编写自己的 STL 容器
是否有关于如何编写与任何 STL 容器类似的新容器的指南?
Are there guidelines on how one should write new container which will behave like any STL container?
推荐答案
这是我从 § 23.2.14 拼凑而成的序列伪容器 注意 iterator_category 应该是 std::input_iterator_tag、std::output_iterator_tag、std::forward_iterator_tag、std::bidirectional_iterator_tag、std::random_access_iterator_tag.另请注意，以下内容技术上比要求的更严格，但这就是想法.请注意，由于迭代器的强大功能，绝大多数标准"函数在技术上都是可选的.
Here's a sequence pseudo-container I pieced together from § 23.2.14 Note that the iterator_category should be one of std::input_iterator_tag, std::output_iterator_tag,std::forward_iterator_tag,std::bidirectional_iterator_tag,std::random_access_iterator_tag. Also note that the below is technically more strict than required, but this is the idea. Note that the vast majority of the "standard" functions are technically optional, due to the awesomeness that is iterators.
template <class T, class A = std::allocator<T> >
class X {
public:
typedef A allocator_type;
typedef typename A::value_type value_type;
typedef typename A::reference reference;
typedef typename A::const_reference const_reference;
typedef typename A::difference_type difference_type;
typedef typename A::size_type size_type;
class iterator {
public:
typedef typename A::difference_type difference_type;
typedef typename A::value_type value_type;
typedef typename A::reference reference;
typedef typename A::pointer pointer;
typedef std::random_access_iterator_tag iterator_category; //or another tag
iterator();
iterator(const iterator&);
~iterator();
iterator& operator=(const iterator&);
bool operator==(const iterator&) const;
bool operator!=(const iterator&) const;
bool operator<(const iterator&) const; //optional
bool operator>(const iterator&) const; //optional
bool operator<=(const iterator&) const; //optional
bool operator>=(const iterator&) const; //optional
iterator& operator++();
iterator operator++(int); //optional
iterator& operator--(); //optional
iterator operator--(int); //optional
iterator& operator+=(size_type); //optional
iterator operator+(size_type) const; //optional
friend iterator operator+(size_type, const iterator&); //optional
iterator& operator-=(size_type); //optional
iterator operator-(size_type) const; //optional
difference_type operator-(iterator) const; //optional
reference operator*() const;
pointer operator->() const;
reference operator[](size_type) const; //optional
};
class const_iterator {
public:
typedef typename A::difference_type difference_type;
typedef typename A::value_type value_type;
typedef typename const A::reference reference;
typedef typename const A::pointer pointer;
typedef std::random_access_iterator_tag iterator_category; //or another tag
const_iterator ();
const_iterator (const const_iterator&);
const_iterator (const iterator&);
~const_iterator();
const_iterator& operator=(const const_iterator&);
bool operator==(const const_iterator&) const;
bool operator!=(const const_iterator&) const;
bool operator<(const const_iterator&) const; //optional
bool operator>(const const_iterator&) const; //optional
bool operator<=(const const_iterator&) const; //optional
bool operator>=(const const_iterator&) const; //optional
const_iterator& operator++();
const_iterator operator++(int); //optional
const_iterator& operator--(); //optional
const_iterator operator--(int); //optional
const_iterator& operator+=(size_type); //optional
const_iterator operator+(size_type) const; //optional
friend const_iterator operator+(size_type, const const_iterator&); //optional
const_iterator& operator-=(size_type); //optional
const_iterator operator-(size_type) const; //optional
difference_type operator-(const_iterator) const; //optional
reference operator*() const;
pointer operator->() const;
reference operator[](size_type) const; //optional
};
typedef std::reverse_iterator<iterator> reverse_iterator; //optional
typedef std::reverse_iterator<const_iterator> const_reverse_iterator; //optional
X();
X(const X&);
~X();
X& operator=(const X&);
bool operator==(const X&) const;
bool operator!=(const X&) const;
bool operator<(const X&) const; //optional
bool operator>(const X&) const; //optional
bool operator<=(const X&) const; //optional
bool operator>=(const X&) const; //optional
iterator begin();
const_iterator begin() const;
const_iterator cbegin() const;
iterator end();
const_iterator end() const;
const_iterator cend() const;
reverse_iterator rbegin(); //optional
const_reverse_iterator rbegin() const; //optional
const_reverse_iterator crbegin() const; //optional
reverse_iterator rend(); //optional
const_reverse_iterator rend() const; //optional
const_reverse_iterator crend() const; //optional
reference front(); //optional
const_reference front() const; //optional
reference back(); //optional
const_reference back() const; //optional
template<class ...Args>
void emplace_front(Args&&...); //optional
template<class ...Args>
void emplace_back(Args&&...); //optional
void push_front(const T&); //optional
void push_front(T&&); //optional
void push_back(const T&); //optional
void push_back(T&&); //optional
void pop_front(); //optional
void pop_back(); //optional
reference operator[](size_type); //optional
const_reference operator[](size_type) const; //optional
reference at(size_type); //optional
const_reference at(size_type) const; //optional
template<class ...Args>
iterator emplace(const_iterator, Args&&...); //optional
iterator insert(const_iterator, const T&); //optional
iterator insert(const_iterator, T&&); //optional
iterator insert(const_iterator, size_type, T&); //optional
template<class iter>
iterator insert(const_iterator, iter, iter); //optional
iterator insert(const_iterator, std::initializer_list<T>); //optional
iterator erase(const_iterator); //optional
iterator erase(const_iterator, const_iterator); //optional
void clear(); //optional
template<class iter>
void assign(iter, iter); //optional
void assign(std::initializer_list<T>); //optional
void assign(size_type, const T&); //optional
void swap(X&);
size_type size() const;
size_type max_size() const;
bool empty() const;
A get_allocator() const; //optional
};
template <class T, class A = std::allocator<T> >
void swap(X<T,A>&, X<T,A>&); //optional
此外，每当我制作容器时，我都会或多或少地使用这样的类进行测试:
Also, whenever I make a container, I test with a class more or less like this:
#include <cassert>
struct verify;
class tester {
friend verify;
static int livecount;
const tester* self;
public:
tester() :self(this) {++livecount;}
tester(const tester&) :self(this) {++livecount;}
~tester() {assert(self==this);--livecount;}
tester& operator=(const tester& b) {
assert(self==this && b.self == &b);
return *this;
}
void cfunction() const {assert(self==this);}
void mfunction() {assert(self==this);}
};
int tester::livecount=0;
struct verify {
~verify() {assert(tester::livecount==0);}
}verifier;
制作 tester 对象的容器，并在测试容器时调用每个对象的 function().不要创建任何全局 tester 对象.如果您的容器在任何地方作弊，这个 tester 类将 assert 并且您会知道您在某处意外作弊.
Make containers of tester objects, and call each one's function() as you test your container. Do not make any global tester objects. If your container cheats anywhere, this tester class will assert and you'll know that you cheated accidentally somewhere.
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