front2 = front1;
++front2;
pos = start + index;
iterator pos1 = pos;
++pos1;
copy(front2, pos1, front1);
}
else {
push_back(back());
iterator back1 = finish;
--back1;
iterator back2 = back1;
--back2;
pos = start + index;
copy_backward(pos, back2, back1);
}
*pos = x_copy;
return pos;
}
//在pos处插入n个元素，值为x
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::insert_aux(iterator pos,
size_type n, const value_type& x) {
const difference_type elems_before = pos - start;
size_type length = size();
value_type x_copy = x;
if (elems_before < length / 2) {
iterator new_start = reserve_elements_at_front(n);
iterator old_start = start;
pos = start + elems_before;
__STL_TRY {
if (elems_before >= difference_type(n)) {
iterator start_n = start + difference_type(n);
uninitialized_copy(start, start_n, new_start);
start = new_start;
copy(start_n, pos, old_start);
fill(pos - difference_type(n), pos, x_copy);
}
else {
__uninitialized_copy_fill(start, pos, new_start, start, x_copy);
start = new_start;
fill(old_start, pos, x_copy);
}
}
__STL_UNWIND(destroy_nodes_at_front(new_start));
}
else {
iterator new_finish = reserve_elements_at_back(n);
iterator old_finish = finish;
const difference_type elems_after = difference_type(length) - elems_before;
pos = finish - elems_after;
__STL_TRY {
if (elems_after > difference_type(n)) {
iterator finish_n = finish - difference_type(n);
uninitialized_copy(finish_n, finish, finish);
finish = new_finish;
copy_backward(pos, finish_n, old_finish);
fill(pos, pos + difference_type(n), x_copy);
}
else {
__uninitialized_fill_copy(finish, pos + difference_type(n),
x_copy,
pos, finish);
finish = new_finish;
fill(pos, old_finish, x_copy);
}
}
__STL_UNWIND(destroy_nodes_at_back(new_finish));
}
}
#ifdef __STL_MEMBER_TEMPLATES
//在pos处插入n个元素，n个元素值为[first last)
template <class T, class Alloc, size_t BufSize>
template <class ForwardIterator>
void deque<T, Alloc, BufSize>::insert_aux(iterator pos,
ForwardIterator first,
ForwardIterator last,
size_type n)
{
const difference_type elems_before = pos - start;
size_type length = size();
if (elems_before < length / 2) {
iterator new_start = reserve_elements_at_front(n);
iterator old_start = start;
pos = start + elems_before;
__STL_TRY {
if (elems_before >= difference_type(n)) {
iterator start_n = start + difference_type(n);
uninitialized_copy(start, start_n, new_start);
start = new_start;
copy(start_n, pos, old_start);
copy(first, last, pos - difference_type(n));
}
else {
ForwardIterator mid = first;
advance(mid, difference_type(n) - elems_before);
__uninitialized_copy_copy(start, pos, first, mid, new_start);
start = new_start;
copy(mid, last, old_start);
}
}
__STL_UNWIND(destroy_nodes_at_front(new_start));
}
else {
iterator new_finish = reserve_elements_at_back(n);
iterator old_finish = finish;
const difference_type elems_after = difference_type(length) - elems_before;
pos = finish - elems_after;
__STL_TRY {
if (elems_after > difference_type(n)) {
iterator finish_n = finish - difference_type(n);
uninitialized_copy(finish_n, finish, finish);
finish = new_finish;
copy_backward(pos, finish_n, old_finish);
copy(first, last, pos);
}
else {
ForwardIterator mid = first;
advance(mid, elems_after);
__uninitialized_copy_copy(mid, last, pos, finish, finish);
finish = new_finish;
copy(first, mid, pos);
}
}
__STL_UNWIND(destroy_nodes_at_back(new_finish));
}
}
#else /* __STL_MEMBER_TEMPLATES */
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::insert_aux(iterator pos,
const value_type* first,
const value_type* last,
size_type n)
{
const difference_type elems_before = pos - start;
size_type length = size();
if (elems_before < length / 2) {
iterator new_start = reserve_elements_at_front(n);
iterator old_start = start;
pos = start + elems_before;
__STL_TRY {
if (elems_before >= difference_type(n)) {
iterator start_n = start + difference_type(n);
uninitialized_copy(start, start_n, new_start);
start = new_start;
copy(start_n, pos, old_start);
copy(first, last, pos - difference_type(n));
}
else {
const value_type* mid = first + (difference_type(n) - elems_before);
__uninitialized_copy_copy(start, pos, first, mid, new_start);
start = new_start;
copy(mid, last, old_start);
}
}
__STL_UNWIND(destroy_nodes_at_front(new_start));
}
else {
iterator new_finish = reserve_elements_at_back(n);
iterator old_finish = finish;
const difference_type elems_after = difference_type(length) - elems_before;
pos = finish - elems_after;
__STL_TRY {
if (elems_after > difference_type(n)) {
iterator finish_n = finish - difference_type(n);
uninitialized_copy(finish_n, finish, finish);
finish = new_finish;
copy_backward(pos, finish_n, old_finish);
copy(first, last, pos);
}
else {
const value_type* mid = first + elems_after;
__uninitialized_copy_copy(mid, last, pos, finish, finish);
finish = new_finish;
copy(first, mid, pos);
}
}
__STL_UNWIND(destroy_nodes_at_back(new_finish));
}
}
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::insert_aux(iterator pos,
const_iterator first,
const_iterator last,
size_type n)
{
const difference_type elems_before = pos - start;
size_type length = size();
if (elems_before < length / 2) {
iterator new_start = reserve_elements_at_front(n);
iterator old_start = start;
pos = start + elems_before;
__STL_TRY {
if (elems_before >= n) {
iterator start_n = start + n;
uninitialized_copy(start, start_n, new_start);
start = new_start;
copy(start_n, pos, old_start);
copy(first, last, pos - difference_type(n));
}
else {
const_iterator mid = first + (n - elems_before);
__uninitialized_copy_copy(start, pos, first, mid, new_start);
start = new_start;
copy(mid, last, old_start);
}
}
__STL_UNWIND(destroy_nodes_at_front(new_start));
}
else {
iterator new_finish = reserve_elements_at_back(n);
iterator old_finish = finish;
const difference_type elems_after = length - elems_before;
pos = finish - elems_after;
__STL_TRY {
if (elems_after > n) {
iterator finish_n = finish - difference_type(n);
uninitialized_copy(finish_n, finish, finish);
finish = new_finish;
copy_backward(pos, finish_n, old_finish);
copy(first, last, pos);
}
else {
const_iterator mid = first + elems_after;
__uninitialized_copy_copy(mid, last, pos, finish, finish);
finish = new_finish;
copy(first, mid, pos);
}
}
__STL_UNWIND(destroy_nodes_at_back(new_finish));
}
}
#endif /* __STL_MEMBER_TEMPLATES */
//在deque头分配新的结点
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::new_elements_at_front(size_type new_elements) {
size_type new_nodes = (new_elements + buffer_size() - 1) / buffer_size();
reserve_map_at_front(new_nodes);
size_type i;
__STL_TRY {
for (i = 1; i <= new_nodes; ++i)
*(start.node - i) = allocate_node();
}
# ifdef __STL_USE_EXCEPTIONS
catch(...) {
for (size_type j = 1; j < i; ++j)
deallocate_node(*(start.node - j));
throw;
}
# endif /* __STL_USE_EXCEPTIONS */
}
//在deque尾分配新的结点
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::new_elements_at_back(size_type new_elements) {
size_type new_nodes = (new_elements + buffer_size() - 1) / buffer_size();
reserve_map_at_back(new_nodes);
size_type i;
__STL_TRY {
for (i = 1; i <= new_nodes; ++i)
*(finish.node + i) = allocate_node();
}
# ifdef __STL_USE_EXCEPTIONS
catch(...) {
for (size_type j = 1; j < i; ++j)
deallocate_node(*(finish.node + j));
throw;
}
# endif /* __STL_USE_EXCEPTIONS */
}
//释放[before_start statr)
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::destroy_nodes_at_front(iterator before_start) {
for (map_pointer n = before_start.node; n < start.node; ++n)
deallocate_node(*n);
}
//释放(finish.node after_finish]
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::destroy_nodes_at_back(iterator after_finish) {
for (map_pointer n = after_finish.node; n > finish.node; --n)
deallocate_node(*n);
}
//添加map结点，指向新的缓冲区，add_at_front=true添加在map头，否则添加在尾
template <class T, class Alloc, size_t BufSize>
void deque<T, Alloc, BufSize>::reallocate_map(size_type nodes_to_add,
bool add_at_front) {
size_type old_num_nodes = finish.node - start.node + 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 + max(map_size, nodes_to_add) + 2;
// 配置新的结点，准备给map使用
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);
// 把原map 內容拷贝
copy(start.node, finish.node + 1, new_nstart);
// 释放放原map
map_allocator::deallocate(map, map_size);
// 设置新map起始位置和大小
map = new_map;
map_size = new_map_size;
}
// 重新设置迭代器 start 和 finish
start.set_node(new_nstart);
finish.set_node(new_nstart + old_num_nodes - 1);
}
// Nonmember functions.
//非成员函数，标准STL算法
#ifndef __STL_NON_TYPE_TMPL_PARAM_BUG
template <class T, class Alloc, size_t BufSiz>
bool operator==(const deque<T, Alloc, BufSiz>& x,
const deque<T, Alloc, BufSiz>& y) {
return x.size() == y.size() && equal(x.begin(), x.end(), y.begin());
}
template <class T, class Alloc, size_t BufSiz>
bool operator<(const deque<T, Alloc, BufSiz>& x,
const deque<T, Alloc, BufSiz>& y) {
return lexicographical_compare(x.begin(), x.end(), y.begin(), y.end());
}
#endif /* __STL_NON_TYPE_TMPL_PARAM_BUG */
#if defined(__STL_FUNCTION_TMPL_PARTIAL_ORDER) && !defined(__STL_NON_TYPE_TMPL_PARAM_BUG)
template <class T, class Alloc, size_t BufSiz>
inline void swap(deque<T, Alloc, BufSiz>& x, deque<T, Alloc, BufSiz>& y) {
x.swap(y);
}
#endif
#if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32)
#pragma reset woff 1174
#endif
__STL_END_NAMESPACE
#endif /* __SGI_STL_INTERNAL_DEQUE_H */
// Local Variables:
// mode:C++
// End:
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